Seismic performance evaluation of reinforced concrete frames infilled with autoclave aerated concrete masonry

Siddiqui, Umair Ahmed
Seismic risk reduction requires detailed assessment and rehabilitation of vulnerable buildings to avoid significant property and life losses. Several reinforced concrete buildings are deficiently designed and constructed and also contain non-engineered unreinforced masonry infill panels which dominate the seismic response and impart excessive lateral forces for which they are not designed for. Therefore, seismic performance assessment procedures recommended in guidelines and codes needs detailed examination through rigorous experimental and analytical research to ensure the adequacy of suggested provisions and modelling parameters. This study investigates the seismic behaviour of four reinforced concrete frames, constructed in the Structural Dynamics Laboratory at Middle East Technical University and tested by the pseudo-dynamic testing procedure. These four specimens are investigated in pairs of two: the “Non-conforming” with material and detailing deficiencies, and the “Code-conforming” compliant with Turkish Earthquake Code 2007. Each pair contains one bare frame while another frame infilled with autoclave aerated concrete (AAC) block masonry. The focus of this study is to experimentally investigate the influence of AAC masonry infill panels on the seismic response of RC frames in both configurations. Numerical modelling of frames is conducted on the OpenSees platform following guidelines of TEC-2007 and ASCE/SEI 41-06.Models, calibrated with experiments using time-history results, are used for assessment using pushover and time-history methods in accordance with the procedures of TEC-2007 and ASCE/SEI 41-06. The presence of AAC infills is found to considerably influence deformation pattern, damage distribution and failure modes in deficient frames whereas in code-conforming frames the effect is not significant. Calibrating the models of deficient frames by using reduced nominal strengths and modified joint-offsets in order to predict accurate seismic response and damage distribution, is not efficient. To capture the deformation pattern on local scale, joint flexibility and frame-infill interaction needs to be explicitly accounted. The assessment of damage in members bounding the infill panels with ASCE/SEI 41-06 provisions gives accurate predictions of observed damages whereas TEC-2007 underestimates the damages for those members.
Citation Formats
U. A. Siddiqui, “Seismic performance evaluation of reinforced concrete frames infilled with autoclave aerated concrete masonry,” M.S. - Master of Science, Middle East Technical University, 2013.