• Structural Engineering and Mechanics
• /
• v.69 no.2
• /
• pp.193-204
• /
• 2019

This paper presents results from experimental and numerical studies on the response of steel-concrete composite box bridge girders under certain localized fire exposure conditions. Two composite box bridge girders, a simply supported girder and a continuous girder respectively, were tested under simultaneous loading and fire exposure. The simply supported girder was exposed to fire over 40% of its span length in the middle zone, and the two-span continuous girder was exposed to fire over 38% of its length of the first span and full length of the second span. A measurement method based on comparative rate of deflection was provided to predict the failure time in the hogging moment zone of continuous composite box bridge girders under certain localized fire exposure condition. Parameters including transverse and longitudinal stiffeners and fire scenarios were introduced to investigate fire resistance of the composite box bridge girders. Test results show that failure of the simply supported girder is governed by the deflection limit state, whereas failure of the continuous girder occurs through bending buckling of the web and bottom slab in the hogging moment zone. Deflection based criterion may not be reliable in evaluating failure of continuous composite box bridge girder under certain fire exposure condition. The fire resistance (failure time) of the continuous girder is higher than that of the simply supported girder. Data from fire tests is successfully utilized to validate a finite element based numerical model for further investigating the response of composite box bridge girders exposed to localized fire. Results from numerical analysis show that fire resistance of composite box bridge girders can be highly influenced by the spacing of longitudinal stiffeners and fire severity. The continuous composite box bridge girder with closer longitudinal stiffeners has better fire resistance than the simply composite box bridge girder. It is concluded that the fire resistance of continuous composite box bridge girders can be significantly enhanced by preventing the hogging moment zone from exposure to fire. Longitudinal stiffeners with closer spacing can enhance fire resistance of composite box bridge girders. The increase of transverse stiffeners has no significant effect on fire resistance of composite box bridge girders.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.4 no.3
• /
• pp.30-37
• /
• 2013

It is same such as the provision of shear buckling strength of steel composite box girder web panel and plate girder web panel in Korea Highway Bridge Design Standards(2012). But the web panel of steel composite box girder is different from the web of plate girder in that the upper slab and lower flange are connected to the web. So a different shear behavior of the girders is expected. In this study, To calculate a reasonable elastic shear buckling strength of steel composite box girder web panel, ABAQUS program was used. The results from F.E.A and previous studies are compared. It is shown that the web shear buckling strength of steel composite box girder of Korea Highway Bridge Design Standards(2012) is the most conservative.

• Steel and Composite Structures
• /
• v.48 no.2
• /
• pp.207-233
• /
• 2023

Steel-concrete composite box girder bridges are widely used in the construction of highway and railway bridges both domestically and abroad due to their advantages of being light weight and having a large spanning ability and very large torsional rigidity. Composite box girder bridges exhibit the effects of shear lag, restrained torsion, distortion and interface bidirectional slip under various loads during operation. As one of the most commonly used calculation tools in bridge engineering analysis, one-dimensional models offer the advantages of high calculation efficiency and strong stability. Currently, research on the one-dimensional model of composite beams mainly focuses on simulating interface longitudinal slip and the shear lag effect. There are relatively few studies on the one-dimensional model which can consider the effects of restrained torsion, distortion and interface transverse slip. Additionally, there are few studies on vehicle-bridge integrated systems where a one-dimensional model is used as a tool that only considers the calculations of natural frequency, mode and moving load conditions to study the dynamic response of composite beams. Some scholars have established a dynamic analysis model of a coupled composite beam bridge-train system, but where the composite beam is only simulated using a Euler beam or Timoshenko beam. As a result, it is impossible to comprehensively consider multiple complex force effects, such as shear lag, restrained torsion, distortion and interface bidirectional slip of composite beams. In this paper, a 27 DOF vehicle rigid body model is used to simulate train operation. A two-node 26 DOF finite beam element with composed box beams considering the effects of shear lag, restrained torsion, distortion and interface bidirectional slip is proposed. The dynamic analysis model of the coupled composite box girder bridge-train system is constructed based on the wheel-rail contact relationship of vertical close-fitting and lateral linear creeping slip. Furthermore, the accuracy of the dynamic analysis model is verified via the measured dynamic response data of a practical composite box girder bridge. Finally, the dynamic analysis model is applied in order to study the influence of various mechanical effects on the dynamic performance of the vehicle-bridge system.

• Steel and Composite Structures
• /
• v.24 no.5
• /
• pp.549-559
• /
• 2017

As few multi-tower single-box multi-cell cable-stayed bridges with corrugated steel webs have been built, analysis is mostly achieved by combining single-girder model, beam grillage model and solid model in support of the design. However, such analysis methods usually suffer from major limitations in terms of the engineering applications: single-girder model fails to account for spatial effect such as shear lag effect of the box girder and the relevant effective girder width and eccentric load coefficient; owing to the approximation in the principle equivalence, the plane grillage model cannot accurately capture shear stress distribution and local stress state in both top and bottom flange of composite box girder; and solid model is difficult to be practically combined with the overall calculation. The usual effective width method fails to provide a uniform and accurate "effective length" (and the codes fail to provide a unified design approach at those circumstance) considering different shear lag effects resulting from dead load, prestress and cable tension in the construction. Therefore, a novel spatial grid model has been developed to account for shear lag effect. The theoretical principle of the proposed spatial grid model has been elaborated along with the relevant illustrations of modeling parameters of composite box girder with corrugated steel webs. Then typical transverse and longitudinal shear lag coefficient distribution pattern at the side-span and mid-span key cross sections have been analyzed and summarized to provide reference for similar bridges. The effectiveness and accuracy of spatial grid analysis methods has been finally validated through a practical cable-stayed bridge.

• Steel and Composite Structures
• /
• v.50 no.3
• /
• pp.347-362
• /
• 2024

Controlling vibrations and noise in steel box girders is important for reducing noise pollution and avoiding discomfort to residents of dwellings along bridges. The fundamental approach to solving this problem involves first identifying the main path of transmission of the vibration energy and then cutting it off by using targeted measures. However, this requires an investigation of the characteristics of flow of vibration energy in the steel box girder, whereas most studies in the area have focused on analyzing its single-point frequency response and overall vibrations. To solve this problem, this study examines the transmission of vibrations through the segments of a steel box girder when it is subjected to harmonic loads through structural intensity analysis based on standard finite element software and a post-processing code created by the authors. We identified several frequencies that dominated the vibrations of the steel box girder as well as the factors that influenced their emergence. We also assessed the contributions of a variety of vibrational waves to power flow, and the results showed that bending waves were dominant in the top plate and in-plane waves in the vertical plate of the girder. Finally, we analyzed the effects of commonly used stiffened structures and steel-concrete composite structures on the flow of vibration energy in the girder, and verified their positive impacts on energy regionalization. In addition to providing an efficient tool for the relevant analyses, the work here informs research on optimizing steel box girders to reduce vibrations and noise in them.

• Smart Structures and Systems
• /
• v.20 no.5
• /
• pp.607-618
• /
• 2017

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.

• Structural Engineering and Mechanics
• /
• v.46 no.4
• /
• pp.519-531
• /
• 2013

To have a better understanding of the torsional mechanism and influencing factors of PC composite box-girder with corrugated steel webs, ultimate torsional strength of four specimens under pure torsion were analyzed with Model Test Method. Monotonic pure torsion acts on specimens by eccentric concentrated loading. The experimental results show that cracks form at an angle of $45^{\circ}$ to the member's longitudinal axis in the top and bottom concrete slabs. Longitudinal reinforcement located in the center of cross section contributes little to torsional capacity of the specimens. Torsional rigidity is proportional to shape parameter ${\eta}$ of corrugation and there is an increase in yielding torque and ultimate torque of specimens as the thickness of corrugated steel webs increases.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.591-596
• /
• 2001

In case of continuous steel box-girder bridges, the magnitude of the longitudinal tensile stress on concrete in internal support is larger than the tensile strength of concrete. In this paper, the parametric study was performed to present the effective magnitude of the longitudinal prestress for reducing the longitudinal tensile stress to decrease under the tensile strength of concrete. The parametric study is conducted with changing the steel box-girder section and the span length of bridge. Three dimensional finite element analyses are conducted with ABAQUS program. The behavior of the steel box-girder bridge with prestress is investigated through experimental works on a analogous steel box-girder bridge model, and their results are compared with those of analytical studies.

• Steel and Composite Structures
• /
• v.14 no.5
• /
• pp.409-429
• /
• 2013

A composite box-girder with corrugated steel webs has been used in civil engineering practice as an alternative to the conventional pre-stressed concrete box-girder because of several advantages, such as high shear resistance without vertical stiffeners and an increase in the efficiency of pre-stressing due to the accordion effect. Many studies have been conducted on the shear buckling and flexural behavior of the composite box-girder with corrugated steel webs. However, the torsional behavior is not fully understood yet, and it needed to be investigated. Prior study of the torsion of the composite box-girder with corrugated steel webs has been developed by assuming that the concrete section is cracked prior to loading and doesn't have tensile resistance. This results in poor estimation of pre-cracking behaviors, such as initial stiffness. To overcome this disadvantage of the previous analytical model, an improved analytical model for torsion of the composite box-girder with corrugated steel webs was developed considering the concrete tension behavior in this study. Based on the proposed analytical model, a non-linear torsional analysis program for torsion of the composite box-girder with corrugated steel webs was developed and successfully verified by comparing with the results of the test. The proposed analytical model shows that the concrete tension behavior has significant effect on the initial torsional stiffness and cracking torsional moment. Finally, a simplified torsional moment-twist angle relationship of the composite box-girder with corrugated steel webs was proposed based on the proposed analytical model.

• Steel and Composite Structures
• /
• v.29 no.4
• /
• pp.437-450
• /
• 2018

A bridge comprising of two girders, such as a twin steel box-girder bridge, is classified as fracture critical (i.e., non-redundant). 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.