Harvard University Stadium by Wayne Lawson.Indd

lessons learned Restoration of Harvard University Stadium By Wayne R. Lawson, P.E.

Harvard Stadium was originally construct- This investigation had several purposes: ed over a fi ve (5) month period in 1903 at a. Correct some of the more serious areas a cost of $310,000. In 1910 the colonnade of concrete spalling and deterioration level columns, wall, and roof were added. while replicating the natural color tone During the renovation in 1929, steel bleach- of the adjacent concrete surfaces. ers were installed at the northeast end mak- b. Investigate concrete cracking and ing the stadium into an oval confi guration methods of repair. and thereby increasing the seating capacity to c. Evaluate through load testing the 57,000. However, in 1952, the bleachers were capacity of a typical in-situ concrete removed, reverting the stadium back to its transfer beam. © original horseshoe shape with a total seatingCopyright Despite signs of deterioration and evidence mation of ASR and unknown variables, which capacity of 37,000. Finally in 1982, at a cost of supplemental framing, CBI recognized resulted in installation of two structural sup- of $8 million, the last renovation was made that the stadium had been successfully utilized port members during the 1982 repairs. including precast concrete seating, making the for over 100 years without signs of overstress A number of top surface loading methods stadium into what we see today. or failure. It was this historical performance were reviewed including mass concrete The physical condition of the stadium in that lead CBI to advise the owner that blocks and water, however these required dis- 2004 varies widely, since elements of the 1903 undertaking a fi eld load test was an expendi- ruption of the stadium activities. By working construction are essentially in the same con- ture that, if successful, would derive signifi cant with a rigging contractor, an underside load- dition as when the stadium was complet- cost saving to the overall stadium restoration ing method was devised, utilizing a crane ed. Elements in this condition are concrete project. Further, section 1709.1 of the sixth counterweight load frame that was supported walls, columns and slabs which have been edition of the Massachusetts State Building by six (6) 25-ton hydraulic jacks and suspend- largely protected from the elements for over Code permits in-site load tests “whenever ed from the subject beam through a steel 100 years. At the other end of the spectrum there is a reasonable doubt as to the stability cable and harness. are structural and some largely architectural or load bearing capability of a completed The existing precast seating was dis- elements which have been severely eroded and building, structure or portion thereof for the connected from the beam and temporarily compromised by the environment through expected loads, an engineering assessment shall supported with additional shoring, provided the years. Some of the problems were caused be required. The engineering assessment shall to allow four inch settlement of the beam in by a lack of understanding of structural involve either a structural analysis or an in-situ the event that a catastrophic failure occurred function and the use of materials of construc- load test, or both.” during the load test. tion, materialsSTRUCTURE which were available in 1903 The Massachusetts State Building Code The loading for the test was calculated in but were unlike their better counterparts requires that the load test be conducted in accordance with ACI Chapter 20. In order available today. accordance with the applicable reference to develop the appropriate test load for the A structure of this sortmagazine with a large expanse standard, which in this case is the American subject beam, CBI fi rst investigated the of concrete has the potential to undergo Concrete Institute (ACI). original 1903 framing conditions. The 1903 thermal expansion and contraction of up to Prior to initiation of the load tests, CBI framing confi guration required that the beam fi ve (5) inches each side of the mass center. completed a preload test investigation to de- support a total test load of 190 kips, to satisfy It appears as though the builders, constrained termine the existing site con- by limited concrete transport ability and few ditions. This investigation construction joint isolation materials, devised included removal of in-situ an approach which was perhaps the fi rst use concrete cores for compres- of segmental construction in the area. This sion testing and petrographic resulted in a great number of slip joints not analysis. Additionally, a pro- always aligned through the structure. With- gram of concrete excavation out the corrosion resistant and deformable and pachometer survey was and low friction materials available today, completed to identify rein- these joints lost much of their usefulness forcing steel locations and early in the life of the stadium. conditions. The interior con- Expansion joints which have “welded” due crete transfer beam at Seating to corrosion and those which have resisted Section 26 was selected for anticipated movement are examples. load testing based on the vi- In 2003, CBI Consulting, Inc. was en- sual appearance of the beam gaged by Harvard University to investigate (extensive cracks, and extreme methods and procedures to be used for effl orescence on the concrete maintenance repair of Harvard Stadium. surface), petrographic confi r-

36 STRUCTURE magazine • September 2005 However, in order to maintain the ASR dete- The restoration of Harvard Stadium illus- riorated beams it is essential that future mois- trates the challenges that face the engineer. ture ingress be prevented while permitting the The completion of a successful project re- moisture within to move outward. quires an ability to evaluate and solve specifi c During the investigation, CBI coordinated and often unique conditions throughout the the installation of sample topical applications design and the construction process. These is- of lithium to existing concrete elements sues require engineering/technical knowledge in attempts to arrest the deterioration due and experience, with a clear understanding of to ASR. With high material costs and the owner’s fi nancial limitations.▪ impregnation variations, it was concluded that this was not an effective solution. Wayne R. Lawson, P.E., is a principal and Therefore, the proposed program of stadium structural engineer with CBI Consulting repairs includes coating the beams with a Inc. in Boston, Massachusetts. During his water barrier system and installation of top 22 years of practice, he has been involved surface cap fl ashings. Additionally, the open in structural design, forensic investigations joints in the stadium seating are to be sealed. and restoration of a variety of structural types and systems. Wayne can be reached at [email protected]. Copyright © ACI 20.3.2. However, with the addition of supplemental beams and columns in 1982, the total test load requirement for the subject beam is reduced to 90 kips. Engineering calculations indicated that the beam could support a total dead + live load of 214 kips when considering only the shear strength of the concrete. Further, the beam has a total dead + live capacity of 282 kips when only fl exure is considered. On the basis of this information, CBI con- cluded that the initial test load should be 90 kips to satisfy the current “as-built” conditions. In the event that this loading was successfully HUNT’N PECK VS. POINT’N CLICK supported by the beam, the test load would be raised to the 1903 framing conditions (190 Simpson’s new Anchor Designer Simpson's time saving Anchor Designer For Advertiser Information, visit kips) and if permissible ultimately to the shear Software makes it easy. Software is easy and straightforward to use capacitySTRUCTURE of the beam concrete (214 kips). And it’s FREE! and it's FREE! Do the math and see Dial gauges were installed at each end for yourself how much time and Our new Anchor Designer Software effort you'll save. Logon to and midspan to measure defl ections during makes it easy to select just the www.simpsonanchors.com the load test. During the test, the load was right anchor for your application. applied in four increments:magazine 90 kips, 160 kips, for a free download and No more flipping through put Anchor Designer to work www.structuremag.org 190 kips and 214 kips. Initially, the entire catalog pages searching for for you today. Or call us at test load was supported by the six (6) hy- specific products, base 800-999-5099 for our new draulic jacks. At each test load increment, the materials or load values - 2005 CD ROM. It includes Anchor jacks were lowered to enable a transfer of the simply enter the performance Designer software along with appropriate load to the beam. Defl ection criteria you need and the program TM complete product/catalog informa- recommends anchor solutions based on measurements were taken by CBI at midspan tion, technical bulletins, code reports test data. Load reductions for variables and adjacent to the supporting columns after and more. each load increment. The defl ections were like spacing and edge distance, base then measured after the fi nal load had been in material thickness and temperature are Whatever the application, place for a twenty-four hour period. The test automatically calculated - without punching Simpson Anchor Systems load was subsequently removed after comple- a single calculator button. Better still, all has the product to the results and calculations can be saved do the job right! tion of the twenty–four hour load period, or printed out for handy reference. and the structure recovered more than ninety percent of the maximum defl ection. The load test results successfully demon- strated that the existing beams could safely support the required dead and live loads.

These results eliminated the need for instal- ANCHORS ADHESIVES P. A .T. CARBIDE lation of permanent supplemental framing, ™ © Copyright 2005 IN THE SPECS - ON THE JOB - AT YOUR SERVICE allowing more expenditures for other nec- Simpson Strong-Tie Co., Inc. SIMPSON STRONG-TIE COMPANY, INC. essary stadium repairs and improvements. 800-999-5099 • www.simpsonanchors.com STRUCTURE magazine • September 2005 37