Simply-supported Girder Research Articles

Performance and sensitivity analysis of UHPFRC-strengthened bridge columns subjected to vehicle collisions

Bridge columns made of normal concrete are evidenced to be susceptible to vehicle collisions. Particularly in the United States, vehicle collision has become one of the primary causes of bridge failures. This is largely due to the low crashworthiness of a conventional reinforced concrete (RC) column. Ultra-high-performance fiber-reinforced concrete (UHPFRC) as one of advanced concrete materials has been experimentally demonstrated to possess excellent strength, durability, impact resistance and energy-absorbing capacity. Accordingly, one type of UHPFRC-strengthened columns was proposed in this study as an alternative to RC columns that may be at risk for vehicle collision incidents. High-resolution finite element (FE) models were developed to investigate the performance of UHPFRC-strengthened columns subjected to vehicle collisions. In the high-resolution FE model, a three-span simply-supported girder bridge (including girder, pier column, column cap, bearing, etc.) was adopted and modelled. Material models regarding normal concrete and UHPFRC as well as the vehicle model were carefully calibrated by experimental data. The influence of initial gravity loads on impact responses was found to be pronounced, and a damping-based method was proposed to efficiently exert permanent loads on pier columns prior to a collision. Three different simplified models, as published in current studies, were investigated to replace the whole bridge model. Two single-column models with different boundaries were shown to have low accuracy. The pier-bent model considering the superstructure gravity was demonstrated as capable of predicting collision-induced responses that are in good agreement with the high-resolution FE model. The impact resistances of both RC and UHPFRC-strengthened columns were extensively investigated using the appropriate simplified model. The crashworthiness of UHPFRC-strengthened column was found to be considerably superior to that of RC column. An extensive parametric study was performed using response surface methodology to explore the influences of reinforcement ratios, thickness of UHPFRC jacket, UHPFRC strength and initial impact speed. The impact-resistant performance is mostly sensitive to changes in the thickness of UHPFRC jacket when the impact speed is not very high. On the contrary, the residual capacity of the bridge column is hardly increased by thickening UHPFRC jacket. In addition, the developed response surface models provided easy estimation of impact-induced responses of an UHPFRC-strengthened column, which have potential use as the surrogates of time-consuming FE simulations to efficiently examine the reliability and optimization of bridge columns under impact loadings.

Non-Stationary Random Vibration Analysis of Railway Bridges Under Moving Heavy-Haul Trains

This paper presents a non-stationary random vibration analysis of railway bridges under moving heavy-haul trains by the pseudo-excitation method (PEM) considering the train-track-bridge coupling dynamics. The train and the ballasted track-bridge are modeled by the multibody dynamics and finite element (FE) method, respectively. Based on the linearized wheel-rail interaction model, the equations of motion of the train-ballasted track-bridge coupling system are then derived. Meanwhile, the excitations between the rails and wheels caused by the random track irregularity are transformed into a series of deterministic pseudo-harmonic excitation vectors by the PEM. Then, the random vibration responses of the coupling system are obtained using a step-by-step integration method and the maximum responses are estimated using the 3[Formula: see text] rule for the Gaussian stochastic process. The proposed method is validated by the field measurement data collected from a simply-supported girder bridge (SSB) for heavy-haul trains in China. Finally, the effects of train speed, grade of track irregularity, and train type on the random dynamic behavior of six girder bridges for heavy-haul railways are investigated. The results show that the vertical acceleration and dynamic amplification factor (DAF) of the midspan of the SSB girders are influenced significantly by the train speed and track irregularity. With the increase in the vehicle axle-load, the vertical deflection-to-span ratio ([Formula: see text]) of the girders increases approximately linearly, but the DAF and vertical acceleration fail to show clear trend.

Lateral-torsional buckling strength and behaviour of high-strength steel corrugated web girders for bridge construction

Corrugated web plates have been used in recent years as the webs of steel girders in bridge constructions thanks for their advantages, especially their superior shear capacities relative to stiffened flat webs. Therefore, they have been extensively investigated under shear compared with their limited investigations on the bending behaviour which was exclusively concentrated on the girders formed from the conventional normal strength steels. On the other hand, the use of high-strength steels (HSSs) in bridges has been increased when large and column-free spaces are key design issues. This paper focuses on the lateral-torsional buckling (LTB) of bridge girders with corrugated webs (BGCWs) built up from HSSs. This is done by using the commercially available finite element (FE) analysis package ABAQUS which has been used to generate parametric studies addressing the different affecting parameters on the behaviour of these girders. Simply-supported girders subjected to uniform bending, representing the worst case in LTB which is used in developing the member capacity design rules in different standards, are used in developing the current nonlinear FE models. The recently suggested warping constants in literature are used to compare the critical buckling moments with the elastic FE predictions. Then, the design model included in the Eurocode 3 is compared with the nonlinear strengths of the girders. The comparisons show that it provides conservative outcomes; therefore a modified version of the design model is suggested by using another buckling curve.

Soil-Structure Interaction on the Dynamic Response of Bridge Piers

The paper analyses the effect of Soil-Structure-Interaction (SSI) on the modal dynamic response of simply-supported span girder bridge with wall piers founded on caissons. A parametric analysis has been carried out in the hypothesis of linear elastic behaviour of all materials (soil and structure) to identify the influence of various design factors, such as the height of the pier, the caisson embedment below the ground level and the soil mechanical properties. The goal of the paper is to highlight SSI effects on the dynamic behaviour of bridges. This is a crucial aspect to be accounted for in order to support monitoring activities on bridges, aimed to structural identification or assessment of structure response under serviceability conditions, or also to have preliminary information for the seismic analysis of the bridge.

Mechanical performance of arch-type continuous slab-deck on simply-supported girder bridge

Mechanical performance of arch-type continuous slab-deck on simply-supported girder bridge

Crack detection using integrated signals from dynamic responses of girder bridges

An innovative approach for the identification of cracks from the dynamic responses of girder bridges was proposed. One of the key steps of the approach was to transform the dynamical responses into the equivalent static quantities by integrating the excitation and response signals over time. A sliding-window least-squares curve fitting technique was then utilized to fit a cubic curve for a short segment of the girder. The moment coefficient of the cubic curve can be used to detect the locations of multiple cracks along a girder bridge. To validate the proposed method, prismatic girder bridges with multiple cracks of various depths were analyzed. Sensitivity analysis was conducted on various effects of crack depth, moving window width, noise level, bridge discretization, and load condition. Numerical results demonstrate that the proposed method can accurately detect cracks in a simply-supported or continuous girder bridges, the five-point equally weighted algorithm is recommended for practical applications, the spacing of two discernable cracks is equal to the window length, and the identified results are insensitive to noise due to integration of the initial data.

Self-Stressed Steel Fiber Reinforced Concrete as Negative Moment Connection for Strengthening of Multi-Span Simply-Supported Girder Bridges

A self-stressed steel fiber reinforced concrete (SS-SFRC) moment connection is proposed to strengthen multi-span simply-supported T-section reinforced concrete (RC) girders. In the proposed moment connection technique, old concrete needs to be removed from adjacent girder ends and negative moment reinforcement is placed into cast-in-place SS-SFRC to develop continuity over the interior support. Two series of tests consisting of 15 girder specimens were conducted to investigate the reliability of the proposed SS-SFRC moment connection. An analytical model is presented to predict the load-carrying capacity of the resulting continuous composite girders. Test results show that SS-SFRC is excellent in preventing concrete cracking at the interior support. Both the load-carrying capacity and the serviceability of the strengthened girders are significantly improved. The analytical model is demonstrated to predict the load-carrying capacity of the resulting continuous composited girders with an acceptable degree of accuracy.

Mathematical Logarithmic Model for Predicting Noise of Simply-Supported PC-Box Girder in High-Speed Railway

When a train runs across a bridge, vibration energy is transmitted from the track structure into the bridge deck and other components which act as different size of ‘sounding boards’. These ‘sounding boards’ also radiate noise, namely, re-radiated noise, which results in ‘hot spots’ in noise maps for bridge sections. Based on the field tests on the noise of 32m double line simply-supported PC-box girder serviced in Chengdu-Dujiangyan High-speed Railway (CDHR) in China, mathematical logarithmic equation for predicting the equivalent A-weighed noise level (LA,eq) is proposed. Predicted results are compared with field ones and the non-parametric tests including two-related samples Wilcoxon and two-independent samples Kolmogorov–Smirnov are carried out, indicating satisfactory results and verifying the reliability of theoretical model. Analysis shows that equivalent A-weighed noise level detects no significant difference between the model predictions and the field measurements at the confidence level of 95%.

Analysis of Dynamic Response of Simply-Supported Girder Bridge in High-Speed Railway Based on the Moving Rows Mass-Spring Model

The vibration theory of beam and D’Alembert principle are used to set up vehicle-bridge system for a simply-supported girder bridge under the moving rows mass-spring model. The kinematic equations of vehicle and bridge are derived separately. And with the force balanced relationship and the displacement compatibility conditions between wheels and rail, the equations of vehicle-bridge system are established. A calculating program is complicated with MATLAB language and solved by Newmark-β method. Results show that the effect of the damping ratio on the impact factor is significant and running speed of the vehicle is one of the main actors resulting in vibration of the system.

Technical Research on Monitor of SLMSS Grider Fabrication for the Passengers Dedicated Line

The yanmiao bridges are used in the 32m prestressed concrete simply-supported box girders on the wuhan-guangzhou passengers dedicated line,they are constucted in the mobile form.To ensure the constuction safety and the accurated line,static load test and monitor for the mobile form were did.The result of test and monitor showed that in the state of work the different parts’force of the mobile form is in the elastic range. The entire beam deflection curve linear is reasonable, they provided the test reference for the the setting of the pre-camber and the control of the box girder’s height.

Research on the Key Technology in Steam Curing for 32m Simple-Supported Box Girder of High-Speed Railway

In the process of steam curing to high-speed railway’s simply-supported box girder, there are some problems must be faced such as the difficulty to determine steam curing system and to achieve automatic temperature control. With the construction site conditions of simple-supported box girder in Longwang beam field which is located on Shijiazhuang-Wuhan (Shi-Wu) section of Beijing-Guangzhou high-speed railway, the paper proposes the appropriate steam system for simply-supported box girders, determines the appropriate equipments, explores the temperature control system in the process of steam curing to the simply-supported box girder's concrete, and takes the temperature test of steam curing in the field. Results show that, the steam curing technology in this paper can increase the production efficiency of beam in production site, and effectively guarantee the prefabricated quality of simply-supported box girder.

Numerical Seismic Analysis of Simply-Supported Girder Railway Bridge under High-Speed Train Load

Along with rapid development of high-speed railway in many countries, recently research on seismic response of high-speed railway bridge under train load has raised much concern among researchers. The whole bridge finite element model is establish to analysis the seismic responses of simply-supported girder railway bridge subjected to high-speed train in this paper, ICE series high speed vehicle is employed as train live load, the vehicle is simulated by moving spring-mass system, The track irregularities can be obtained by Simpack software, the birdge incluing superstructure and substructure is three-dimensional space beam element, the bottom of piers is proposed consolidated. elastic seismic responses of bridge system and elastic-plastic deformation of piers considering different train speeds are calculated. The calculation results indicate that, seismic responses of bridge system are increase with the increase of train speed and earthquake intensity, and the bottom of piers will step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred within 1.4 meters of bottom of pier. The numerical results can provide some references for design of high-speed railway bridge.

Galerkin Solutions of the Simply-Supported Steel and Concrete Composite Girder in Considering Relative Slips and Shear Lags

By mean of potential energy various principles,the governing differential equations of the steel and concrete composite girder in considering relative slips between steel girders and concrete slabs and shear lag effects of the flanges and the concrete slab are derived. The equations are solved by Galerkin method. It is shown from the calculating example that the proposed method not only is easy to calculate, but also has high convergent speed

Dynamic Response of Simply-Supported Curved Girder Bridges due to Vehicles

The purpose of this paper, for which a finite element bridge model with 7 degrees of freedom per node and the 1/4 vehicle model with six parameters were established, is to analyze the dynamic response of curved girder bridges under vehicular loads. In the numerical simulation, the vibration characteristics of simply-supported curved girder bridge are analyzed, and the effect to the impact factors were also studied for different radiuses of curvature, eccentricities, ratios between bending and torsion stiffness, and vehicle speeds. The simulated results show that not all the first 5 natural frequencies increase with the variation of radius of curvature. The impact factor variations of vertical deflection and torsion angle are not uniform when parameters changed, and the impact factor of torsion angle would be much larger than that of vertical deflection under the same conditions.

Stochastic space vibration analysis of a train-bridge coupling system

The Pseudo-Excitation Method (PEM) is applied to study the stochastic space vibration responses of train-bridge coupling system. Each vehicle is modeled as a four-wheel mass-spring-damper system with two layers of suspension system possessing 15 degrees-of- freedom. The bridge is modeled as a spatial beam element, and the track irregularity is assumed to be a uniform random process. The motion equations of the vehicle system are established based on the d'Alembertian principle, and the motion equations of the bridge system are established based on the Hamilton variational principle. Separate iteration is applied in the solution of equations. Comparisons with the Monte Carlo simulations show the effectiveness and satisfactory accuracy of the proposed method. The PSD of the 3-span simply-supported girder bridge responses, vehicle responses and wheel/rail forces are obtained. Based on the <TEX>$3{\sigma}$</TEX> rule for Gaussian stochastic processes, the maximum responses of the coupling system are suggested.

Strengthening multiple span simply-supported girder bridges using post-tensioned negative moment connection technique

A post-tensioned negative moment connection technique is proposed to strengthen old multiple span simply-supported T-section reinforced concrete (RC) girders. In this technique, old concrete is removed from girder ends and flanges, a diaphragm is placed between the two adjacent girder ends over the interior support and negative moment steel strands are installed in new cast-in-place concrete and post-tensioned to make continuity. A total of six two-span simply-supported T-section RC girders were cast and five of them strengthened using the provision of the proposed post-tensioned negative moment connections. Both laboratory tests and nonlinear finite element (FE) analysis were conducted to investigate the structural performance of the strengthened RC girders. The moment redistribution in the strengthened continuous RC girders was also measured and is discussed. It is shown that the proposed post-tensioned moment connection technique can reliably transfer the negative moment over the support and markedly increase member stiffness and the load-carrying capacity of existing multiple span simply-supported RC girders. The validity of the FE analysis was also demonstrated through comparisons with experimental results.

Dynamic interaction analysis of a LIM train and elevated bridge system

A three-dimensional dynamic interaction model is developed for a LIM (linear induction motor) train and elevated bridge system, which is composed of a LIM-driven vehicle submodel and a finite element bridge submodel. Each LIM vehicle is modeled by a 27 degrees-of-freedom dynamic system. The expressions for the electromagnetic force between the linear motor and the reaction plate are derived, and the force model is established. By applying a modal superposition technique to the bridge submodel and using the measured track irregularities as the self-excitations of the train-bridge system, the equations of motion are established for analyzing the dynamic responses of the LIM vehicle and the elevated bridge. The proposed framework is applied to a 3-span elevated bridge with 29.9 m simply-supported girders. The full histories of the LIM train traversing the bridge are simulated, from which the dynamic responses of the LIM vehicle and elevated bridge system are obtained. The proposed method may help to find a way to assess the dynamic properties of elevated bridges and the running safety of a LIM train with reasonable computational effort.

Aseismic displacement analysis of multi-supported bridge to multiple excitations

The purpose of this paper is to study the aseismic displacement of multi-supported bridge to multiple seismic excitations. The first part deals with the systematic way of simulation of spatial variation of seismic waves. The evolutionary spectrum model was adopted, and the model parameters were estimated based on the data recorded by SMART-1 array. The local soil effect was also adopted in this simulation model. The second part deals with the stochastic earthquake analysis of multi-supported structures. The stochastic earthquake response of simply-supported girder bridge subjected to spatial variation of seismic wave was studied as an example. The relative displacement between the top of two piers was carefully examined as a function of model parameters as well as the local soil condition. It is found that the variation of structural properties between two adjacent structures have significant effects on the aseismic displacement between two supports. The local soil conditions, such as the depth of soil deposit, wave coherence, may also have an important effect on this aseismic displacement of multi-supported bridge.