DAMAGE RESULTING FROM THE
OKLAHOMA CITY BOMB
by
JASON L. SWOFFORD, B.S.C.E.
A THESIS
IN
CIVIL ENGINEERING
Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE
IN
CIVIL ENGINEERING
Approved
December, 1996 5í5r3 ACKNOW^LEDGMENTS
The author expresses his síncere appreciatíon to H. Scott Norville, Ph.D.,
P.E., Director of Glass Research and Testing Laboratory, Texas Tech University,
Lubbock, Texas, for the opportunity and guidance in the completion of this
survey. The author thanks James R. McDonald, Ph.D., P.E., and Milton L. Smith,
Ph.D., P.E., for their wiUingness to serve as committee members and their
suggestions for improving the report. The author also thanks H. J. NorviUe,
Ph.D., for editorial and critical comments. Furthermore, the author expresses
genuine gratitude to his father, Duane Swofford, and brothers, Randy and
Andrew Swofford, for their support in attaining his goals for higher education.
Finally, the author thanks his fiancé, Lisa Blackwell, for her patience and
encouragement.
11 TABLE OF CONTENTS
ACKNOWLEDGMENTS. 11 ABSTRACT v LIST OF TABLES vi LIST OF FIGURES vii
CHAPTER I. INTRODUCTION 1 Background 1 Purpose 1 Content of the Report 2 n. LITERATURE REVIEW 3 Introduction 3 Blast Waves 4 Previous Blast Damage Investigations 8 m. DAMAGE ZONES 12 Damage Investigation 12 Damage Zones 13 Significance of Zones and Design Considerations.... 15 IV. DAMAGE SURVEY 17 Introduction 17 Buildings Under Investigation 18 Organízation of the Data 20 Data for Buildings Situated in Zone 1 27 Data for Buildings Situated in Zone 2 65 Data for Buildings Situated in Zone 3 110 Discussion of the Impulse Associated With a 50% Probability of Failure 110 Significance of the Impulse Associated With a 50% Probability of Failure 113 V. OBSERVATIONS AND CONCLUSIONS 114 Introduction 114
111 .... 114 Observations ... 116 Conclusions . 117 Significance ^^^ LIST OF REFERENCES
IV ABSTRACT
Early on the morning of April 19,1995, terrorists detonated a large amount of high explosives on NW 5th Street, just north of the Alfred P. Murrah
Federal Building in Oklahoma City, Oklahoma. A rental truck contained approximately 5000 pounds of ammonium nitrate and fuel oil. Several buildings surrounding ground zero suffered structural damage, and many buildings suffered severe window breakage. The explosion killed 168 people and injured more than 600 others in proximity and away from ground zero. Flying glass shards resulting from fractured windows caused the majority of the injuries.
The bombing of the Alfred P. Murrah Federal Building marked the largest terrorist act experienced in the United States. This document reports on the damage to structures caused by the blast, and more specifically the performance of various window glass types and window constructions. LIST OF TABLES
1 Buildings in Proxinuty to Ground Zero 18 2 Buildings North of Ground Zero 20 3 Buildings South of Ground Zero 20 4 Buildings Not Subjected to Additional Study 24 5 Data for Buildings Not Subjected To Additional Study 25 6 Building 3, Oklahoma Resources Board 35 7 Building 5, YMCA 41 8 Building 12, Journal Record Building 55 9 Building 13, Storefronts, Offices, and Apartments 60 10 Building 14, Single Story Buildings 63 11 Building 15, Empty Stores 66 12 Building 16, Public Library 81 13 Building 19, Regency Apartments 86 14 Building 20, Southwestern Bell Telephone Building 93 15 Building24, Bankof Oklahoma 105 16 Building 25, Federal Reserve Bank 108
VI LIST OF FIGURES
1 Time History of an Idealized Blast Wave (Kinney and Graham, 1985) 5 2 Load-impulse of Blast Waves (Kinney and Graham, 1985).. 7 3 Damage Zones 14 4 Map of Buildings in Proximity to Ground Zero 19 5 Map of Buildings North of Ground Zero 21 6 Map of Buildings South of Ground Zero 22 7 Alfred P. Murrah Federal Building 28 8 Alfred P. Murrah Federal Building Photographed from Bomb Crater 29 9 Northeast Column of Alfred P. Murrah Federal Building. . . 30 10 East Side of Alfred P. Murrah Federal Building 31 11 View of Alfred P. Murrah Federal Building from Southeast. 33 12 View Along NW 5th. Building on Right is Oklahoma Resources Board. Building on Left is Alfred P. Murrah Federal Building 34 13 Athenian Restaurant 37 14 North Side of YMCA in Background. Storefronts on South Side of NW 6th in Foreground 38 15 Windows on South Side of YMCA 39 16 Windows on East Side of YMCA 40 17 North Wall, First United Methodist Church 43 18 West Wall, First United Methodist Church 44 19 North Wall, Federal Courthouse 45 20 Parking Lot North of Ground Zero and South Wall of Joumal Record Building 47 21 South Wall of Joumal Record Building 48 22 West Side of Joumal Record Building 49 23 Upper Floors on North Side of Joumal Record Building. ... 50 24 Entrance on North Side of Joumal Record Building 51 25 Storefront Windows on Ground Floor, North Side of Joumal Record Building 52 26 Debris on North Side of Joumal Record Building 53
vu 27 Interior Wall Damage, Joumal Record Building 56 28 Ceiling and Roof Damage, Joumal Record Building ^^ 29 West Facade, Storefronts, Offices, and Apartments 58 30 Storefronts on South Side of NW 6th 61 31 Fractured Glass, Entrance to Empty Stores 64 32 Frame Failure at Main Entrance of Durham Post Office 67 33 Glass Shards in Wall, Durham Post Office, East of Entrance. 68 34 Glass Shards in Wall, Durham Post Office, 15' Behind Entrance 69 35 East Wall, Old St. Joseph's Cathedral 71 36 Stained Glass Windows Blown Out of East Wall of Old St Joseph's Cathedral 72 37 Plexiglass from East Wall of Old St Joseph's Cathedral 73 38 Rectory Old St Joseph's Cathedral 74 39 East Wall, Unidentified Building D 76 40 Glass and Film North of Unidentified Building D 77 41 Glass Shards in Office of Unidentified Building D 78 42 Glass Shards in Office Wall, Unidentified Building D 79 43 Boarded-up Windows in the Upper Floors of Old Post Office 82 44 Glass on Dean A. McGee Avenue South of Old Post Office. 83 45 East Wall, Regency Apartments 85 46 South Facade, Southwestem Bell Telephone Building 87 47 Tempered Glass Shards from Southwestem Bell Telephone Building 89 48 IG Units in East Wall of Southwestern Bell Telephone Building 90 49 Glass in Street on East Side of Southwestem Bell Telephone Building 91 50 Bloody and Tom Shirt Found on East Side of Southwestem Bell Telephone Building 92 51 Typical Interior Damage, Southwestem Bell Telephone Building 94 52 Glass Shards in Wallboard, Southwestern Bell Telephone Building 95
Vlll 53 Glass Shards and Film, Southwestem Bell Telephone Building 96 54 Glass Shard with Film in Wallboard, Southwestem Bell Telephone Building 98 55 Storefronts on North Side of NW 6th 99 56 Fractured Windows (Dver Entrance, South Facade of Anthony's 101 57 Window Film from Anthony's 102 58 Sporadic Breakage, North Wall, Bank of Oklahoma, Oklahoma Plaza 103 59 Northeast Comer, Bank of Oklahoma, Oklahoma Plaza. . . . 104 60 North Side, Federal Reserve Bank 107 61 Laminated Glass in Smashed Revolving Door, Oklahoma Gas & Electric 109 62 North Wall, Oklahoma Gas & Electric 111
IX CHAPTER I
INTRODUCTION
Background Early on the morning of April 19,1995, terrorists detonated a large amount of high explosives on 5th Street, just north of the Alfred P. Murrah Federal
Building in Oklahoma City, Oklahoma. The high explosives consisted of approximately 5000 pounds of ammonium nitrate and fuel oil (ANFO) contained in a rental truck. The blast caused severe structural damage to the Alfred P.
Murrah Federal Building, as well as damage to several buildings surrounding ground zero. Air blast pressure fractured windows over a large area of
Oklahoma City. Besides the persons the blast directly killed or injured, flying glass shards injured between 400 and 500 persons, including persons not in proximity to ground zero. In total, the blast killed 168 persons, and injured more than 600 others.
Purpose
Investigating window glass breakage has several purposes. Data from this investigation provides insights into the performance of different types of window glass and window glass constructions. Knowledge of the breakage patterns in areas not immediately in proximity to ground zero can aid in determining the blast impulse. Finally, breakage data can be correlated with injury data to aid in the formation of risk and lethality models associated with blasts. The ultimate objective of this study is to document data that will lead to a development of more blast resistant window constmctions, thus reducing the number of deaths and injuries in similar future events.
Content of the Report
This report presents an overview of the categorization of window glass damage with respect to ground zero, the point of détonation of the explosives. It includes observations of window glass survival and failure of window glass and window glass constructions. It also defines the spatial limits of window glass breakage. While the report does not contain detailed information concerning every window fractured in the explosion, it presents an overview of observed window glass breakage. CHAPTER n
LITERATURE REVIEW
Introduction
Designers are reevaluating their philosophies about structural design due
to an increase in bombings and explosions in the United States. Blast loadings
on structures occur primarily from terrorist attacks or accidental explosions. The
Explosives Unit-Bomb Data Center (EU-BDC) received reports of more than 1900
explosive bombing incidents in 1994, a 6% increase from 1993 (EU-BDC, 1994).
The primary targets of these incidents include residences, commercial facilities,
vehicles, open areas, and academic facilities. In 1994, bombings injured 308
people and kiUed 31 people (EU-BDC, 1994). The bombing of the Alfred P.
Murrah Federal Building in Oklahoma City, Oklahoma on April 19,1995, reinforced the need for changes. The Oklahoma State Department of Health
(OSDH) reported 614 people received medical treatment for blast related injuries and 168 people lost their lives (OSDH, 1995). This one incident accounted for nearly twice the yearly total of injuries and five times the yearly total of deaths associated with blasts reported in 1994. In Ught of these occurrences, architects and engineers must give more consideration to the design of buildings at risk of experiencing blast loadings during their service life. Blast Waves
According to Kinney and Graham (1985), blast waves form as a result of rapid releases of energy. Comprehension of the properties of blast waves is important Two different phases, positive and negative, comprise blast waves.
The positive phase generally has more intensity and shorter duration than the negative phase. Three basic properties describe blast waves: peak overpressure, duration, and load-impulse. For the purposes of discussion, Figure 1 shows an idealized pressure-time history. At an arrival time, t^, the pressure spikes to the peak value of overpressure, p°. After reaching the peak overpressure, the pressure decays exponentially. The duration of the positive phase, t^, normally constitutes the duration of the blast wave. The load-impulse defines the magnitude of the blast The author discusses each of these three characteristics below.
Peak Overpressure
Peak overpressure constitutes a measure of the initial shock intensity of the blast wave (Kinney and Graham, 1985). The magnitude of the peak
overpressure depends on charge size and range from ground zero. As the shock wave propagates outward from ground zero, the magnitude of the overpressure decreases. At great distances from the source, the shock wave a degenerates into a sound wave. OVERPRESSURE
ir 3 co 00 UJ æ a.
TIME
Figure 1. Time History of an Idealized Blast Wave (Kinney and Graham, 1985). Duration
Duration of the blast wave describes the time required for the shock front and positive pressure phase to pass a particular point (Kinney and Graham,
1985). The duration of the positive phase relates directly to blast damage.
Damage increases as the duration increases because forces act for a longer period
of time. Duration of the negative phase usually lasts twice as long as that of the positive phase. However, the forces associated with the positive phase greatly
overshadow those associated with the negative phase.
Load-impulse
Positive phase impulse relates directly to the ability of a blast wave to cause damage (Kinney and Graham, 1985). Impulse is the product of force and time. The positive phase impulse depends on the peak overpressure, the duration of the shock wave, and the rate of decay of the positive phase. Figure 2 shows two blast waves, A and B, with equal peak overpressures and durations, but different decay rates. The area under the positive phase of the pressure-time history for a particular wave represents the positive phase impulse for the blast wave. Therefore, blast wave B has a greater impulse than blast wave A. h DURATION, t.
Figure 2. Load-impulse of Blast Waves (Kinney and Graham, 1985). Previous Blast Damage Investigations
Blocker and Blocker (1949) reported on the explosion which occurred in the Texas City harbor on April 16,1947. The Grandcamp, a French ship, sat docked in the harbor. The ship contained 2,300 tons of ammonium nitrate fertilizer, small amounts of munitions, peanuts, and large amounts of twine balls. Early that morning, a fire was reported on board the ship. At 9:12 A.M., the fire ignited the fertilizer and the Grandcamp exploded. The explosion caused a tidal wave ten feet tall, washing large barges up to 100 feet ashore.
The area surrounding the harbor was primarily petroleum and chemical warehouses. Many of the buildings were destroyed by the blast, and several secondary fires resulted from flaming missiles and debris. A residential area northwest of the harbor suffered very heavy damage. Several large buildings in the downtown area, approximately two miles from ground zero, suffered heavy structural damage. AIl of the glass in the area was destroyed. In addition, a second ship, High Flyer, caught fire. High Flyer had 961 tons of ammonium nitrate fertilizer on board. Rescuers attempted to tow the ship out of the harbor before it exploded, but their efforts were unsuccessful. Rescuers did notice an orange smoke similar to the smoke which was present on the Grandcamp and were able to evacuate the area before High Flyer exploded. Therefore, the second explosion caused few casualties. Investigators found missiles from High
Flyer weighing up to two tons as far as 4500 feet from ground zero. Even more
8 secondary fires broke out as a result of the second explosion. The second blast wave and secondary fires destroyed most of the buildings that survived the initial blast In all, the two explosions injured or killed over 3000 people.
GRTL (1987) documented damage from two accidental explosions that occurred in Ft. Worth, Texas in 1986, each within one mile of the other. The first explosion occurred at the Frank Kent CadiIIac Dealership on March 12,
1986. Workmen ruptured a natural gas line while trenching. Workmen believed the gas line to be abandoned. The Frank Kent Cadillac Dealership fiUed with gas. An unknown source ignited the gas. The blast blew out windows in buildings surrounding the dealership more than half a mile away.
The second incident in downtown Ft Worth occurred at the McLean
Building on December 7,1986 (GRTL, 1987). The blast shattered glass in high-rise buildings and storefronts more than three blocks away. The McLean
Building was the only building to suffer structural damage. Investigators reported window pane sizes, ranges, angles of incidence, and the number of panes broken for 35 buildings in the surrounding area.
Explosions from non-accidental sources are also important. Terrorist attacks occur most commonly in Europe or the Middle East. However, experts fear a rise in terrorist activities in the United States. Brismar and Bergenwald (1982) recorded data from the bombing of a railway station in Bologna, Italy. At 10:25 A.M., August 2,1980, terrorists bombed one of the largest central railway stations in Europe. Perpetrators placed the bomb in a suitcase and left it on a luggage rack in the waiting room at the station. The railway station coUapsed, burying people in mbble.
Altogether, the bomb injvired 291 persons and killed 73 persons. Experts claim this as one of the most disastrous terrorist attacks in history.
Scott, Fletcher, PuUiam, and Harris (1986) documented the bombing of the
Bemit Intemational Airport, which kiUed more Americans than Lebanese. On
October 23,1983, a truck fuU of explosives crashed into a terminal at the airport
The explosion destroyed the building, which contained sleeping American marines of the 24th Marine Amphibious Unit (MAU). The attack on the airport left 234 individuals dead, and at least 112 individuals injured.
The frequency of terrorist attacks in America increases annually. The
World Trade Center Bombing in New York comprises an excellent example. (Dn
Febmary 26,1993, a tmck exploded in the underground parking garage of the
World Trade Center . On April 19,1995, terrorists detonated a bomb outside the
Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, kiUing 168 people. Window damage extended several blocks surrounding the Murrah building (Norville et al., 1996). More recently, May 20,1996, terrorists placed a
10 bomb outside FBI offices in Laredo, Texas. Officials continue to investigate the details of this attack.
The increase in terrorist attacks in the United States gives rise to grave concern. Engineers are revising existing methods of design applicable to structures likely to experience blast loadings. Due to both economic and aesthetic constraints, designers cannot produce completely bomb-proof structures. On the other hand, if they use certain glazing products, give careful attention to load paths and connections, and pay further attention to detail, their designs can provide a significant impact on the performance of the structures and the reduction of injuries, should an explosion occur.
11 CHAPTER m
DAMAGE ZONES
Damage Investigation
Glass Research and Testing Laboratory (GRTL) investigators arrived in
Oklahoma City, Oklahoma on April 20,1995, the day following the explosion.
The investigators' objective consisted of gathering information pertaining to and
documenting the performance of different types of window glass in a blast
scenario.
Investigators agree that no commercially designed curtain wall system
could have significantly reduced the structural damage to the Alfred P. Murrah
Federal Building. Most likely, no commercial wall system could have reduced
the damage, injuries, or deaths that occurred in this building. Glass is not an
issue in the case of the Alfred P. Murrah Federal Building. Therefore,
investigators concentrated their research efforts on the buildings surrounding the Federal Building.
Upon arrival, the investigators gained access to the sealed perimeter established by law enforcement officials. Officials did not allow investigators to collect samples of glass or make any measurements of window dimensions, glass thicknesses, or distances that shards flew from their frames. Officials onlv allowed the GRTL investigators to document the event with photographs. GRTL
12 investigators surveyed the area inside the sealed perimeter on foot
Investigators surveyed the remainder of the area surrounding the Federal
Building both on foot and by automobile. The survey continued through
Saturday, April 22,1995. On return trips to Oklahoma City, the investigators gathered information conceming glass in buildings at the time of the explosion.
Damage Zones
Upon compiling all of the information gathered during the survey, GRTL researchers established three different zones categorizing areas that shared similar damage characteristics. The limits are approximate and subject to change as more information becomes available. Figure 3 shows the three zones surrounding ground zero, marked by the large "X". The heavy lines delineate the zone boundaries.
Zone 1
Zone 1 contains the buildings in proximity to ground zero. Buildings in this zone suffered severe structural damage. Some of the stmctures suffered partial or total coUapse. Zone 1 delineates an area which experienced almost total window fracture. Buildings in Zone 1 include the Alfred P. Murrah Federal
Building, the Journal Record Building, the Athenian Restaurant, the Oklahoma
13 Figure 3. Damage Zones. Scale 1"=1300'
14 Resources Board, the YMCA, and First United Methodist Church, among others.
AU deaths resulting from the explosion occurred in Zone 1.
Zone2
Buildings lying in Zone 2 experienced moderate stmctural damage.
These buildings suffered 85-100% window fracture. Buildings in Zone 2 include the Regency Apartments, the Durham Post Office, Old St Joseph's
Cathedral and Rectory, the Southwestem Bell Telephone Building located at 707
NW 6th Street, offices and apartments, empty stores, and the Old Post Office, among others.
Zone 3
Buildings in Zone 3 sustained little or no stmctural damage. Window breakage in Zone 3 varied from 0-85% in different buildings. Buildings in Zone
3 include Boatman's Bank, among others.
Significance of Zones and Design Considerations
These zones assist investigators in analyzing window glass performance.
In Zone 1, where the major structural damage occurred, window failure is inevitable. Glass will fail in buildings that are primary targets of terrorists' bombs and in buildings immediately surrounding these targets. The primary
15 consideration for designing windows located in Zone 1 consists of minimizing injuries by reducing the size and number of large glass shards. Injury reduction also dictates design for windows in Zone 2. In Zone 3, the primary window design parameters consist of maintaining the integrity of the buildings coupled with the minimization of glass related injuries. Proper window design in Zones
2 & 3 can significantly reduce injuries and avoid costly damage to the interior of buildings.
16 CHAPTERIV
DAMAGE SURVEY
Introduction
The U. S. Naval Surface Warfare Center contacted GRTL in August of
1995 and requested that its staff gather whatever information still existed concerning windows and window giass constmctions in Oklahoma City at the time of the bombing. In its efforts to fulfill this charge, investigators made two subsequent visits to Oklahoma City. The information requested consisted primarily of those items investigators were unable to collect during the original survey: building heights, window dimensions, glass thicknesses, and distances shards flew. Investigators inspected several buildings during their subsequent visits including: the Southwestern Bell Telephone Building, the Oklahoma
Resources Board, and the Journal Record Building, among others. They also interviewed building managers in efforts to obtain additional data.
GRTL investigators used the window glass data to estimate the positive phase impulse associated with a 50% probability of breakage for windows in the damaged buildings. This chapter presents a summary of information gathered during the original survey as well as data gathered during subsequent visits.
17 Buildings Under Investigation
Investigators surveyed buildings surrounding ground zero. Figure 4 shows the buildings that are closest to ground zero. Investigators assigned the building numbers in the approximate order surveyed. Table 1 identifies each of the buildings according to the building number in Figure 4. Table 1 also indicates the zone in which the building is situated corresponding to Figure 3.
Table 1. Buildings in Proximity to Ground Zero. Building Number Building Name Zone 1 Alfred P. Murrah Federal Building 1 2 Durham Post Office 2 3 Oklahoma Resources Board 1 4 Athenian Restaurant 1 5 YMCA 1 6 First United Methodist Church 1 7 Federal Courthouse 1 8 Unidentified Building B 2 9 Old St Joseph's Cathedral 2 10 Rectory Old St Joseph's Cathedral 2 11 Unidentified Building D 2 12 Joumal Record Building 1 13 Storefronts, Offices, and 1 Apartments 14 Single Story Buildings 1 15 Empty Stores 1 16 AT&T Building and Public Library 2 17 Old Post Office 2 18 Unidentified Building F 2 19 Regency Apartments 2
18 p^~^ -;—r snc 'T^i J "1 c NW 6TH ST. 11 3 PARKINC 12 ^
• > o 4 > 1 15 4 r—» ^ V ^m -Cround Z»ro NW 5TH ST.
^ARKING > ioD h > D
NW 4TH ST. r T7=>a~~ Mí W1i ^ 1 TLJ^
PARKING 17 16 ) OEAN A. MCCEEv /kVE. Zl C
Scale (Feet) 50 100 ?00 xo
Figure 4. Map of Buildings in Proximity to Ground Zero.
19 Figure 5 shows buildings north of ground zero. Table 2 identifies each of
the buildings according to the building number in Figure 5. Table 2 also
indicates the zone in which the building is situated corresponding to Figure 3.
Table 2. Buildings North of Ground Zero. Building Number Building Name Zone 20 Southwestem Bell Telephone 2 Building 21 Storefronts on NW 6th 2 22 Anthony's Annex 2 23 Anthony's 2
Figure 6 shows buildings to the south of ground zero. Table 3 identifies
each of the buildings according to the building number in Figure 6. Table 3 also
indicates the zone in which the building is situated corresponding to Figure 3.
Table 3. Buildings South of Ground Zero. Building Number Building Name Zone 24 Bank of Oklahoma 2 25 Federal Reserve Bank 2 26 Oklahoma Gas & Electric 2 27 Boatman's Bank 3
Organization of the Data
This section presents the information requested by the U. S. Naval Surface
Warfare Center. Building heights, window dimensions, glass thicknesses, and
20 J r^ '-a 0 , , PARKING j J n PARK ING 1—: PARKINC
ARKING 20 "S j
TJ
PARKING 11
Scole (Feet) V> 1® w xo
Figure 5. Map of Buildings North of Grotmd Zero.
21 'Z m ^YMOvoaz^^^^a M ^ '^aí t § r IVI ! e bl > •< > M j í cc b o co w •- ^ 1 •< oc IJ o o o 1 < s: r a> N 1 : •3AV NOSNiaOa N L . b •3AY NosNraoa N c 0vvj a fr^ a O o o •5 lO CVÍ
WH H —1\ ]J ;3 o
fd
'J •3AV NOSOnH N a>
t>0 UH
22 distances glass shards flew are reported for the buildings in which these data
were available. Table 4 presents a listing of buildings for which no data were
obtained during subsequent visits to Oklahoma City and the reason no
information was found. Table 5 presents all of the available information
concerning those buildings listed in Table 4.
Subsequent tables present information for each building for which data
were obtained. Each table presents the building heights and typical glazing
information for a particular building. The first column identifies the nominal
dimensions of typical windows in the building. The second column presents the
glass type and construction. The third column identifies the orientation of the
window in terms of the direction the exterior surface of the window glass faces.
The fourth colunm presents the distances shards flew into the building. The fifth
column presents the distances shards flew away from the building. The sixth
column estimates the percentage of breakage for each orientation in the building.
The seventh column estimates an impulse associated with a 50% probability of
breakage for each window size and orientation.
The positive phase impulses associated with a 50% probability of window
glass breakage were estimated using a dynamic failure prediction methodology developed by GRTL (NorviUe, 1990). This methodology uses a dynamic finite difference plate analysis coupled with the theory of fracture methodology for window glass (Beason, 1980; Norville and Minor, 1985; Norville et al., 1991).
23 Table 4. Buildings Not Subjected to Additional Study. Building Reason for No Additional Number Building Name Study 1 Alfred P. Murrah Federal Building Building Demolished 2 Durham Post Office Building Chained and Locked 4 Athenian Restaurant Building Demolished 6 First United Methodist Church Building Chained and Locked 7 Federal Courthouse Entry Absolutely Prohibited 9 Old St Joseph's Cathedral Building Under Renovation, Entry Absolutely Prohibited 10 Rectory Old St. Joseph's Cathedral Building Demolished 11 Unidentified Building D Building Demolished 16 AT&T Building No Information Available 17 Old Post Office No Information Available 18 Unidentified Building F No Information Available, Entry Absolutely Prohibited 21 Storefronts on NW 6th Renovation Completed, No Information Concerning Glazing Prior to Bombing 22 Anthony's Annex Renovation Completed, No Information Concerning Glazing Prior to Bombing 23 Anthony's Renovation Completed, No Information Concerning Glazing Prior to Bombing 26 Oklahoma Gas and Electric Building Permanently Closed
The basic assumption is that annealed (AN) monolithic (Mono) window glass strength is approximately equal to that of glass having undergone normal in-service weathering for approximately 20 years. Further assumptions in computing blast impulses associated with 50% probabiUty of breakage include:
1. An equivalent charge weight of 4000 Ib of TNT,
24 u ^ fc f) S _QJ ^ ,2 Q> 3 ^ ^ < 3 3 3 (8 o o o .2 C8 •w o o ^ c8 "s cs C8 8 0 < or-l rH -H > > > > > t-H 6 ûí w w C8 (8 C8 •^ g C g C e- p^ ^ D D D Dc D (X< , DQ
0) cu _QJ 3 3 3 3 1 1 CO > > 6 > C8 C8 > > 6 6 (0 C8 C3 C c C8 (8
DISTANC E c c B BUILDING ' D D D D D D D AWA Y FRO M SHARD S FLE W c O m O r, ^ ^ S ^ ^ ^ -2 ,2 •J3 O 50 fc ^ 3 3 3 3 3 3 3 3 CS C8 C8 co •^ -S in -2 2; 9 z ã "s C8 •^ •^ > > > > > > >C8 >C8 < cHn E< t^q C=rJ ^ «8 6 C8 C8 C8 C8 6 C8 /=\ CD J 1—' C c g c c C c C O D Ei; CQ D D D D D D D D H
B »-H u ^ ^ 0z ^OJ Z _Q) .2 ,2 ^ ^ g 3 3CO 3 3 3 3 CO (8 -2 '5 "s c8 'S > H > > > > > âí TYP E C8 UH C8 C8 C8 o GLAS S o" o H X Q> lO rH fS o o o o S^ ^ 00 ?5 T—l tN CT) w 3 S K v« X . Om C O Z w Û D £ T—1 '-' fj f^ r-t fN Tf v£> t> O o 5 § 1—1 -H '-*-H' !I6J pû '^ 25 u 2^ 2t <0 10 0 8 8 (3\ 8 fN 8 OX I RC E ;AK . rH rH C=í w »^ rH DH PLCUH OKQ < 3 0 0 0 in "S CO co r-i 0 0 (ft ) > RD S FLE W A Y FRO M 5TANC E ILDING ' C8 6 3 6 C D -2 ^ S ^ 3 3 3 3 C8 C8 C8 C8 "s "s "s "s 0 0 (ft ) > > > > C8 C8 C8 CB 3 C C C C SHARD S DISTANC E BUILDING ' FLE W INT O D D D D T3 0) «-Z* C -2 S ^ g •43 • 0 3 3 3 c -2 JÊ g u ê o C8 "S 0 1 > > 3 TYP E C8 C8 C8 U GLAS S < ENTAT I C C < s D D Dc u « IN G l E C ^ 2 X s Q> íV S 3 C (A 52 CQ C8 U u w, c c ffl C C8 CQ 0 < 0 _Q) cn cc C8 3 -r! ^- •^ c V V Ê c 0 c c 0 Q; V4-I 0 0 X TS Q; X C8 ^ ÍS ^ i-i X •C^ 0 ^-c^ ^-c« !2 Å s c D CD < < 0 S Ê 9 0 c^ g Cse . £ o .^0 (u8 _-s^ Z w U 2 £ (30 rH fN rH tN tN ?1 (N D D £ pû <-< 26 2. Fully Tempered (FT) window glass fracture strength is approximately 4 times that of annealed window glass having the same nominal dimensions, 3. Heat Strengthened (HS) window glass fracture strength is approximately 2 times that of annealed window glass having the same nominal dimensions, 4. Laminated Window Glass (LG) fracture strength is approximately equivalent to that of annealed monoHthic window glass having the same nominal dimensions, and 5. The fracture strength of one ply of an Insulating Glass (IG) unit is approximately 0.9 times that of the same glass type having the same nominal dimensions. Data for Buildings Situated in Zone 1 Building 1, Alfred P. Murrah Federal Building Figure 7 shows the front of the Alfred P. Murrah Federal Building from the west side. The front facade of the building originally was a 1 in. thick bronze insulating glass curtain wall. The explosion destroyed the front facade and much of the interior structure of the building. The rubble sHd down the front of the building onto NW 5th Street. Figure 8 shows the destroyed north facade of the Federal Building photographed from the bomb crater. Figure 9 shows a main column at the northeast corner of the Federal Building. Figure 10 shows 27 Figure 7. Alfred P. Murrah Federal Building 28 Figure 8. Alfred P. Murrah Federal Building Photographed from Bomb Crater. 29 Figure 9. Northeast Column of Alfred P. Murrah Federal Building. 30 ^r^- Figure 10. East Side of Alfred P. Murrah Federal Building. 31 the east facade of the Federal Building. This photograph shows three unbroken windows on a wall encasing a stairwell near the top left edge. Figure 11 views the Federal Building from the southeast. The same three unbroken windows in Figure 10 are more easily seen in this figure. Investigators found tempered glass shards from windows in the south facade of the Federal Building at the base of the Federal Courthouse (Building 7). These shards flew between 75 and 100 yd after the bomb exploded. Building 3, Oklahoma Resources Board The Oklahoma Resources Board, situated on the northeast corner of NW 5th Street and N. Harvey Avenue, to the west of ground zero, suffered severe structural damage from the explosion. Figure 12 shows the south portion of the west side of the building. Air blast pressure severely damaged the glass block wall, propelUng the wall outward towards the west. Air blast pressure fractured all windows in this building and blew resultant glass shards from their frames. Table 6 presents information for windows in the Oklahoma Resources Board. The Athenian Restaurant, labeled as Building 4, partially shielded the Oklahoma Resources Board from the blast The investigators observed numerous glass shards embedded in drywall. Investigators based their estimates of distances glass shards flew into the building through observations and measurements from windows to interior walls and partitions. They based 32 Figure 11. View of Alfred P. Murrah Federal Building from Southeast. 33 Figure 12. View Along NW 5th. Building on Right is Oklahoma Resources Board. Building on Left is Alfred P. Murrah Federal Building. 34 CN W t? .L,. W < t O O O O S w o 8 o O S ^ É wg < s u O in in 8 PÛ 6 CC < U7T D:: O •b CD tN w fN fN (C u 6 6 6 -^ £ < C 0) O S > ^ 'c H -^o 60 P Tec h 2; for m nd e xa s o rds . 3 ,a> (53 Pû H 3 Q) «*, H X < o o O ^ (fi Z • 0) OJ (« § s-^J o H ^ 2 g ^ ula r ind c dict i o sto p o O o H c c c o o o o f w ePr e endi c itio n u QJ (V i- X3 D in Pí Z co < < t: o, S û. H < 3 TJ ^ !::; g X*-i 2t« "ud --0" o o 3 h "3 mea s Dyn a io r w u exter i (iû c S c Q) Q) X X X istanc i c irecti o o ase d o irs t in X X X P P Cû H in in in •^ 3 CÛ 35 their estimates of distances glass shards flew outside the Oklahoma Resources Board from observations they made during the initial survey. While the blast severely damaged the Oklahoma Resources Board, the owners are renovating the building. Building 4, The Athenian Restaurant The blast destroyed the Athenian Restaurant, shown in Figure 13. Building 5. YMCA The YMCA, situated to the east of ground zero with NW 5th Street running along its south side, suffered severe damage from the explosion. GRTL investigators were unable to approach this building during their initial survey because of security. Air blast pressure fractured virtually all of the windows and caused severe damage to the interior of the building. Figure 14 is a photograph of the north side of the YMCA. Figure 15 shows windows on the south side of the YMCA. Small wingwalls did not supply any protection to the windows from the blast. Figure 16 shows windows on the east side of the YMCA. Air blast pressure fractured virtually all of the windows on the east side of the building and propelled the resultant shards from their frames. Table 7 presents information for windows in the YMCA Building. The investigators made estimates of distances glass shards flew from the YMCA 36 WM^^'^'^BT^^^^VI' Figure 13. Athenian Restaurant. 37 Figure 14. North Side of YMCA in Background. Storefronts on South Side of NW 6th in Foreground. 38 .. w. 1.'.'... Figure 15. Windows on South Side of YMCA. 39 ^" ^ Figure 16. Windows on East Side of YMCA. 40 1—1 ^—' W 5 fc O ^ ^ < t^ ts O O 8 8 8 8 8 2 8 ^ u ^ orH rH S o rH r-* 6 T-^ t-H rH 6 rH 0 S < •^ •^ ÊgS CL, OQ < ^ 9 0 QJ 0) s in in tn ir> ir> tn •s ca (0 CB 03 03 rc fc ^ ii VH in o 0 O .o .0 ^ 6 6 6 6 6 cu cu cu 4iJ 4^ y ^ 3 4-c> 4-C* c c C c o 3 T3 i*^ 5S5 C oAI U ; rH T-H rH rH rH rH 1 O 6 6 6 6 6 ^ •T3 P Q) D f X ii ! < Pû z ^ H 1—0 ( nd e xa s H Æ 4~» X, 4-> js X 4-» X X X rds . < 4-j % 4-> 3 r°^ -• 1- t^ Z 2 Z 2 Z 2 2 Z 2 o—« ~ X X Firs t i Noi n c Esti m rH rH rH • Dire c 0 i IT) (3N (JN T-l vC • Fro m in ' • Dista i ' Base d 00 00 -^ ÍS (*i T—1 rH rH rH rH rH rH rH 2 ^B ^ '5 CQ 41 windows based upon videotapes made by the U. S. Army Corps of Engineers. Uniformly, the first interior wall or partition stopped glass shards flying to the inside of the building. With one exception, for windows on the north side of the building, the investigators could make no reasonable estimates of distances shards flew outside the building. Building 6, First United Methodist Church Rescuers used the First United Methodist Church as a temporary morgue during cleanup operations. The blast pressure fractured and blew out most of the windows in the church. Figure 17 shows the north side of First United Methodist Church. Figure 18 shows broken windows on the west side. Building 7, Federal Courthouse Figure 19 shows the north side of the Federal Coiu-thouse, closest to the Federal Building. Air blast pressure fractured virtually every window above the ground floor in this building. In addition, investigators found tempered glass shards from the Federal BuUding on the sidewalk at the base of Federal Courthouse. 42 Rg«rel7.NorthWal],FirstUnitedMethodist Church. 43 Figure 18. West Wall, First United Methodist Church. 44 s'liii'; '¥»b~''^' -^fi .s^; *t-' j&Éi : ^W* ^" -=;;3tøf. ^ '^ '•í Figure 19. North Wall, Federal Courthouse. 45 Building 12, Tournal Record Building The Journal Record Building, situated to the north of ground zero with NW 6th Street running along its north side, is separated from ground zero by a parking lot. The parking lot covers the south and east portion of the block where the Joumal Record Building is located. Figure 20 shows the south wall of the Joumal Record Building that faces the parking lot. Figure 21 shows the upper portion of the south wall. Blast pressure tore the roof off, and fractured and propelled shards from virtually every window in the Joumal Record Building. Figure 22 shows the west wall of the Joumal Record Building. No glass remains in the window frames along the west wall. Figure 23 shows the upper portion of the north wall of the Journal Record Building. No glass remained in these frames. An interview with a tenant revealed that many of the glass shards from these windows flew into the offices. Figure 24 shows two laminated glass doors on the north entrance to the building. These doors were closed at the time of the explosion. The laminated glass that glazes the door on the left, the one propped open, is fractured but remains in the frame. The laminated glass that glazes the door on the right is also fractured and only partially puUed from its frame. Figure 25 shows large storefront window openings created by blast pressures propelUng the annealed glass Utes from their frames. These windows were located on the ground floor, west of the doors shown in Figure 24. Figure 26 shows glass and debris on the north side of the Journal Record Building. 46 Figure 20. Parking Lot North of Ground Zero and South Wall of Journal Record Building. 47 ' «• _< -_-sî Figure 21. South WaU of Journal Record Building. 48 Figure 22. West Side of Journal Record Building. 49 Figure 23. Upper Floors on North Side of Journal Record Building. 50 Figure 24. Entrance on North Side of Journal Record Building. 51 Figure 25. Storefront Windows on Ground Floor, North Side of Journal Record Building. 52 Figure 26. Debris on North Side of Journal Record Building. 53 Table 8 presents information for windows in the Joumal Record Building. Owners of the Journal Record Building aUowed the investigators to make one trip inside the building. The blast caused severe damage to the interior of the building. Figure 27 shows damage to an interior wall on the south side of the building. Figure 28 shows the damage to the ceiUng and the roof which investigators photographed from the 4th floor. The investigators based their estimates of distances glass shards flew into the buUding through observations and measurements from windows to interior waUs and partitions. The U.S. Army Corps of Engineers reported some shards flew through one or more drywaU partitions in this building. The investigators observed numerous glass shards embedded in walls and doors throughout the building. The investigators based their estimates of distances glass shards flew outside the building from observations they made during their initial survey. Building 13, Storefronts, Offices, and Apartments Building 13, situated on the northwest corner of NW 6th Streets and N. Robinson Avenue, to the northeast of ground zero, is a three story structure with storefronts and offices on the ground floor. Apartments occupy the second and third floors. Air blast pressure fractured and propeUed resultant shards from virtuaUy aU of the windows. Figure 29 shows the west facade of this building. 54 rH 5 ô5 g ê in "^ rH CD •^ in 00 CNÍ (3N " ÍN fN CN CN O o (ft ) 6 6 6 6 6 BUILDING ' (N FLEWINT O TANC E SH A T—I C/) ÍS bO l-H C P 2 3 H-0t PÛ ^1=1 00* Eas t Eas t Wes t Nort h Sout h Sout h NTA T Nort h o „- w 3 Q) (8 S i2 ci,; (C 0 •T3 z JS (J ^^ 0 (C c*- o o o o o ite d H—t C X f-H OH o bO-tí 10 8 f t ^.2 Lamin e NMo n NMo n NMo n NMo n H t-' AN-I G NMo n s < < < < < Z 0 < u •^ 00 1/ 4 1/ 8 1/ 8 1/ 8 1/ 4 C 5 < 0 rH eight : X Z 55 o X X X X X X X (3N 00 00 in CN to ^ <-H IN ^BlZ^- (/3 §g.s S in in •^ c X X X X X X X -5 P P tS tl 0 § in (J\ •^ 00 o in 00 55 Figure 27. U\terior WaU Damage, Journal Record Building. 56 Figure 28. CeUing and Roof Damage, Journal Record Building. 57 Offices, and Apartments. 29. Westfacade,Storefronts, Figure 58 For security reasons, GRTL investigators were not able to approach this building during their initial survey. Table 9 presents information for windows in storefronts, offices, and apartments. The investigators based their estimates of distances glass shards flew into the building through observations and measurements from windows to interior walls and partitions. The investigators observed numerous glass shards embedded in waUs and doors throughout the building. The investigators based their estimates of distances glass shards flew outside the buUding from observations they made during their initial survey. Building 14, Single Story Buildings Building 14, located on the south side of NW 6th Street, east of Building 13 and northeast of ground zero, is a one story structure with storefronts and offices. Figure 30 shows the storefronts. The nominal thickness of the glass in each storefront window was 1/4 in. The glazing in the doors was nominal 1/4 in. thick laminated glass. Air blast pressure fractured the annealed glass in the windows in the rightmost storefront in Figure 30, the one to the extreme right with the sign labeled "Fine Jeweby," and blew the shards into the building. The laminated glass in the door of this storefront fractured, but remained in its frame. The same situation occurred in the second storefront from the right, the one with no sign. In the storefront with the sign "ABC Loans" above the door. 59 *0 >—V cn a> d^ cr ^ o o\ in a\ rH rH o 3 ^ ÍN CN a\ o\ in in * in E •- iri iri vC K Tjî •^ k—4 ^*-^ W ^fc O ^ r, < o o o > DIMENS r r^ r^ co Pû 60 SouthSideofNW6th. Figure 30. Storefronts on 61 only the window farthest to the right fractured and fell from its frame. Figure 30 also shows two storefronts to the west of the "Fine Jewehy" shop. Air blast pressure fractured all the windows in these two storefronts and propelled resultant glass shards from their frames. Table 10 presents information for windows in the single story buildings. The investigators based their estimates of distances glass shards flew into the buildings through observations and measurements from windows to interior walls and partitions. The investigators based their estimates of distances glass shards flew outside the building from observations they made during their initial survey. Building 15, Empty Stores The major portion of this building, located along the west side of N. Broadway, nearly due east of ground zero, was mostly vacant, but an undetermined part of it was used for storage. Air blast pressure fractured and propelled resultant shards from most of the windows in this building. Figure 31 shows a typical storefront on the east side of this building. Blast pressure fractured the laminated glass glazing the door at the right, but the Hte remains in its frame. Blast pressure also fractured the laminated glass glazing the window to the left of the door, but the hte remains in its frame. However, air blast 62 in co co 00 æ o6 00 iri w < U < o o o o o o o ^O su < o ^ w S CQ < s 2 < ^ ^» (0 5 í^ u in c in 00 p (N o ÍN U ^ I iz; < D o < > Cû P u. cn ÍS 0) JH LJ i^ o •icw o U >^ (N 6 i >^ V 6 o •- < j I—' C 63 l • •.^5s: 3»as^«r ^^^iwcsfapr" ^í^W^lRS^S. •CiT. « ,>'•!••»: •'-'^- . • i^í,\ Figure 31. Fractured Glass, Entrance to Empty Stores. 64 pressure fractured the annealed glass window further to the left and blew the resultant shards from the frame. Table 11 presents information for windows in storefronts. This building stood vacant inunediately foUowing the blast and at the times of the investigators' subsequent visits. The investigators could not gain entrance. Consequently, the investigators could make no estimates of distances shards flew from windows into the building with the exception of laminated glass windows that fractured but did not release shards. The investigators based their estimates of distances glass shards flew outside the building from observations they made during their initial survey. Pata for Buildings Situated in Zone 2 Building 2, Durham Post Office Figure 32 shows the deformation at the top of the aluminum frame around the main entrance to the Durham Post Office. Due to safety regulations, tempered glass glazed the entryway. Figure 33 shows the wall at the east side of the entrance. Tempered glass shards from the entrance are embedded in this wall. Figure 34 shows tempered glass shards embedded in the wall 15 ft behind the entrance. The dark area on the right side of this figure is an opening through which postal employees served the pubUc. Fortunately, no one was standing in this opening at the time of the explosion. 65 â5 H ?^ vO VO 00 <3N C^ ^* in T-i T-H §8 00 (N (N rH 00 rH rH 5 0 is! I< ITÍ iri iri (p)si- n IMP L w írf^ •_ w ^fc U ^ ^ < O § § o O^ < S § § CJ\ § &í w H &OH- Ci- PQ» < ^ 9 ^ ^ 1/^ o o o in o w 5 P S' 8 ÍN (N o o 6 6 rH t-H U ^ HJ ^ 6 6 6 6 o ss§ pla n 0) Mo d 0 face s 0) ^ o c 1- ^ •" 0 (0 2 TJ T3 0 Q) 0 0 O o O 0 --1 H c c c c c c co CO c Predic t ^rohibi t ndicul a s acros o o o 0 o o c --* DÍ win d 2 2 2 2 2 2 E - QJ QJ u hn CO u c 2 2 2 2 2 2 -J J5 ^ ~ ~ CD il d < < < < < < 2 2 3b , ^0 . tJCQ- tra r 3 02 < < (« ^ u u X u db y ^ ant , 6 add o X 00 Tf •^ •^ í5 (» '^ •* •^ 60 n Dynam i í—1 T-H r-< I—1 '—1 > n exterio r e s measu r Rva c t-H rH \T- t "Ô .^ y o < 0 c SS B 2 m ^ X X X X X X X X X vû CN tN (N (N ild i rec t se d sta r (i n co 00 C 3 -1 X X X X X X X X -6 P P m CQ U 66 Figure 32. Frame Failure at Main Entrance of Durham Post Office. 67 Figure 33. Glass Shards in Wall, Durham Post Office, East of Entrance. 68 p JfMB % JlÍ fai 'íiii' r"f Ti' itiâ- Figure 34. Glass Shards in Wall, Durham Post Office, 15' Behind Entrance. 69 Building 8. Unidentified Building B Investigators did not survey Unidentifíed Building B, g structure. Building 9. Old St Toseph's Cathedra Old St Joseph's Cathedral has a brick facade. Fi; wall. Plexiglass covered the stained glass windows to p: the elements. Air blast pressure tore the Plexiglass co and destroyed the windows and their frames. Fi two of the windows. Figure 37 shows Plexigl Building 10. Rectorv Old St Toseph's Cathedral Building 10 served as the Old St Joseph's Cathedral R( to have withstood the blast pressures remarkably well. The li hung windows in this building were most Ukely double strength 3/16 in. thick glass. Air blast pressure fractured and blew out all th( Figure 38 shows the northeast comer of this structure. Debris, presumi the truck containing the explosives, impacted the column just to the right o: downspout 70 Figure 35. East Wall, Old St Josephs Cathedral. 71 Figure 36. Stained Glass Windows Blown Out of East Wall of Old St Joseph's Cathedral. 11 Figure 37. Plexiglass from East Wall of Old St. Joseph's Cathedral. 73 Figure 38. Rectory Old St. Joseph's Cathedral. 74 Building 11, Unidentified Building D Unidentified Building D was an office building with a brick facade. The windows, which were installed long after the original construction, consisted of an IG unit below a horizontal muUion and a tempered glass Hte with window film above the muUion. Figure 39 shows the east wall of this building. Numerous glass shards and film are lying on the street among the debris. Figure 40 shows a piece of film along the south wall of this structure with several shards around it and a few shards adhering to it The IG unit had a tempered outer Ute and an annealed inner lite. Figure 41 shows an office viewed through an east window opening blown out during the explosion. Glass shards are piled against the opposite wall approximately 12 ft behind the window. Figure 42 shows dagger-Uke glass shards embedded in the same waU. The shard above the coat rack penetrated the waUboard at a height greater than that of the top of the IG unit from which it originated. Building 16, AT&T BuUding and PubUc Library The outhne of Building 16, located at the northeast corner of N. Robinson and Dean A. McGee Avenues, to the south-southeast of ground zero, on the map in Figure 4 encompasses two distinct buildings. The eastern portion of Building 16 is the AT&T Building. The westem portion contains the Downtown Branch of the Oklahoma City Library. Glass breakage occurred in both buildings. AU 75 Figure 39. East WaU, Unidentifíed Building D. 76 Figure 40. Glass and Film North of Unidentifíed Building D. 11 Figure 41. Glass Shards in Offíce of Unidentifíed Building D. 78 Figure 42. Glass Shards in Offíce WaU, Unidentifíed Building D. 79 windows on the ground floor of the Ubrary fíactured as did most on the second floor. Sporadic breakage occurred in the AT&T building, more on the north side than on the south side. Cleanup crews began boarding openings prior to the arrival of GRTL investigators. Table 12 presents information for windows in the PubUc Library. Library personnel aUowed the investigators into some areas of the Ubrary. The investigators based their estimates of distances glass shards flew into the building through observations and measurements from windows to interior waUs and partitions. They further based their estimates on interviews with Ubrary employees. The investigators noted that the blast fíactured several interior glass partitions. The investigators based their estimates of distances glass shards flew outside the building from observations they made during their initial survey. Bmlding 17. Old Post Offíce Annealed glass windows on the upper floors of the Old Post Offíce fractured, see Figure 43, and large, dagger-Uke shards feU onto the sidewalk on the north side of Dean A. McGee Avenue, shown in Figure 44. Building 18. Unidentifíed Bmlding F Unidentifíed BuUding F sufíered sporadic glass breakage. 80 CT) Q) *^ c^ c 04 00 in CO irí s « (N tri i9n c-^u -J7L CN iri tN CO (N vd w ^ ... w a> ^ ^ < o 1 o o o o 8 o C8 o o o 8 o 0 ^ < orH »-H rH > T-H rH orH rH rH c^ w Kí C D < Pí Q < c^- *<ã^ in If) in < in in in in in cs 2 rH 0 H H^ .t-* X o X X X j= JS (A (A ^mi ^-1 ^-f < OJ 0 ^>3» >- 3 ^^3 ^•^3 3 3 ^ 0 O ^ ^ cH C C^ CT) C^ c8 pq >—H cn « Q ^ 0 2 0 H 0 o o 0 o 0 0 o o c c c c c c c c c o o o o o 0 o o 0 ^ gD s 2 s 2 2 s 2 2 2 ^^ 2 2 2 2 2 2 2 2 2 Í8 .£) n s < < < < < < < < < 0 U X 't '^ QC •^ Tí< 00 "t 00 •^ J 2 tû t-H T-l rH T-l r-i rH T-l rH rH 'S o 2< fr0\ -^ X X X X X X X X X X '-•'"•« (N T-H o l-H v£) vD vO vO 81 Figure 43. Boarded-up Windows in the Upper Floors of Old Post Offíce. 82 • i - -^ - '*/ÎLi*iJP'^fc,_r- - •- »• .'-l -- '% -« - .*. Figure 44. Glass on Dean A. McGee Avenue South of Old Post Offíce. 83 Building 19, Regency Apartments GRTL investigators were not able to approach the Regency Apartments, located at the northeast comer of NW 5th Street and N. Hudson Avenue, west of ground zero, due to security measures in efíect during their initial survey. Aír blast pressure fíactured and propelled shards from most of the windows on upper floors. U.S. Army Corps of Engineers' investigators indicated that several lower floor windows glazed with laminated glass fractured. The laminated glass remained in the frames. Figure 45 presents a partial view of the east wall of this building. Table 13 presents information for windows in the Regency Apartments. The investigators based their estimates of distances glass shards flew into the building from videotapes made by the U.S. Army Corps of Engineers. The investigators based their estimates of distances glass shards flew outside of the building on observations during the initial survey coupled with U.S. Army Corps of Engineers' videotapes. Building 20, Southwestern Bell Telephone Building Figure 46 shows the south facade of the Southwestem Bell Telephone Building, located on the north side of NW 6th Street, north of ground zero. Air blast pressure fractured virtually every window located on the south side of the building. Annealed glass with a daytight application of window fílm glazed the 84 Figure 45. East Wall, Regency Apartments. 85 in vO ^s in O; vC (N (N (N (N 00 (N t^ 00 fD fO fO fO oD E K w' in CL, •- iri CD v£> vC 'í' o< K K 2 Ci, 1—1 ^—^ pq <^w o í fc U X X ^ ^ < O o -2 8 8 8 8 o '5 in 8 s 0 ^ < c > Ov > p=í m w ^9 J2 5 ^ u tr> ID ift m ITi l/l íB ifi »/1 C o O o o O o o o •^4 0) CO fO fO fO fO "s cn fD (ft ) 1 1 co 1 > >es 6 6 6 08 6 6 as AW A o o o .NCE : LJILD I C c D D 5|cn w " •:? 1—1 < P u. u C s o; Cií W) < 0 7T cy. X^^ cn 2 in in in in in in o "b "b •b r-i T-l »—1 T—1 T—1 T—1 (N (N (N (N V w ir p £" O 6 o O O 6 6 6 6 6 W) 5S5 <5Í» c (/1—)1 p pû 2 0H^ H X X X X X X X X 4-j ^j 1^^ 1*^ ^mJ ^•t 4-> (A < 3 3 3 3 3 ^3^ o ^^3 0) ^ O 0 O w1 ^ cn c8 C^ ^ C^ U) 2 CD m1—( flS fií H 0 2 0 0 c U U U U U U O U U %4^^M >.u t—< H-^ H^ ^H ^H 1—^ 1 ^^ r-i o 2 2 2 2 2 2 2 S S (N TYP E 2 < < < < < < < < < NSTR U 0 < u TT 00 00 00 00 86 Figure 46. South Facade, Southwestern Bell Telephone Building. 87 south facade. The window fílm neither held glass in the fíame, retarded breakage, nor held the shards together after they fell out. Figure 47 shows tempered glass shards adhering to tom bits of window fílm. The east wall of this building was glazed with IG units that had either aimealed or heat strengthened glass in the outer Ute. Figure 48 shows three of the IG units. The outer lite acted as a sacrifícial lite, fíacturing, while the inner lite remained unbroken. Had all the windows in this building behaved in this manner, the building contents would have been undamaged by the explosion. The glass fíom the outer lites fell to the street below as shown in Figure 49. Figure 50 shows cleanup workers holding a bloody and torn shirt found among the glass shards on the east side of the building. The location of the individual wearing the shirt at the time of the explostion is unknown. Table 14 presents information for windows in the Southwestern Bell Telephone Building. The investigators gained access to this building on both subsequent visits. Figure 51 shows damage which was typical to all rooms throughout the building. Glass penetrated and passed through wallboard located behind fractured windows, shown in Figure 52. They noted that window fílm covered the window glass on the south side of the building, facing ground zero. Despite the use of window fílm, the investigators observed numerous instances of glass shards embedded in soUd core doors and drywail on all floors of the building. Figure 53 shows glass shards which penetrated the 88 .•• .V ' .-,.»••-' •'•- •'*^^ '^'' y/.f^*' 'i -^: -•• * : î->---^--\:-^ Figure 47. Tempered Glass Shards from Southwestern Bell Teiephone Buiiding. 89 Figure 48. IG Units in East Wall of Southwestern Bell Telephone Building. 90 Figure 49. Glass in Street on East Side of Southwestem Bell Telephone Building. 91 Figure 50. Bloody and Torn Shirt Found on East Side of Southwestern Bell Telephone Building. 92 cn Qí cr, fO 00 in o D 9 g g rri T t r-1 T—1 I—1 iri ^ OH -S CN tN "* •^ • 2^H ^—s^. w in o CN o 8 S 8 § o o O rH 1—1 ROXIMA T ERCEN T ÆAKAG E Cu(^, c- OQs to < c 3 s^ ^9 S ^ Pû X 3 o; 5 ^ u ^ ^ c c o § in in • •-< (8 o g 1 o o U > j ^ 1 X BU I o 0 EW A 5TA N 2 2 H » HJ Q u. '03 E « c < 0 n tH : H u in in in in o o ^§ã^ fO CO t—1 0» w .^ Q Æ: co o o o 1 6 6 o 6 6 o T3 2 for m CN Tec h 0 W) H-H <Å nd e H X 4-* xa s 73 < (A 4-rf 3 c 3 3 (U a; m «8 Q «5 •<^ H X o W V 2 C^ tu cn w ^ 2 w w C (« • 0» Q) (A 3 Í-wH Pû Cií w c o .2 0 SJ X •^ •rf •^ •^ •^ •* Q .2 ii J 2 (/i c I—1 I—1 T—1 r-t 1—1 < 0 T-l t-l 'S (J c X X X X X X X C -o 2 m ^ X X X ,, c 73 tN CN (N •^ DIME N 5 Cû 93 Bell Telephone BuiWing. I,teriorDamage,Southwestern Figure 51. Typical 94 -'^'•^^'^-'^— Figure 52. Glass Shards in Wallboard, Southwestern Bell Telephone Building. 95 Figure 53. Glass Shards and Film, Southwestem Bell Telephone Building. 96 wallboard and sheets of film midst numerous shards laying at the base of the wall. Glass shards penetrated the wallboard with pieces of film stiil adhered as seen in Figure 54. The investigators based their estimates of distances glass shards flew into the building upon measurements from the windows to the first interior wall or partition. They based their estimates of distances glass shards flew outside the building on observations during the initial survey coupled with U.S. Army Corps of Engineers' videotapes. Building 21, Storefronts on NW 6th Building 21 contained storefronts with their windows and doors facing south. (See Figure 55.) Cleanup crews boarded the openings and doors prior to the arrival of GRTL investigators. Glass and debris, however, remained on the sidewalk. A brick parapet wall on the east side of this building coUapsed into the adjacent alley during the explosion. Building 22, Anthony's Annex Air blast pressure fractured all the windows facing south. Cleanup crews boarded the openings prior to the arrival of GRTL investigators. 97 I Figure 54. Glass Shard with Film in Wallboard, Southwestern Bell Telephone Building. 98 Figure 55. Storefronts on North Side of NW 6th. 99 Building 23, Anthonv's The windows in Anthony's building consisted of tempered glass with a dayhght appHcation of window fihn. Air blast pressure fractured most of the windows on the south side of the building, shown in Figure 56. Figure 57 shows glass shards and window film lying in the street south of this building. The window film did not significantly reduce breakage, nor did the film hold the glass in the frame after fracture. Also, the film did not maintain a majority of glass shards adhering to it Building 24, Bank of Oklahoma Figure 58 shows the sporadic window glass breakage, indicated by boarded openings, on the upper floors of the Bank of Oklahoma Building, located on the southwest comer of N. Robinson and Dean A. McGee Avenues. Curtains can be seen blowing through openings at the left of the photograph. Figure 59 shows boarded openings where windows failed on the northeast corner of the ground floor. Table 15 presents information for windows in the Bank of Oklahoma. The investigators could not obtain actual distances glass shards flew into the building. hiterviews with empioyees indicated that shards were stopped by the first interior wall or partition. The investigators based their estimates of distances glass shards flew outside the buiiding on observations during the 100 SouthPacadeofAnthony's. FracturedWindowsOverEntrance, Figure 56. 101 57. WindowFilmfromAnthonys. Figure 102 Sporadic Breakage, North Wall, Bank of Oklahoma, Oklahoma Plaza. Figure 58. 103 Figure 59. Northeast Corner, Bank of Oklahoma, Oklahoma Plaza. 104 00 00 00 00 vO t-H 0 D c •^ •^ Í8 ;s ^ in cu .j. vrj ^D \o ^d vb vb vb vb 2h—( >wo^. w <^w ^ 0) í fc U X 3 X 2 2 < 0 0 fN fN 'S in "s > > 8 6 6 6 T-l r-t «>3 CB r-t B C c PERC E c c BREA K PPROX I D D D D < ^ 9 W AWA Y I D D D D lANCES H JS if) w 5? p-J O Q n. M-l O S Dí < 0<í?n j) o; S 0) ^ ^ (U S. > > > > > > > > ^ i^ C8 > CD 1—< ^ "S Q "? D 3 Ê-S Pû 2 v*-Sl t"^" 0 iri '2 (B -C •4^ X -C C X 4-^ 3 0 T( 0 0 3 (8 0 ^ H J= 0 _- (/î NTA T 2 2 cB 2 . (D 0 C 5 •" 0 8, 2 Ci, 0 H0H H Qí c \U U U U U U U u u u ^^ _0 »—H ^-4 ^-H o f wind c (30 (U endicula r e Predict i 1 ^^ ^~^ ^ 2 2 2 2 ^ ^ 0) •^ C/ mea s 0 i< X oxte r Dyn a TT •^ -ÍT TT t -r -r -r (8 HJ 2 (/•, <^y < 0 r-i —1 T-l T—1 r—i r-H T-H r-t 'S X X X X X X X X X "c •^ d o n ctio n vO vO 00 ance s ^o 00 V. (fl lA (/•, c (in. ) ,c (3N NOMI N \o ,—. co fO m fD t ^* •* T Cc DIMENS K "3 C 105 initial survey. The investigators discovered that permanent deformation of window frames occurred during the blast and, as a result, windows continue to break. Building 25, Federal Reserve Bank A thick iron lattice covered the windows on the lower floors in the Federal Reserve Bank, located on the southeast comer of N. Harvey and Dean A. McGee Avenues. Window glass behind this lattice did not fracture. Window glass above the lattice fractured as indicated by the boarded openings shown in Figure 60. Tabie 16 presents information for windows in the Federal Reserve Bank. The investigators based their estimates of distances glass shards flew into this building on measurements coupied with interviews of building personnel. They based their estimates of distances glass shards flew into the street on observations during the initial survey. When computing blast impulses associated with a 50% probabiiity of breakage, the investigators used "equivalent" rectangular dimensions for two windows that had curved tops. Buílding 26, Oklahoma Gas & Electric Figure 61 shows the bottom of a revolving door panel glazed with laminated glass on the northeast corner of the Oklahoma Gas & Electric Building. The explosion badly damaged the door and bent the frame. The 106 Figure 60. North Side, Federal Reserve Bank. 107 H^2H ''*—O^. W f—1 (p. < f-i w § 2 U 8 8 8 8 á>< uá ^< rH T-l r-< T—1 o^ < lA l/S l/S lA eí w w 00 (50 » 00 û- PL, {v; (^ pû < sg ^ ^ ^ 0 ^9 3 3 3 X 2: C c C _C 'S 'S 'S 'S c w 5 Q 3 X X X pû 2 < 3 0 0 0 0 0) 0 0 0 0 2 2 2 2 t<í> 5? 1-1 (A Q u^ 01 eíí S 13 Pá < O7. Q5 'de r cT) 2 á •V ^ ^ ^ Ol rn '—1 ?> '^ in in in in Q> CN T-H tN T—1 1 6 6 0 6 c -t: c in CN Idi n Ê -f Qí '3 2 ^ 0 flj 2 2 (11 OJ (/1 W Z HH 0 Tabl . a r t o plan « n s use d t o 2 do w faco s :tio n Mod i •ppe d gla s 0 .£ 3 ^S ií .9 0 0 0 0 H c c c c 0 0 0 w^H p 0 •4^ X J 2 to T—1 o n oxtorio r < 0 ce s measu r o n Dynam i itorio r wal l ilon t recta n 2 00 ^ X X X X 0 T—1 fN X ^ -2 1 •; 'l é w ^ vO to X X X X c Q Q OÛ U- W 108 Figure 61. Laminated Glass in Smashed Revolving Door, Oklahoma Gas & Electric. 109 laminated glass fractured but remained in the frame. Figure 62 shows glass block panels on the north facade. Although the faces of some of the glass blocks cracked, they remained intact Cleanup crews boarded the monoHthic annealed glass windows above the glass block. A security guard on duty in the building informed GRTL investigators that shards from these windows were blown 30 ft into the building. Data for Buildings Situated in Zone 3 Building 27, Boatman's Bank High performance IG units glazed the Boatman's Bank. An observer reported that building motion was visible to the naked eye immediately after the explosion. In subsequent visits to Oklahoma City, the investigators discovered that six monohthic ground floor windows and one IG unit on the twelfth floor in the North Tower fractured. Window washers taped the IG unit in place to prevent fallout. Discussion of the Impulse Associated With a 50% Probabi ity of Failure The Dynamic Failure Prediction Model (DFPM) possesses the capabilities of analyzing window glass lites subjected to blast loadings. The estimates of the impulses associated with a 50% probability of failure resulted from the analysis of each window configuration using the DFPM. 110 Figure 62. North Wall, Oklahoma Gas & Electric. 111 Input Options The DFPM contains three input options. For each of the three options, the user defines the geometric and strength properties of the window glass. For Option 1, the user identifies the pressure-time history of a blast wave. For Option 2, the user inputs an equivalent TNT charge weight and a standoff distance. The DFPM calculates a probabihty of failure for input Options 1 and 2. Option 3 allows the user to define the desired probability of failure and charge weight The DFPM iterates to a standoff distance relating the probability of failure and charge weight, and also provides the impulse for the charge weight and standoff. The author utilized Option 3 in generating all of the reported impulses associated with a 50% probability of failure. Calculation of the Impulse The DFPM utilizes curve-fit equations found in the computer program "CONWEP." The positive phase of the blast wave is assumed to be triangular, and does not account for the effects of rehef waves off the edges of structures. With the charge weight and standoff distance, the DFPM provides a duration of the positive phase. Since the positive phase of the wave is assumed to be triangular, the area under the pressure-time history is half the peak over pressure times the duration. The impulse represents the area under the 112 pressure-time curve. All of the impulse estimates are based on the reflected peak overpressures. Significance of the Impulse Associated With a 50% Probabilitv of Failure The estimates of the impulse two primary purposes. These impulses aid investigators in evaluating the performance on not only window glass and window glass constructions, but also structural performance when subjected to blast loadings. Secondly, by studying the window breakage patterns and impulses associated with failure investigators formulate estimates of the actual pressures exerted by the blast in different areas away from ground zero. The careful documentation of explosions, whether accidental or terrorist, provides very useful information in designing window glass and structures to better protect the occupants of buildings, contents of buildings, and persons outside and in proximity to buildings. 113 CHAPTER V OBSERVATIONS AND CONCLUSIONS Introduction In the event of an explosion, the primary function of window glass is to maintain the closure of the building. The benefits of maintaining the building envelopeare threefold. Most importantly, maintaining the closure of the building envelope reduces the number of injuries and deaths caused by both air blast pressure and flying glass shards. Secondly, preserving the building envelope reduces the amount of damage to the contents and interior of the building caused by either air blast pressures or flying glass shards. Lastly, cleanup efforts are expedited. Observations Zone 1 Virtually all of the buildings within Zone 1 sustained significant structural damage. The primary concern for glass design is to reduce the number of glass shards, consequently reducing the number of injuries. Investigators observed several glazing types and constructions in Zone 1 including: IG units, laminated glass, glass block, monohthic glass, and monolithic annealed glass with a daylight apphcation of window film. Of these 114 types and constructions, laminated glass in doorways was the only glazing material that remained in its frame after the explosion. Air blast pressure fractured all lites in IG units and propelled the resultant glass shards from their frames. Similarly, with the exception of three htes in the Alfred P. Murrah Federal Building, air blast pressure fractured all monohthic annealed htes and propelled the resultant glass shards from their frames. Glass block did not perform well in Zone 1. Zone2 Buildings in Zone 2 suffered extensive window glass breakage accompanied by little or no structural damage. The same glazing types and constructions as in Zone 1 were also observed in Zone 2. Investigators documented repeated instances where fractured laminated glass remained in its frame, protecting the occupants and contents of buildings while releasing no glass shards. Investigators observed IG units in Zone 2 in which air blast pressures fractured the outer lite only. The IG units successfully maintained the integrity of the building, protecting the occupants and the contents of the building. However, air blast pressures fractured the outer lite, propelling the resultant shards away from the building, posing a severe threat persons in proximity to these units at the time of the explosion. Glass block walls performed well in Zone 2, protecting the occupants and the contents of the 115 building while producing few glass shards. Monolithic glass of all types performed poorly in Zone 2. In several storefronts, air blast pressures fractured monolithic lites and propelled the resultant glass shards from their frames; however, adjacent laminated lites fractured but remained in their frames releasing no glass shards. Window film applied to windows did not provide any observable reduction in window breakage. Window film did not retain window glass in the frames foUowing fracture. Window film did not significantly reduce the number of glass shards propelled from window frames by air blast pressures. Zone 3 Buildings in Zone 3 suffered sporadic window giass failure. Laminated glass and IG units performed well in Zone 3. No glass block was observed in buildings located in Zone 3. Monolithic glass performed well when it did not fracture. Conclusions The performance of window glass and window glass constructions in blast scenarios is characterized by its ability to maintain the integrity of the buiiding, and minimize the quantity and size of flying glass shards. Laminated glass performed more adequately in all zones than any other window glass type 116 or construction. IG units were marginally successful in Zone 2, where they did maintain the building envelope. IG units were more successful in Zone 3. Monohthic glass, whether AN, HS, or FT, performed poorly in all three zones, when it fractured. Monolithic glass retrofit with a dayhght application of window film showed no advantages. The film did not aid in resisting fracture. The film did not aid in maintaining the closure of the opening. The film did not retairi a large amount of shards. When designing windows to provide protection from a blast, careful consideration should be given to the type of window glass, window glass construction, and framing. The window will hkely fail if the frame is unable to keep the glazing material in place. Significance This survey is meaningful because explosive forces have a significant impact on window glass, window glass constructions, and window glass frames. The information contained herein impacts several areas of research, including: window design methodologies to resist blasts, assessment of hazards posed by blasts in urban areas, and prediction of injuries and/or deaths due to an explosion, either terrorist or accidental. 117 LIST OF REFERENCES Beason, W. L., "A Failure Prediction Model for Window Glass." Institute for Disaster Research, Department of Civil Engineering, Texas Tech University, Lubbock, TX, 1980. Blocker, Virginia and Blocker, T. G., Jr. "The Texas City Disaster: A Survey of 3,000 Casualties." American ournal of SurgerV/ November, 1949. Brismar, Bo and Bergenwald, Lennart "The Terrorist Bomb Explosion in Bologna, Italy, 1980: An Analysis of the Effects and Injuries Sustained." The Toumal of Trauma, Vol. 19, No. 3. The WiUiams and Wilkins Co., 1982. FBI Explosives Unit-Bomb Data Center (EU-BDC) General Information Bulletin 95-2. Federal Bureau of Investigation, U. S. Department of Justice, 1994. Glass Research and Testing Laboratory (GRTL). "Evaluations of Window Glass Response to Low-Level Blast Waves." Glass Research and Testing Laboratory, Department of Civil Engineering, Texas Tech University, Lubbock, TX, 1987. Kinney, Gilbert F. and Graham, Kenneth J. Explosive Shocks in Air: Second Edition. Springer-Verlag New York Inc, 1985. Norville, H. Scott. "Dynamic Failure Prediction for Annealed Window Glass Lites." Glass Research and Testing Laboratory, Department of Civil Engineering, Texas Tech University, Lubbock, TX, December, 1990. NorviUe, H. Scott and Minor, J.E. "The Strength of Weathered Window Glass." Bulletin of the American Ceramic Society, Vol. 64, No. 11, November, 1985. Norville, H. Scott, Bove, P.M., and Sheridan, D. "Failure Prediction for Thermally Tempered Window Glass Lites." Glass Research and Testing Laboratory, Department of Civil Engineering, Texas Tech University, Lubbock, TX, February, 1991. NorviUe, H. Scott, Swofford, Jason L., Smith, Milton L., and King, Kim W. "Survey of Window Glass Broken by the Oklahoma City Bomb on April 19,1995, Revised." Glass Research and Testing Laboratory, Department of Civil Engineering, Texas Tech University, Lubbock, TX, March, 1996. 118 Oklahoma State Department of Health (OSDH). "Summary of Physical Injuries Directly Associated with the Oklahoma City Bombing." October 1,1995. Scott, Brett A., Fletcher, J. Raymond, Pulliam, Morris W., and Harris, Robert D. "The Beruit Terrorist Bombing." Neurosurgery, Vol. 18, No. 1. The Congress of Neurosurgery, 1986. 119 PERMISSION TO COPY In presenting this thesis in partial fulfillment of the requirements for a master's degree at Texas Tech University or Texas Tech University Health Sciences Center, I agree that the Library and my major department shall make it freely available for research purposes. Permission to copy this thesis for scholarly purposes may be granted by the Director of the Library or my major professor. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my further written permission and that any user may be liable for copyright infringement. Agree (Permission is granted.) OADK Studént's Signature Date Disagree (Permission is not granted.) Student's Signature Date ^ p CD P ? D CO T-H ^ t-0^ ^ «5 -o Ê H X ^' <^ X C X ii .4-» 3 Q; « < l-l S S 0 1 1 1 o x; ^ ^ O „- 1/1 2 Q; QJ (/1 s o •£ 00 00 Ê 00 (A p Q) W QJ r-1 rH rH rH rH "5 c < O rH U o X X X X X X X X C 3