HISTORICAL-TECHNICAL SERIES
(ISTORICAL 0(ISTO ERSPECTIERSP VE IN E IN ECTI RICAL 0 THE $EVELOPMENT OF 0RECAST 0RESTRESSED #ONCRETE "RIDGES
3INCE THE EMERGENCE OF PRECAST PRESTRESSED CONCRETE BRIDGES IN THE 5NITED 3TATES IN THE EARLY S INNOVATIONS AND DEVELOPMENTS HAVE PROPELLED THIS m EXIBLE AND EXPEDIENT CONSTRUCTION MATERIAL INTO A WIDE VARIETY OF APPLICATIONS INCLUDING THE ERECTION OF LONGER BRIDGE SPANS CARRIED BY CONCRETE SUPERSTRUCTURES 4HE LAST FEW DECADES HAVE WITNESSED THE EMERGENCE OF PRESTRESSED CONCRETE AS A MAJOR PLAYER OF THE 53 BRIDGE MARKET n A REMARKABLE TRANSITION FROM A RELATIVELY UNKNOWN MATERIAL RELEGATED TO SHORT SPANS TO A SUCCESSFUL COMPETITOR OVER ESTABLISHED MATERIALS AND METHODS 4HE l RM OF 0ARSONS "RINCKERHOFF 6IJAY #HANDRA 0% 0" IS PROUD TO HAVE CONTRIBUTED TO THE DEVELOPMENT AND EXPANSION OF 3ENIOR 6ICE 0RESIDENT PRECAST PRESTRESSED CONCRETE SYSTEMS 4HIS ARTICLE HIGHLIGHTS SIGNIl CANT 0ARSONS "RINCKERHOFF 1UADE AND PROJECTS INCLUDING THE l RST MAJOR USE OF PRECAST PRESTRESSED CONCRETE $OUGLAS )NC .EW 9ORK .EW 9ORK IN THE &IRST 3UNSHINE 3KYWAY "RIDGE &LORIDA AND THE EARLY APPLICATION OF SPLICED GIRDER BRIDGES FOR LONGER SPANS
hat factors spurred precast, willingness of our predecessors to try prestressed concrete appli- new ideas. 7cations into the mainstream The goal of this article is to present of bridge construction? It is widely an historical overview of a variety of agreed that the major contributors to PB projects, including several award- the evolution of this building material winning structures that are recognized are: advances in concrete material tech- for innovative designs, construction 2OBERT 7ARSHAW 0% nology; greater latitude in AASHTO methodologies, and material applica- 6ICE 0RESIDENT Specifi cations; development of a con- tions. Selected projects range from 0ARSONS "RINCKERHOFF 1UADE AND siderable body of research; improve- those constructed in the early 1950s $OUGLAS )NC ments in system hardware, precasting – when PB was at the leading edge in .EW 9ORK .EW 9ORK technology and transportation systems; developing and implementing precast, and an expanding knowledge base. prestressed concrete technology across However, the real impetus behind the many different bridge types – to cur- present success of precast, prestressed rent endeavors. Of course, the authors concrete in state-of-the-art bridge con- recognize that the fi rm’s accomplish- struction has been the ingenuity and ments represent a microcosm of the
0#) */52.!, innovative efforts and events that have occurred throughout the larger industry as a whole. Although PB has used precast, pre- stressed concrete technology on hun- dreds of bridges, viaducts and ramps, the following 13 representative proj- ects are highlighted in this article: • First Sunshine Skyway Bridge, Florida • Pelican Island Causeway, Texas • First & Second Hampton Roads Bridge/Tunnel, Virginia • Atlantic City Expressway, New Jersey • Halawa Interchange, Hawaii • Fort Weaver Road Bridge, Hawaii • Keehi Interchange, &IG "Y THE MID S 4HE &IRST 3UNSHINE 3KYWAY "RIDGE IN 3T 0ETERSBURG Hawaii &LORIDA CROSSED A REMARKABLE DISTANCE OF MILES KM AND WAS NOTABLE FOR • James River Bridge, MORE THAN MILES KM OF PRECAST PRESTRESSED CONCRETE CONSTRUCTION FOR THE LOW LEVEL BRIDGE SECTIONS Virginia • West Seattle Freeway Bridge, Washington The 16,000 ft (4880 m) of low-level &)234 3%#/.$ • New Sunshine Skyway Bridge, bridge spans consisted of precast, pre- (!-04/. 2/!$3 Florida stressed concrete girders. This project • Ocean City-Longport Bridge, "2)$'%45..%, was particularly notable for its use of New Jersey precast, prestressed concrete construc- (AMPTON 6IRGINIA • East Pascagoula Bridge, AND tion for more than 3 miles (4.8 km) of Mississippi low-level bridge structure, one of the On behalf of the Virginia Department • Central Artery/Tunnel Project, of Highways, PB designed and super- Massachusetts first projects to use this construction technique in such magnitude. vised the construction of both the First and Second Hampton Roads Crossings. &)234 35.3().% Connecting Hampton and Norfolk, the 3+97!9 "2)$'% 0%,)#!. )3,!.$ projects consisted of an immersed tube #!53%7!9 tunnel in the shipping channel flanked 3T 0ETERSBURG &LORIDA by approach trestles (see Fig. 3). 'ALVESTON 4EXAS TO TO The overall project included 3.5 miles PB planned, designed, prepared For the Galveston County Navigation (5.6 km) of water crossing with 6150 contract documents (plans and speci- District No. 1, PB designed and pro- ft (1875 m) of south approach trestles fications), and performed technical vided technical inspection of construc- and 3250 ft (991 m) of north approach inspection of construction for the tion for this 8000 ft (2440 m) crossing trestles for each of the two crossings. First Sunshine Skyway Bridge for the over the Galveston ship channel that Two parallel structures accommodate Florida State Road Department (see connects 51st Street in Galveston with two lanes of traffic in each direction. Fig. 1). This exceptionally long water Pelican Island (see Fig. 2). Precast, pre- The first crossing was commissioned in crossing over Tampa Bay extended for stressed concrete girders were used for 1957 and the second parallel crossing a distance of 15 miles (24 km), from was opened to traffic in 1976. the 1500 ft (457 m) long approaches Maximo Point in the city of St. Peters- In the Second Hampton Roads cross- to the 160 ft (49 m) single-leaf rolling burg, to its southern terminus, 4 miles ing project, the trestle structures were (6.4 km) north of Bradenton. lift bascule span. The crossing carries a designed for two alternative pier types: The crossing was divided into eleven two-lane vehicular roadway, a pedestri- one featured precast, post-tensioned sections: six hydraulic fill embankment an sidewalk and a single railroad track. spun cylinder concrete piles, 54 in. (1370 sections, a high level cantilever bridge The Pelican Island Causeway was mm) in diameter, with precast concrete section, a double-leaf bascule bridge the first major structure in the United pile caps, while the other included eight section, a fixed steel beam bridge sec- States to use prestressed concrete deck 24 in. (610 mm) square precast, preten- tion, and two low-level bridge sections. slabs for a railroad crossing. sioned concrete piles with cast-in-place
.OVEMBER $ECEMBER (CIP) concrete caps. The contractor chose the cylinder pile precast cap al- ternative for construction. The super- structure consisted of seven rows of AASHTO-PCI Type III precast, pre- stressed concrete beams spaced at 6.3 ft (1.9 m) with a composite CIP deck slab.
!4,!.4)# #)49 %802%337!9 !TLANTIC #ITY .EW *ERSEY TO After World War II, when the auto- mobile industry was growing dramati- cally, the need for paved roads was in great demand. States were struggling to accommodate the increased traffic and enlisted private engineering companies to assist in designing roads and bridg- es. By 1954, 28 states, including New Jersey, were involved in the develop- ment or construction of 7500 miles (12,070 km) of toll roads. In 1950, the Atlantic City Express- way toll road development began. PB was retained as general engineer- ing consultant to design, manage the section design consultants (SDC), and supervise the construction of 44 miles (71 km) of a four-lane roadway be- tween Turnersville and Atlantic City (see Fig. 4). PB proposed a unique method to ac- celerate bridge construction and lower &IG 0ELICAN )SLAND #AUSEWAY IN construction costs by standardizing the 'ALVESTON 4EXAS WAS THE lRST MAJOR STRUCTURE IN THE 5NITED 3TATES TO USE PRECAST PRESTRESSED CONCRETE DECK SLABS FOR A RAILROAD CROSSING
&IG 4HE &IRST AND 3ECOND (AMPTON 2OADS "RIDGE4UNNEL IN 6IRGINIA CONSISTED OF AN IMMERSED TUBE TUNNEL IN THE SHIPPING CHANNEL ONE OF THE MID BAY TUNNEL APPROACHES IS SHOWN IN THIS AERIAL PHOTOGRAPH
0#) */52.!, The bridges utilized several types of structural systems. Some bridges have conventional precast, prestressed con- crete stringers (standard I-girders) with CIP slabs continuous for superimposed dead load and live load, while others have CIP reinforced concrete box gird- er construction. However, two bridges used unique construction methods for the time, featuring what is now known as spliced girder technology to extend span lengths using precast concrete girders (see Fig. 6). The available precast AASHTO-PCI Type IV girders [limited to 104 ft (31.7 m) in length] were spliced with cantile- ver box superstructures – in the form of mushroom piers – to create two spans of 132 ft (40.2 m) each. The mushroom piers and the support at the end of the pier that received the girders were &IG 4HE !TLANTIC #ITY %XPRESSWAY IN .EW *ERSEY WAS PART OF THE TREMENDOUS erected using falsework. The girders GROWTH IN NATIONAL TRANSPORTATION INFRASTRUCTURE FOLLOWING 7ORLD 7AR )) )N THIS were erected with one end sitting on PROJECT THE DESIGN FOR THE PRECAST PRESTRESSED GIRDERS WAS STANDARDIZED FOR EFlCIENT the falsework and the other end resting PRODUCTION AND COST SAVINGS on the abutment. The CIP deck over the girders was bridge components: SDCs would sub- interchange in Honolulu on the island then placed along with the closure pour mit their bridge framing plans and PB of Oahu (see Fig. 5). The interchange between the ends of the girders and would design all precast, prestressed connects four major highways: Inter- the pier, resulting in a two-span con- concrete girders in two procurement state H-1, Interstate H-3, the Moanalua tinuous bridge. This spliced girder de- contracts. A system was developed Freeway, Halawa Heights Road, and sign made economical use of standard wherein all girders for the project numerous secondary roads and streets. precast members, while stretching the were designed using only five different The interchange consists of 16 major span lengths beyond anything that had strand pretensioned forces. The differ- bridges, nearly all of which use precast, previously been accomplished in the ence between the pretensioned force prestressed concrete girders. United States. and the required prestressing for the girders was made up by introducing post-tensioning. This standardized approach allowed for the very efficient production of girders, resulting in substantial cost savings and an acceleration in construc- tion. After fabrication, the girders were stored in the precast yard, each marked with an appropriate bridge and girder number that coincided with numbers on the framing plans. Each bridge con- tractor was then able to pickup the ap- propriate girders at the precast yard and transport the precast members to their respective site for erection.
(!,!7! ).4%2#(!.'% (ONOLULU (AWAII TO In 1967, PB was retained by the Ha- waii Department of Transportation to &IG 4HIS INTERCHANGE IN (ONOLULU (AWAII CONSISTED OF MAJOR BRIDGES NEARLY manage and design a large, complex ALL OF WHICH USED PRECAST PRESTRESSED CONCRETE GIRDERS
.OVEMBER $ECEMBER &/24 7%!6%2 traffic flow. As part of this highway create an open span over a wide median 2/!$ "2)$'% widening, a new bridge was required and both shoulders on the Farrington over Farrington Highway that would Highway. Accordingly, PB conceived, %WA $ISTRICT (AWAII maximize span length and eliminate designed and built a bridge with piers TO piers in the median to allow for addi- located only in the shoulders, requiring Fort Weaver Road, located in the Ewa tional future widening or the addition a span of 132 ft (40.2 m) between the District adjacent to Honolulu, required of mass transit. The bridge needed to piers (see Fig. 7). widening to accommodate increased accommodate seven lanes of traffic and Since there was not enough length for the back spans to balance the main span as in a conventional scheme, the bridge was planned with a CIP con- crete box superstructure with drop-in precast, prestressed girders developed for the Keehi Interchange (see below). The box superstructure was continued in the back spans as a constant depth section and counterweighted to accom- modate the dead and live load forces from the main span, and thus provide a positive downward force at the ends of the bridge. One end of the approach slab also rested on the concrete box. Since the end of the box structure with its dia- phragm is similar to an abutment, an &IG 4HE (ALAWA )NTERCHANGE INCORPORATED SPLICED PRECAST PRESTRESSED CONCRETE integral bridge concept was applied to GIRDERS TO CREATE SPANS OF FT M AN UNPRECEDENTED ACCOMPLISHMENT FOR THE eliminate conventional abutments. 5NITED 3TATES IN
&IG &ORT 7EAVER 2OAD "RIDGE NEAR (ONOLULU (AWAII MAXIMIZED SPAN LENGTH WITHOUT PIERS IN THE MEDIAN TO ALLOW FOR FUTURE IMPROVEMENTS
0#) */52.!, +%%() ).4%2#(!.'% (ONOLULU -ETROPOLITAN !REA (AWAII TO One of the most complex sections of roadway ever built in Hawaii, Oahu’s Keehi Interchange (see Figs. 8 to 10) was the fi nal link in Interstate H-1. The interchange connects the H-1 Freeway to Nimitz Highway (main artery to Waikiki), Dillingham Boulevard and the Lunalilo Freeway/Middle Street In- terchange. Located near Honolulu International Airport, the interchange is the state’s busiest traffi c corridor, with average daily traffi c volumes of almost one- quarter million vehicles. Designing and constructing this complex interchange &IG )NTERWOVEN CONl GURATION OF THE )NTERCHANGE NECESSITATED LONG SPANS RESULTING in diffi cult soil conditions was a once- IN THE USE OF MUSHROOM PIERS AT DROP IN SPANS
0RESTRESSED #ONCRETE 'IRDERS
6ARIES -AX
+EEHI ) +EEHI )& !!3(4/ ))
+EEHI ))&
+EEHI )6 +EEHI )6& +EEHI 6)
&IG 3ECTION DRAWINGS ILLUSTRATE THE CUSTOMIZED PRECAST CONCRETE GIRDERS DESIGNED FOR THE +EEHI )NTERCHANGE IN (AWAII
.OVEMBER $ECEMBER In summary, as compared to AASHTO-PCI shapes, the Keehi Beams: • Are lighter, slimmer and less expensive. • Provide more efficient use of cross section. • Require less material to obtain the same span length. • Can accommodate increased prestress force to extend spans to greater lengths. • Offer the ability to precast locally on existing beds. • Allow for efficient construction with fewer, more widely spaced girders. • Are able to accommodate both 0.5 and 0.6 in. (12.7 and 15.2 mm) diameter strands (a contract option permitted the precaster to utilize either &IG 4HIS size of strand). AERIAL VIEW SHOWS THE COMPLETED +EEHI The Keehi Interchange is situated )NTERCHANGE ONE OF in an extremely poor geotechnical THE MOST COMPLEX location near the area where the Keehi SECTIONS OF ROADWAY Lagoon discharges into the Pacific EVER BUILT IN (AWAII Ocean. The upper 10 to 15 ft (3.1 to 4.6 m) of soil in the area is coral and sand in-a-lifetime engineering challenge The Keehi Interchange girders are underlain with a maximum of 150 ft for the project planners. The project’s all precast, pretensioned concrete. Be- (45.7 m) of extremely soft and uncon- scale was impressive, incorporating the cause the interchange was such a large solidated clay. As a result, the piles had following elements: project, it was decided early in the to be 100 to 230 ft (30.5 to 70.1 m) • 1.9 mile (3.1 km) long, 3.3 planning stages to develop more ef- long. The extreme soil conditions also million sq ft (0.3 million m2), ficient girder shapes than those avail- required application of several new three-level interchange. able from the standard AASHTO-PCI construction technologies. • 328 spans varying in length from beams. Consequently, an intensive Because the soil needed to be con- 18 to 216 ft (5.5 to 65.8 m). study and evaluation was undertaken solidated in the abutment and embank- • Total length of girders = 179,000 to develop new precast concrete gird- ment areas, the first application of wick linear ft (54,560 m). er shapes. Local precasters were con- drains in lieu of sand drains was ad- • Total piling lengths: the 16.5 sulted and the Keehi Beams (Type IV opted for this project. A second inno- in. (420 mm) octagonal piles = and VI girders) were developed along vation involved the piles. The 16.5 in. 768,000 ft (234,090 m); the 20 in. with the fascia girders which met the (420 mm) octagonal precast concrete (508 mm) square piles = 19,200 ft architectural preference for a smooth piles were tested and evaluated to de- (5852 m). appearance. termine proper alignment of the as- • Individual pile lengths up to In developing the shapes, the bot- driven pile. 230 ft (70.1 m) with mechanical tom flange widths for the Type IV and Pile testing included: the ability of splices. VI girders were kept the same as the the bitumen pile coating to resist down- • First use of wick drains for soil AASHTO-PCI beams to avoid the cost ward drag through the upper and lower settlement in the United States. of new pallets. The web width was soil layers; adoption and behavior of Although most of the novel engi- reduced to a point where the angular mechanical splices; pile driving forces neering features and design achieve- volcanic aggregates for concrete used for hard- and soft-driving using elec- ments of the interchange are hidden in Hawaii could be uniformly vibrated tronic dynamic analyzers; and mitiga- from motorists who admire its grace- down to the bottom flanges and not be- tion of the heavy down drag forces due ful sweeping lines, many innovations come trapped in the web reinforcement. to compressible clay. in precast concrete technology were Ultimately, PB was able to achieve a For the first time in the United States, accomplished during the course of the 20 percent cost savings due to lighter 0.6 in. (15.2 mm) diameter strands were project; this was particularly true of the beam design and reduced substructure used for pretensioned piles as a speci- girders and pilings. and foundation loads. fied alternative for contractors.
0#) */52.!, In another instance, the interwoven configuration of the Keehi Interchange ramps made it difficult to use equal spans or very long spans. PB overcame this issue by using mushroom piers can- tilevered both longitudinally and trans- versely, with cantilevers varying from 25 to 41 ft (7.6 to 12.5 m). By using the newly developed beams, spans up to 216 ft (65.8 m) were attained. Over time, this innovative beam design has proven to be a success and has been ad- opted as Hawaii’s state standard.
*!-%3 2)6%2 "2)$'% 2ICHMOND -ETROPOLITAN !REA 6IRGINIA TO &IG #OMPLETED IN THE *AMES 2IVER "RIDGE IN 6IRGINIA IS ALMOST ENTIRELY A In 1972, the Virginia Department of PRECAST CONCRETE STRUCTURE THAT PROVIDES A SMOOTH RIDING SURFACE BY MINIMIZING CREEP Transportation retained PB to design CAMBER IN THE DESIGN and manage the construction of the New James River Bridge. This 4.4 mile proaches and a new vertical lift bridge native II, the substructure was made (7.1 km) long crossing of the James (see Fig. 11). up of 24 in. (610 mm) square precast, River near its estuary with Chesapeake For the low-level bridge approaches, prestressed concrete piles with CIP pile Bay is almost entirely a precast con- the contract documents permitted two caps. The cylinder piles were up to 240 crete bridge designed and built in two precast alternates for each of the sub- ft (73.2 m) in length. Alternative I was phases. Phase I of the project consisted structure and superstructure elements. chosen by the winning contractor. of a 3.8 mile (6.1 km), two-lane low- In Alternative I, the substructure con- The superstructure was also bid with level approach and two temporary sisted of three precast, prestressed 54 two alternates. Alternative A consisted cross-overs to an existing vertical lift in. (1372 mm) diameter concrete cyl- of Type IV precast, prestressed con- bridge. Phase II encompassed build- inder piles with precast concrete pile crete beams with a CIP concrete deck ing the two-lane high-level bridge ap- caps integrated into the piles. In Alter- slab, whereas Alternative B called for
&IG 4HE SUPERSTRUCTURE OF THE *AMES 2IVER "RIDGE WAS BID WITH TWO ALTERNATIVES THIS PHOTOGRAPH SHOWS THE ERECTION OF THE MOST ECONOMICAL AND SUCCESSFUL SOLUTION A MONOLITHIC DESIGN IN WHICH THE GIRDERS AND TOP SLAB WERE CAST AS A SINGLE UNIT
.OVEMBER $ECEMBER In Phase II, the two-lane low-level approaches were continued as high- level approaches to meet a new vertical lift bridge. The high-level approaches consisted of 54 in. (1372 mm) precast, prestressed cylinder piles battered at a 1:6 slope with CIP pile caps and ham- merhead piers. The number of piles varied from four to eight depending on location. The superstructure consisted of Type III and V AASHTO-PCI pre- cast, prestressed beams with CIP slabs. The Type V beams were extended to 122 ft (37.2 m).
7%34 3%!44,% &2%%7!9 "2)$'% 3EATTLE 7ASHINGTON TO &IG ,OCATED IN A SEISMIC AREA THE APPROACHES OF THE 7EST 3EATTLE &REEWAY "RIDGE 7ASHINGTON WERE OF CONTINUOUS SPAN CONSTRUCTION FOR BOTH SLAB AND PB served as a design consultant for SUPERIMPOSED DEAD AND LIVE LOADS the high-level approaches to the West Seattle Freeway Bridge, a concrete seg- mental main span bridge in Washington (see Figs. 13 and 14). The approaches consisted of numerous spans of about 150 ft (45.7 m) in length accommodat- ing two parallel 50 ft (15.2 m) road- ways with breakdown shoulders. This bridge was unusual because its approaches were of continuous span construction for both slab and superim- posed dead and live loads. The beams, Washington State Standard Precast girders (partially pretensioned and par- tially post-tensioned), were designed as simple spans for beam self weight. The construction sequence for the bridge progressed as follows: • Casting of piers without the cap. • Erection of temporary towers on either side of the pier to support the beam weight. &IG 7EST 3EATTLE &REEWAY "RIDGE CONTINUITY PIERS • Erection of beams and provision of temporary support. a monolithic design (see Fig. 12) that This difference in stresses caused the • Placement of the pier cap included five lines of girders with their bottom flanges of the beams to creep diaphragm with additional bottom flange, web, and top slab all (shorten) more than the top flange, re- reinforcement to that projecting cast as a single unit. The spans were all sulting in beams bowing upward and from the beams and the negative 75 ft (22.9 m) in length and 36 ft (11 m) causing a bumpy ride. moment area of the deck slab in width, out-to-out. Alternative B was To overcome this creep camber prob- (beam ends featured shear keys the low bid and was the one chosen for lem, the design team limited the dif- similar to precast segmental construction. ferential dead load compressive stress construction). On previously built bridges con- between the top and bottom fibers to • Post-tensioning of the girder line structed using monolithic superstruc- 200 to 300 psi (1.4 to 2.1 MPa). This and diaphragm together. tures, there was a problem involving solution provided a smooth ride for the • Casting of the top deck slab in the creep camber because of the large dif- traveling public, greatly minimized fu- positive moment area after curing ference in dead load stresses between ture creep camber, and delivered a du- of the negative moment area deck the top and bottom fibers of the beam. rable structure. slab concrete.
0#) */52.!, This construction method, one of After pile driving, the piles were re- the piers, redesigning the diaphragm, the first of its type in a highly seis- inforced at the top by drilling holes and and strengthening the deck slab since mic environment, was continuous for grouting steel reinforcing bars in the it acts as a horizontal diaphragm. The all loads except for the weight of the field to fix the piles into the footing. parallel roadway piers were also con- girders themselves. This procedure al- Structural analysis showed that par- nected by a frangible strut at the foot- lowed for the extension of bridge spans tial ship impact loads could be resisted ing level (see Fig. 16) designed to fail by about 20 to 30 ft (6.1 to 9.1 m) using within the pier exposed to a collision, in ductility at an optimum load; this Washington State DOT standard pre- while the remaining load would need to design was realized after testing vari- cast girders. be resisted by the participation of adja- ous cross sections in the field. (For cent and parallel piers. more information on this project, see .%7 35.3().% To allow force transfer to adjacent the July-August 1988 PCI JOURNAL, 3+97!9 "2)$'% piers and the parallel roadway piers, it pp. 96-123.) was necessary to strengthen the piers, The Sunshine Skyway Bridge won a 3T 0ETERSBURG &LORIDA by providing shear blocks at the top of PCI Design Award in 1987. TO As part of a construction manage- ment contract with other consultants, PB was retained by the Florida De- partment of Transportation (FDOT) to redesign the low-level approaches (of the First Sunshine Skyway Bridge, dis- cussed above) to resist an equivalent static ship impact force of 1000 kips (4448 kN). The low-level approaches are dual structures extending 4283 ft (1306 m) north and 8737 ft (2663 m) south (see Fig. 15). The overall bridge length is 21,880 ft (6669 m) with 2430 ft (741 m) of north and south high-level approaches and a main span length of 4000 ft (1219 m). The design of the low-level ap- proaches for ship impact was totally unprecedented at the time. Previously, ship impact design was only performed for the piers adjacent to the naviga- tional channel. Since this was a rede- sign and the contract was already bid, the type of pile, pier, and superstructure had to be retained. Nonetheless, strength improvements to resist ship impact forces to the piles, piers and superstructure were feasible. After considerable analytical effort in- volving the evaluation of various pil- ing configurations, and in consultation with the FDOT and the contractor, a solution using precast pilings was de- vised. Both parallel structures were also brought into action to resist the ship impact force. The footing directly affected by the impact force contained four piles bat- tered longitudinally, whereas the rear footing contained three vertical piles. The piles had to resist normal static and dynamic loads in addition to the ship &IG "UILT BETWEEN AND THE .EW 3UNSHINE 3KYWAY "RIDGE IN &LORIDA impact force. The piles were strength- CALLED FOR THE DESIGN OF LOW LEVEL APPROACHES FOR SHIP IMPACT PREVIOUSLY SHIP IMPACT ened with additional prestressing. DESIGN WAS ONLY PERFORMED FOR THE BRIDGE PIERS ADJACENT TO THE NAVIGATION CHANNEL
.OVEMBER $ECEMBER spans in deep water are comprised of a post-tensioned spliced girder design. The approach spans vary in length from 87 to 120 ft (26.5 to 36.6 m) and consist of conventional AASHTO girders made continuous for live load. &IG 4HE The deep-water spans near the center ROADWAY PIERS OF of the bridge, including the new navi- THE .EW 3UNSHINE gation span, consist of three separate "RIDGE WERE three-span continuous units made up CONNECTED BY A of Modified AASHTO Type VI 90 in. FRANGIBLE STRUT AT THE FOOTING LEVEL THAT (2286 mm) deep spliced post-tensioned WAS DESIGNED TO FAIL concrete I-girders with a maximum IN DUCTILITY AT AN span length of 222 ft (67.7 m) (see OPTIMUM LOAD Fig. 18). The substructure consists of pre- /#%!. #)49 65 ft (19.8 m) clearance above mean stressed concrete cylinder pile bents for the approach spans in shallow ,/.'0/24 "2)$'% high water. This structure replaced a low-level double-leaf bascule bridge water. The deep-water main spans are /CEAN #ITY .EW *ERSEY TO spanning over an inlet leading to the supported by hammerhead piers on pile caps formed with precast concrete AND TO Atlantic Ocean (see Fig. 17). The new cofferdams constructed near the water For the County of Cape May and the 26-span bridge utilizes a prestressed level and founded on concrete cylin- New Jersey Department of Transpor- concrete multi-girder superstructure der piles that extend as much as 110 ft tation, PB designed the Ocean City- supporting a reinforced concrete deck (33.5 m) below the inlet bottom. Con- Longport Bridge, a 3450 ft (1052 m) slab constructed using half-depth pre- struction of the bridge was completed long, high-level fixed bridge with a cast concrete panels, while the main in September 2002. (For further details
&IG 0RECAST CONCRETE COFFERDAMS FORMED THE FOUNDATIONS FOR THE HAMMERHEAD PIERS OF THE /CEAN #ITY ,ONGPORT "RIDGE IN .EW *ERSEY ;0HOTO COURTESY OF 'REGG +OHL !# 0HOTO=
0#) */52.!, caps and the piles. Precast, prestressed concrete double-tee beams were then positioned on top of the pier caps to provide a durable, low-maintenance structure. The precast concrete solution was chosen by the contractor for ease of construction, reduced construction time, and lower cost versus the original bridge rehabilitation option. The Ocean City-Longport Bridge was the winner in two categories of the 2003 PCI Design Awards Program – the Harry H. Edwards Industry Ad- vancement Award and the Best Bridge with Spans Greater than 135 ft (41 m).
%!34 0!3#!'/5,! "2)$'% *ACKSON #OUNTY -ISSISSIPPI TO At the request of the Mississippi &IG /CEAN #ITY ,ONGPORT "RIDGE SHOWN IN THIS PHOTOGRAPH IS THE ERECTION Department of Transportation, PB OF THE THREE SPAN CONTINUOUS UNITS MADE UP OF -ODIlED !!3(4/ 4YPE 6) IN was retained (as a subconsultant to MM DEEP SPLICED POST TENSIONED CONCRETE ) GIRDERS WITH A MAXIMUM SPAN a local company) to design the East LENGTH OF FT M Pascagoula River Bridge located in Jackson County. The bridge, which on the Ocean City-Longport Bridge, a method that provided a cofferdam at exceeds 3000 ft (914 m) in length, is see cover article in November-Decem- the water level to enable the concrete constructed with modified Florida bulb ber 2003 PCI JOURNAL, pp. 32-45.) pile cap to be constructed in a dry con- tee girders as well as AASHTO-PCI The harsh site conditions created dition. Contract drawings were devel- I-girders along its entire length, except by the swift currents and rough seas oped utilizing a high strength, 5000 psi for the post-tensioned spliced I-gird- common to this inlet dictated that the (35 MPa) precast concrete cofferdam ers designed for the main span (see amount of work performed in the water to construct the footing (pile cap). Figs. 19 and 20). be minimized, so several innovative The precast concrete cofferdam of- The main span of the bridge is a concepts were included in the design. fered the following benefits: three-span continuous post-tensioned The two most significant concepts were • Allowed construction of the pile I-girder configuration of 196 - 250 - the temporary support method used for cap in a dry condition. 196 ft (60 - 76.2 - 60 m). The bridge the spliced girder erection and the use • Eliminated the need for costly deck is nearly 137 ft (41.8 m) wide, of precast concrete cofferdams to form formwork for the pile cap. 7.5 in. (191 mm) thick, and consists the foundations for the hammerhead • Provided a method of protection of 16 lines of girders typically spaced piers. for the structural pile cap at 8.66 ft (2.64 m). The girder section The bridge components for the concrete, as the cofferdam was was developed based on a modified continuous spliced-girder spans were left in place and was considered 6 in. (152.4 mm) deep Florida Bulb Tee designed so that the girders could be sacrificial. with an 8 in. (20.3 mm) web. erected without the need for costly • Off-site fabrication permitted The two pier tables over the main falsework by temporarily making the quick erection once the piles were piers have a haunch girder that var- piers integral with the pier-table girders completely installed at the pier. ies linearly from 6 to 10 in. (152 to through the use of temporary tie-downs. During construction, the contractor 254 mm) in depth at the support. The Strongbacks were used to support the proposed a precast concrete alterna- haunch girders were spliced with 139 drop-in girders. These connections tive in lieu of rehabilitating the existing and 148 ft (42.3 and 45.1 m) of 6 ft avoided the need for any temporary structure as a fishing pier. The proposal (1.8 m) constant depth girders in the support towers for the superstructure, consisted of precast concrete pier caps end span and main span, respectively. resulting in considerable cost savings. that were supported by the existing con- Lateral stability of the girders was For the deep water foundations, pile crete piles. The piles were wrapped in provided by post-tensioned CIP dia- groups consisting of 54 in. (1372 mm) fiberglass jackets that were filled with phragms located at each spliced joint, diameter prestressed concrete cylinder concrete to extend the piles to the de- main pier supports, and end girder sup- piles were used with a pile cap con- sired elevation and extend service life. ports. structed at the water level. To construct High strength bolts were used to Each girder was post-tensioned con- the pile cap, it was necessary to utilize form the connection between the pile tinuously with four 10 - 0.6 in. (10 -
.OVEMBER $ECEMBER way Administration, the PB/Bechtel joint venture was the first to use the newly developed New England bulb tee girders. Initially, these girders were used for a temporary bridge, and later used for permanent bridges. Where long span bridges ended, transition bridges and slab-on-pile bridges were used. The transition bridges involved New Eng- land bulb tee shapes 1200 and 1400 (see Fig. 21). They were developed for spans from 60 to 90 ft (18.3 to 27.4 m) in length and at different girder spacings for both simple and continuous spans. To avoid requiring each section de- &IG 5SING MODIlED &LORIDA "ULB 4EE GIRDERS AS WELL AS !!3(4/ 0#) ) GIRDERS sign consultant to individually design THE %AST 0ASCAGOULA "RIDGE IN -ISSISSIPPI SHOWN UNDER CONSTRUCTION HERE EXCEEDS FT M IN LENGTH beams to suit specific requirements, PB designed and developed standard drawings that covered the span range mentioned above and girder spacings of 7 to 11 ft (2.1 to 3.4 m), including diaphragms and deck slab. The sub- structure, consisting of 16 in. (406 mm) square piles with CIP pile caps, was also standardized. This standardization concept was economical because it of- fered design consistency and optimized girder and substructure design. Similar standardization was also used for slab-on-pile bridges (see Figs. 22 and 23) whenever the roadway grade would be close to the ground and post-construction settlement of the sub- soil was likely. This concept included 16 in. (406 mm) precast, prestressed piles in a grid arrangement with 24 ft (7.3 m) (maximum) intervals along the &IG %RECTION OF %AST 0ASCAGOULA "RIDGE GIRDER roadway and 20 ft (6.1 m) intervals perpendicular to the roadway. 15.2 mm) diameter strand tendons. cient strength, the remaining tendons A precast circular shell with a bot- The special feature of this bridge is the were stressed. tom opening was placed with the pile asymmetrical span length of the haunch projecting into the shell and the annu- girder. The girder length on the side #%.42!, !24%29 lar space was concreted, thus provid- span was intentionally designed longer 45..%, 02/*%#4 ing a seismically resistant connection. than the main span side to ensure a posi- Inverted precast concrete tee-beams tive reaction at the temporary support in "OSTON -ASSACHUSETTS connected the piles in the longitudinal the side span during erection. TO 0RESENT direction, upon which 7 in. (178 mm) The post-tensioning force was ap- The massive Central Artery/Tunnel precast slabs were placed. A CIP deck plied in stages. The first 50 percent Project, known for its many innova- slab, 5 to 8 in. (127 to 203 mm) thick, of the tendons were stressed after tions in bridge and tunnel construction, was placed on top of the precast deck completion of girder erection, includ- also involved new concepts in small followed by a 1.5 in. (38 mm) micro- ing the closure pour at the splice loca- and medium span bridges. With the silica overlay. tion. After completion of the deck slab, assistance of the Massachusetts Turn- Starting in May-June 2000 and end- when the deck concrete reached suffi- pike Authority and the Federal High- ing in March-April 2001, a series of
0#) */52.!, six articles were published in the PCI JOURNAL on the innovative features of the Central Artery/Tunnel Project. These articles were co-authored by Vijay Chandra, Anthony L. Ricci, Paul J. Towell, Peter A. Mainville, Elie H. Homsi, Keith Donnington, Ted Wis- niewski, Jennifer Hill and Ru-Chu Hsu. The authors were collectively honored by the PCI with the 2001 Robert J. Lyman Award for their series of papers on this project.
#/.#,5$).' 2%-!2+3 PB is proud to have been an active participant in the evolution of precast, prestressed concrete technology from its introduction in the United States. &IG .EW DESIGN CONCEPTS WERE DEVELOPED FOR THE #ENTRAL !RTERY4UNNEL 0ROJECT PB implemented precast concrete tech- "OSTON -ASSACHUSETTS nology on many long bridge projects while simultaneously advancing the state-of-the-art of bridge construc- tion. Notable among these advances were: the application of spliced girder technology; implementation of 0.6 in. (15.2 mm) diameter strands; and de- signing precast, prestressed concrete bridges to resist major ship impact forces. Over the years, PB also played a role in developing efficient designs for bridge construction, including: economical girder shapes; very long precast, prestressed piles; standardiza- tion of the design of New England bulb tees for bridges; and precast shells for footings and other purposes. It is hoped that these advancements have helped &IG #ENTRAL !RTERY4UNNEL 0ROJECT SLAB ON PILE UNDER CONSTRUCTION to reshape the precast concrete indus- IN "OSTON -ASSACHUSETTS try through the decades and have been a catalyst for further innovations.
!#+./7,%$'-%.43 The authors wish to thank the Florida, Texas, Hawaii, Massachusetts, Virginia, Washington, New Jersey and Mississippi Departments of Transpor- tation for giving PB the opportunity to implement so many new technolo- gies on bridge projects. The authors also want to thank the many precast- ers who provided their expertise dur- ing the development of numerous new techniques and concepts. And finally, it is important to recognize the many engineers who participated and con- tributed in these developments over the &IG ! SLAB ON PILE BRIDGE IS SHOWN BEFORE THE CLOSURE WALL WAS COMPLETED AT THE past 50 years. #ENTRAL !RTERY4UNNEL 0ROJECT
.OVEMBER $ECEMBER