تاثير بازشوهاي نامنظم بر خصوصيات لرزه اي ديواره هاي برشي بتن آرمه

چكيده انگليسي :

The Effect of Irregular Openings on Dynamic Behavior of Concrete Shear Walls Mohammad Reza Dehkordi m dehkordi@cv iut ac ir Date of Submission March 16 2011 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors Dr Kiachehr Behfarnia Kia@cc iut ac ir Adviser Dr Farhad Behnamfar Farhad@cc iut ac ir Abstract People have always needed house But increasing in human population in these last decades make it unavoidable to build safe and economical residential structures Concrete shear walls are one of the main lateral resisting elements in high rise buildings Architectural and mechanical restrictions in many cases demands opening in concrete walls However there is not sufficient information about dynamic behavior of such walls The aim of this study was determination of characteristics of walls with regular and irregular openings For this purpose 5 10 and 15 story walls were modeled with various types of openings in size and location Area of openings was 5 and 20 of story area where located in center eccentric and staggered in studied models Eccentric and staggered openings were built in left or right of wall centerline with 25 percent of eccentricity Nonlinear static pushover analysis was conducted using Perform 3D program to investigate the influence of regular and irregular openings on dynamic behavior of shear walls From the analysis pushover curve that shows base shear force against increasing of roof displacement was obtained All of the diagrams were idealized by bilinear envelope with Krawinkler and Nassar s method 1992 and then nonlinear parameters such as ductility and reduction factor obtained Openings cause changes in dynamic behavior of shear walls such as ultimate load reduction factor ductility and higher mode effects Eccentric openings in most cases cause larger ductility and reduction factor Stagger openings was more helpful for the higher walls than the walls with less stories Effect of all types of openings on dynamic characteristics of shear walls in this study was decrease with increasing in the height of the wall or wall wide Generally obtained results shown that the openings in some situations may cause better seismic behavior in shear walls For example openings may provide walls with larger reduction factor and greater ductility However use of openings may improve seismic behavior in some type of shear walls but also reduction in ultimate load restricts designers in use of very large openings To compare the target displacement with the real displacement that structure may encountered in an earthquake time history nonlinear dynamic analysis were conducted for all models Three pair of records form Elcentro Northridge and lomaprieta earthquakes used to conduct nonlinear dynamic analysis The results shown that the target displacement values that obtain from FEMA 356 guideline in shear wall structures are less than the real one that the earthquake causes in structures so the corrective coefficient equal to the nonlinear dynamic analysis drift divided by target displacement were suggested to multiply to the target displacement for shear wall structures Keywords concrete shear walls pushover reduction factor nonlinear dynamic

دهكردي، محمدرضا

تاثير بازشوهاي نامنظم بر خصوصيات لرزه اي ديواره هاي برشي بتن آرمه

آناليز استاتيكي غير خطي , ضريب رفتار