Effect of the Seismic wave Direction on the Collapse of RC Box Girder Bridges

Effect of the Seismic wave Direction on the Collapse of RC Box Girder Bridges

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M. M. Husaina, Heba A. Mohameda, Ayman Aboraiab

aStructural Engineering Dept., Faculty of Engineering, Zagazig University, Zagazig 44519, Egypt.

bConstruction and Building Dept., High Institute of Engineering, October 6th city, Giza. 12592, Egypt.

Abstract:- The gradual collapse of ordinary structures due to gravity and blast loads is the subject of a significant number of research studies. The progressive collapse caused by seismic actions, especially of bridge structures, is being investigated by a few others. Some of the serious earthquakes in the past have resulted in significant damage or the collapse of bridge buildings, resulting in devastating losses. New analysis and monitoring methods for the damage process, from initial failure to final collapse and can follow the structural failure trend, have been built in order to construct new improved earthquake-resistant bridges. The current paper analyzes the behavior of bridge progressive collapse by serious seismic actions using the Applied Element Approach [AEM], which takes into account the separation of structural members or components, from failure to complete collapse, and falling contact debris or impact forces. A monolithic RC box girder bridge were numerically analyzed under the influence of Kobe seismic ground motion in longitudinal and transverse directions. The results showed that the effect of the seismic wave in the longitudinal direction of the bridge was more destructive than that in the transverse direction.

Keywords:- Progressive collapse; applied element method; box girder; Ground motion direction

1. INTRODUCTION

Progressive collapse phenomenon is defined as the global damage or collapse behavior of a large part of the structural system that is caused by a failure of a relatively small or localized part of the structure. Structural Progressive collapse occurs as a result of failure of one or more structural members or components. The load is transferred in the structural system due to changes in the distribution of stiffness, the pattern of the stress behavior, and/or the structural boundary conditions (Krauthammer et al., 2002). This initial failure results in other structural elements being further overloaded and later fail. Studies on the progressive collapse of existing structures have focused primarily on high impact as in blasting or irregular loading. Not so much attention is paid to the vulnerability of structures, especially bridges, with regard to progressive collapse during earthquakes (Starossek U., 2006).

Wibowo et al., (2009) studied the seismic progressive collapse of RC bridges during earthquakes. They modeled only a continuous bridge that was previously experimented with "Guedes, 1997. The results have shown a good agreement. The separation of structural components resulting from fracture failure and impact forces from falling debris had been taken into consideration. The results have shown a significant influence on the performance of bridges during major earthquakes that were visible in its progressive collapse analysis. These also demonstrate the need to include progressive failure mechanisms in the assessment of seismic design efficiency and bridge evaluation that would not only lead to a better and more robust earthquake- resistant design for new structures but also more efficient retrofitting and reinforcement strategies for older structures.

In a similar vein, Salem et al., (2016) analyzed numerically the collapse of Tsuyagawa Bridge damaged by the Tohoku Tsunami in March 2011. The Tohoku Tsunami swept across Japan's eastern coast killing over 15,000 people and missing over 2,500. The tsunami caused more than 400,000 buildings to collapse and more than 250 coastal bridges to be washed away. The analysis showed accurately the collapse behavior of the bridge, showing that the bridge collapsed at a water velocity of 6.6 m/s caused by its piers' flexural failure. Tsuyagawa Bridge's AEM analysis has shown the ability to simulate the 2011 Tohoku Tsunami collapse effectively, although the analytical results showed less ductility when compared to reality.

Domaneschi et al., (2020) analyzed numerically the collapse of the viaduct over the Polcevera Valley in Genoa that collapsed in August 2018. This incident left 43 deaths, and several injuries caused by a collapse of a portion of the highway connection. The results of the analysis showed that the stay cable was the most important item whose failure caused the collapse. Furthermore, the simulation model indicated that the main girder triggered the collapse and the large visible displacements involved in their collapse would have warned the authorities of the impending fault.

2. APPLIED ELEMENT METHOD

The Extreme Loading for Structures (ELS) program, developed by ASI-2018 is based on the AEM, which was initially developed by Tagel-Din and Meguro (2000a, b) at the University of Tokyo in 1998 to solve problems related to two-dimensional plane stresses. It was later expanded to solve three-dimensional problems. The AEM is a novel method of modeling that adopts the discrete cracking concept in AEM. Structures are modeled as an element assembly. The elements are not rigid and connected by normal and shear springs along their joint surfaces. These springs are responsible for normal and shear stresses transfer between adjacent elements. Each spring represents a certain volume of material stresses and deformations. Once the connecting springs

fail, each of the two adjacent elements can be completely separated. The AEM adopts fully nonlinear path-dependent material constitutive models. AEM is a stiffness-based approach in which an overall stiffness matrix is formulated and equilibrium equations for each of the stiffness, mass and damping matrices for structural deformations (displacements and rotations) are nonlinearly solved. The equilibrium equation solution is an implicit one that takes step-by-step dynamic integration (Newmark- beta time integration procedure) (Bathe 1995; Chopra 1995). If the springs connecting the elements are ruptured, two adjacent elements are separated from each other. Elements may separate, recontact, or contact other elements automatically depending on the structural response.

3. MATERIAL MODELS

3.1 Modeling concrete and reinforcing steel3.2 Bridge bearing material6.1. Bridge layout6.2 Material properties9.1. Reinforcement reduction effect9.3. Collapse analysis of the different bridge models during Kobe ground motionCONFLICT OF INTEREST STATEMENTDATA AVAILABILITY STATEMENTFUNDING STATEMENT

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