Essay Example on Performance-based seismic engineering








Introduction Performance based seismic engineering is the modern approach to earthquake resistant designs The promise of performance based seismic engineering PBSE is to erect structures with predictable seismic performance 1 PBA performance based analysis generally uses the pushover analysis which is then verification by nonlinear static procedures like Coefficient Method Capacity Spectrum Method N2 Method etc 2 Procedures from this category accrued from the philosophy of performance based seismic design PBSD recognize the fact that structural damage is mainly determined by lateral displacement or drifts 3 One of the NSPs are consisted of Capacity Spectrum Method CSM suggested by Freeman and collaborators 1975 and 1998 4 and implemented in ATC 40 guidelines 1996 U S Army 1986 ATC 1996 FEMA 2000 Then this method was modified by Fajfar in 1999 5 The use of shear wall had begun on the eve of 20th century The problem for the structural engineers then was to find the optimum design frame for tall RCC buildings and the location of shear walls to act against earthquakes 6 The solution is strengthening and adding more stiffness of the critical structural members to reduce the damage against lateral loads 7

The use of shear wall system which is among the conventional load bearing systems and proven to be economical in buildings up to 35 stories high it is very common in multi storied buildings in earthquake prone zones 8 Pushover analysis is a nonlinear static method described in Eurocode 8 2003 In this method lateral force thrust distribution is applied to the structure and monotonically increased Plot of the total base shear versus roof displacement is then obtained which indicates any premature failure or weakness which is termed as capacity curve 9 Software available to perform nonlinear static pushover analysis are ETABS SAP ADINA SC Push3D Extended Three Dimensional Buildings Systems ETABS a Structural Analysis finite element program that works with complex geometry and monitors deformation at all hinges to determine ultimate deformation It has built in defaults for ACI 318 material properties and ATC 40 and FEMA 273 hinge properties Also it has the capability for inputting any material or hinge property ETABS 9 7 deals with the buildings only 10 ETABS 9 7 have features of performing PBA by going through some simple steps 11 Statement of problem Bangladesh is one of the most densely populated countries in the world 

There is a big rush for urbanization throughout the major cities Besides this Bangladesh is in a big threat of major earthquake disaster A magnitude of 8 earthquake can destroy about 70 000 or more building in capital alone 12 So it is a burning question that what might be the solution that can help to minimize the loss as well as provide a suggestion in design phase of building structure The recent dimensions of the problem that we are facing are i Rapid but sustainable urbanization ii Major threat of Earthquake iii Economically efficient and technically effective solution against earthquake This research will focus on taking better decision under these circumstances Shear wall system is the most economic earthquake resistant building system till now 13 Moreover building structure of regular geometry shows better performance against earthquake This work is intended to make a better combination among economic and desirable section of shear wall for a regular building pattern with a variety of soil property An effort will be made to visualize a good combination among these parameters that will help to design a new building structure as well as to assess an existing one in a very effective way Methodology Selection of Building plan Two types of regular building plans will be selected for analysis

One is square and the other is rectangular Both of plans have same surface area of 60 ft x 60 ft The buildings are located in Sylhet city which is an earthquake prone zone of Bangladesh Zone 3 according to BNBC 2006 Assortment of the shape of shear wall Ten different types of shear wall will be introduced in this research work In the case of choosing shear wall section economical and desirable shape of shear walls have given priority Soil property The response to earthquake motion of a structure founded on a deformable soil can be significantly different from the response of the same structure on a rigid foundation rock 14 15 In order to predict the effect of soil properties on building structure soil profiles described in UBC 1997 will be used in this work Selection of building model A building model is a particular combination of criterions specified above A number of total 300 models of different combinations are expected to be analyzed in this research work Analysis software ETABS Extended

Three Dimensional Analysis of Building System ETABS Version 9 7 will be used for the analysis The analysis in ETABS 9 7 involves the following four steps includes modeling static analysis designing and pushover analysis Analytics of building model and accumulation of result Using ETABS buildings will be analyzed for three different cases This analyzation will be performed for both linear static method and pushover method with aid of ETABS After the analysis different structural performance parameter s values will be collected Comparative study A comparative study will be carried out based on the analysis result The focal point will be the best combination of criterions that shows a better performance in case of seismic loads and possess Discussion A good number of efforts were conducted to make structures safe and hazard proof Still this search is going on in both simplified and more complex way Out comes of this paper are expected to reflect a better view about designing and assessment of structures in hazard prone areas Also results will help in decision making in case of choosing building models and their possible behavior An overall contribution will result in a sustainable infrastructure development which is a key demand for the modern world

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