Modified Partial Capacity Design (M-PCD): achieving partial sidesway mechanism by using two steps design approach

L S Tanaya,P Pudjisuryadi,H Herryanto

doi:10.1088/1755-1315/907/1/012003

Abstract

Partial Capacity Design (PCD) has been developed by using magnification factor to keep some columns undamaged during major earthquake. By doing so, the structures will experience the partial side sway mechanism which is also stable, instead of the beam sidesway mechanism. However, in some cases, structures designed by PCD method failed to show the partial side sway mechanism since unexpected damages were still occurred at some columns. In this research, modification of PCD method is proposed by using two structural models in the design process. The first model is used to design beams and columns which are allowed to experience plastic damages, while the second model is used to design columns which are intended to remain elastic when the structure is subjected to a target earthquake. Two nominal earthquakes corresponding to Elastic Design Response Spectrum (EDRS) level with seismic modification factors (R) of 8.0 and 1.6 are used in the first and second structural models, respectively. It should be noted that the second model is identical to the first model except that the stiffnesses are reduced for elements to simulate potential plastic damages. This proposed method is applied to symmetrical 6 and 10 storey buildings with seismic load according SNI 1726:2012 and with soil classification of SE in Surabaya city. A Non-linear Static Procedure (NSP) or pushover analysis and Non-linear Dynamic Procedure (NDP) or time history analysis are employed to evaluate the performance of the structure. The evaluation is conducted at three earthquake levels which are nominal earthquake that is used in second model, earthquake corresponding to EDRS level, and maximum considered earthquake (MCER) specified by the code (50% higher than EDRS level). The building performances satisfy the drift criteria in accordance with FEMA 273. However, the partial side sway mechanism was not achieved at NDP analysis at maximum seismic load, MCER.

Highlights

Due to major seismic event, structures may develop a collapse mechanism, either beam side sway mechanism or soft storey mechanism (Figure 1)
In some cases, structures designed by Partial Capacity Design (PCD) method failed to show the partial side sway mechanism since unexpected damages were still occurred at some columns
The evaluation is conducted at three earthquake levels which are nominal earthquake that is used in second model, earthquake corresponding to Elastic Design Response Spectrum (EDRS) level, and maximum considered earthquake (MCER) specified by the code (50% higher than EDRS level)

Summary

Introduction

Due to major seismic event, structures may develop a collapse mechanism, either beam side sway mechanism or soft storey mechanism (Figure 1). Other collapse mechanism was proposed namely the partial side sway mechanism (Figure 2) where some exterior columns are designed to remain elastic and interior columns are allowed to be in plastic condition preventing the soft storey mechanism. A second structural model with some stiffness modifications to stimulate expected plastic damaged is used to obtained the exterior columns design forces, rather than using a magnification factor as in the original PCD method. This method, the Modified Partial Capacity Design (M-PCD) is expected to perform more effectively in achieving the partial side sway mechanism, since distribution of internal forces at nonlinear stage are analysed directly in the second model.

Storey

Findings

Results and discussions