Seismic Performance Evaluation of Reinforced Concrete Moment Resisting Frames with Various Ductility in Low Seismic Zone

Abstract

Problem statement: Bangkok, the capital of Thailand, is at moderate risk for distant earthquake due to the ability of soft soil to amplify ground motion about 3-4 times although it locates in low seismic zone. In addition, before the enforcement of seismic loading for buildings in the Ministerial Law in 2007, many existing reinforced concrete buildings in Bangkok may have been designed without consideration for seismic loading and did not incorporate the special detailing provisions that required for ductile concrete frames. Now, guidelines for seismic loading of buildings of Thailand (DPT 1302-52) have been recently improved by adopting ASCE7-05. Approach: This study is focused on the effects of the new guidelines on cost estimates and the seismic performance of a nine-story reinforced concrete apartment building with various ductility by the nonlinear static and nonlinear dynamic analyses compared with a Gravity Load Designed (GLD) building. Five selected ground motion records are investigated in the analyses. In order to examine the influence of design ductility classes, the seismic forces on moment resisting frame buildings are defined according to the newly proposed seismic specifications of Thailand with ductility from 8, 5 and 3, corresponding to Special Ductile (SDF), Intermediate Ductile (IDF) and Ordinary Ductile (ODF) frames, respectively. The various frames are assumed to have collapsed if the local drift exceed of 3, 2.5, 2 and 1% for SDF, IDF, ODF and GLD, respectively. Results: SDF is more ductile than that of ODF, however, the strength of SDF is less than ODF. For inelastic designs, SDF decreases stiffness and increases deflection of structures. As for the effect on cost estimates, ODF is the most expensive among ODF, IDF and SDF. Costs of SDF and IDF in Bangkok are quite similar. The study found that the average PGAs for the failure state for SDF, IDF, ODF and GLD are 0.76, 0.60, 0.50 and 0.29g, respectively. Moreover, for the failure state of GLD with volumetric ratio of horizontal confinement within joint panel less than 0.003, the average PGA is only 0.15g. Conclusion/Recommendations: These various frame designs are predicted to just achieve the Immediate Occupancy (IO) performance level. The results also indicate that all frames including GLD are able to withstand a design earthquake. The SDF and IDF are the two best options in consideration of cost and seismic performance.

Finite Element Analysis of Large Capacity Endplate Steel Connections

“…Over the past four decades, steel moment resisting frames have become popular and widely used in steel construction, mainly due to their tremendous energy dissipating characteristics under cyclic loading which represents the ground-shaking and earthquake environments. In January 17, 1994, the Northridge earthquake (6.8 on the Richter scale) struck Los Angeles causing significant wide range damage to various buildings of different heights (Yee et al, 2011;Yalciner and Hedayat, 2010; Choopool and Boonyapinyo, 2011;Abu-Lebdeh et al, 2011;Aziz and Ching, 2010). Brittle fracture in column webs, column flanges, welds and shear tabs were reported.…”

A New Viewpoint for Seismotectonic Zoning

“…In order to get access to distribution mode of seismic deformation various seismotectonic studies have been conducted (Unesco, 1985;Berberian, 1976;Nowroozi, 1976;1979;Nowroozi and Ahmadi, 1986;Mirzaei et al, 1999;Tavakoli and Ghafory-Ashtiani, 1999;Ansari et al, 2009. However the seismic studies are important in various scales (Benmenni and Benrachedi, 2010;Amiri and Tabatabaei, 2008;Al-Zoubi, 2005;Chakraborty and Choudhury, 2009;Hazarika, 2009;Choopool and Boonyapinyo, 2011;Abu-Lebdeh et al, 2011;Teachavorasinskun et al, 2009;Escobar et al, 2008;Mayoral and Romo, 2008;Musmar, 2007;Singh and Roy, 2009), but the seismotectonic zoning are mainly conducted in largescale without any effort on small-scale basis because of problems and disputes. It is possible to clarify the basis of ambiguities and disputes concerning on zonings through bringing up a basic problem and also considering subjectivity with regard to method and quality of zonings.…”