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SE4-001
14:20
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14:40
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BRIDGE SEISMIC PERFORMANCE FROM RECENT MAJOR EARTHQUAKE RECONNAISSANCE
This paper provides an overview of the bridge seismic performance from damage reconnaissance of past three major earthquakes, including 2008 Wenchuan Earthquake (M. 7.9) in China, 2010 Maule Earthquake (M. 8.8) in Chile, and the 2011Tohoku Earthquake (M. 9.0) in Japan; and proposes a further study regarding improving bridge seismic safety and resilience. In the 2011 Tohoku Earthquake, The catastrophic damages resulting from strong ground motions and huge tsunami impacts in Tohoku and Kanto regions in Japan. Various transportation infrastructures were damaged, especially in the coastal area of Iwate, Miyagi, Fukushima and Ibaraki Prefectures. Highway Bridge damaged were categorized into three type: 1. Effect of tsunami, 2. Effect of strong ground motion; and 3. Effect of soil liquefaction. Total f about 80 highway bridges were fallen down due to tsunami in Iwate, Miyagi, Fukushima, Ibaraki and Chiba prefectures. Under the offshore Maule Earthquake, many spans of precast prestressed discontinuous girder bridges with continuous decks fell off their supports, probably due to significant in-plane rotation of the superstructure as a result of severe shaking. Lateral steel stoppers used to provide both vertical and lateral restraints on girders were largely unsuccessful due to their inadequate connection detail to cap beams and abutments. Reinforced concrete shear keys performed well as fuses limiting the transfer of excessive seismic loads from the superstructure to the foundation of bridges even though they could be optimized for maximum energy dissipation as part of the lateral restraint system at the bottom flange of girders. In Wenchuan earthquake, damages to the 14 observed bridges reminded the researchers of damage suffered during the 1971 San Fernando Earthquake in California. The bridges had few seismic details such as long seats, large shear keys, or tightly spaced transverse reinforcement. Most arch and girder bridges collapsed due to surface rupturing of the seismic faults in the Longmen-Shan thrust zone. A significant portion of roadways and bridges were pushed away or buried by landslides in the steep slopes of mountainous terrain. Although we have observed some similar damaged cases in these three reconnaissance, such as lack of seat width and weak connection details, we also have found and learned some uniqueness of damage or failure modes in each individual ones, such as tsunami effects and vertical ground motions effects. There is a need to study and review all these damage modes and develop a better technology or strategies in improving the next generation seismic design or retrofitting codes.
W. Phillip Yen
bridge, earthquake reconnaissance, seismic performance
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SE4-014
14:40
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14:55
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AN OVERVIEW OF EARTHQUAKE ENGINEERING RESEARCHES ON BRIDGE STRUCTURES IN NCREE AFTER THE 1999 CHI-CHI EARTHQUAKE
This paper presents an overview of the earthquake engineering researches on bridge structures in NCREE after the 1999 Chi-Chi earthquake that are categorized into six main parts. The first part relates to the development and revision of seismic design codes in Taiwan for highway and railway bridges. The second part reviews the progress of seismic evaluation and retrofit activities for old bridges which includes some relevant criteria and regulations for seismic evaluation and retrofitting design as well as the development of retrofitting methodology in Taiwan. The third part presents the development and application of new bridge structural systems in NCREE such as post-tensioned precast segmental bridge column system, bridge pier with interlocking multi-spiral transverse reinforcement, steel and reinforced concrete composite bridge pier system, and precast segmental bridge piers constructed with modular methodology. The fourth part relates to the development and field application of bridge structural monitoring systems. Two main branches are developed in NCREE, one is the bridge scouring monitoring system and the other is the Fiber Bragg Grating (FBG) bridge health monitoring system. The fifth part talks about a life-cycle based bridge management system for disaster prevention developed in NCREE that can be employed to improve the efficiency and the quality of bridge inspection work and to evaluate the capacity of bridge disaster resilience. The final part presents the development of a temporary rescue bridge system that is portable, reusable, and easily assembled by unskilled residents for emergency rescue services in the aftermath of typhoon or earthquake events.
Zheng-Kuan Lee, Fang-Yao Yeh, Ping-Hsiung Wang, Yu-Chen Ou, Hsiao-Hui Hung, Chin-Kuo Su, Xiao-Qin Liu, Chun-Chung Chen
1999 Chi-Chi Earthquake, bridge structure, rescue, Seismic Design, structural monitoring
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SE4-012
14:55
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15:10
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INTRODUCTION OF THE TAIWAN FREEWAY BRIDGE SEISMIC RETROFIT PROGRAM
After Chi-Chi Earthquake struck Taiwan on September 21, 1999, Taiwan Freeway Bureau, MOTC actively took preventive measures for bridges that were opened to traffic. Based on the seismic vulnerability rating results and prioritization studies by using the Taiwan Earthquake Loss Estimation System (TELES), Taiwan freeway bridge authority initiated a three-phase seismic retrofit program in 2000.The National Science Council of Taiwan started HAZ-Taiwan project in 1998 to promote researches on seismic hazard analysis, structural damage assessment, and socio-economic loss estimation. The associated application software (TELES) integrates various inventory data and analysis modules to fulfill three objectives. First, it helps to obtain reliable estimates of seismic hazards and losses soon after occurrence of large earthquakes. Second, it helps to simulate earthquake scenarios and to provide useful estimates for local governments or public services to propose their seismic disaster mitigation plans. Third, it helps to provide catastrophic risk management tools, such as proposing the seismic insurance policy for residential buildings.This paper reports the overall program scope, seismic evaluation criteria, retrofit method, budget and schedule. The information is valuable for engineers and stakeholders from managing system perspective.
Kang-Yu Peng, Ming-Sing Wu
concrete jacketing, damper, prioritization, seismic retrofit, steel jacketing, TELES
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SE4-015
15:10
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15:25
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Response of Bridges with Foundation Exposure under Near-fault Seismic Demand
Bridges located in flood-prone regions commonly suffer from serious foundation exposure caused by riverbed scour. Although the serviceability of the bridge may not be directly affected, the loss of surrounding soil reduces the lateral stiffness and strength of the foundation and alters the seismic performance of the structure. When these bridges are subjected to near-fault earthquakes, strong ground excitation with long-duration pulses produces a large inelastic deformation in the columns or piles, causing unexpected damages to the bridge. Given that many bridges located in near-fault regions suffer from serious scour problems, assessing their response at different scourdepths under near-fault seismic demands is relevant. In this study, the seismic response and damage potential of a bridge subjected to near-fault and far-field ground excitations were assessed using time history analysis. The bridge was assumed to be suffering from riverbed scour with various depths of foundation exposure. The two earthquakes used were based on the ground motion records given from the same station and adjusted by siteresponse analysis so that the intensities of the two ground excitations are comparable. Results from the study highlight that comparing to the far-field earthquake, the long-duration pulse in the near-fault earthquake produces large inelastic deformations in the bridge column or piles, and therefore, induces the potential for unrepairable damages. Although the seismic response of bridge column reduces with increasing the scour depth, the potential for the foundation to be damaged by the earthquake increases. Once the scour depth exceeds a critical level, unexpected foundationdamage controls the seismic performance of the bridge. Results given by time history analysis were also used to validate an analytical approach for assessing the critical scour depth for seismic performance of a bridge.
Shin-Tai Song
bridges, multiple hazards, near-fault earthquake, soil-structure interaction
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SE4-017
15:25
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15:40
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PARAMETRIC STUDY ON THE SEISMIC RESPONSES OF SIMPLY-SUPPORTED BRIDGES CROSSING FAULT-RUPTURE ZONES
The main objectives of present paper are to investigate the effects of fault-crossing on the seismic performance of simply supported bridges, and to identify key parameters that may affect the responses. The considered parameters include the friction coefficient of the rubber bearing supports, the distance between the superstructure and the transverse seismic stoppers, and the fault crossing angle with respect to the axis of bridges. Nonlinear time history analyses with multi-support input was adopted to perform this analysis. The adopted ground motion records were the recorded accelerograms collected during Hualien earthquake that struck the east coast of Taiwan on February 6, 2018. For comparison purpose, the corresponding case without fault-crossing considerations was also analyzed. The analysis results show that neglecting the effect of fault crossing will lead to significant underestimation of the torsional forces at the column bases and the relative displacement between neighboring girders for the simply supported bridges. In addition, different friction coefficient of bearing and different gap distance provided by the seismic stoppers would result in different behavior of the bridge. Therefore, the simulation of bearing system should be as realistic as possible.
HSIAO HUI HUNG, Chang-Wei Huang
bridge crossing faults, fault offset, multi-support displacement input, simply supported bridge
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