Performance Of Bridge Structures Research Articles

Constitutive model and mechanical properties of grade 1960 steel wires under fire and post-fire conditions

The structural performance of the bridges under fire accidents has gradually become one of the hot issues in bridge safety. The fire resistance of the cables is a critical factor in the structural performance of cable-stayed bridges. The mechanical properties of 1960 high-strength steel wires at elevated temperatures were investigated in this paper. Tensile tests on steel wires were performed at various high temperatures and after cooling. The failure modes and mechanical properties of steel wires after heating and cooling were investigated in detail. The results show that mechanical properties such as yield strength and ultimate strength are continuously degraded as temperature rises at both high-temperature and after-cooling test, while elastic modulus and elongation are not changed significantly after heating–cooling process. A constitutive model was proposed based on two-segment Ramberg–Osgood model for both high temperature and cooling processes. It is shown that the proposed model well reflects the material behavior for both processes.

Study on Vehicle-Bridge Coupled Vibration of Curved Girder Bridges under Different Road Surface Grades

This study explores the impact of different levels of road surface smoothness on the dynamic response of bridges. By conducting a detailed analysis under five different conditions of road surface smoothness, the mechanisms by which road surface irregularities affect the dynamic characteristics and safety performance of bridge structures are revealed. The research employs the finite element simulation method to compare and analyze the changes in key dynamic indicators such as vertical displacement, torsional angle, torque, and bending moment of bridges under different grades of road surface smoothness. The results indicate that a decrease in road surface smoothness significantly increases the dynamic response of bridges. The findings provide important reference information for bridge engineers in the design and maintenance of bridges.

Prediction of bridge structure deformation and strain based on dynamic testing and intelligent algorithms

The field load test is a direct and effective method for evaluating the performance of bridge structures. However, existing bridge field static load tests are costly and inefficient; moreover, they obstruct traffic and cause unavoidable damage to the bridge structure. As an alternative the the static load test, a random model update method based on bridge dynamic load tests and the Bayesian inference is proposed in this paper. The bridge static load test results were predicted with a high accuracy. To speed up the Bayesian method to infer the posterior probability density of the updated parameters, the Gaussian process was used in place of the finite element model, and the Bayesian inference used the Markov chain Monte Carlo method based on the delayed rejection adaptive Metropolis algorithm. First, the parameters to be modified for the bridge structure analysis model were determined based on the global sensitivity analysis method. Second, a uniform design sampling method was used to establish the Gaussian process optimization model to update the random model of the bridge structure. Finally, a reinforced concrete truss arch bridge was used to verify the correctness of the static load results of the bridge predicted by the random model update method based on dynamic load testing and Bayesian inference. The research results reveal that the prediction results of the bridge static load test based on the dynamic load test and Bayesian inference method agree with the actual test results.

Static Behavior Prediction of Concrete Truss Arch Bridge Based on Dynamic Test Data and Bayesian Inference

The field load test is a direct and effective method for evaluating the performance of bridge structures. However, the existing bridge static load tests on site are costly, inefficient, and obstruct traffic; moreover, improper loading may also cause some damage to the bridge structure. This paper proposes a random model update method based on bridge dynamic load tests and the Bayesian inference as an alternative to the static load test. The Gaussian process model was used instead of the finite element model to reduce the cost of model calculation. Furthermore, choose the Markov Chain Monte Carlo (MCMC) method based on delay rejection adaptive Metropolis algorithm for Bayesian inference to improve the speed of the Bayesian method inferring the posterior probability density of updated parameters. First, the parameters to be updated for the bridge structure analysis model were determined based on the global sensitivity analysis method. Second, a uniform design sampling method was used to establish the Gaussian process optimization model to update the random model of the bridge structure. Finally, a reinforced concrete truss arch bridge was used to verify the correctness of the static load results of the bridge predicted by the random model update method based on dynamic load testing and Bayesian inference. The results show that the predicted results of the bridge static load test based on the dynamic load test and Bayesian reasoning method have an excellent agreement with the measured results, and this method can effectively overcome the adverse effects of the existing bridge static load test.

A review studying of damages inspection methods and structural performance assessment of bridges structures

A bridge can serve as a primary link between highways, railroads, crossroads, two river margins, and between mountains. The design, advancement, and global building of bridges are among the most fascinating and significant achievements in civil engineering. Bridges must be designed and built to be secure, effective, and cost-effective. Evaluation of the bridge structure is a topic that is becoming more and more important in the decision to address the deterioration of the bridge structure. To determine the actual strength of the bridge structure, its service life, and the real load scale, appropriate design and analysis procedures must be adopted. The main purpose of this study is to review the structural performance evaluation, damage inspection processes, different types of damages, static and dynamic analysis, and related studies to evaluate the structural performance of bridge structures.

Experimental Research on Fatigue Performance of Reinforced Concrete T-Shaped Beams under Corrosion-Fatigue Coupling Action.

Highway bridges in coastal areas are seriously affected by the marine environment, while most of the existing test methods for bridge-reinforced concrete beams considering both corrosion and fatigue factors are carried out in an alternating manner, which cannot reflect the actual service conditions of the bridge structure. This paper focuses on an experimental study of the coupled influence of reinforcement corrosion and fatigue loading in reinforced concrete T-shaped beams. A novel loading test device that can realize the corrosion-fatigue coupling effect is designed, and then six reinforced concrete T-shaped beams are fabricated and tested. For the corrosion-fatigue coupling test beams, the variation law of beam cracks, failure modes, steel strain development law, load-deflection relationship, and fatigue life are analyzed and compared with that of the simple fatigue test beams. The test results show that the cracks of the test beam develop continuously with the fatigue loading times under the corrosion-fatigue coupling environment. The fatigue failure modes are all brittle fractures of the main steel bars, which present the shape of uneven oblique section tearing. The new testing device and approach can provide direct insights into the interaction of reinforcement corrosion and cyclic loading on the fatigue behavior of T-shaped RC beams, which can be further used to understand the long-term performance of bridge structures under complex marine environments.

Experimental study on the ultimate bearing capacity of damaged RC arches strengthened with ultra-high performance concrete

With the deterioration of the infrastructure and the increasing traffic volume, the service performance of bridge structures dramatically dropped. Strengthening and retrofitting these bridges with ultra-high-performance concrete (UHPC) can effectively improve their mechanical properties and durability. In this paper, the experimental investigation of the behavior of damaged RC arches strengthened with UHPC is presented. Three strengthened arches, including one arch strengthened with C50 (RC1-C50) and two arches strengthened with UHPC (RC2-UHPC, RC3-UHPC), were tested under asymmetric load. Load-deflection behavior, crack propagation pattern and hinge formation mechanism are extensively studied. Results indicated that the initial crack load and ultimate bearing capacity of composite arches strengthened by UHPC were respectively enhanced by 185% and 186%, showing good effects of strengthening and toughening on the original arch. On the premise of closing the cracks in the original arch ring, the stiffness and ductility of the composite arch strengthened with UHPC (RC2-UHPC) were improved by 58% and 34%, respectively. Different from the arch strengthened with C50 (RC1-C50), no obvious cracking and separation phenomena were observed in the interface of composite arches strengthened with UHPC in the whole process of eccentric loading. The combination of keyway and planting bar (rigid and flexible) can provide reliable bonding between the UHPC and the original structure. Finally, the calculation model for predicting the cracking load and ultimate capacity of the composite arches were proposed, and the calculation results are in good agreement with the experimental results.

Effect of near-fault vertical ground motions on failure mode of long-span sea-crossing cable-stayed bridges

Existing investigations have proved that the near-fault vertical ground motion (VGM) would have a significant effect on the seismic performance of bridge structures. This study mainly investigates the combined effect of VGM and horizontal ground motion (HGM) on failure mode and component damage sequence of long-span sea-crossing cable-stayed bridges. For this purpose, a long-span sea-crossing cable-stayed bridge considering the pile-soil effect and hydrodynamic effects is selected in this paper. The seismic demand models and limit state models are developed under the combination of VGM and HGM to perform the component fragility analysis, which aims to evaluate the damage state and sequence of key components. The results indicate that VGM has little effect on the damage probability of the bearings, but an adverse effect on the damage probability of the pylons and piers. The vulnerable component would be changed from the bearing to the pier and pylon with strong VGM. Meanwhile, the three-dimensional fragility surface of each component based on the horizontal peak ground velocity (Vx) and the ratio of vertical to horizontal component (αV/H) is obtained by convolution. Thus, the effects of Vx and αV/H on the damage mechanism of the cable-stayed bridge in different damage states are quantified.

Property Analysis of Double-Sided Composite Waterproofing Sheet for Simultaneous Application on Asphalt Concrete and Latex-Modified Concrete Pavements for Bridge Decks

Waterproofing in pavements can determine the waterproofing performance of the entire bridge structure. In this study, two types of pavement layers, asphalt concrete (APC) and latex-modified concrete (LMC), are investigated as options to improve the waterproofing performance of bridge structures with either APC or LMC-type pavement by installing a double-sided adhesive waterproofing sheet. The material performance of the proposed waterproofing sheet was evaluated for deterioration factors such as temperature change, chemical erosion, cracking behavior, and water pressure as stipulated in the Korean industrial standards (hereinafter referred to as KS) for bridge waterproofing materials. The waterproof sheet was directly installed on to specimens with the respective two pavement types to evaluate the field application performance. As a result of the evaluation, the physical waterproofing performance of the proposed waterproofing sheet satisfies all standard quality conditions, and as a result of direct application to APC and LMC pavement, the waterproof performance is at least 8% to 130% higher than the standard quality standard in APC pavement, and LMC pavement shows high performance, up to about 320%. Therefore, it is expected that the newly proposed waterproofing sheet as a bridge deck surface waterproofing material can be considered as a feasible option to improve the waterproofing performance for both APC and LMC pavement.

Temperature distribution simulation and thermal properties investigation of hollow slab beam based on meteorological data

Natural environment has a great impact on the performance of bridge structures, such as the ambient temperature, solar radiation, climate extremes and so on. Due to the lack of regional pertinence in the provisions of the existing specifications on the temperature load standard, and the lack of verification of its adaptability of hollow slab beam bridge in the reconstruction and expansion project, it is necessary to study the temperature load of the beam based on the temperature data of the area where the bridge site is located. Based on the measured meteorological data, the cross-section temperature distribution characteristics of the hollow slab beam and the temperature load effect were investigated. The vertical temperature load model of the short and medium-span hollow slab beam was proposed according to the simplified temperature curve. Firstly, based on the annual measured meteorological data, the plane model was established to analyze the temperature distribution characteristics of the hollow slab beam. Secondly, according to the temperature field distribution of the beam cross-section, the solid model of 16 m hollow slab beam was established to analyze the distribution of the temperature load effect. Finally, based on the preliminarily proposed temperature curve, vertical temperature load models were proposed by introducing the theory of extreme value extrapolation. The studies have shown that the temperature of the hollow slab beam is approximately horizontal distributed, and temperature extreme value appear at the location of the beam web. The roof and floor of the hollow slab beam are compressed and the webs are tensioned in the positive temperature difference state, the stress condition is opposite under the negative temperature difference state. The positive and negative temperature load models can meet the extrapolation requirements of the bridge design reference period. This study innovatively proposed a temperature load model based on the temperature curve corresponding to the most unfavorable effect of the beam. The extrapolation idea in the derivation of vehicle load model is introduced as well. And a temperature load model suitable for the extension of hollow slab bridges in Guangdong is established in this study.

A comprehensive approach for bridge performance evaluation under rockfall impact integrated with geological hazard analysis

Rockfall is one kind of major hazard that seriously threatens the safety of bridge structures passing through mountainous areas. The complexity of geological conditions in mountainous areas makes it difficult to determine the initial impact parameters of falling rock in the bridge performance analysis. At present, the subjective and deterministic methods are adopted to get the initial motion parameters of the falling rock for evaluating the structural responses. In this paper, the probability distributions of falling rocks collision parameters are obtained by the rockfall Monte Carlo simulations. Then the characteristic values from the probability distribution of rock motion parameters are taken as the input parameters in the dynamic simulation of bridge structure. Finally, three-dimensional nonlinear dynamic analysis is employed to evaluate the safety of the bridge structure under rockfall hazards. The residual resistance index (RRI) is presented for quantifying the post-impact performance of bridge pier and girder under rock collision. The structural safety is mainly dominated by the impact mass and translational velocity of the falling rock rather than the rotational velocity and impact angle. The rock shape also has non-negligible influence on the structural dynamic responses and performance, and the cube-like rock induces more severe structural damage than other shapes. According to the RRI and probability distribution of rock mass, the non-exceedance probability of RRI is obtained which can be used for the risk analysis of rockfall impacting on bridges. The proposed comprehensive approach for bridge performance evaluation considers the uncertainty of rockfall characteristics, and it provides more reasonable solution to investigate the impact performance of bridge structure under rockfall disasters.

Visual Multimedia Intelligent Computing System for Seismic Performance of Bridge Structure Based on Object-Oriented Technology.

In order to further promote the standardization of seismic performance design of bridge structures, one must ensure the quality of bridge design and improve design efficiency. First, based on the basic principle of the probabilistic pushover method, the randomness of the structural pushover curve is attributed to the randomness of plastic hinges. Second, the visualization of seismic performance of bridge structures based on the object-oriented technology is adopted. So that the randomness of seismic action can be considered in the analysis of seismic performance. Finally, the limit state equation of the seismic performance of the structure is used to evaluate the reliability of the seismic performance of the bridge in each limit state conveniently. The results show that the failure probability of the structure in each limit state is less than 0.5 under different basic accelerations from 0 to 0.4 g. The software method is simple in calculation and has a strong adaptability, avoiding the difficulty of seismic reliability analysis caused by large-scale simulation and large amount of calculation of traditional structures. Therefore, this method can be easily applied to the probabilistic analysis of seismic behavior of bridge structures under large earthquakes without evaporative deformation failure criterion.

RESIDUAL PERFORMANCE ANALYSIS OF BRIDGE STRUCTURE CONSIDERING HEAVY LOAD EFFECT

The structural performance of bridges eventually decreases, and risk in bridge operations increase, as well as the equivalent effect of vehicle loads, particularly heavy traffic. To further clarify the relationship between the residual performance of the bridge under heavy traffic and the fatigue damage, a batch of prestressed concrete fatigue test beams was designed. The equivalent fatigue load, considering the heavy load effect, was determined through investigation and statistics of actual traffic load data. The fatigue failure morphology and crack development of the test beam under the equivalent fatigue load were analyzed based on the fatigue damage principle. The constant amplitude fatigue test method was used to analyze the development law of concrete residual strain, non-prestressed tendon residual strain, and prestressed tendon residual strain. Based on the damage model theory, the damage equation between the damage variable D and the cumulative residual plastic strain ?p considering the effects of heavy traffic was found. In addition, through the test data, the fatigue damage evolution curve based on the development of residual strain was obtained. Research results show that the fatigue test failure is a bending failure of the non-prestressed tendon fatigue fracture. The fatigue life of the beam reduced drastically when the heavy load effect is considered. From the perspective of residual performance, the residual strain of concrete is a good indicator for calculating the fatigue damage index of beams. The research results provide an early warning of fatigue failure and performance evaluation.

Crushing behavior and protective performance of varying cores in UHPFRC-steel-foam sandwich structures: Experiment, optimal selection and application

A novel sandwich structure composed of ultra-high performance fiber reinforced concrete (UHPFRC) face panels and core steel structures has been demonstrated to possess good potential in infrastructure protections against accidental collision actions in the previous studies. The core structure plays a crucial role in energy absorption behavior and crashworthiness performance but has not yet been examined. Four different core structures (i.e., traditional frame (TF) type, ectopic frame (EF) type, corrugated plate (CP) type, and horizontal tube (HT) type) are prepared and tested under quasi-static crushing tests in this study. The influence of the polyurethane (PU) foam is also experimentally studied for various core structures. To identify the best performing configuration for structural protection, technique for order preference by similarity to an ideal solution (TOPSIS) method is utilized in the evaluation of the crushing performance. The weight values required in the use of the TOPSIS method are carefully examined based on the entropy method and different design purposes. The best-performing configurations are recommended for various weight values. Results indicate that filling the PU foam is often beneficial to polarize the performance of the UHPFRC-steel sandwich structure. The finite element (FE) modeling method is developed and validated by the crushing tests on different sandwich structures. The best-performing sandwich structures identified with an emphasis on high crushing force efficiency (CFE) are applied to develop new protective structures for improving the performance of bridge structures under rockfall impacts. Numerical results show that the proposed protective structures can effectively protect the bridge structure and reduce the damage caused by rockfall impacts.

Utilizing a new self-centering hysteresis model to assess the seismic vulnerability of a long-span cable-stayed bridge equipped with SMA wire-based roller bearings

A novel shape memory alloy wires-based smart roller bearing (SMA-RBs) has been developed and its cyclic behavior under reverse cyclic loadings has been experimentally investigated. However, its efficacy and performance in enhancing the seismic performance of bridge structures have not been well understood and proven. A new self-centering hysteresis model for SMA-RBs has been proposed to properly simulate their hysteretic behavior, which has been experimentally validated through a pseudo-static test. A methodology is proposed to determine the four damage states of SMA-RB (i.e. slight, moderate, extensive, and collapse) considering the contribution of SMA wires. The smart SMA-RBs are utilized for a cable-stayed bridge in China. The vulnerability of two reference bridges, i.e. the floating system (FS) and rigid system (RS), and one isolated bridge equipped with SMA-RBs (SMA-RBS) are compared at component and system levels. The applicability of three commonly used intensity measures (IMs), i.e. PGA, PGV, and Sa(T1), are evaluated and PGV turns out to be the optimal IM for long-span cable-stayed bridge systems. Results show that incorporating SMA wires in roller bearings can decrease the failure probabilities of the bearing. The piers and towers with SMA-RBs lead to lower seismic fragility over the towers and piers in the reference bridges. The RS is the most vulnerable bridge whereas the SMA-RBS is the least vulnerable bridge among the four bridges. The SMA-RBS experience a much lower collapse damage probability compared to RS ad FS.

Fire hazard assessment, performance evaluation, and fire resistance enhancement of bridges

Although the performance of bridge structures under prescriptive fire scenarios has been the subject of numerous studies, performance-based approaches are yet to be developed to achieve an efficient and economical design. This paper presents a performance-based framework that identifies bridges at high fire risk, produces realistic fire scenarios, provides an open source tool to apply the realistic fire load to the thermomechanical model and evaluate the structural performance of the bridge. It also provides guidance to improve the fire resistance of the bridge. The proposed framework is implemented by simulating the I-65 overpass fire accident in 2002, Birmingham, Alabama, USA. Firstly, fire risk of the bridge is estimated by considering various criteria such as the social and economic impact of fire, structural vulnerability, and the likelihood of fire. Secondly, a realistic fire scenario is developed using the real fire accident data by conducting computational fluid dynamics (CFD) simulations. Thirdly, the newly developed open source FSDM framework is utilised to apply the realistic fire load to the thermomechanical model and finally, the fire resistance of the bridge structure is estimated. The unprotected bridge failed after 12 min of fire exposure which is found in compliance with the actual failure time of the bridge during the accident. Further thermomechanical analyses are performed applying different thicknesses of fire protection to estimate the suitable amount of fire protection to achieve improved fire resistance. It is observed that the fire resistance of the bridge can be enhanced up to 60 min by providing a fire protection of 12 mm thickness. This framework presents an important methodology for the highway department and bridge engineers to identify bridges at high fire risk and accurately determine the amount of fire protection required to reduce the fire risk and enhance the fire resistance of these bridges.

Mathematical Modeling of Linear Static and Dynamic Analysis for Pier Height Effect on the Structural Performance of Bridges Structures

The results of linear static analysis explained that the increasing of pier heights was leaded to rise the values of positive bending moment, tensile stresses, and downward vertical deflection. Whereas the compressive stresses and negative bending moment were decreased, indicating that the structural performance of bridge structure representing by stiffness, bearing capacity of structural members, and elasticity will decrease and the bridges structures will be damaged. Therefore, the bridges structures need safe design when using tall piers by adopting high quality materials such as high strength concrete, more steel reinforcement, more prestressed tendons, and increasing of cross section dimensions of girders and piers. The results of modal analysis show that the un-loaded dynamic frequency for three types of bridges models were decreased when the pier heights were increased, indicating that the stiffness of bridges structure was became low with higher pier height. According to response spectra and time history analysis results, the loaded dynamic frequency (vibration state) and dynamic displacement were increased when the pier heights were increased, showing that the bridge of structure will suffer from high vibration when the pier height was high. It can be concluded that from this study, the piers heights have significant effects on the static and dynamic structural performance of bridges structures under traffic loads.

Physical and Virtual Simulation of the Experiment of Bridge Structure under Static Load

Simulation experiment is an important method to study the performance of bridge structure, among which the simulation experiment of the structure under static load is an effective way to evaluate bridge quality and bearing capacity. In this paper, a 1:25 reduced-scale model of vehicle and bridge is used to simulate the performance of the practical bridge under static load. The finite element analysis is used for virtual simulation, and scale model experiment is used for physical simulation. Comparing the results of physical simulation and virtual simulation for the experiment, it is found that the two are basically the same, verifying the accuracy and effectiveness of this method. Physical simulation and virtual simulation complement each other, which plays an important role in promoting the experimental research and teaching in bridge engineering.

Influence of Restrainer Piers on the Seismic Performance of Long Bridges with Equal-Height Piers

Pounding may occur between the main girders under the action of strong earthquakes, so as between main girders and abutments. This causes excessive longitudinal displacement of the main girder and unseating damage to bridges. Because long bridges in mountainous areas with high intensity are easy to unseat, the authors studied the influence of restrainer piers, expansion joint spacings (EJSs), and the span on the seismic performance of long bridges. The ABAQUS finite element software was used to simulate a bridge dynamic analysis model considering the elastoplasticity of the pounding effect of the pier and the beam. By inputting El-Centro, Northbridge, and Taft seismic waves, the time-history analysis of the seismic response of long bridges was carried out. The results indicated that a reasonable number of restrainer piers, an appropriate EJS, and a span could effectively reduce the maximum relative displacement of pier-beams. This behavior will improve the seismic performance of bridge structures. Moreover, for a 24-span equal-height beam bridge, the optimum seismic effect was obtained when 3 restrainer piers, an EJS of 70 mm, and a 50 m span were used.

EVALUASI KINERJA STRUKTUR JEMBATAN PELENGKUNG AKIBAT BEBAN GEMPA DENGAN ANALISIS RIWAYAT WAKTU

The behavior of the arch bridge structure has its own peculiarities in distributing loading. The curved shape of the structure allows the structure's own weight to be transferred to the foundation as the normal compressive force without bending. the load is transferred through the semicircular structure to the abutments on either side. The curved (semicircular) design will naturally shift the load received by the floor of the bridge vehicle towards the abutment which keeps both sides of the bridge from moving sideways. Earthquake is a dominant horizontal cyclic loading of a structure. The performance of bridge structures due to the effects of earthquake loading is an important aspect that needs to be taken into account in designing and evaluating the bridge structure. The method used in this study is time history analysis. This article aims to evaluate the performance of arch bridge structures due to earthquake loads by using time-history analysis method. The results of the structure performance show that. The performance of the bridge due to the loading of the Loma prieta earthquake is generated from the period scale that has been analyzed with the 10 second period of the first earthquake for each result. Based on the results of Midas analysis, the strongest location where the damage occurs is in the middle of the bridge road. At the coordinates of 19 the largest displacement is at joint 268 of 1.177169 mm and for U2 of 0.0194 mm and U3 of 31.763771 mm.