This paper is intended to review the main causes and mechanisms of bridge collapse. The common factors resulting in bridge collapse are first reviewed. These factors are classified into two broad categories, namely, natural factors (including flood, scour, earthquake, landslide, debris flow, hurricane, typhoon, wind, etc.) and human factors (including imperfect design and construction method, collision, vehicle overloading, fire, terrorist attack, lack of inspection and maintenance, etc.). Then the collapse modes of a few major types of bridges are reviewed and some relevant measures adopted in the current practices are discussed. It is hoped that this paper will provide a concise but comprehensive summary of information needed by researchers and engineers to understand the collapse mechanisms of the major bridge types and how the current practices deal with these issues. Meanwhile, much effort is made to identify future research needed to better understand this topic and to find better solutions ...

State-of-the-Art Review on the Causes and Mechanisms of Bridge Collapse

This paper presents a hydrodynamic experiment that examines the wave forces acting on the superstructure of coastal highway bridges to gain insight into the mechanical characteristics of the wave forces caused by the combination of storm surges and huge waves. The experiment is unique in that the specimen is a full bridge model, including its superstructure, substructure, and neighboring segments. After introducing the experimental setup and test program, this study analyzes the quasi-static and slamming components of the vertical wave force, the horizontal wave force of the superstructure in different clearances, wave heights, and wave periods. The test results are subsequently compared with two theoretical models suggested by Douglass and AASHTO guidelines to provide the experimental validation of those models. By comparing the test results and the existing models, a number of observations and discussions are produced to improve the accuracy of those theoretical models further.

Hydrodynamic Experiment of the Wave Force Acting on the Superstructures of Coastal Bridges

The storm surge, wind, and waves produced by Hurricane Ike in 2008 caused notable damage to the transportation infrastructure in the Houston/Galveston region of Texas. This paper presents the lessons learned from damage to bridge infrastructure in the Houston/Galveston region observed after Hurricane Ike, with comparisons to empirical evidence from past hurricane events on common failure modes and design details affecting bridge performance under hurricane-induced loads. A rich set of damage data is developed, drawing upon postevent inspections and reconnaissance data to present details such as bridge type, failure mode, and surge elevation for the 53 damaged bridges. Many of the damaged structures in the region were either constructed of timber or were low-clearance water-crossing bridges, and these bridges were often completely destroyed by the storm surge and wave loading. Scour and debris also hampered the performance of both major structures and rural bridges. The evidence from the performance of these structures highlights the need for new design alternatives or retrofits such as the use of shear keys and restrainer cables, grated decks, or replacement of timber bridges with box-culvert structures, among other solutions.

Impact of 2008 Hurricane Ike on Bridge Infrastructure in the Houston/Galveston Region

Recent natural extreme events, such as Hurricane Ike in the U.S. (2008), Tohoku tsunami in Japan (2011), and Typhoon Haiyan in Southeast Asia (2013), have caused significant damage to the decks of coastal bridges. The failure of the structure occurs when wave-induced loads on the decks of coastal bridges exceed the bridge capacity, resulting in partial removal or a complete collapse of bridge decks. Tsunami, storm waves, and storm surge are known to be the ultimate agents of such failures. An understanding of the failure mechanism and possible solutions require a better knowledge of the destructive loads on the structure. Interaction of surface waves with the bridge deck is a complex problem, involving fluid–structure interaction, wave breaking, and overtopping. Possible submergence of the deck and entrapment of air pockets between girders can increase destructive forces and add to the complexities of the problem. In recent years, remarkable progress has been made on this topic, resulting in some new findings about the failure mechanism and the destructive wave loads. A review of the key studies on wave loads on the coastal bridge decks, including those in the past and very recently, is presented here. Emphasis is given to the pioneering works that have significantly improved our understanding of the problem. Challenges associated with the existing solutions are highlighted, and suggestions for future studies are provided.

Review of Wave Loads on Coastal Bridge Decks

Although coastal bridges have exhibited significant susceptibility to damage during hurricane-induced wave and surge events, probabilistic models are lacking to quantify the vulnerability of bridges under a range of structural or hazard parameters and support hurricane risk assessment and mitigation activities. This paper introduces a computationally efficient methodology to assess the fragility, or conditional failure probability, of bridges, targeting the deck shifting or unseating failure mode, which is a predominant severe mode of failure for vast inventories of simply supported span bridges. The method propagates uncertainties in parameters affecting the structural capacity and demand, such as mass density, connection strength, material properties, workmanship, and wave parameters. Fragility surfaces are derived in which failure probability is presented over a range of relative surge elevation and wave heights. The application of this technique is shown through a regional fragility assessment of 136 bridges in the greater Houston area. The results reveal that a failure zone emerges in the fragility surfaces of the bridges studied, with a dramatic transition in probability of failure. Additionally, bridges with similar trends in fragility surfaces can be readily classified based on estimates of their mean mass per span length. Finally, application of the new vulnerability models in a case-study regional risk assessment for Hurricane Ike reveals consistency with observed damage and also offers an opportunity for future studies to investigate alternative scenarios for risk-mitigation planning or extensions of the methodology to consider other regions or failure modes.

Probabilistic Modeling of Bridge Deck Unseating during Hurricane Events

Bridge decks in Escambia Bay were damaged during the storm surge of Hurricane Ivan in 2004. In this study, a numerical wave-load model based on the incompressible Reynolds averaged Navier–Stokes equations and k-e equations has been used to investigate dynamic wave forces exerted on the bridge deck. The volume of fluid method is adopted in the model to describe dynamic free surface, which is capable of simulating complex discontinuous free surface during wave breaking and wave-deck interactions. The model was satisfactorily tested against experimental data of uplift wave forces on horizontal plates. The validated model was applied to investigate wave forces acting on the bridge deck in Escambia Bay in the case of Hurricane Ivan. The time history of wave profiles, turbulent velocity fields, and dynamic uplift and horizontal forces acting on the full-scale bridge deck were simulated and analyzed. Results indicate that, during the storm surge event of Hurricane Ivan, the maximum uplifting wave forces were lar...

Hong Xiao

Papers

Numerical Modeling of Dynamic Wave Force Acting on Escambia Bay Bridge Deck during Hurricane Ivan