Journal of Bridge Engineering

Box-beam bridge shear key connection designs are investigated by conducting full-scale structural tests. The authors’ evaluation included connection details, which are considered current good practice using high-strength nonshrink grout in combination with transverse posttensioning and novel details using ultra-high-performance concrete (UHPC). The factors that affect shear key performance, including simulated traffic loading, thermal loads, level of transverse posttensioning, and different connection designs, are presented in this paper. A simplified model for calculating the transverse shear is proposed, and the possible transverse tensile force caused by eccentrically placed loads is discussed. The performances of different connection details are presented and compared. The findings of the research can be used to assist bridge owners in the use of this economical bridge type and can provide innovative solutions that advance state-of-the-practice in bridge construction.

Transportation Technology Center, Inc. (TTCI) is investigating the feasibility of using vehicle-based systems to detect railroad bridge impairments to supplement regular bridge inspections. Test results show that an onboard track deflection measurement system and two different track geometry measurement systems are capable of detecting changes in pier elevations, and some of the systems can detect changes in bridge span deflection in an open-deck trestle. A series of tests detecting weak stringers and pier elevation changes in an open-deck trestle bridge was performed at the Bridge Deflection Test Facility (BDTF). This paper presents results from three vehicle-based systems in different test setups: (1) A track deflection measurement system and a track geometry measurement system were tested on a Federal Railroad Administration (FRA) track measurement vehicle, (2) another track geometry measurement system was tested on a lightweight passenger car, and (3) a track deflection measurement system was tested on a conventional hopper car.

Typical small-to-medium–span highway bridges in China are often installed with economical laminated-rubber bearings that allow for thermal movement of girders and concrete shear keys that restrain transverse girder displacement. However, the damage investigation after the 2008 Wenchuan earthquake had shown that sliding between the girder and the laminated-rubber bearings was a common phenomenon that caused excessive girder displacement and damage to shear keys, expansion joints, and abutments. The bearing sliding can actually act as isolation for the piers, which suffered from a small amount of damage during the earthquake. Therefore, a new seismic design strategy for typical girder bridges has been proposed in which the bearing sliding acts as a fusing mechanism to mitigate the seismic demands of piers, and unseating-prevention devices are used to control the bearing displacement. This paper investigates the seismic performance of three transverse unseating-prevention devices (concrete shear keys, yielding steel dampers, and friction dampers) for a typical simply supported girder bridge. The results show that if the unseating-prevention devices are properly designed, the seismic demands of piers can be effectively reduced, and the bearing displacement can also be controlled to satisfy the performance objectives. Yielding steel dampers and friction dampers are suggested to be used in place of concrete shear keys to improve the bridge seismic performance.

A method for predicting the bounds of vehicle-induced bridge responses with uncertain bridge and vehicle parameters is presented. The uncertainties in the parameters of the bridge and vehicle are represented with interval variables instead of conventional random variables with known probability distributions. First, a three-dimensional vehicle–bridge interaction (VBI) system, which has no closed-form solution and can account for road roughness, is established. Then, by introducing the interval analysis method (IAM) based on the first-order Taylor series expansion, the expressions of the bridge responses, including displacement and bending moment at the midspan, can be explicitly given as functions of the interval parameters, and the lower and upper bounds of the bridge responses are determined by the particle swarm algorithm instead of direct interval arithmetic to avoid excessive overestimation of the responses. The subinterval technique can also be adopted to improve the accuracy of the IAM. A numerical example is provided, and the results show that, compared with the conventional Monte Carlo method, the proposed IAM is capable of obtaining the bounds of the bridge deflection and bending moment without much sacrifice of accuracy while requiring much less computational effort. This indicates that the proposed method can be effectively and efficiently applied to predicting the bounds of the dynamic responses of complicated VBI systems with interval uncertainties. An example is also used to demonstrate the applicability of the IAM to field bridges when only limited information about the bridge and vehicle is available.

In recent years, increasing attention has been paid to the collapse failures of long-span continuous rigid-frame bridges under strong earthquake excitations. This paper presents the results of a study in which a 1:15 scaled two-span prestressed concrete continuous rigid-frame bridge model with box-type piers was tested using the shake-table array test system to investigate the seismic response characteristics. Two nonlinear finite-element (FE) models were constructed. The first was a single-girder model that was used to simulate the seismic response under weak seismic waves. The second was an explicit dynamic FE model that was used to simulate the collapse and failure mechanisms of the scaled bridge under strong earthquakes. Testing revealed that the response of the central pier of the prestressed concrete continuous rigid-frame bridge was the largest under seismic excitation, and the damage first appeared at the lower end of the central pier in all cases. The numerical simulations revealed that traveling wave effects have a beneficial effect on the displacement at the top of all piers. The explicit dynamic model was able to predict the failure modes and collapse process of the scaled bridge model. The plastic hinges emerging at the ends of the piers were considered the main failure modes, and the collapse process changed with different seismic wave excitations. Such tests and analyses can provide useful reference for the seismic-strengthening and anticollapse design of prestressed concrete continuous rigid-frame bridges with a long span.

The current practice for bridge-fatigue design may have underestimated the effect of dynamic vehicle loading and truck overloading on the fatigue life of steel bridges. In this study, a new approach for fatigue design of steel bridges was proposed that considers the effect of these two factors more rationally. A three-dimensional vehicle–bridge coupled model was developed to simulate the interaction between the bridge and vehicle. A simply supported steel I-girder bridge was used as an example for illustration of the proposed approach. The fatigue vehicle model was adopted from the AASHTO LRFD code, and overloading was considered by increasing the gross weight of the truck model. Numerical simulations were conducted to study the influence of three important parameters—road surface condition (RSC), vehicle speed, and truck gross weight—on the fatigue damage of the bridge considered. The results show that the RSC and truck gross weight both have a significant impact on the bridge-fatigue damage. By considering the cumulative fatigue damage caused by each truck passage under different RSCs and the deterioration process of the RSC during its whole lifecycle, a simple and reasonable expression was proposed for bridge-fatigue design. The proposed approach improves the current bridge-fatigue design method in that it rationally considers the vehicle dynamic effect, the influence of overloaded trucks, and the deterioration of RSC, which have a large influence on bridges’ fatigue life.

The flexural capacity of a well-designed RC column deteriorates under extreme ground motion as a result of crushing of the core concrete and buckling of the longitudinal bars in the plastic hinge regions. Thus, it is important to minimize damage at the plastic hinge region to develop high-performance bridge columns. A column that uses ultrahigh-performance concrete (UHPC) segments at the plastic hinge region is proposed to address this issue. Three reduced-scale columns were constructed and tested at the Tokyo Institute of Technology in Japan. Two of the columns with different plastic hinge details were investigated using bilateral cyclic loading. The first column had a reinforced concrete core encased in an UHPC jacket. The second column had an UHPC hollow-core plastic hinge combined with posttensioning. Both columns were designed to have approximately the same nominal strength. They were tested under orbital bilateral cyclic loading customized to impose flexural deformations and investigate the possibility of twisting of the columns. The column that had a solid concrete core was able to carry the applied axial load to a drift of 6%. The posttensioned column was able to carry the applied axial load to a drift of 3.5%. The third column was tested to investigate the seismic performance of the first column, which had a concrete core, under hybrid simulation. The proposed UHPC column exhibited good performance for a seismic-resistant column. Energy dissipation and hysteresis damping were also calculated. Two analytical approaches were used to estimate the columns’ capacities.

The current paper relates the state of the art of construction of viaducts with a movable scaffolding system (MSS). Two different procedures are introduced: the traditional sequence and the new sequence applied to some viaducts in Spain. The traditional sequence consists of two phases: first, concreting the bottom slab and webs, and then concreting the top slab of the deck. Once the first and second casting phases are completed, the total prestressing force is introduced. The new sequence consists of concreting a self-supporting core (i.e., the bottom slab, webs, and only a portion of the top slab). Once the self-supporting core has hardened, a partial prestressing force is introduced so that the scaffolding can be advanced to the next span; the central zone of the top slab is cast in a second phase. Both sequences are described here with their constructive peculiarities and issues.

Quick recovery of damaged bridges following natural disasters is most vital and helpful. The authors are developing a new type of emergency bridge with the scissor mechanism of expanding equipment as a quick recovery solution. This paper proposes the design method based on the solution of the equilibrium equations for a full-scale experiment of a scissors-type bridge in static mechanics. This method can obtain the dominant sectional force for each scissor member of the bridge. The presented design method was evaluated in comparison with the experimental data of a loading test for a full-scale scissors-type bridge that can withstand the load of a light vehicle. It was confirmed that this method is useful for a recovery bridge system.

A buried composite arch bridge system using concrete-filled fiber-reinforced polymer tube arches was recently developed for short span bridges. The research reported in this and a subsequent paper seeks to advance understanding of soil–structure interaction in these bridges through laboratory testing and numerical modeling simulations of subscale arch systems. This paper focuses on the experimental testing of stiffness-matched, half-scale three-arch bridge systems with 5:1 and 8:3 span-to-rise ratios tested in a controlled laboratory environment. Arches were cast in concrete foundations, placed in a self-reacting, timber soil box, and covered with decking. Deflection, strain, and soil pressure were recorded at eighth points along the span of the center arch and only at the apex and foundations of the outer arches. The bridges were backfilled with lifts of compacted granular soil until soil grade elevation was 610 mm above the decking apex. The bridges were loaded with a sequence of line loads at seven different positions along the span and were then loaded to failure with an apex line load. Experimental results reported here include the effects of backfilling, service live-load testing, and ultimate loading.

In this study, soil–structure interaction in a buried arch bridge system is numerically investigated with two models. Model predictions of arch bending moments and ultimate capacities are compared with the load test performance results of two buried structures from a companion paper. A novel finite-element model was developed using an arch discretized with beam elements and soil discretized with spring elements initialized during progressive backfill simulation. Nonlinear soil-spring force is determined from vertical overburden pressure and earth pressure coefficient dependent on arch deflection. A nonlinear soil-continuum finite-element model was developed using software with Mohr-Coulomb soil plasticity. Experimental moments are compared with model results for backfilling, a series of service-level line loads, and ultimate capacity with an apex line load. The soil-spring model does reasonably well at predicting arch moments and ultimate capacity, and the incorporation of deflection-dependent earth pressure is important when predicting ultimate capacity. The soil-continuum model agrees well with the soil-spring model for service positive moments.

This paper describes the experimental testing of 48-year-old concrete bridge girders that were fabricated using lightweight concrete. After the bridge was decommissioned, three girders were transported to the Systems, Material, and Structural Health (SMASH) Laboratory at Utah State University (USU). The double-tee girders were tested to quantify the effective prestress, flexural capacity, and deck punching shear strength. The experimental results were compared with calculated values based on recommended procedures in the AASHTO LRFD bridge design specifications. The AASHTO refined method underestimated the loss of prestress of the three girders by an average of 17.6%. The calculated flexural capacities were overestimated by an average of 34.0% when compared with the measured values. This unconservative result is believed to be a result of the deck deterioration. The average calculated punching shear capacity was within 3.0% of the measured values. The experimental results were also compared with analytical values using computer software. These nonlinear finite-element analyses (FEAs) were found to replicate the behavior of the flexural and punching shear experiments in terms of both the failure mechanism and magnitude.

This paper presents a numerical analysis of the nonlinear interaction between water waves and the movable superstructure of a coastal bridge. An improved mesh update method is used to dynamically configure the computational meshes solving the Navier-Stokes equations for viscous and incompressible free surface flows with the volume of fluid (VOF) method. To maintain the mesh quality as the bridge deck is displaced, the computational domain is separated into several parts corresponding to a specific type of body motion. The numerical model results have been compared with the laboratory experiments conducted at Oregon State University with good agreement. This hydrodynamic model is then used to simulate the failure process of the prototype U.S. Highway 90 (US 90) Bridge during Hurricane Katrina (2005). It is found that the bridge deck is most vulnerable to be displaced by the waves when the bridge is partially submerged because of the combined effects of the vertical and horizontal wave forces. Numerical experiments of the US 90 Bridge shed light on the sway and heave responses of the bridge deck to different wave height conditions. It is shown that a significant wave height of 2.6 m would result in a failure of the bridge deck. A critical wave height (2 m) based on the incipient motion of the bridge deck is recommended for screening the vulnerability of other bridges similar to the US 90 Bridge in hurricane-prone areas. Moreover, the computed maximum heave response can be used as a reference for engineers to design the shear key height to prevent a bridge deck from horizontal displacement.

In this paper, a numerical model using interface elements is proposed for the sequential analysis of nonlinear track–bridge interaction by taking the loading history into consideration. Longitudinal resistance tests were conducted on track fastening systems to determine changes in track resistance that occur at the instant of application or release of a vertical load. On the basis of the test results, longitudinal track stiffness laws for a nonballasted track were established for different loading cases including constant vertical load, sudden application of vertical load, and sudden release of vertical load. In addition, an interface element adaptive to various loading cases that can be incorporated into a conventional FEM was formulated for modeling the track resistance. Furthermore, a numerical algorithm for a practical solution of the nonlinear system equation was developed. The validity and applicability of the proposed analysis method were verified by conducting extensive parameter studies on a simply supported bridge and a multispan bridge.

This study investigated the safety and stability of light-rail trains that run on multispan simply supported bridges (MSSBs) and have experienced some settling and girder deformation caused by both foundation settlement and girder deflection/camber. A three-dimensional dynamic nonlinear finite-element model for a light-rail train track–MSSB interaction system, which took into account rail irregularities, girder deformation, wheel–rail contact, and coupling effects, was developed. A case study analyzed a four-car light-rail train rolling on a MSSB, and the relationships between the girder deformation and running performance under various speeds were obtained. The results indicate that speed is the dominant factor that contributes to the safety and stability of the light-rail train when girder deformation is present. In addition, the influence of girder deformation was found to be greater on safety than on stability. In real applications, it is recommended to pursue advanced monitoring and evaluation techniques for safe operation of light-rail train systems.

This technical note presents and evaluates a simple approach for estimating the degradation of bridge decks caused by chloride-induced corrosion degradation. This approach uses the Monte Carlo method and combines a local deterministic mechanics-based model for predicting surface cracking time and a global probabilistic model for predicting a degradation curve by using random variables. The predicted damage severity is mapped to the National Bridge Inventory rating scheme. Simulation results are shown to be in reasonable agreement with the documented ratings of bridges from different regions in the state of Michigan. Implementation of the method into a computer program is discussed to illustrate how the approach can allow mechanics-based models to be more accessible to highway agencies for condition assessment and for projecting the performance of existing and new reinforced concrete bridge decks.