Journal of Bridge Engineering

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.

Accounting for waterway vessel collision is required in the structural design of bridges spanning navigable waterways. During collision events, massive waterway vessel groups such as barge flotillas are capable of dynamically transmitting horizontal forces to impacted bridge components. Furthermore, collision-induced forces can be sufficient to collapse piers or roadway spans in the vicinity of the impact location. If collapse takes place, economic loss is suffered because of subsequent traffic rerouting and bridge replacement costs. Additionally, fatalities may occur if the roadway is occupied during or shortly after collapse. This paper focuses on the development of a probability of collapse expression for bridge piers subject to barge impact loading, where the relationship can be readily integrated into existing bridge design methodologies. The expression is developed by employing probabilistic descriptions for a multitude of random variables related to barge traffic characteristics and bridge structures in conjunction with nonlinear dynamic finite-element analyses of barge-bridge collisions. Highly efficient, advanced probabilistic simulation techniques are necessarily incorporated into the barge-bridge collision analysis framework to allow feasible estimation of structural reliability parameters. These parameters facilitate the formation of an expression that, in turn, bridge designers can use to estimate probabilities of structural collapse attributable to barge collision, without performing probabilistic analyses.

Initial development work for an in situ fatigue sensor for the detection of fatigue damage in steel bridge structures is presented. The in situ fatigue sensor is designed to be bonded to the base structure and is based on the strain-life fatigue analysis method. Sensors are constructed of electrically conductive material with notched sensor arms producing varying stress concentration factors. The sensor operates on the principle of predictable progressive failure of the parallel arms as fatigue damage is accumulated in the base structure. Experimental results of the behavior of the fatigue sensor under constant amplitude loading of a base structure-mimicking carrier specimen are compared with the simulation results obtained by the finite-element analysis method and show reasonable agreement.

A road bridge containing disused flatbed rail wagons as the primary deck superstructure was performance tested on a low-volume, high-axle load traffic road in Queensland, Australia, and some key results are presented in this paper. A fully laden truck of total weight 28.88% of the serviceability design load prescribed in the Australian bridge code was used; its wheel positions were accurately captured using a high-speed camera and synchronized with the real-time deflections and strains measured at the critical members of the flat rail wagons. The strains remained well below the yield and narrated the existence of composite action between the RC slab pavement and the wagon deck. A three-dimensional grillage model was developed and calibrated using the test data, which established the structural adequacy of the rail wagons and the positive contribution of the RC slab pavement to resist high-axle traffic loads on a single lane bridge in the low-volume road network.

This paper describes a methodology for evaluating alternative corrosion management strategies for a steel roadway bridge based on a total cost-benefit analysis. In this analysis, the impacts of girder type and preservation intervention selection on the bridge owner, users, and public are considered. The methodology is demonstrated for a steel girder bridge in Wallis, Switzerland. Painted carbon steel and unpainted weathering steel girders are investigated. The investigated preservation interventions are the following: protection by painting, protection by metalizing, and replacement. Deterioration of the girders by corrosion is modeled probabilistically. Following the methodology demonstration, sensitivity studies are performed, wherein the corrosion environment, traffic volume, and detour length during interventions are varied. The effects of these variations on the various benefit types are then discussed and the conditions under which the various corrosion management strategies may be optimal are identified.

External prestressing technology has achieved wide application in bridges. Although previous tests have made great progress in shear behavior of externally prestressed concrete beams, the research mainly focused on simply supported beams. To study the effects of joints and large negative moments on the shear behavior of segmental externally prestressed concrete continuous beams, a series of cantilever beam specimens were designed to simulate the negative moment regions in continuous beams. Then, the crack developing behavior, failure mode behavior, and mechanical behavior of specimens with different shear span to effective depth ratios, joint types, joint locations, and ratios of internal to external tendons were investigated in this experimental study. The test results show that failure cracks of segmental specimens are web shear cracks, whose locations and inclination angles are independent of joints. Eventually, both sides of the specimens move relatively along failure cracks and the specimens fail suddenly. The results also reveal that the deflections of segmental specimens after cracking develop very quickly, and the stress increments of prestressing tendons reach 20–24% of the tensile strength, which are larger than those of monolithic specimens. In addition, the shear strength provided by the concrete effects in regions near the interior supports of continuous beams is lower than that in regions near the supports of simply supported beams, and the contributions of the stirrup and prestressing tendon to the shear strength are 14–21 and 8–18%, respectively, in which the contribution of stirrup is greater than that of simply supported beams.

The technical note presents the results and conclusions of the field tests under service loads that were conducted on a corrugated steel plate (CSP) railway culvert. On the basis of the measured displacements, use of the frequency domain decomposition method determined the frequencies of this culvert. Interferometric radar was used to monitor displacements of this culvert. The comparison between dynamic coefficients, received from three bridge standards and the experimental dynamic amplification factor (DAF), is also presented. The DAFs from tests were in the range of 1.10–1.375. The frequencies of the CSP culvert, caused by kinematic excitations, did not exceed 5.5 Hz. In turn, the maximum displacements of the CSP railway culvert ranged from $0.08\times {10}^{-3}$ to $0.65\times {10}^{-3} \text{m}$. Conclusions drawn from the tests can be helpful in the assessment of the dynamic behavior of such CSP culverts.