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A parking garage constructed using precast double tees supported by structural steel experienced an overload condition from snow removal operations that resulted in severe cracking and localized failures. Structural analyses of the affected members revealed insufficient shear reinforcement in the precast concrete shallow dapped end regions. Subsequent surveys revealed a significant number of additional cracked double tees. An inspection and testing program was developed to assess the ability of the as-built double tees to resist code-prescribed loads. The program included ground penetrating radar (GPR) to locate reinforcement on a statistically relevant sample and full-scale load testing on selected double tees that represented approximately 90 percent of the population. The load tests demonstrated double tees with similar conditions were capable of resisting code-prescribed loads, limiting repairs to only those locations, where existing conditions were not comparable to those present in the load-tested members. Guidelines based on crack width and location were developed for assessing the need to repair individual double tees.

Presents a case study on the use of architectural precast concrete as a cost-effective approach to restore an historic park facility in Chicago, Illinois. The main entrance portico of the facility was originally constructed with an elaborate limestone beam or entablature, carried by massive limestone columns. The carved limestone architrave (soffit), frieze, and cornice (upper projection) pieces of the entablature were attached to backup brickwork and concealed steel lintel beams with metal anchors. After significant stone damage and movements occurred due to long-term corrosion of embedded steel components, several limestone soffit pieces were removed from the building for safety. The restoration design utilized architectural precast concrete with a formed soffit having the identical proportions, texture and color as the damaged architrave stone pieces, and had structural capacity to replace the existing steel lintel beams. The design provided a unique, cost-effective approach for replacing deteriorated and damaged components, while retaining the original, intricate limestone carvings.

Physical and mechanical testing was conducted on composite stone faced aluminum honeycomb panels manufactured in the United States for use as exterior veneer panels on buildings. Testing was conducted on specimens cut from new stone faced panels as well as stone faced panels removed from service. For comparison purposes specimens cut from new unfaced honeycomb panels were also tested. The purpose of the testing was to measure certain strength, durability, and performance characteristics of the faced honeycomb panel’s composite construction. The stone faced specimens tested included those faced with travertine, limestone, and granite. Old travertine faced specimens had been in service for more than 18 years. The results very strongly suggest that the structural performance of the composite panel is dominated by the aluminum honeycomb portion. The stone portion is essentially a thin veneer adhered to the honeycomb that provides little if any structural strength.

Modern building facade design concepts consider all cladding materials, including dimension stone cladding, as nonstructural elements designed to transmit localized gravity and lateral loads to the primary building structural elements. In practice, the structural backup behind dimension stone cladding can take a wide variety of forms, including cast-in-place concrete shear walls, brick and concrete masonry units, aluminum curtain wall system framing, hot and cold rolled steel subframes, and precast concrete panels and members. The flexural stiffness of these backup systems can vary widely, with cast-in-place concrete shear walls on one end of the stiffness spectrum and aluminum curtain framing on the other. The stiffness of dimension stone cladding relative to the backup system can have a significant effect both on the stresses induced in the cladding and the loads transmitted through the cladding anchors. Likewise, the stiffness of the anchor elements and the backup system can affect the loading and stress distribution within the cladding panels. This paper addresses some of the issues associated with the interaction of dimension stone cladding panels, panel anchors, and metal backup structures, and the effects of relative stiffness on load and stress distributions. Information is presented that was obtained from laboratory tests and analyses for new designs, as well as investigations of dimension stone cladding failures.

One of the most important aspects of designing dimension stone cladding involves determining the configuration, size, and spacing of the anchorages that will affix the stone panels to the underlying building substrate. Information from many sources, including material strength testing, anchorage strength testing, and knowledge of the stress states created within stone cladding panels by loaded anchorages, is crucial to this process. In this paper, relationships are examined between material strength, anchorage strength, and induced stress states for four common anchorage configurations: edge dowels, Type 31 back anchors, and edge kerfs with strap and split-tail anchors. For each of these four anchor types, the relevant material and anchorage strength test data obtained for a medium-grained granite, in conjunction with finite element computer analyses of the stress states induced in the stone panels by the anchors and within the material strength test specimens, are presented. Material strength test configurations evaluated include ASTM C 880 Standard Test Method for Flexural Strength of Dimension Stone, ASTM C 99 Standard Test Method for Modulus of Rupture of Dimension Stone, and a proposed test for punching shear currently under consideration by ASTM Subcommittee C18.01. All anchorage strength tests were performed in accordance with ASTM C 1354 Standard Test Method for Strength of Individual Stone Anchorages in Dimension Stone.

Natural stone has been used for centuries as building material. In historical time it was mainly used as load bearing elements, but within the past 50 years a new processing technique has made it commercially feasible to produce and use thin facade cladding. Unfortunately, a number of marble facades on buildings in both Europe and elsewhere have had serious problems with deterioration of the stone material. The TEAM (TEAM = TEsting and Assessment of Marble and limestone) project consortium represents nine European countries and comprises 16 partners, representing stone producers and trade associations, testing laboratories, standardization and certificate bodies, consultants, building owners and caretakers and producers of fixing and repair systems. The project had a budget of approximately 5 million dollars and was partly funded by the European Commission under the contract no. G5RD-CT-2000-00233. Two of the main objectives in the TEAM project were: — To understand and explain the mechanisms of the expansion, bowing, and loss of strength leading to degradation of marble and limestone clad facades. — To prevent the use of deleterious marble and limestone by introducing a draft for new European standards. This paper presents some of the important conclusions drawn from a literature review carried out within the TEAM project—and was based on an extensive review of literature on marble and limestone deterioration dating from the late 1800s to 2006 and the results of the TEAM project. The comprehensive information from more than 70 selected literature references is reviewed and discussed in order to describe the present knowledge on the causes and mechanisms responsible for the bowing and strength loss of thin marble cladding. In the following, the literature and TEAM findings are grouped under a number of headings proposed to explain observations. Thus, the information from the literature is compared and supplemented with the results from the TEAM project in order to present a good overview of the existing, most relevant, knowledge in the field. The literature review reveals that only few researchers have examined the durability problem from a broad perspective. In addition, no conclusive answer about the mechanisms and influencing factors can be given. The TEAM project has made it possible to identify several of the key influencing factors in marble degradation, the relative importance of various factors, and to gain a deeper understanding of the mechanisms involved.