Steel Box Girder Bridge Research Articles

Parameters influencing redundancy of twin steel box-girder bridges

A bridge comprising of two girders, such as a twin steel box-girder bridge, is classified as fracture critical (i.e., nonredundant). In this study, the various bridge components of the twin steel box-girder bridge are investigated to determine if these could be utilized to improve bridge redundancy. Detailed finite-element (FE) models, capable of simulating prominent failure modes observed in a full-scale bridge fracture test, are utilized to evaluate the contributions of the bridge components on the ultimate behavior and redundancy of the bridge sustaining a fracture on one of its girders. The FE models incorporate material nonlinearities of the steel and concrete members, and are capable of capturing the effects of the stud connection failure and railing contact. Analysis results show that the increased tensile strength of the stud connection and (or) concrete strength are effective in improving bridge redundancy. By modulating these factors, redundancy could be significantly enhanced to the extent that the bridge may be excluded from its fracture critical designation.

Design of multi-span steel box girder using lion pride optimization algorithm

In this research, a newly developed nature-inspired optimization method, the Lion Pride Optimization algorithm (LPOA), is utilized for optimal design of composite steel box girder bridges. A composite box girder bridge is one of the common types of bridges used for medium spans due to their economic, aesthetic, and structural benefits. The aim of the present optimization procedure is to provide a feasible set of design variables in order to minimize the weight of the steel trapezoidal box girders. The solution space is delimited by different types of design constraints specified by the American Association of State Highway and Transportation Officials. Additionally, the optimal solution obtained by LPOA is compared to the results of other well-established meta-heuristic algorithms, namely Gray Wolf Optimization (GWO), Ant Lion Optimizer (ALO) and the results of former researches. By this comparison the capability of the LPOA in optimal design of composite steel box girder bridges is demonstrated.

Probabilistic Modeling of Fatigue Damage in Orthotropic Steel Bridge Decks under Stochastic Traffic Loadings

Fatigue truck models with deterministic parameters were developed int a stochastic vehicle flow model. A response surface method was used to approximate the function between vehicle axle weight and equivalent fatigue stresses with few training data to solve the time-consuming problem of bridge finite element analysis under traffic flow loads. A probabilistic fatigue damage modeling method was presented and applied to the rib-to-deck details of steel box girder bridges. Finally, the fatigue damage model was applied to the reliability assessment of steel box girder bridges, and influences of traffic flow parameters on structural fatigue reliability were studied. Numerical results indicate that the higher occupancy rate of heavy vehicle flow in a slow lane than in a fast lane mainly explains the decrease in the fatigue reliability of corresponding rib-to-deck details. The increase in vehicle axle weight causes a rapid decrease in the fatigue reliability index of steel box girders. The fatigue reliability index of rib-to-deck detail in the slow lane decreases from 3.42 to 0.72 when the annual linear growth factor ranges from 0 to 1%. The stochastic fatigue vehicle flow model and the probabilistic model for fatigue damage exhibit considerable potential in the probability assessment of bridge fatigue damage.

Vehicle models for fatigue loading on steel box-girder bridges based on weigh-in-motion data

On the basis of massive data collected by the Weigh-in-motion (WIM) system of XiHouMen Bridge, analysis of fatigue-loaded vehicle models and theoretical fatigue life of U ribs butt weld of steel box girder are discussed in this paper. Firstly, basic vehicle information can be obtained from preliminary statistics of various types of vehicles data and the vehicles passing XiHouMen Bridge are divided into seven types based on the number of axles and axle groups. Secondly, the statistical distribution functions of gross vehicle weight under different loading conditions and wheelbase for each type of vehicle are developed to obtain the equivalent fatigue vehicle load. Then, the parameters of various types of fatigue-loaded vehicles are determined by combining the mathematic expectation of gross vehicle weight distribution with Palmgren-Miner fatigue damage accumulation theory. Finally, the seven types of fatigue-loaded vehicles are applied to the component-coupled finite element model of the steel box girders in XiHouMen Bridge and the theoretical fatigue life of the U ribs butt weld can be estimated. This research provides a reference to define the vehicle models for fatigue loading on steel box-girder bridges based on WIM data.

Line Laser Scanning Thermography System for Paint Thickness Estimation

In this study, a novel paint-thickness visualizing (PTV) system is proposed using a line laser thermography and image processing algorithms for the paint thickness estimation. The prior paint-thickness techniques have a high accuracy for estimating paint-thickness on steel structures, but thetechnical hurdles exist for using real structures such as contact type and single point inspection. The proposed PTV system offers advantage of non-contact and non-invasive paint-thickness inspection over the existing techniques. Once the proposed PTV system generates thermal waves on thesteel structure surface using line laser beam scanning, the corresponding thermal responses are measured using an infrared (IR) camera. According to the paint thickness, the thermal wave reflecting phenomena alters at the layer between paint and steel structure and the newly proposed image processing algorithm quantifies the amount of the altered thermal wave reflection with visualizing the paintthickness distribution. The performance of the proposed PTV system was verified through lab scale tests with painted steel structure. Six types of paints which are used for a real steelbox girder bridges were used for the verification and 40 μm of the paint thickness difference was successfully visualized.

Development of Standard Fatigue Vehicle Force Models Based on Actual Traffic Data by Weigh-In-Motion System

Abstract Fatigue damage caused by vehicle-induced forces is a critical factor that affects the safety and the longevity of steel box girder bridges. Accurate vehicle force models are essential for quantifying fatigue in the design and the evaluation of bridge structures. Vehicle forces are random and exhibit significant variations, so to accurately determine a statistical distribution, a large amount of information and measurements is required. In this study, vehicle traffic information gathered by a weigh-in-motion (WIM) system at the Xihoumen Bridge, an over-water suspension bridge in Zhoushan, China, was analyzed for data such as the vehicle type, the gross weight, the axle weight (force), and the wheelbase. New insights into the analysis of measured vehicle information to obtain vehicle fatigue forces required for numerical simulations were gained. In addition, methods to determine various important vehicle parameters such as gross and axle weights and wheelbase were described. These techniques can be used to determine vehicle-induced fatigue forces for bridge structures.

An Comparative Study of Metaheuristic Algorithms for the Optimum Design of Structures

Metaheuristic algorithms are efficient techniques for a class of mathematical optimization problems without having to deeply adapt to the inherent nature of each problem. They are very useful for structural design optimization in which the cost of gradient computation can be very expensive. Among them, the characteristics of simulated annealing and genetic algorithms are briefly discussed. In Metropolis genetic algorithm, favorable features of Metropolis criterion in simulated annealing are incorporated in the reproduction operations of simple genetic algorithm. Numerical examples of structural design optimization are presented. The example structures are truss, breakwater and steel box girder bridge. From the theoretical evaluation and numerical experience, performance and applicability of metaheuristic algorithms for structural design optimization are discussed.

Fatigue behavior of epoxy asphalt concrete and its moisture susceptibility from flexural stiffness and phase angle

Epoxy asphalt concrete (EAC) has been widely used in large span steel box girder bridges recently. The fatigue performance of EAC is critical in the pavement design on steel box girder. The four-point beam fatigue test was employed to evaluate the fatigue performance of EAC. The moisture susceptibility was evaluated by comparing the fatigue behaviors of the dry and moisture conditioned samples. The fatigue life was determined through four criteria: the yield point from Weibull plot, the half modulus ratio (SR) point, the peak phase angle point, and the sample failure. The results showed that the fatigue lives of EAC can be higher than conventional asphalt concrete by one or two orders in magnitude, indicating an excellent fatigue performance. Both the strain level and testing temperature have a significant influence on the fatigue behavior of the EAC, similar to conventional asphalt concrete. While phase angle has been rarely reported in previous studies, the finding indicated the peak phase angle point has a good potential to be used as a criterion of determining fatigue life of EAC after compared with other parameters. Moisture damage has a great influence on the fatigue performance of EAC according to the noticeable fatigue life reduction.

Vehicle Loads for Assessing the Required Load Capacity Considering the Traffic Environment

The effects of traffic loads on existing bridges are quite different from those of design live loads because of the various traffic environments. However, the bridge maintenance and safety assessment of in-service bridges maintain the design load capacity without considering the current traffic environment. The real traffic conditions on existing bridges may require a load capacity that is considerably different from the design. Therefore, the required load capacity of an existing highway bridge should be determined according to the extreme load effects that the bridge will experience from the actual traffic environment during its remaining service life for more rational maintenance of the infrastructure. A simulation process was developed to determine evaluation vehicle loads for bridge safety assessment based on the extreme load effects that may occur during the remaining service life. Realistic probabilistic traffic models were used to reflect the actual traffic environment. The presented model was used to analyze the extreme load effect on pre-stressed concrete (PSC) and steel box girder bridges, which are typical bridge types. The traffic environmental conditions included the traffic volume (2000–40,000), the proportion of heavy vehicles (15–45%), and the consecutive vehicle traveling patterns. The spans of the sample bridges were 30 m (PSC bridge) and 45 or 60 m (steel box girder bridge). In the results, the extreme load effects tended to increase with either the traffic volume or proportion of heavy vehicles. The evaluation vehicle loads for bridge safety assessment may be adjusted with the traffic conditions, such as the traffic volume, the proportion of heavy vehicles, and the consecutive vehicle traveling patterns.

Evaluation of welded joints of vertical stiffener to web under fatigue load by hotspot stress method

The feasibility of intermittent fillet weld at the connection of vertical web stiffener and web plate in steel box girder bridge was studied considering vehicular fatigue loading. The study was conducted using FEM models taken from real three span steel box girder bridge with three box-girders connected by reinforced concrete deck. Web-to-stiffener connections at the middle of span and near the support of the bridge were studied in detail using refined 3D linear finite element analysis. Then, using structural hot spot stress approach, fatigue load induced stress was evaluated on the welded parts, and parametric study was conducted on a range of intermittent fillet weld parameters to evaluate the maximum fatigue load induced stress. The results of the parametric study are compared with maximum fatigue stress thresholds specified in design codes to verify the applicability of the proposed detail. Finally, some conclusion and recommendations are given on the applicability of intermittent fillet weld for web-to-stiffener connections of steel box girder bridges.

Reliability-Based Dynamic Analysis of Progressive Collapse of Highway Bridges

Structural systems optimized to meet member design criteria specified in design standards may not provide sufficient levels of structural robustness to withstand possible local failures that could be caused by unforeseen extreme events. In fact, the sudden failure of an element may result in the failure of another creating a chain reaction that might progress throughout the entire structure or a major portion of it leading to catastrophic collapse. Concerns about possible threats to major bridges instigated interest in developing criteria for evaluating their robustness. Bridge-specific criteria are needed as existing procedures for buildings are not suitable for bridges because of differences in their structural configurations and their dead and transient loads.This paper describes a methodology for assessing the capability of bridges to resist progressive collapse while accounting for the uncertainties in the applied loads and the load carrying capacities of the members as well as the system of damaged structures. The reliability analysis methodology is illustrated using models of a steel box girder bridge and a steel truss bridge subjected to different initial damage scenarios. The paper outlines how the results from reliability-based structural dynamic analyses can be implemented to develop structural robustness criteria that would lead to consistent levels of safety.

连续曲线钢箱梁桥车桥耦合动力响应参数分析

采用七自由度空间曲梁单元和七自由度车辆模型模拟桥梁和车辆，基于频率功率谱等效的方法模拟桥面不平度，分析了连续曲线钢箱梁的车桥耦合动力响应，建立起车桥耦合系统动力学模型，经自编程序对其进行动力响应研究。结果表明：当桥梁曲率半径小于某定值后，其各项响应量值将迅速增大，且扭矩的动力放大效应要大于弯矩；桥梁位移动力放大系数随横向加载车道数的减小而增大，随纵向车辆行驶间距的增大而增大，但响应量值大大减小。 By simulating the bridge with 7-DOF spatial curved beam element and the vehicle with 7-DOF ve-hicle model, the vehicle-bridge coupled dynamic response of continuous curve steel box girder bridge was investigated. As vibration source, the road irregularity was simulated by frequency power spectrum equivalent method. The vehicle-bridge coupled dynamics model was established and its dynamic response was studied by self-compiled program. The results show, when bridge curve radius is less than a fixed value, its various responsive values increase rapidly, and the dynamic magnified factor (DMF) of torque is larger than bending moment; the DMF increases with the decrease of transversal loaded-lane-number and the increase of longitudinal vehicle distance, but corresponding responsive value is greatly reduced.

Considering Low Frequency Sound Propagation in Bridge Design

This paper investigates low frequency sounds radiated from a two-span continuous steel box girder bridge, three-span continuous steel plate girder bridge and three-span continuous prestressed concrete bridge. Those three bridges were selected as candidate bridges crossing a rural town. Velocity responses of bridges are estimated by a three-dimensional traffic-induced bridge vibration analysis, and those velocity responses are used in the frequency-domain sound propagation analysis by means of boundary element method. The propagation of sound pressure in the time-domain was also investigated. The inverse fast Fourier transformation was used to convert the sound pressure in the frequency-domain to the sound pressure at any point around the bridges in the time-domain. The analytical study showed that the lowest sound pressure level among three bridges was observed at the two-span continuous steel box girder bridge demonstrated.

강박스거더교의 설계 유효온도 산정을 위한 실험적 연구

강박스거더교의 설계 유효온도 산정을 위한 실험적 연구

Investigation of free vibration and ultimate behavior of composite twin-box girder bridges

Multi spine composite concrete-deck steel-box girder bridges became a very popular choice in highway bridges due to their high torsional and wraping stiffness as well as for economic and aesthetic reasons. This study presents an experimental investigation on both elastic and ultimate behavior of composite box girder bridges in order to study the effect of internal cross bracing between box girders along with the curvature effect at different loading stages. Three composite concrete deck-steel simply-supported twin-box bridge models, two curved and one straight, were fabricated, and tested. First, the response of each model was monitored under free-vibration excitation, then an eccentric loading was applied and the corresponding deflections were recorded in the elastic range. Finally, the bridge models were tested up to collapse. The structural behavior of the three bridge models was compared at the three loading stages. It was noticed that the presence of an external cross bracing system between the steel boxes had an insignificant effect on the developed deflection and the fundamental natural frequency in the elastic range of loading. On the other hand, these external bracings assisted in decreasing the developed deflection approaching failure and in increasing the load carrying capacity by about 8.9%. In addition, the external bracing ensured a better distribution of the stresses under ultimate loading conditions. Moreover, the experimental findings were verified numerically using finite element modeling. A good agreement was noticed to exist between the experimental findings and the numerical results.

Applicability of GFRP Reinforcements for the Structural Design of Steel Box Girder Bridge Decks

Applicability of GFRP Reinforcements for the Structural Design of Steel Box Girder Bridge Decks

Assessment of acceleration responses of a railway bridge using wavelet analysis

One of more effective and practical ways in Structural Health Monitoring (SHM) is assessing structural movements and detecting corresponding damages in both time and frequency domains. Recently, the wavelet analysis has been used widely in many engineering applications, e.g., SHM, damage detection, and simulation of earthquake ground motions. In this study, the wavelet analysis in one and two dimensions is applied to investigate and assess the movement behavior of a high-speed train railway bridge using the acceleration measurements. Moreover, the wavelet analysis is used to evaluate the degree of correlation between different acceleration measurement points under the different passage train speeds. The high-speed train railway bridge is a double track steel box girder bridge with 50 m length. The high-speed train was controlled to pass over the bridge with four different speeds, i.e. 290, 360, 400, and 406 km/hr. Furthermore, two train passage cases were considered to examine the main girder's deformation behavior under loaded and unloaded railway tracks simultaneously. The results show that the wavelet analysis proves to be an efficient tool to investigate the frequency content of the acceleration measurements. Finally, the unloaded track suffers more vibration than the loaded track particularly when increasing the train speed.

Reliability-based progressive collapse analysis of highway bridges

Structural systems optimized to meet member design criteria as specified in current design standards and specifications may not provide sufficient levels of robustness to withstand a possible local failure following an unforeseen extreme event. In fact, the failure of one structural element may result in the failure of another creating a chain reaction that might progress throughout the entire structure or a major portion of it leading to catastrophic collapse. To reduce the chances of such collapses, the U.S. General Services Administration (GSA) established a set of procedures and criteria to evaluate the robustness of buildings using traditional deterministic methods. Although widely accepted and used for the progressive collapse analysis of buildings, the GSA criteria may not be suitable for bridges because of the differences in their structural configurations and in the nature and intensity of their permanent and transient loads. Furthermore, it is not clear how the existing criteria take into consideration the large uncertainties associated with estimating the applied loads and the capacity of structural systems to resist collapse following the initiation of a local failure. Because performing direct probabilistic analyses may be impractical for routine engineering practice, following current code calibration processes, design guidelines and standards can specify incremental progressive collapse analysis criteria that are calibrated based on structural reliability concepts to ensure consistent levels of safety for the pertinent range of applications, load levels and structural types and configurations.The objective of this paper is to describe a methodology for performing probabilistic progressive collapse analyses and calibrating incremental analysis criteria for highway bridges accounting for the uncertainties in the applied loads and the load carrying capacities of the members as well as the system. The reliability analysis methodology is illustrated using models of a steel box girder bridge and a steel truss bridge subjected to different initial damage scenarios. The paper outlines how the results from several reliability analyses can be implemented to develop criteria that would lead to consistent levels of safety and reliability. Such criteria can, in the future, be used to propose progressive collapse analysis guidelines for bridges that are compatible with the principles of Load and Resistance Factor Design (LRFD) methods.

Thermal Effects on Curved Steel Box Girder Bridges and Their Countermeasures

AbstractOwing to its light self-weight, low heat capacity and large thermal expansion coefficient, the application of the curved steel box girder bridge with small and medium spans has gained popularity for the construction of urban infrastructure. However, sun exposure could easily increase the maximum temperature difference at the bottom of steel box beam by 25°C. With the effect of nonuniform temperature field and overloaded vehicles, the edge inside the curved steel box girder bridge may be separated from the remaining structure, resulting in overturning. Thus, more attention needs to be paid in order to prevent the separation. In this paper, an overturning resistance analysis of a three-span curved steel box girder bridge located in Hangzhou, China was performed. A model was proposed based on the measurement of temperature field to the steel box girder. The separating displacement due to temperature variations was predicted and verified by the measurement results. As a result, changes in supporting r...

콘크리트 충전 강상자형 교량의 진동사용성 평가 연구

콘크리트 충전 강상자형 교량의 진동사용성 평가 연구