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

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.