International Concrete Abstracts Portal

This Symposiuml Publication includes 48 papers from the ACI Fifth International Confrence on Innovation in Design with Emphasis on Seismic, Wind, and Environmental Loading, Quality Control, and Innovation in Materials/ Hot-Weather Concreting, held in December 2002 in Cancun, Mexico. Topics include the behavior of flared-column bents under seismic loading, marine exposure of high-strength light-weight concrete, and seismic strengthening of a nonductile concrete frame building. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP209

When insulated concrete sandwich panels are used in the envelope of a building, the experior and interior are subjected to two different environments. The exterior concrete wythe is subjected to outside weather swings in the temperature and humidity causing thermal expansion and contraction, whereas the interior is exposed to a controlled steady room temperature environment. Dimensional change in the panel depends primarily on the height of the panel and the relative change in temperature. The severity increases when the outside concrete wythe of a tall panel is supported (and hence constrained) on the foundation dlowing vertical movements only at the top. If these weather cyclic movements are restricted, the panels may experience cracking and eventually may experience a premature failure. Therefore, the tie system used in the panels should be flexible enough to accommodate these differential movements. This often is the most critical issue in the service life of the building when sandwich panels are used. There is no standard test method available to evaluate the thermal non-uniform cyclic behavior of insulated panel systems. The authors have followed a sci- entific approach to evaluate these stresses by subjecting the ties to real life cycles occurring over a period of time. The system used in this study includes a low-conductivity polymer connector with extruded polystyrene rigid foam insulation. The testing was continued until the failure of the system or to more than 100 years of equivalent cycling (the expected service life of the building), whichever is less. This paper focuses on the methodology developed and parameters considered in developing the criteria for testing weather cycles. The procedure may be followed to evaluate any given insulated panel system to predict its long-term durability.

The performance of beam-to-column connections subjected to reversed cyclic loading depends on several variables. In this investigation, the effects of eccentric spandrel beams, wide normal beams, column section aspect ratio, loading in two principal directions, and slab participation on the inelastic behavior of beam-to-column connections are studied. The experimental program features three 3/4-scale exterior reinforced concrete beam-column-slab subassemblies. The major design variables for the specimens are the eccentricity of the spandrel beam with respect to column, beam and column section aspect ratios, and joint shear stress level. Results of the experimental program, including load-displacement response, beam plastic hinge rotation, joint distortion, and bond deterioration are presented in this paper.

After the August 17, 2000 Kocaeli, Turkey, Earthquake (Mw = 7.4) Degenkolb Engineers sent a field reconnaissance team to observe earthquake related building damage in Turkey. Observations were made in Adapazari, which is located approximately 52 km northeast of the earthquake epicenter and 3 km directly north of the North Anatolian Fault. In Adapazari, a range building performance for the typical low-rise concrete frame residential building was observed. The building performance varied from virtually no damage to complete collapse. A four-story residential building in Adapazari that was observed to have signficant structural damage was chosen for evaluation. The building was evaluated using a Tier Three evaluation in accordance with FEMA 310, Handbook for the Seismic evaluations of Buildings - A Prestandard. As expected, the evaluation indicated the building would not meet the Life Safety Performance Objective of FEMA 310 for the 10% exceedance in 50-year earthquake. Traditionally, buildings with Life Safety deficiencies would be strengthened to comply with current building code. Rather than strengthening the building with a traditional code based upgrade, a conceptual strengthening scheme for Life Safety Performanee was developed using FEMA 356, Prestandard and Commentary for the Seismic Rehabilitation of Buildings. The strengthening scheme, which includes the addition of concrete shear walls, is presented. In addition, a comparison between the FEMA 356 lateral design force level requirements for the strengthened building and current Turkish Building Code is presented.

The finite-element method is used to carry out parametric analyses on the thermal response of simulated defects in fiber-reinforced polymer (FRP) lami- nates applied to a concrete substrate. The aim is to assess the potential for qualtitative infrared thermography in not only detecting a flaw but also being able to describe its physical characteristics. Three parametric studies are presented, namely: 1) relationship between the thermal input, the maximum signal, and the maximum surface temprature; 2) effects of flaw depth and the number of FRP layers; and 3) effect of flaw width. From these simulations, procedures are established for selecting the thermal input and estimating the flaw depth and width.