Comparative Study of Direct Analysis Method and Effective Length Method on Structural Steel Piperack Using STAAD Pro V8i Software

Abstract

Stability analysis is one of the most important aspects in the design of steel structures, including structural steel piperack. Based on AISC 360-16, there are two recommendation of stability analysis method, that is DM (Direct Analysis Method) and ELM (Effective Length Method). Since AISC 360-10, the DM method is used as the main method of structural stability analysis instead of the ELM method. The ELM method was not eliminated but was changed to an alternative method. The DM and ELM are two different stability analysis methods. The DM is a stability analysis based on second order elastic analysis, while ELM is a stability analysis based on elastic linear analysis. In this study, the two stability analysis methods will be compared to the structural design of the SPRK-22 (subpiperack-22) in the Jambaran-Tiung Biru project, Bojonegoro, East Java, Indonesia. The dimention of SPRK-22 is 54 m long and 6 m wide, and 12,75 m high. In addition, there is a loop structure with a length is 3 meters, a width is 6 m and a height is 9,75 m. The results of the analysis compared between the two methods are the ratio of structural members, beam deflection, column drift due to wind and column drift due to seismic. Based on the results of the analysis using the STAAD Pro V8i software, the DM produces a more conservative structure. The DM resulted in a ratio of 1,04% greater structural member, beam deflection 24,5% greater, column drift due to wind 9% greater and column drift due to seismic 26% greater than the ELM method.