COMPARISON OF TWO STAGE AND ONE STAGE MODELING IN EARTHQUAKE RESISTANT BUILDINGS WITH SOIL-STRUCTURE INTERACTION ANALYSIS

• Main Author: Abdillah, Alfi
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/50271
• Institution: Institut Teknologi Bandung

Earthquake-resistant building modeling that is very commonly used by engineers is two-stage modeling. Separate modeling between the upper structure which is designed to be flexible and the lower structure which is designed to be more rigid. This modeling is very practical because it considers the structure to be above a rigid placement by ignoring flexible soil behavior. However, the actual structure rests on soil which is flexible and can deform. Another method that can be used to approximate the actual conditions is by modeling the complete structure without separating the upper and lower structures by including the soil-structure interaction effect. This modeling is also known as one-stage modeling. To get the effect of soil-structure interaction in one-stage modeling, the soil at the base of the structure and covering the basement walls is modeled as a spring. This spring has a value of stiffness and damping depending on the characteristics of the soil. The calculation of the value of the stiffness and damping of soil springs in this modeling is based on the method of Pais and Kausel (1988). In this study, the concrete structures were modeled by varying the number of floors of the superstructure, the number of basement floors, and the class of the soil site. The structural models were analyzed using two-stage modeling and one-stage modeling with the same analytical procedure, namely the dynamic linear response spectra procedure. Because using the same analysis procedure, the results of the one-stage and two-stage modeling analysis can be compared. The parameters being compared are the natural period of the structure, the base shear force, the shear force of each floor, the deviation of each floor, and the drift. The results of this study prove that the design results from one-stage modeling are more economical than those from two-stage modeling. Thus, the results of the two-stage modeling are more conservative. This is evidenced by the results of the research in this report, where the shear force of each floor in one-stage modeling is smaller than in two-stage modeling. especially on short structures with SE soil site class. However, tall structures also need to be analyzed with the effect of soil-structure interaction, because in this study there is a maximum deviation in the tall structure that exceeds the allowable deviation.