Journal of Bridge Engineering

The structures of Santiago Calatrava are noted for their adventurous forms, and Calatrava is heralded as a hybrid architect/engineer whose works represent an integration of both disciplines. While there have been a number of publications on the structures of Calatrava, nearly all have focused on the architecture or artistry of them without addressing how well they fulfill the requirements or represent great works of structural engineering. Here a thorough structural analysis of one of Calatrava’s most well known bridges is performed to determine how well it achieves the goals of structural engineering. This provides insight as to how well Calatrava’s works represent engineering as art and what we can learn from his works in the context of great works of structural art.

A significant portion of the nation’s aging bridge inventory consists of flat slab concrete bridges. Many of these bridges were constructed in the middle third of the 20th century, and although they are in generally good condition, they were not designed to carry modern highway loads. This research builds on prior studies that indicate that the equivalent strip width method—prescribed by AASHTO and widely used for the analysis of flat slab bridges—may be overly conservative and lead to underprediction of bridge structural capacity. The development of finite-element (FE) analysis software designed specifically for the load rating of flat slab bridges is presented. The FE software formulation and convergence were verified by comparison with predictions from commercial FE software under realistic loading scenarios. Results of live load tests of an instrumented, in-service flat slab bridge are reported. The FE model-predicted slab moments were shown to be conservative relative to the moments inferred from the load test data for a range of truck positions. Fourteen in-service flat slab bridges were load rated with both FE analysis and the equivalent strip method to assess the degree of conservatism inherent in the AASHTO approximate analysis. The results show an average increase in rating factor of approximately 26% when using FE analysis and that 58% of the bridges predicted to be under capacity using AASTHO approximate methods are sufficient based on FE analysis.

This paper presents the experimental work of two full-scale Bailey bridge segment load tests. The Bailey bridge segments were tested using a 130-t Universal Tester. The midspan deflections of panel assemblies were observed during the loading. Axial strains of several critical members were also measured. The axial capacities of the top chord members are compared with the calculated AASHTO nominal axial compression resistances. Experimental results are also compared with elastic and inelastic analyses using unsymmetrical sections. Test results show that (1) the inelastic lateral buckling occurred in compression chord members; (2) AASHTO-LRFD Article 6.9.4 generally predicts conservative results; (3) the effect of partial fixity of connections on the response of the structural model is insignificant and may be neglected in the analysis; and (4) a two-dimensional nonlinear inelastic analysis predicts a higher load-carrying capacity because it is not able to capture the out-of-plan stability behavior. It is recommended that Bailey-type bridges may be tested in their actual loading conditions to investigate their exact behavior, and more work is needed in the area of numerical modeling to simulate nonlinear inelastic lateral torsional behavior of the Bailey-type bridges. The CALTRANS is currently working closely with several prefabricated modular truss bridge manufacturers to develop the guidelines for temporary prefabricated modular steel truss bridges. Research findings presented in the paper are beneficial to this development.

Most bridges are aging and do not have complete design information. Hence, field testing for the evaluation of the structural performance and health of bridges is becoming essential, but even sophisticated modern structural analysis techniques cannot replace field testing, especially in the case of determining the live-load performance of bridges. Furthermore, field data can be used to calibrate and fine-tune an analytical model to match the behavior observed in the field. In this paper, details of full-scale field testing and performance-evaluation studies carried out on a typical steel plate girder railway bridge under increased axle loads are presented. One of the primary objectives of the study is to evaluate the longitudinal force caused by the increased axle loads of freight wagons. The bridge superstructure is extensively instrumented to measure the responses under various static and dynamic tests carried out using the test train formation with increased axle loading. The strategies adopted for evaluating structural response parameters are discussed. In addition, dispersion of the longitudinal force from the rail to the superstructure is evaluated using an innovative fixture together with the appropriate instrumentation scheme. It is found that around 50% of the longitudinal force generated at the rail level is transferred to the bridge substructure of the instrumented span. Using the load spectra adopted in the current study, the remaining fatigue life of the bridge is also evaluated using different damage models and is estimated to be around 150 years. The methodologies developed and implemented for the health assessment of plate girder bridges would pave the way for undertaking timely maintenance.

The collapse of the Interstate 35W bridge in Minneapolis, Minnesota, in 2007 brought into question the strength of large-size gusset plates in steel truss bridges. To provide new data on the behavior and strength of large-size bridge-type gusset plates, experimental tests were performed and are described in this paper. The research program focused on sway-buckling behavior and test variables included plate thickness, compression diagonal flexural stiffness, initial out-of-plane imperfection, and member load combinations. Unique to this test program was the direct consideration of different compression diagonal out-of-plane flexural stiffnesses on plate buckling behavior and capacity. Results showed that sway-buckling behavior and ultimate capacity were affected by initial out-of-plane imperfections of the plate and the out-of-plane bending stiffness of the truss compression diagonal. Results also showed that the effective length factor, $K$, a parameter used in present load rating guides, did not accurately predict sway-buckling capacity, and the Whitmore section approach may not be the best approximation for use in plate sway-buckling behavior. A stepped-column approach was shown to illustrate and predict the effect of the plate-member stiffness interaction on buckling capacity.

This paper focuses on the fragility-based seismic vulnerability assessment of retrofitted multicolumn bridge bents. Fragility curves are developed to assess the relative performance of various retrofit methods under both near-fault and far-field ground motions. A probabilistic seismic demand model (PSDM) is used in generating the fragility functions. Through nonlinear dynamic analysis, fragility curves are developed for multicolumn bridge bents retrofitted with four different retrofit techniques, specifically carbon fiber–reinforced polymer (CFRP) jacketing, steel jacketing, concrete jacketing, and engineered cementitious composite (ECC) jacketing. Following the performance-based evaluation approach, this study aims to investigate the effectiveness of different retrofitting methods to minimize the overall seismic vulnerability of deficient bridge bents. To investigate the seismic responses of the retrofitted bridge bents, a total of 40 earthquake excitations, of which 20 are near-fault and 20 are far-field ground motions, are utilized to evaluate the likelihood of exceeding the seismic capacity of the retrofitted bridge bents. The use of fragility curves for retrofitted bridge bents will aid in expressing the potential impact of retrofit on the bridge bent vulnerability. The results obtained from this study indicate that the bridge bents retrofitted with ECC and CFRP jacketing possess less vulnerability at different damage states under both near-fault and far-field earthquakes.

In the current study, the nonstationary random responses of moving wheels induced by road roughness in a time domain were obtained and treated as the nonstationary inputs to study the nonstationary vibration of a high-pier bridge under vehicles with variable speed. A full-scale vehicle model with 12 degrees of freedom was used; vehicle wheels were considered as patch contact instead of point contact with the bridge road surface. The vehicle-bridge coupling equations were established by combining the equations of motion of both the bridge and vehicle using the displacement relationship and the interaction force relationship at the contact patches. The midspan deflections caused by the stationary and nonstationary inputs were compared with the measured responses under different parameters including vehicle acceleration and vehicle deceleration. The verified results showed that the proposed method can accurately simulate the vibration of the bridge under vehicles moving with variable speeds. Using the stationary random process to model the road surface disturbance to vehicles with variable speeds, the dynamic effects can be either underestimated or overestimated. The proposed method was then used to study the ride comfort for vehicles moving with a variable speed on high-pier bridges.

This paper combines an experimental study and computational fluid dynamics (CFD) simulations to investigate the influence of dynamic properties and position of upper rivulet on rain–wind-induced vibration (RWIV) of stay cables. The reproduction of the RWIV of a stay cable model is first performed based on artificial rainfall wind tunnel tests with an ultrasonic transmission thickness measurement system, which can obtain the characteristics of rivulets on the surface of the stay cable model. On the basis of the test results, CFD simulations are then used to study the aerodynamic influence of an upper rivulet using two different CFD models: a vibrating cable model with a moving upper rivulet and a vibrating cable model with a fixed upper rivulet. CFD simulations suggest that the existence of the upper rivulet do not sufficiently to excite RWIV. It is confirmed that, when an upper rivulet oscillates in a specific range at the same frequency of a cable, it can significantly vary the aerodynamic force acting on the cable with the same frequency of the cable and the aerodynamic resonant excitation will lead to the occurrence of RWIV.

This paper describes an experimental program conducted to investigate the effects of fluid-structure interaction on the modal dynamic response of three reduced-scale bridge pile foundations submerged partially or totally in water. The vibration periods of the specimens are measured for the two lateral modes and first torsional mode using ambient and forced vibration tests. The results are presented and discussed as a function of surrounding water levels and the number and geometrical patterns of the piles. Three-dimensional (3D) finite-element models of the tested specimens surrounded by different water levels are built, and the results are successfully validated against the obtained experimental data. The built numerical models are used to compute 3D modal hydrodynamic pressures. A systematic analysis of the period ratios and 3D hydrodynamic loads is presented to characterize the effects of pile cap, water height, and the number and geometrical pattern of the piles on dynamic response. The experimental and numerical results of this research allow a better understanding of the complex dynamically induced fluid-structure interaction effects in the response of deepwater bridge pile foundations.

Precast concrete segmental bridges with external tendons are becoming widely constructed all over the world. The main objective of this study is to obtain a further understanding of the behavior of joints when they are subjected to combined shear and bending. Nine specimens of precast concrete segmental beams (PCSBs) with external tendons were match cast and tested: six of the specimens were tested under combined shear and bending; two specimens were tested under pure bending; and one specimen was tested under direct shear. Failure processes and modes, joint resistance, and strains of stirrups and prestressing tendons were recorded in the tests. Based on the results of the experiment, the study analyzed the mechanism of combined shear and bending resistance for dry and epoxied joints when loads were located in the immediate vicinity of the joint. Additionally, simplified failure modes of dry and epoxied joints subjected to combined shear and bending were presented in this paper. On the basis of the simplified failure modes, formulas were deduced for evaluating the resistance of joints when failure occurred in a joint section with loads applied in the immediate vicinity of the joints. The formulas provided a rational prediction of the joint resistance under combined shear and bending, which in turn verified the rationality of the proposed failure modes.

This paper presents the development of high-strength precast prestressed double-Tee girders for bridge construction. These girders use high-strength concrete (103 MPa), Grade 550 welded wire reinforcement, and 18-mm-diameter Grade 1860 prestressing strands at 51- by 51-mm spacing. The double-Tee section was used to simplify girder production and erection and to maximize span-to-depth ratio, which improves the construction economy and speed. To evaluate the efficiency of the developed girders, two full-scale 15.24-m long, 1.21-m wide, and 0.5-m deep single-Tee girders were fabricated by a precast producer and tested at the University of Nebraska structural laboratory. Transfer length measurements, development length testing, flexure capacity testing, and vertical and horizontal shear testing were conducted for each specimen. Test results have shown that the proposed high-strength bridge double-Tee girder can be designed using current LRFD bridge design specifications. Preliminary design charts for different girder sizes were presented to demonstrate the efficiency of these girders for short- and medium-span bridges.

Accelerated bridge construction techniques have resulted in state-of-the-art options that save time and money during the construction of new or existing bridges. One such group of techniques that has generated considerable interest is the use of precast-concrete deck panels. Using precast-concrete deck panels allows for off-site curing, thus eliminating long delays from formwork construction and concrete curing time. Despite the benefits, problems can develop as a result of the inherent joints between the individual panels. These joints are locations for potential leakage, which can result in corrosion or inadequate long-term performance. Posttensioning the precast deck panels helps to eliminate leakage, but conventional longitudinal posttensioning systems require complete deck replacement in the event of a single faulty deck panel. The proposed posttensioned curved-strand connection presented in this paper allows for single-panel replacement. The capacity of the proposed curved-strand connection was investigated to compare its behavior with that of other systems currently in use. The curved-strand connection was found to be comparable to a standard posttensioning system. The ultimate capacity of the curved-strand connection in negative bending was found to be 97% of the standard posttensioning connection.

Portable and rapidly deployable bridges are critical for providing access routes for troops during military operations and for restoring vital lifelines for communities affected by large-scale disasters. This paper reviews the history and the state of the art in portable and rapidly deployable bridge technology, primarily for U.S. systems. Four types of deployable systems are presented, including (1) rapidly erectable gap-crossing bridges (e.g., Bailey Bridge, Medium Girder Bridge), (2) vehicle-launched bridges (e.g., Armored Vehicle–Launched Bridge, Dry Support Bridge), (3) river-crossing solutions (e.g., M4T6, Improved Ribbon Bridge), and (4) causeways (e.g., Navy Elevated Causeway System, Lightweight Modular Causeway System). Discussion of each design emphasizes the technology itself, its application throughout history, and the evolution of the forms in relation to one another. The paper concludes with a discussion of the future of these technologies. The paper provides the first review of portable and rapidly deployable bridge technology in civil engineering literature and is of general interest to those who would like to learn more about this technology for military and disaster-relief purposes.

The passive force-deflection relationship for abutment walls is important for bridges subjected to thermal expansion and seismic forces, but no test results have been available for skewed abutments. To determine the influence of skew angle on the development of passive force, laboratory tests were performed on a wall with skew angles of 0, 15, 30, and 45°. The wall was 1.26 m wide and 0.61 m high, and the backfill consisted of dense compacted sand. As the skew angle increased, the passive force decreased substantially, with a reduction of 50% at a skew of 30°. An adjustment factor was developed to account for the reduced capacity as a function of skew angle. The shape of the passive force-deflection curve leading to the peak force transitioned from a hyperbolic shape to a more bilinear shape as the skew angle increased. However, the horizontal displacement necessary to develop the peak passive force was still between 2 and 4% of the wall height. In all cases, the passive force decreased after the peak value, which would be expected for dense sand; however, at higher skew angles, the drop in resistance was more abrupt. The residual passive force was typically 40% lower than the peak force. For nearly all skew angles, the transverse shear resistance exceeded the applied shear force on the wall so that transverse movement was minimal. Computer models using the plane strain friction angle were able to match the measured force for the no skew case as well as for skewed cases when the proposed adjustment factor was used.

The deterioration and ageing process make the reliability of bridges a time-variant problem. However, most studies about time-dependent reliability focus on material corrosion and damage, less attention is given to the effects of concrete creep on the reliability of bridges. This paper presents a case study to investigate the influence of concrete creep on the serviceability reliability of concrete-filled steel tube (CFST) arch bridges, which have a wide application in China. The structural creep effect was analyzed by Model B3 and the age-adjusted effective modulus method; the reliability analysis was performed by Monte Carlo simulation with the Latin Hypercube sampling method, considering random variables involved in three aspects: creep model uncertainty, and variations of material and geometric properties. The analytic results show that the serviceability reliability of CFST arch bridges decreases due to creep, and creep model uncertainty is the most important factor for the structural creep effects and serviceability reliability.

Piles in integral-abutment bridges (IABs) may experience plastic deformation and low cycle fatigue as a result of cyclic loading induced by daily and seasonal temperature variations. This paper presents guidelines that will help to determine the amount of deformation in piles, evaluate the type of deformation (elastic versus plastic), and establish the fatigue life of the piles in IABs. To illustrate the steps of the process, the case of an IAB is studied in which the length of the bridge is varied as a parameter between 122 and 549 m. The effect of bridge length on daily and seasonal strain amplitude in piles and daily and seasonal fatigue life is evaluated. Plastic deformation was observed in all bridges analyzed, indicating a possibility of low cycle fatigue in these bridges. Palmgren-Miner is used to evaluate the combination effects of both daily and seasonal temperature cycles and the contribution of each cycle type. The results show that daily cycles are the main cause of damage and that the contribution of seasonal temperature cycles is negligible. The fatigue life was found to be about 42 years in a bridge with a length of 122 m and decreases exponentially as the length of the bridge increases to 9.5 years in a 549-m-long bridge.