An-Najah Staff

Design of seismically resistant structures in Palestine is presently an obligatory requirement according to the local government bylaws because the region lies well within an active earthquake prone zone. The Seismic Zones in Palestine are either in 1, 2A, 2B and 3; i.e. between 0.15g and 0.3g which are equivalent to about 5 - 6.9 degrees on the Richter Scale. Local structures are generally designed  in accordance with the 1997 Uniform Building Code regulations with the intention of providing life safety performance under a potential design earthquake; the ubiquitous Jordanian Design Code is a replicate of the UBC97. Furthermore, structural analysis is accomplished by either the Equivalent Lateral Load Method or the Response Spectrum Method. Seldom does mundane structural engineering resort to time domain analysis. Present local design practices assume that structures continue to behave elastically which may not be the case under strong seismic events.

Contemporary building structures in Palestine are, by enlarge, comprised of reinforced concrete frames in-filled with masonry walls but the interaction of the later with the rest of the structure is seldom investigated. Masonry structures therefore refer to buildings that have exterior infill un-reinforced stone-clad walls. The present undertaking presents a detailed structural study example that includes, inter alias, a regular and an irregular plan of a common six story edifice; the same exercise is repeated for a twenty story edifice. The numerical models investigated are built with due respect to the common construction practices and the local building materials and are subjected to the expected seismic action. The discourse follows the philosophy of Performance Based Seismic Engineering procedure better known as FEMA 356 Nonlinear Pushover Analysis and using the universally acclaimed Finite Element Method software ETABS 2015. The PBSE procedure is gaining popularity worldwide because it is capable of adequately addressing existing as well as new structures. It has the capability of predicting the points of weakness within the structure, so that remedial retrofitting procedures may be applied if and when they become necessary or for testing the adequacy of new structural designs.

The focus of the following study is the relevance of nonlinear analysis to local building structural systems; or conversely a study of the adequacy of the local construction systems to comply with modern seismic design requirements and approach knowing the severity of tremors potentially expected in Palestine.