Long-span Continuous Rigid Frame Bridge Research Articles

The influence of shear surface quality on the mechanical properties of long-span prestressed continuous rigid-frame bridge

PurposeThe long-span continuous rigid-frame bridges are commonly constructed by the section-by-section symmetrical balance suspension casting method. The deflection of these bridges is increasing over time. Wet joints are a typical construction feature of continuous rigid-frame bridges and will affect their integrity. To investigate the sensitivity of shear surface quality on the mechanical properties of long-span prestressed continuous rigid-frame bridges, a large serviced bridge is selected for analysis.Design/methodology/approachIts shear surface is examined and classified using the damage measuring method, and four levels are determined statistically based on the core sample integrity, cracking length and cracking depth. Based on the shear-friction theory of the shear surface, a 3D solid element-based finite element model of the selected bridge is established, taking into account factors such as damage location, damage number and damage of the shear surface. The simulated results on the stress distribution of the local segment, the shear surface opening and the beam deflection are extracted and analyzed.FindingsThe findings indicate that the main factors affecting the ultimate shear stress and shear strength of the shear surface are size, shear reinforcements, normal stress and friction performance of the shear surface. The connection strength of a single or a few shear surfaces decreases but with little effect on the local stress. Cracking and opening mainly occur at the 1/4 span. Compared with the rigid “Tie” connection, the mid-span deflection of the main span increases by 25.03% and the relative deflection of the section near the shear surface increases by 99.89%. However, when there are penetrating cracks and openings in the shear surface at the 1/2 span, compared with the 1/4 span position, the mid-span deflection of the main span and the relative deflection of the cross-section increase by 4.50%. The deflection of the main span increases with the failure of the shear surface.Originality/valueThese conclusions can guide the analysis of deflection development in long-span prestressed continuous rigid-frame bridges.

Seismic performance analysis of long-span continuous rigid frame bridge with Engineered Cementitious Composite at expansion joints

In this paper, OpenSees software is used to establish a numerical simulation analysis model of a long-span continuous rigid frame bridge with Engineered Cementitious Composite (ECC) expansion joint reinforcement scheme. The seismic response characteristics and laws of structures with ordinary concrete and ECC concrete at expansion joints are compared and analyzed, and their seismic performance is evaluated. The results show that the use of ECC material at the beam end position can effectively reduce the peak response of the structure under earthquake action and reduce the number of collisions. ECC material has a strong energy dissipation capacity and can reduce the collision damage of the beam section near the bridge expansion joint under earthquake action.

Response Characteristics of Irregular Continuous Rigid Frame Bridges with Long-Span and High-Rise Piers under Ground Motion Excitations with Different Fault Distances

An innovative seismic performance evaluation strategy for irregular rigid frame bridges with a long-span and high-rise piers under the action of ground motions with different fault distances is presented in this paper. A total of 129 mainshock records taken during the Wenchuan earthquake, from national seismic stations with different fault distances, were analyzed using statistical methods, to determine the attenuation characteristics of the intensity index of the Wenchuan earthquake records from the perspective of aseismic engineering, and the attenuation of the acceleration response spectrum is discussed. The Miaoziping Bridge on the Dujiangyan–Wenchuan Expressway, which was damaged in the Wenchuan earthquake, is taken as the analysis background; two sets of samples for long-span continuous rigid frame bridges with different pier heights are constructed, to discuss the seismic response characteristics of continuous long-span rigid frame bridges; and representative values for the natural periods of these two bridge structural groups are subsequently compared and analyzed. After the peak responses for various bridges with various pier heights are determined through a response spectrum analysis under the action of ground motions with different fault distances, and the surfaces for the obtained peak responses are fitted and the response characteristics for different fault distances are discussed. It is shown in the results that the seismic response characteristics of the continuous rigid frame bridges with long-span and high-rise piers were significantly different under the action of the ground motions with different fault distances, and the seismic responses of these two bridge groups were distinctly larger under the action of near-fault ground motions. Furthermore, based on the above research, suggestions for the pier arrangement and bridge site selection for continuous rigid frame bridges with long-span and high-rise piers are also discussed. The results of this paper also provide some theoretical guidance for the sustainable development of bridges with long-span and high-rise piers, from the perspective of bridge seismic response characteristics.

Structural Performance Evaluation After Cracking During the Construction of Long-Span Continuous Rigid-Frame Bridges

Structural Performance Evaluation After Cracking During the Construction of Long-Span Continuous Rigid-Frame Bridges

Fatigue Safety Assessment of Concrete Continuous Rigid Frame Bridge Based on Rain Flow Counting Method and Health Monitoring Data

The fatigue of concrete structures will gradually appear after being subjected to alternating loads for a long time, and the accidents caused by fatigue failure of bridge structures also appear from time to time. Aiming at the problem of degradation of long-span continuous rigid frame bridges due to fatigue and environmental effects, this paper suggests a method to analyze the fatigue degradation mechanism of this type of bridge, which combines long-term in-site monitoring data collected by the health monitoring system (HMS) and fatigue theory. In the paper, the authors mainly carry out the research work in the following aspects: First of all, a long-span continuous rigid frame bridge installed with HMS is used as an example, and a large amount of health monitoring data have been acquired, which can provide efficient information for fatigue in terms of equivalent stress range and cumulative number of stress cycles; next, for calculating the cumulative fatigue damage of the bridge structure, fatigue stress spectrum got by rain flow counting method, S-N curves and damage criteria are used for fatigue damage analysis. Moreover, it was considered a linear accumulation damage through the Palmgren-Miner rule for the counting of stress cycles. The health monitoring data are adopted to obtain fatigue stress data and the rain flow counting method is used to count the amplitude varying fatigue stress. The proposed fatigue reliability approach in the paper can estimate the fatigue damage degree and its evolution law of bridge structures well, and also can help bridge engineers do the assessment of future service duration.

Intelligent safety assessment method for demolition construction of closure segment of long-span continuous rigid frame bridges

In order to clarify the risk of demolition construction of large-span continuous rigid structure bridge and put forward an intelligent safety assessment method to ensure the safety of demolition construction of the closure segment. Taking a concrete continuous rigid bridge as an example, this paper uses the combination of finite element analysis, theoretical calculation and actual measurement verification to study the influencing parameters and construction safety assessment methods of the long-span continuous rigid bridge in the demolition construction stage of the closure segment. The results show that the parameters that have a great influence on the stress state of box girder and pier during the demolition stage of the closure segment are mainly the self-weight of the structure, tendon prestress state and construction temperature difference. Through the influence envelope analysis of each parameter, it is clear that the ultimate failure mode caused by the most unfavorable parameter combination in the demolition stage of the closure segment is the crushing of the bottom plate of the box girder in the middle span, and the cracking of the piers on the side span at the top and the variable section. In order to further accurately evaluate the construction safety in the demolition stage of the closure segment, based on the long-term down-warping state inversion analysis of the box girder, the identification method of cross-section damage and prestress loss of the box girder and the calculation results of engineering examples are given. Finally, a safety assessment method of the most unfavorable section based on the principle of influence matrix is proposed. Through the analysis of an example, the safety of the closure segment demolition construction is clarified, and the correctness of the analysis is verified by intelligent monitoring means.

Dynamic Analysis of a Coupled System of High-Speed Maglev Train and a Flexible Long-Span Continuous Rigid Frame Bridge

The dynamic characteristics, deformation and installation accuracy of the bridge structure will have a greater impact on the response of maglev system. This study performs the dynamic analysis of a flexible long-span continuous rigid frame bridge induced by high-speed maglev train. To achieve this, the spatial coupling analysis model is first established. Then, the influence of track irregularities and speed on the maglev system is analyzed. In addition, the mechanism of vertical resonance of the bridge and vehicle under the action of harmonic loads at low speed is also studied by a semi-analytical approach. The results show that the influence of the long-span bridge deformation on car-body vertical acceleration is greater than that of track irregularity. The resonance exists between train and the long-span bridge at low speed. When the frequency of the harmonic loads is consistent with the basic frequency of the bridge, it will cause the bridge resonance. The resonant speed range of the rigid car-body is 20–40[Formula: see text]km/h. During bridge design, it shall be avoided that the basic frequency of the bridge is consistent with that of the vehicle.

Seismic Responses and Damage Control of Long-Span Continuous Rigid-Frame Bridges Considering the Longitudinal Pounding Effect under Strong Ground Motions

Continuous rigid-frame bridge (CRFB), a type of bridge adopting the unique form of pier-girder consolidation, combines a T-shaped rigid frame with a continuous girder. CRFBs located in western China are likely to suffer destructive earthquakes, which may result in serious damage to bridges. To study the longitudinal seismic responses and damage control of different structure types of the CRFB under strong ground motions, this work develops three nonlinear dynamic analysis models considering the initial internal force state and longitudinal girder-pier pounding effect based on the OpenSEES (version 3.3.0) platform. Moreover, the present study comparatively analyzes the displacement responses, internal force of piers, pounding force and times, and damage condition of the three models and investigates the effectiveness of tuned inerter-based dampers (TIBDs) in controlling seismic responses of the CRFB. The numerical results show that the longitudinal seismic responses of the main piers in the three models are obviously different, especially when subjected to near-fault ground motions. The peak pounding force at the abutments is much larger than at the transition piers, while the pounding times are the opposite. Under near-fault ground motions with a peak ground acceleration (PGA) of 0.4g, the main piers may be damaged moderately or even more seriously, and the bearings are completely destructive. The TIBDs can effectively control the maximum seismic responses and damage degree of the CRFB under pulse-like near-fault ground motions. Among them, both the tuned viscous mass damper and tuned inerter damper are ideal and useful devices. This study can provide useful references for the seismic design and performance analysis of CRFBs.

Global reliability evaluation of a high-pier long-span continuous RC rigid frame bridge subjected to multi-point and multi-component stochastic ground motions

High-pier long-span continuous RC rigid frame bridges would be more vulnerable to seismic spatial variability and multi-component nature due to their large geometric dimension. However, research on seismic performance of these bridges subjected to multi-point and multi-component ground motions is sparse. In this study, the unified expression of spectral decomposition integrating spectral representation method and proper orthogonal decomposition based on coherency function matrix is derived. Then the dimension-reduction representation is developed for sample realization of multi-point and multi-component non-stationary stochastic ground motions with merely three elementary random variables, which bypasses the challenges of high-dimensional randomness degree and huge computation expense faced by the Monte Carlo simulation scheme. Thereafter the accurate seismic response analysis of a high-pier long-span bridge is numerically scrutinized combining with the probability density evolution method to further expound the effectiveness of the dimension-reduction model. Finally, a heuristic global reliability evaluation strategy employing relative displacement angle of bridge pier segments as criterion is proposed inspired by the idea of equivalent extreme-value event. Benefiting from this, both the refined reliability evaluation of bridge members and the structural global reliability can be accomplished, providing the possibilities of quantitative seismic performance assessment and earthquake resistance optimization design from an overall perspective.

Endurance time analysis of seismic performances of long-span continuous rigid-frame bridges with corrugated steel webs

The seismic performances of continuous rigid-frame bridges must be evaluated efficiently and accurately using simplified methods during their design and strengthening. As a simplified method to evaluate the seismic performances of bridges, the endurance time method can be used to simulate the complete process of the collapse of an intact bridge via nonlinear time history analysis. The endurance time method is a novel approach of generating seismic acceleration time steps, which allow engineers and researchers to obtain maximal information from the states of the structures with the lowest computational cost. The Fei-Long Bridge—a long-span continuous rigid-frame bridge with corrugated steel webs—has the largest span of this kind in the world and is situated in a medium-risk seismic zone. In this study, we investigated the applicability and accuracy of the endurance time method to estimate the seismic performance of the bridge. Three endurance time accelerograms were generated as seismic inputs based on the design response spectrum provided by the Chinese specifications for the seismic design of highway bridges. In addition, 16 natural far-field and 16 natural near-fault ground motions were selected for incremental dynamic analysis. The seismic response characteristics of the bridge obtained by the endurance time method and incremental dynamic analysis were compared. The results of the endurance time method are observed to be within the envelope of the incremental dynamic analysis results, with an average error lower than 5%, and the median value of the endurance time method agrees well with the mean curve of the incremental dynamic analysis results. Therefore, the endurance time method can be used as a novel simplified and efficient method to evaluate the seismic performances of continuous rigid-frame bridges with corrugated steel webs.

Study on reinforcement methods for 0# block of long-span prestressed continuous rigid frame bridges

Long-span continuous rigid frame bridges are widely used due to their good overall performance, small deformations and good seismic properties. However, quality is difficult to guarantee during construction, which affects the bearing capacity of the bridge and the safety and durability of the structure. In order to improve the mechanical performance of continuous rigid frame bridges, the extended cross section method and the external prestressing method are discussed based on an engineering example. By comparing before and after reinforcement, the results show that the internal stresses of the reinforced structures by the two methods meet the bearing requirements. After the comparative analysis, it was concluded that the extended section method can be applied to the reinforcement of continuous rigid frame bridges under certain conditions, which can serve as a reference for other bridge reinforcement projects.

Research on seismic response of long-span continuous rigid frame bridge in degraded permafrost regions

Research on seismic response of long-span continuous rigid frame bridge in degraded permafrost regions

Research on seismic response of long-span continuous rigid frame bridge in degraded permafrost regions

Research on seismic response of long-span continuous rigid frame bridge in degraded permafrost regions

Correlation Analysis of Ground Motion Duration Indexes and Nonlinear Seismic Responses of a Long-span Continuous Rigid-Frame Bridge with High-Rise Piers

ABSTRACT To investigate the correlations of duration indexes and the nonlinear seismic responses of long-span continuous rigid-frame bridges with high-rise piers (CRFB-LH), an irregular CRFB-LH was selected as the prototype bridge. A construction stage analysis model was simulated in MIDAS/Civil, where the actual construction process was considered and the internal force state was extracted. After that, a nonlinear dynamic analysis model of the CRFB-LH with the equivalent internal force state was simulated via OpenSees. A bracketed duration and significant duration with a continuous-time interval were selected as the duration indexes. Sixty ground motion records with total duration values ranging from 9.91 s to 300 s were used in the nonlinear dynamic analysis. The correlation between the two duration indexes and the nonlinear seismic responses of the CRFB-LH under total-duration ground motions were analyzed. Finally, the effect of different duration indexes on the nonlinear seismic responses of the CRFB-LH was discussed under 30 long-duration ground motions intercepted according to D b0.1g , D s5-75% and D s5-95%. The numerical results show that the correlations of D s with nonlinear seismic responses are better than those of D b, and the latter heavily depends on the absolute acceleration threshold. D s5-95% is preferred for calculating the total hysteretic energy dissipated (HED) from the CRFB-LH. Additionally, while the amount of total HED is not determined by the total duration, the effective time interval of the ground motion duration under different duration indexes has a significant influence on the total HED.

Analysis of the stability of the construction phase of rigidly constructed bridge based on pile-earth effect

In the rapidly emerging Yunnan-Guizhou-Sichuan region, high-pier and long-span bridges are mostly high-pier and long-span continuous rigid-frame bridges over 100 meters, and the stability of their high-piers becomes more and more important. In order to study the stability of the structure under the action of pile-soil, the Wugong Bridge in Guizhou was used as a supporting project, and a large-scale finite element software was used to establish a construction model considering the effect of pile-soil. The influence of this type of bridge on the linear elastic stability of the structure under the action of pile-soil and the geometric nonlinear stability after considering the deflection of the structure is compared and analyzed.

Sensitivity Analysis of Factors Affecting down Deflection of Long-span Continuous Rigid Frame Bridge

In order to deeply analyze the factors affecting the excessive mid-span deflection of the long-span continuous rigid frame bridge in service, this paper uses the Shaanxi A Bridge as the supporting project and uses the finite element analysis software Midas Civil to establish the bridge model. Put forward the factors that may affect the deflection, adopt a sensitivity analysis method that controls the value of a single factor while other factors remain unchanged, and repeatedly adjust the model parameters to obtain the deflection calculation results. According to the results, determine whether the factor is the main influencing factor of deflection. The research results show that structural stiffness, prestress loss, environmental temperature, and concrete shrinkage and creep are the main factors affecting the deflection of rigid frame bridges. The degree and direction of their influence on deflection are different. The research results can provide reference and guidance for actual engineering.

Seismic response analysis of high-pier long-span continuous rigid-frame bridges under far-field long-period ground motions

The seismic response of a high-pier long-span continuous rigid frame bridge under the action of far-field long-period ground motions is studied. A numerical calculation model of a high-pier long-span continuous rigid frame bridge whose span layout is (95+170+95)m is established by using finite element software. According to the established wave selection criteria, 10 long-period far-field seismic records and 10 ordinary seismic records are selected from the strong earthquake record database. Using the dynamic time history analysis method, the seismic response of the bridge structure under the far-field long-period seismic record and the ordinary seismic record was obtained through calculation, and a comparative analysis was carried out. The results show that the seismic response of a high-pier long-span continuous rigid frame bridge under far-field long-period ground motions is significantly greater than that of ordinary ground motions, the effect of ground motion spectrum characteristics should be considered in seismic design of such Bridges.

Time-varying Reliability Analysis of Long-span Continuous Rigid Frame bridge under Cantilever Construction Stage based on the Monitored Strain Data

Abstract: In general, the material properties, loads, resistance of the prestressed concrete continuous rigid frame bridge in different construction stages are time-varying. So, it is essential to monitor the internal force state when the bridge is in construction. Among them, how to assess the safety is one of the challenges. As the continuous monitoring over a long-term period can increase the reliability of the assessment, so, based on a large number of monitored strain data collected from the structural health monitoring system (SHMS) during construction, a calculation method of the punctiform time-varying reliability is proposed in this paper to evaluate the stress state of this type bridge in cantilever construction stage by using the basic reliability theory. At the same time, the optimal stress distribution function in the bridge mid-span base plate is determined when the bridge is closed. This method can provide basis and direction for the internal force control of this type bridge in construction process. So, it can reduce the bridge safety and quality accidents in construction stages.

Extreme value distribution and dynamic reliability estimation of high-pier bridges subjected to near-fault impulsive ground motions

The seismic behaviour of high-pier and long-span bridges in fault zones is significantly influenced by the near-fault impulsive effect. In view of this, this study evaluates the extreme value distribution and dynamic reliability of high-pier bridges built in fault zones. First, based on the improved maximum entropy method constrained with fractional moments, a new method is proposed to evaluate the extreme value distribution of nonlinear structure seismic response. In the proposed method, the fractional moments are evaluated by the Latin hypercube sampling, and a linear system of equations that determine the initial value of fractional exponents and Lagrange multipliers is illustrated to improve the stability of the simplex algorithm. Second, based on the obtained extreme value distribution, the seismic reliability of structure is estimated by the simple numerical integration. Two numerical examples, including a nonlinear single-degree-of-freedom system and a three-storey nonlinear shear frame, are adopted to validate the proposed method. Finally, the seismic reliability of a typical high-pier and long-span continuous rigid frame bridge located in southwest of China is evaluated by the proposed method and some critical conclusions are drawn. The results obtained from this study not only indicate the accuracy and efficiency of the proposed method but also can provide some direct guidelines for the seismic design of the high-pier and long-span bridges in fault zones.

Static Load Test Study on Long-span Continuous Rigid Frame Bridge with V-shaped Pier

Taking the main bridge of the shuidong bridge in Youxi country of Fujian province as background, this paper develops the static characteristic analysis and static load test study on long-span prestressed continuous rigid frame bridge with V-shaped pier. By the analysis and comparison between the measured data and FEA results, it evaluates the working condition of the bridge. The results show: Firstly,each evaluation indicator tested meets the requirements of “Test methods for large-span concrete bridges” Secondly, the strain efficacy coefficient of measured points in top plate of each control section is within 0.65∼0.74, and that of the measured points in bottom plate is within 0.64∼0.73, the residual strain of the measured points is less, therefore, the safety stock of the bridge is sufficient, and it is on the flexible working condition basically; Finally, the measured value and the theoretical value of deflection curves along the longitudinal bridge is compatible, the efficacy coefficient of vertical deformation is within 0.55∼0.85, and the severity of the practical structure is more.