Modal pushover analysis on reinforced concrete arch bridge to estimate seismic responses

¹ Politeknik Negeri Padang, Jurusan Teknik Sipil, 25163 Padang, Indonesia
² Universitas Bung Hatta, Jurusan Teknik Sipil, 25133 Padang, Indonesia
³ Universitas Mercubuana, Jurusan Teknik Sipil, 11650 Jakarta, Indonesia

^* Corresponding author: lukman@pnp.ac.id

Abstract

This paper presents an evaluation study of the performance of reinforced concrete arch bridge structures under earthquake load. The study is aimed to investigate the seismic performance of Wreksodiningrat Bridge, located in the province of Yogyakarta, Indonesia. This bridge is a three spans reinforced concrete arch bridge with a main span length of 75 m and two side spans with a length of 35 m, respectively. This study is a part of a large project carried out by the Ministry of Public Works to study the impact of the new 2016 Indonesia Seismic Design Code for Bridges (SNI 2833:2016). The main objective of this paper is to determine the displacement demands due to earthquake load based on the new seismic code design for bridges, SNI 2833:2016. In addition, demand capacity ratios (D/C) of the main structural components, such as the compression arch and main column (pier) at the fixed support, are also reviewed in this paper. The analysis was carried out using nonlinear modal pushover analysis. The arch bridge modeling is three dimensional, where structural elements such as beams, columns, and compression arches are modeled as frame elements. The plastic hinges are modeled as fiber hinges with unconfined and confined concrete material stress-strain relationship following Mander formula. The analysis result shows that the displacement demands of the bridge are 2.9 cm and 20 cm in the longitudinal and transverse direction, respectively. The D/C ratios of the compression arch due to demand earthquake load are 0.74 and 0.95 in the longitudinal and transverse direction of the bridge, while the D/C ratios of the pier are 0.15 and 0.80 in the longitudinal and transverse direction. Based on the above results, it is concluded that the studied bridge is able to withstand the seismic load requirements in the new Indonesia Seismic Design Code.