• Steel and Composite Structures
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• v.26 no.2
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• pp.183-196
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• 2018

The traditional prestressed concrete composite box-girders with corrugated steel webs have several drawbacks such as large deflection and potential local buckling. In this study, two methods were investigated to optimize and improve the prestressed concrete composite box-girders with corrugated steel webs. The first method was to replace the concrete bottom slab with a steel plate and the second method was to support the concrete bottom slab on the steel flanges. The behavior of the prestressed concrete composite box-girders with corrugated steel webs with either method was studied by experiments on three specimens. The test results showed that behavior of the optimized and upgraded prestressed concrete composite box-girders with corrugated steel webs, including ultimate bearing capacity, flexural stiffness, and crack resistance, is greatly improved. In addition, the influence of different shear connectors, including perfobond leisten (PBL) and stud shear connectors, on the behavior of prestressed concrete composite box-girders with corrugated steel webs was studied. The results showed that PBL shear connectors can greatly improve the ultimate bearing capacity, flexural stiffness and crack resistance property of the prestressed concrete composite box-girders with corrugated steel webs. However, for the efficiency of prestressing introduced into the girder, the PBL shear connectors do not perform as well as the stud shear connectors.

• International Journal of Concrete Structures and Materials
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• v.8 no.1
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• pp.43-59
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• 2014

Many bridges are subject to lateral damage for their girders due to impact by over-height vehicles collision. In this study, the optimum configurations of carbon fiber reinforced polymers (CFRP) laminates were investigated to repair the laterally damaged prestressed concrete (PS) bridge girders. Experimental and analytical investigations were conducted to study the flexural behavior of 13 half-scale AASHTO type II PS girders under both static and fatigue loading. Lateral impact damage due to vehicle collision was simulated by sawing through the concrete of the bottom flange and slicing through one of the prestressing strands. The damaged concrete was repaired and CFRP systems (longitudinal soffit laminates and evenly spaced transverse U-wraps) were applied to restore the original flexural capacity and mitigate debonding of soffit CFRP longitudinal laminates. In addition to the static load tests for ten girders, three more girders were tested under fatigue loading cycles to investigate the behavior under simulated traffic conditions. Measurements of the applied load, the deflection at five different locations, strains along the cross-section height at mid-span, and multiple strains longitudinally along the bottom soffit were recorded. The study investigated and recommended the proper CFRP repair design in terms of the CFRP longitudinal layers and U-wrapping spacing to obtain flexural capacity improvement and desired failure modes for the repaired girders. Test results showed that with proper detailing, CFRP systems can be designed to restore the lost flexural capacity, sustain the fatigue load cycles, and maintain the desired failure mode.

• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.663-674
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• 2017

This paper presents an approach for evaluating performance of prestressed concrete (PC) bridge girders exposed to fire. A finite element based numerical model for tracing the response of fire exposed T girders is developed in ANSYS. The analysis is carried out in three stages, namely, fire temperature calculation, cross sectional temperature evaluation, and then strength, deformation and effective prestress analysis on girders exposed to elevated temperatures. The applicability of the computer program in tracing the response of PC bridge girders from the initial preloading stage to failure stage, due to combined effects of fire and structure loading, is demonstrated through a case study, and validated by test data of a scaled PC box girder under ISO834 fire condition. Results from the case study show that fire severity has a significant influence on the fire resistance of PC T girders and hydrocarbon fire is most dangerous for the girder. The prestress loss caused by elevated temperature is about 10% under hydrocarbon fire till the girder failure, which can lead to the increase in deflection of the PC girder. The rate of deflection failure criterion is suggested to determine the failure of PC T girder under fire.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1327-1336
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• 2013

In this study, the effects of corrugated webs on the ultimate behavior of horizontally curved I-shaped girders are investigated. Because of the geometric characteristics of corrugated plates, corrugated webs can be used for enhancing torsional and warping stiffness of plate girders. Many researches have been conducted to study the effects of corrugated webs on the ultimate behavior of straight girders. But, the studies of the ultimate behavior of horizontally curved girders with corrugated webs, which generally show out-of plane behavior manly, have been rarely performed so far. By performing inelastic-nonlinear analysis, the ultimate behavior of curved girders with corrugated webs is studied in this paper. Laterally unsupported length and subtended angle of girders, and length of height of corrugation of webs are considered as the geometric parameters which would be expected to affect the ultimate behavior. By this analytical study with considering the geometric parameters, the changes of ultimate behavior and load carrying capacity of curved girders with corrugated webs are investigated. Also, the effects of corrugated webs on the increase of load carrying capacity for curved girders are studied with comparing to the capacity of general curved girders with flat webs. According to the analytical results, corrugated webs can be used to increase the ultimate load carrying capacity of curved girders, because of their high torsional and warping stiffness. But, it is also indicated that they may decrease the load carrying capacity of curved girders which have relatively small subtended angle or initial curvature, because of an accordion effect.

• Computers and Concrete
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• v.25 no.6
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• pp.497-507
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• 2020

This paper presents a numerical method for evaluating fire performance of prestressed concrete (PC) T shaped bridge girders under combined effect of structural loading and hydrocarbon fire exposure conditions. A numerical model, developed using the computer program ANSYS, is employed to investigate fire response of PC T shaped bridge girders by taking into consideration structural inherent parameters, namely; arrangement of prestressing strands with in the girder section, thickness of concrete cover over prestressing strands, effective degree of prestress and content of prestressing strands. Then, a sequential thermo-mechanical analysis is performed to predict cross sectional temperature followed by mechanical response of T shaped bridge girders. The validity of the numerical model is established by comparing temperatures, deflections and failure time generated from fire tests. Through numerical studies, it is shown that thickness of concrete cover and arrangement of prestressing strands in girder section have significant influence on the fire resistance of PC T shaped bridge girders. Increase in effective degree of prestress in strands with triangular shaped layout and content in prestressing strands can slow down the progression of deflections in PC T shaped bridge girder towards the final stages of fire exposure, to thereby preventing sudden collapse of the girder. Rate of deflection based failure criterion governs failure in PC T shaped bridge girders under most hydrocarbon fire exposure conditions. Structural inherent parameters incorporated into sectional configuration can significantly enhance fire resistance of PC bridge girders; thus mitigating fire induced collapse of these bridge girders.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.387-392
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• 2002

In many years, post-tensioning method has been used for structural reinforcement of RC structures due to easy installation and good quality control. This study presents practical application results for the effectiveness of structural post-tensioning reinforcement of the FCM bridge girders, cement silos and building girders. For the FCM bridges deflected excessively at the end of girders, for cement silos cracked vertically at silo surface and for building girders deflected due to heavy load from roof, the external post-tensioning method was used for uplifting deflected girders and closing cracks with increasing resisting capacity of the structures. It was demonstrated that all the items were rehabilitated nearly to the initial construction status according to the field test results.

• Structural Engineering and Mechanics
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• v.40 no.3
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• pp.297-313
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• 2011

As bridge conditions in the United States continue to deteriorate, rapid bridge replacement procedures are needed. Decked precast prestressed concrete (DPPC) girders are used for rapid bridge construction because the bridge deck is precast with the girders eliminating the need for a cast-in-place slab. One of the concerns with using DPPC girders as a bridge construction option is the durability of the longitudinal joints between girders. The objectives of this paper were to propose a method to use a spring element modeling procedure for representing welded steel connector assemblies between adjacent girders in DPPC girder bridges, perform a preliminary study of bridge performance under multiple loading scenarios and bridge configurations, and discuss model flexibility for accommodating future field data for model verification. The spring elements have potential to represent the contribution of joint grout materials by altering the spring stiffness.

• Steel and Composite Structures
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• v.6 no.1
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• pp.1-14
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• 2006

Experiments have been carried out on six composite and two plain steel plate girders under shear loading to understand the elastic and inelastic behaviour of such girders. The failure mechanism assumed and used to develop design equations is normally based on the failure patterns observed in the experiments. Therefore, different types of cracks and failure patterns observed in the experiments are reviewed briefly first. Based on the observed failure patterns, a design method to predict the ultimate shear capacity of composite plate girders is proposed in this paper. The values of ultimate shear capacity obtained using the proposed design method are compared with the corresponding experimental values and it is found that the proposed method is able to predict the shear capacity accurately.

• Steel and Composite Structures
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• v.7 no.6
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• pp.469-486
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• 2007

The paper is concerned with the behavior of tapered steel plate girders, primarily subjected to shear loading; experimental as well as finite element results obtained from the studies are presented in this paper. In the experimental study, 11 large-scale girders, one of uniform section and 10 tapered, were tested to failure and all girders were analysed by finite element method. The results are compared and the accuracy of the finite element modeling established. A parametric study was carried out with thickness of web, loading direction and taper angle as parameters. An analytical model, based on Cardiff model for girders of uniform cross-section, is also proposed in the paper.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.17.1-24
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• 1995

In tennelling lattice girders have basically the same function as steel arch supports. They serve as elements of temporary lining and in some cases also as part of the permanent lining. Also lattice girders are closely connected with that of the shotcreting lining technique. This paper presents the results of modelling test for analysing shorcrete rebound, shotcreting time and finding void spaces using the aretificial tunnel wall which consist of wood to evaluate the site applicability of lattice girders for tunnel support. Test results indicate that in case of using lattice girders as a tunnel support material, shotcrete rebound, shotcreting time and occurrence of void spaces are relatively reduced comparing to H-beam steel rib. And we can get some informations ths lattice girder has various advantages when we use it as one of tunnel support materials.