COMPARISON OF RESULTS AND EVALUATION OF SEISMIC PERFORMANCE OF REINFORCED CONCRETE STRUCTURES DUAL SYSTEM OF 30-STORY BUILDINGS IN JAKARTA CITY BASED ON PRACTICAL MODEL AND EMPIRICAL MODEL APPLIED TO EARTHQUAKE LOADS ACCORDING TO SNI 1726:2012 AND SNI 1726:2019 THROUGH NONLINEAR TIME HISTORY ANALYSIS

• Main Author: Sakha Syakura, Abdan
• Format: Theses
• Language: Indonesia
• Subjects: Teknik sipil
• Online Access: https://digilib.itb.ac.id/gdl/view/84764
• Institution: Institut Teknologi Bandung

Every building must be carefully planned to withstand both gravitational and seismic loads. Specifically for seismic loads, it is impossible to accurately predict the location, timing, and magnitude, making them a natural phenomenon that can occur anytime and anywhere. One way to anticipate this is by updating the Indonesian National Standards (SNI) for earthquake-resistant building structure design. The SNI regulations issued include SNI 1726:2002, SNI 1726:2012, and SNI 1726:2019. A fundamental observation from the old regulations to the latest ones is the increase in the maximum seismic acceleration values on the design response spectrum graph in several areas. For example, in Jakarta with medium soil conditions, the maximum seismic acceleration value according to SNI 2002 was 0.55g, according to SNI 2012 it was 0.57g, and according to SNI 2019 it was 0.62g. Based on this analysis, building structures planned according to the old SNI standards should be evaluated using the latest SNI. By using an evaluation method that applies the concept of Performance-Based Design (PBD) through Nonlinear Time History Analysis (NLTHA), the nonlinear characteristics of each type of structural element must be analyzed so that its deformation capacity can accommodate seismic loads. The evaluated structure is a 30-story dual-system reinforced concrete building in Jakarta with medium soil conditions. The structural modeling was conducted using the Perform3D program. The seismic loads consist of two levels: Design Basis Earthquake (DBE) and Maximum Considered Earthquake (MCE). Eleven pairs of actual time histories were first amplitude-scaled to the response spectrum graph. The analyzed models consist of three types: the practical model (model 1), the empirical model (model 2), and the conservative model (model 3). The results of these three models were compared through two stages of analysis. The first stage compares the practical and empirical models applied with seismic time history loads according to the 2012 Seismic SNI, determining which model is more conservative. The second stage compares the conservative model applied with time history loads according to the 2012 and 2019 Seismic SNI, followed by a seismic performance evaluation against the relevant regulations. The global results reviewed include roof drift ratio, maximum inter-story drift, residual inter-story drift, and floor shear forces, while the local results include the performance level of structural elements through maximum usage ratio values, plastic hinge formation distribution, and cyclic curves. In the first stage of analysis, the global seismic performance results of the structure showed nearly identical values at both DBE and MCE levels. This result may occur due to at least three main reasons: the similarity in stiffness on the backbone curve of structural elements, the nearly identical distribution of post-earthquake yield plastic hinge formation, and the majority of the primary beam structural elements remaining in an elastic state. Meanwhile, the local seismic performance results of the structure showed significant differences. At the DBE level, the comparison of maximum usage ratio values for the beam in the empirical model was 199.65%, and for the column, it was 129.56%, with more IO plastic hinge formations, and certain beam cyclic curves showed more severe damage compared to the practical model. At the MCE level, the comparison of maximum usage ratio values for the beam in the empirical model was 116.51%, and for the column, it was 128.88%, with far more IO and LS plastic hinge formations, and certain beam cyclic curves showed sudden strength degradation. The ductility of the beam and column structural elements significantly affected the local performance results. The empirical model is considered conservative because it provides a more severe post-earthquake condition, making it suitable for use in the second stage of analysis. Therefore, practitioners can begin to consider using the empirical model approach as it offers more realistic performance levels and cyclic curves than the practical model. In the second stage of analysis, the global and local seismic performance results of the structure were compared. The empirical model with time history according to the 2019 Seismic SNI showed higher performance results with significant differences due to a 37% amplitude scale factor difference compared to the empirical model with time history according to the 2012 Seismic SNI. The global performance evaluation results showed that the roof drift ratio did not exceed 1% at the DBE level and 2% at the MCE level, the maximum inter-story drift did not exceed 3% according to the 2019 Seismic SNI, the residual inter-story drift did not exceed 1% according to TBI 2017, and the floor shear forces did not exceed the limits according to ASCE 7-16 equations. The local performance evaluation results showed that the maximum usage ratio values, plastic hinge formation distribution, and cyclic curves had not reached the LS performance level at the DBE level or the CP performance level at the MCE level, so the structure remained safe when subjected to time history loads according to the latest Seismic SNI. Thus, the use of the modal response spectrum method in actual structural design according to SNI 1726:2012 still meets the deformation capacity of the structure at least for SNI 1726:2019, but the local performance results should be re-evaluated if there is an increase in seismic acceleration in SNI 1726:20xx in the future.