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Anjiazhuang super major bridge on the national highway 109 new line expressway is a control engineering for the entire project. The left and right main bridges are located on circular curves with radii of 1 600 m and 1 500 m respectively, crossing the Fengtai-Shacheng railway,Yongding River and the current National Highway 109, with high requirements for bridge construction safety, flood control and environmental protection. To solve the problems of using rotation method for construction across railways and the high water blocking ratio of piers, innovatively proposed design schemes for large-span curved steel truss bridges constructed using pier top rotation method and large-diameter thick walled concrete-filled steel tubular piers. The left and right main bridges adopt (248. 95+248. 95) m steel truss cable-stayed bridge and (171. 95+171+75. 25) m continuous steel truss bridge,with rotation lengths of (248+248) m and (171+171) m respectively, piers in the river adopt concrete-filled steel tubular piers. Based on the relevant engineering construction conditions at the bridge site, the paper analyzes the selection criteria for the arrangement of main bridge span, bridge types and pier structures in the river, and briefly introduces the design content of the main bridge superstructure,substructure and foundation,rotation system, etc. The bridge breaks through the technical bottleneck that. steel truss bridges are not suitable for pier top rotation construction, and expands the scope of application of continuous steel truss bridges and pier top rotation method construction technology; The use of large-diameter thick walled concrete-filled steel tubular piers effectively reduces the cross-sectional size of piers and expands the application range of concrete-filled steel tubular structures; The construction and stress characteristics of large-span curved steel truss bridges are relatively complex, by using BIM forward design technology, precise expression of complex structural information and design intent is achieved, improving design efficiency. [ABSTRACT FROM AUTHOR]

The friction pendulum system (FPS) is a crucial tool for seismic protection. However, effectiveness in curved bridges, especially controlling torsional moments (TMs), has not been thoroughly assessed. This study evaluates how well a continuously curved bridge equipped with FPS performs under various earthquake loadings. The study assesses FPS efficiency, considering factors like multidirectional impacts, seismic motion strength, incidence angle variations, and ground motion characteristics. Finite element modeling of the bridge structure was conducted using SAP2000v20 Finite Element Analysis software. Three earthquake scenarios (near fault, far fault and forward directivity) were considered. The study also examines the bidirectional behavior’s impact on the bearing and pier interaction. A sensitivity analysis was performed for the bridge response concerning bearing design parameters for each earthquake scenario. The results show that FPS bearings significantly reduce the bridge’s seismic response. Bidirectional excitation was found to be critical for curved bridges, increasing displacement compared to unidirectional motion. Under unidirectional excitation, the isolated bridge with FPS reduces TMs by approximately 26–54%. In bidirectional excitation, FPS remains effective, reducing TMs by about 14–43%. This study underscores the importance of FPS in enhancing seismic resilience, particularly in controlling torsional responses in complex, curved bridges in varying seismic conditions.

This paper presents the impact of varying the input seismic excitation directions on the system fragility of a geometrically complex highway bridge structure. The traditional approach of fragility derivation in the principal loading directions (longitudinal and transverse) results in an under/overestimation of the system fragility. To reduce such errors, the contribution of all major vulnerable components to the system fragility in the critical loading direction must be considered. For this purpose, a series of nonlinear time-history analyses were conducted for a testbed configured geometrically curved highway bridge structure in Japan. Shear strain, ductility, and distortion strain were considered as engineering demand parameters for bearings, concrete pier, and steel piers, respectively. The demand dependency among the components was considered using the correlation coefficient matrix for fragility estimation. Subsequently, fragility functions with respect to the input loading directions were generated for the bridge components and system to quantify their sensitivity to seismic input excitation directions. The results show that the component fragility is significantly influenced by the input excitation direction. A relative comparison of the system fragility for different loading directions indicated that a 150° loading direction yielded a higher fragility demand. The findings suggest that the critical fragility assessment should not always be decided only along the principal loading directions. [ABSTRACT FROM AUTHOR]

To address the rapidly growing demands of traffic congestion, more highway bridges have been constructed, especially curved bridges. With more curved bridges designed and constructed, people have conducted a comprehensive analysis of the structural performance. Due to the nature of the structural complexity of curved bridges, dynamic responses of the curve bridges vary dramatically from the standard linear bridges. Although some work has been conducted to investigate the curved bridge dynamic analysis under seismic inputs, the framework for analyzing the curved bridges’ vulnerability under various angles of inputs is still lacking. In this paper, we conducted a series of curved bridge seismic analyses based on different inputs and conducted a parametric study of the bridge performance using finite element models. We conducted time history analyses by applying seismic inputs to investigate the bridge dynamic responses based on different angle inputs and other different structural parameters. We developed an approach identifying the most vulnerable direction of the seismic inputs and the strongest dynamic responses for curved bridges based on time series analysis. This approach was validated with the dynamic analysis of a simplified bridge model. The method developed in this paper will help improve the curved bridge design code and further provide suggestions about mitigating seismic response for device design.

Copyright of Journal of Southeast University / Dongnan Daxue Xuebao is the property of Journal of Southeast University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To address the rapidly growing demands of traffic congestion, more highway bridges have been constructed, especially curved bridges. With more curved bridges designed and constructed, people have conducted a comprehensive analysis of the structural performance. Due to the nature of the structural complexity of curved bridges, dynamic responses of the curve bridges vary dramatically from the standard linear bridges. Although some work has been conducted to investigate the curved bridge dynamic analysis under seismic inputs, the framework for analyzing the curved bridges' vulnerability under various angles of inputs is still lacking. In this paper, we conducted a series of curved bridge seismic analyses based on different inputs and conducted a parametric study of the bridge performance using finite element models. We conducted time history analyses by applying seismic inputs to investigate the bridge dynamic responses based on different angle inputs and other different structural parameters. We developed an approach identifying the most vulnerable direction of the seismic inputs and the strongest dynamic responses for curved bridges based on time series analysis. This approach was validated with the dynamic analysis of a simplified bridge model. The method developed in this paper will help improve the curved bridge design code and further provide suggestions about mitigating seismic response for device design. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Suspension rail transit is a new type of urban rail transit system with medium and low traffic volume, and it has been widely used in China in recent years. Suspension rail transit car body is a yaw structure and greatly affected by wind load. Therefore, it is necessary to study the coupling vibration of wind-vehicle-bridge model. In this paper, a wind-vehicle-bridge coupling analysis model with 100m radius and 20m span is established with finite element software Ansys, Fluent and multi-body dynamics software Universal Mechanism, and the differences in dynamic response of train body and track beam under centrifugal wind and centripetal wind are compared and analyzed. The situation of a train crossing the bridge is judged by the stability index. The results show that transverse wind has great influence on the vehicle body's lateral ride stability, and with the increase of wind speed, the vehicle body's lateral ride stability coefficient gradually increases and the ride stability decreases. For wind-vehicle-bridge, centrifugal wind aggravates the dynamic response of bridge and vehicle compared with centripetal wind. With the same wind speed, the maximum dynamic displacement of bridge under centrifugal wind load increases by about 36% compared with centripetal wind load, and the train ride coefficient also increases significantly by about 10%~20%. [ABSTRACT FROM AUTHOR]

Lead Rubber Bearings (LRBs) represent one of the most widely employed devices for the seismic protection of structures. However, the effectiveness of the same in the case of curved bridges has not been judged well because of the complexity involved in curved bridges, especially in controlling torsional moments. This study investigates the performance of an LRB-isolated horizontally curved continuous bridge under various seismic loadings. The effectiveness of LRBs on the bridge response control was determined by considering various aspects, such as the changes in ground motion characteristics, multidirectional effects, the degree of seismic motion, and the variation of incident angles. Three recorded ground motions were considered in this study, representing historical earthquakes with near-field, far-field, and forward directivity effects. The effectiveness of the bi-directional behavior considering the interaction effect of the bearing and pier was also studied. The finite element method was adopted. A sensitivity study of the bridge response related to the bearing design parameters was carried out for the considered ground motions. The importance of non-linearity and critical design parameters of LRBs were assessed. It was found that LRBs resulted in a significant increase in deck displacement for Turkey ground motion, which might be due to the forward directivity effect. The bi-directional effect is crucial for the curved bridge as it enhances the displacement significantly compared to uni-directional motion. [ABSTRACT FROM AUTHOR]

The traditional restraint systems limit the deformation of curved bridge under temperature load, which results in radial and tangential secondary internal forces in the bridge. This paper proposes a pin-bearing restraint system (PBRS) for curved bridge, which can relax the rotational deformation of curved bridge under temperature load. Its configuration and working mechanism are illustrated. The finite element model of a curved bridge with PBRS is established using ANSYS software, and nonlinear time history analysis is conducted. The pounding force and pounding number between pin and slot under ground motion are analyzed. The pin stiffness, the gap and the ratio of upper structure mass to lower structure mass are selected for parametric study. The results show that the pounding force and pounding number present dramatic changes with pin stiffness. As the pin stiffness increases, the pounding force presents a logarithmic linear tendency, and the pounding number shows a reduce tendency. Gap has little influence on pounding force and pounding number. The radial pounding force and pounding number increase with the increase of mass ratio. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Presents a self-developed framework for vehicle–bridge interaction simulation. • Validated using a laboratory experiment and an earlier numerical case. • Specialized for large vehicle–bridge systems and decks with slopes and curves. • Proposes a vehicle library input criteria that unifies all existing road vehicles. • Reveals new phenomena of large viaduct systems under asynchronous seismic excitation. The coupled motion between bridges and vehicles is known as vehicle–bridge interaction (VBI). It is crucial for bridge design, monitoring, and vehicle safety and comfort. VBI studies typically rely on general-purpose finite element (FE) software. Although precise, they are not optimized for simulating large-scale bridges with numerous vehicles, which can result in long processing times and modeling challenges. This paper presents a self-developed framework in MATLAB™ for large-scale VBI simulation. The framework divides the simulation task into five modules and supports asynchronous seismic excitation (ASE), handles different deck geometries, unifies all road vehicle models and inputs with a vehicle library, supports variable vehicle velocity (VVV) and different traffic scenarios, and handles wheel–deck detachment. All functions have been designed with easily accessible interfaces to facilitate secondary development. The framework was verified using a 2D sprung mass benchmark case compared to a closed-form solution, and a 3D simplified model compared to commercial FE software. It was also validated through a laboratory experiment. Further demonstrations of a large-scale VBI system highlighted new phenomena and emphasized the significance of considering the ASE effect in similar systems. With ongoing improvements, the framework has the potential to become a practical tool for VBI simulation. [ABSTRACT FROM AUTHOR]

This study investigation is intended to research the dynamic response of horizontally curved bridges under heavy vehicle loads. Most of the main factors that affect the bridge dynamic response due to moving vehicles are considered. An improved 3D grid model, based on commercial software ANSYS Mechanical APDL, is developed for the analysis of curved bridges following the 3D shear-flexibility grillage analyzing method. A simplified numeric method, considering the effect of random road roughness and its velocity term, is developed for solving the interaction problem. With the model and numerical method presented, a series of parametric studies are conducted to study the curved bridge dynamic interaction. Based on the investigation of determining factors of curve bridge dynamic interaction, the expression of the upper-bound envelop for impact factors of maximum deflection is given with different surface conditions and highway speed limits as a function of bridge fundamental frequency or bridge central angle. A study is conducted on comparing these empirical equations and serval other major design codes, comments and suggestions are then made based on the discoveries.

In this paper, three curved floating bridge concepts with a uniform span of 500 m and different radii of curvature are proposed for the crossing of the coastal waters in Singapore. The bridge girder is supported by 4 pontoons along the bridge length and the two ends are connected to the shore. Three different girder cross-sections are considered. Static analysis is first carried out considering the bridge's self-weight, water current forces and various tidal conditions. Next, eigen value and regular wave analyses are performed to assess the effect of bridge radius, cross-sectional rigidity and end connection on the bridge behaviour. Based on the results, several bridge configurations are selected for further study. Finally, irregular wave analysis is carried out to investigate the realistic bridge performance under operational and extreme environmental conditions. Conclusions are drawn based on the simulation results. Recommendations on the design parameters for further investigations are made. [ABSTRACT FROM AUTHOR]

To study the influence of near-fault and far-field (FF) ground motions on a curved girder bridge, a 1:10 scale curved bridge shaking table test model was constructed. Three types of ground motions, namely, near-fault pulse (NP), near-fault non-pulse (NN), and FF ground motions, were selected and employed in the test model. The test results indicated that the seismic response of the curved bridge in the excitation of NP ground motion is significantly higher than that in the excitation of NN and FF ground motions, and is destructive to the curved bridge. The displacement of the curved bridge has spatial characteristics in the excitation of NP ground motions. The rotation generated by the curved bridge is easy to cause bearing shedding or girder falling at the low pier. The amplification of pier height increases the displacement response at the high pier. [ABSTRACT FROM AUTHOR]

The geometry of skewed and curved bridges can cause complexity of their dynamic response and difficulty of analysis against earthquakes. In addition, when vibration occurs in the curved bridges, due to their specific geometry, the vertical, flexural, and torsional vibrations of the deck are coupled. The present study was carried out aiming to investigate the effect of non-uniform vertical excitation of the bridge piers with various vertical/horizontal acceleration ratio (V/H) on the pounding phenomenon in concrete curved bridges subjected to near-source earthquakes. For this purpose, the analytical method was employed using the expansion of the functions of structural dynamics on a two-span continuous concrete bridge model, consisting of continuous flexural/torsional beam elements for the deck, springs for the rubber bearings, and rods as the bridge piers. The non-uniform vertical excitations of the piers were induced to the whole system by the harmonic functions in the form of transient wave transfer functions, and then the equations of the entire system were solved using the Eigen functions. The induced waves can cause separation of the box girder deck from the rubber bearing along with the vertical and horizontal displacement as well as the torsion of the box girder around the longitudinal axis of the bridge. After each separation, the deck returns back and hit the rubber bearing, resulting in a vertical pounding force on the bearing and the pier. The analyses results show that when the curved beam is subjected to a non-uniform vertical excitation with a various V/H, the lateral displacement of the deck are up to 21% larger than when the bridge is excited by considering a value of V/H = 2/3. The results also show when the excitation frequencies are different in different piers of the bridge, the pounding force can be increased up to three times, for some specific curvature angle, comparing to the case of equal excitation frequency in all piers. [ABSTRACT FROM AUTHOR]

Curved pedestrian bridges are important urban infrastructure with the desired adaptability to the landscape constraints and with aesthetic benefits. Pedestrian bridges feature thin cross-sections, which provide sufficient load capacities but lead to low natural frequencies that make the bridges susceptible to vibration under pedestrian excitation. This study investigates the lateral vibration of a curved bridge with a small radius down to 20 m, proposes an approach to mitigate the lateral vibration of bridges with large curvatures using distributed multiple tuned mass dampers (MTMD), and conducts in-situ bridge tests to evaluate the vibration mitigation performance. The lateral vibration was investigated through in-situ tests and finite element analysis as well as the code requirements. The key parameters of the distributed MTMD system were improved by strategically selecting the mass ratio, bandwidth, center frequency ratio, and damper number. The results showed that the curved bridge was subjected to significant lateral vibration due to the coupling of torque and moment, and the recommended design parameters for the studied bridge were derived, i.e., the total mass ratio is 0.02, bandwidth is 0.15, center frequency ratio is 1.0, and damper number is 3. The proposed approach effectively improves the deployment of MTMD for lateral vibration control of the curved bridge. The field tests showed that the vibration was reduced by up to 82% by using the proposed approach. [ABSTRACT FROM AUTHOR]

A substructure hybrid test is an effective approach to reproduce the seismic behavior of engineering structures. The structure is partitioned into several substructures; those with complex behavior are analyzed experimentally, whereas the others are analyzed numerically, combining the merits of physical experiments and numerical simulations. Previous studies often loaded physical substructures in two or three translational directions. Simultaneous rotational loading in three Cartesian axes is difficult because the load testing device has to be configured spatially, resulting in control problems due to strong coupling. Special expertise in mechanical engineering is necessary to solve this problem. To this end, this study proposes an integrated load testing device suitable for physical loading in all six degrees-of-freedom simultaneously. The device is based on a Stewart platform and can provide a large axial force required by most gravity-bearing components. It also has a large inherent stiffness necessary to obtain the force-displacement curve from damage through complete failure. This paper describes the force-displacement mixed control based on the Stewart configuration, which is necessary for testing engineering structures. Control software is developed and interfaced with the mid-ware OpenFresco to coordinate the numerical substructure. A hybrid test is conducted using a small-scale, electronic-driven load testing device. The test ran smoothly without any malfunctions, demonstrating the excellent performance of the testing system. [ABSTRACT FROM AUTHOR]

The present article proposes a novel framework for analyzing the dynamic responses of suspended monorail vehicles running over curved bridges under crosswinds. In this model, the curved bridge model is established with the finite element method and vehicles are simulated as a multibody system. Subsequently, a wind model is proposed with the wind tunnel test, spectral representation method, and yaw wind-decomposition method, taking into account the effects of the angle between the wind and vehicle changes when vehicles pass through the curved bridge. Finally, a suspended monorail curved bridge is analyzed to demonstrate the effect of the wind model on the vibration of the system. The results show that wind direction has a great effect on the lateral dynamic response of curved bridges, the lateral force of guiding tire, and the vertical force of running tire. The influence of crosswind on the dynamic response of the vehicle decreases with the increase of running time of vehicle on curved bridges. [ABSTRACT FROM AUTHOR]

The Huilan interchange built in Mianzhu City, China, in 2004 experienced serious damages during the Wenchuan earthquake in 2008. Due to the irregularity and eccentricity, the curved ramp bridge suffered significant spatial action from the earthquake shaking, where several short piers failed in a bending-shearing-torsional mixed damage pattern. To ascertain the reason for the failure of short piers, the seismic performance of the curved bridge was reproduced and evaluated by large-scale hybrid tests. In the hybrid tests, the curved bridge C was selected as the prototype structure to reproduce the failure scenario, for which the 3/4 scale model of pier No. 2 was physically tested by a large spatial loading system to reproduce the spatial failure mode in all six degrees of freedom. The rest of the structure was modeled by OpenSees to simulate the earthquake response. Several rounds of hybrid tests were conducted, and it was found that pier No. 2 first yielded in the flexural mode, then changed to the mixed flexural-shear mode, and finally failed in the shear mode with a torsion effect. These results are generally consistent with the post-earthquake observations. • Seismic tests on the small-radius curved bridge via large-scale hybrid test were conducted; • The failure scenario of RC Pier considering complex spatial boundaries was reproduced; • Typical failure modes of the small-radius curved bridge were characterized by comparing large-scale hybrid test with post-earthquake observations. [ABSTRACT FROM AUTHOR]

A viaduct is an important structural form in intercity railway networks, and the curved bridge is inevitable in railway line network planning. When the vehicles cross through the curved bridge, the transverse load experienced by the bridge is much larger than that of the straight bridge due to the centrifugal forces. Therefore, in the bridge resonance analysis, in addition to the vertical moving vehicle load, it is also imperative to consider the radial vehicle load. In order to systematically analyze the dynamic impact factor (or dynamic load allowance) and resonance conditions of the curved intercity railway viaduct, a numerical model is developed. The reliability of the proposed model is assessed by comparing it with the existing literature. Taking the curved viaduct of Zhengzhou-Xuchang railway as a case study, the theoretical resonance velocity, dynamic impact factor, and dynamic time-history response under resonance velocity are calculated. The parameters of different spans, curve radius, and speeds are analyzed, and the reasonable ranges of bridge natural vibration frequency are determined. [ABSTRACT FROM AUTHOR]

Horizontally curved bridges have been mostly built with steel plate I-girders or tub girders. In the past 15 years, curved concrete girders have been successfully used in several states, including Nebraska, Colorado, and Florida. This paper addresses the design of curved concrete girder bridges using ultra-high-performance concrete (UHPC) by combining state-of-the-art spliced girder technology and UHPC technology. It also proposes a number of unique features that result in further simplification of precast concrete production and construction. Critical design criteria are discussed. The system development of curved UHPC girder bridges and necessary construction steps are elaborated through a numerical example of a three-span bridge, which shows greatly reduced concrete quantities when compared with recently constructed curved concrete girders. With UHPC designed as proposed here, horizontally curved bridges are expected to be cost competitive with conventional concrete and more economical than structural steel. [ABSTRACT FROM AUTHOR]

Curved multi-frame box-girder bridges with hinges are widely used in the United States due to the large spanning capacity, construction simplification and construction cost economy. This type of bridge frequently has the characteristics of column height asymmetry, adjacent bridge frames vibrating discrepancy. The combination of curved shape and random seismic excitation angles could aggravate the irregularity of the structural seismic response. In this study, an OpenSees model is established for an example bridge, and the hinge is taken as a key component to observe. The impacts of seismic excitation angles and column height layouts on fragility are investigated through the comparison of the fragility curves. The conclusions list the most unfavorable seismic excitation angles corresponding to the fragilities of bridge system, plug-type concrete elements in hinges, hinge restrainers, columns, abutment bearings as well as the secondary components, respectively. The symmetrical column height layout is proved to be beneficial to mitigate the damage risks of restrainers in intermediate hinges and reduce the fragility of the bridge system. This study can provide a reference for the rapid assessment of the fragile position and damage degree of bridges through structural configuration and shape, as well as the seismic excitation angle. [ABSTRACT FROM AUTHOR]

Shaking table test is an important means for the seismic research of structures, and many scholars have conducted shaking table tests on bridge structures. However, relatively few studies have focused on a curved bridge with a longitudinal slope. In this research, a 1/10-scale test model of a curved bridge with the different pier hights was designed by the principle of structural test similarity. The seismic records in the hanging-wall (HW), footwall (FW), and neutral zones were selected to conducted shaking table tests. Results showed that the seismic spectrum and peak value are remarkably affected by HW ground motions and have strong destructive power. The dynamic response of the curved bridge is remarkable under HW seismic records. The motion form of main girder is spatial and produces obvious rotation under HW seismic records. The displacement response of the curved bridge is closely related to the height of piers and the angle between pier displacement and seismic input directions. The displacement responses at the beam end and the bearing displacement are related to the motion state of the main girder. [ABSTRACT FROM AUTHOR]

This study aims to assess, in a probabilistic manner, the effect of seismic excitation direction on the performance of a 638 m‐long, 12 span prestressed concrete bridge with significant curvature in plan on the basis of overall monetary repair loss. By means of a large number of nonlinear dynamic analyses, the optimum intensity measure (IM) was selected from a pool of twenty candidates considering the impact of seismic excitation direction. Next, the variability of bridge loss with respect to the seismic incidence angle under different groups of earthquake intensities was obtained. Finally, the applicability of combination rules for the seismic performance of curved bridges was evaluated based on the multidirectional loss assessment results. Meanwhile, the effects of seismic excitation direction and earthquake intensity on the evaluation of combination rules were also revealed. Results indicate that velocity‐related or/and structural‐dependent IMs are more appropriate for the probabilistic seismic demand analysis of curved bridges. It is also notable that the total bridge loss gradually turns out to be independent of the seismic excitation direction as the seismic intensity increases and the damage develops throughout the structure. Additionally, the widely used 100/30 and 100/40 rules may lead to an unconservative estimation for the loss of the curved bridge. The above findings highlight the necessity of addressing the issue of ground motion directionality in a rigorous probabilistic manner and pave the way for further research on qualifying the influences of geometric configuration, material parameters, soil type and the consequent soil‐structure interaction effect. [ABSTRACT FROM AUTHOR]

This study investigation is intended to research the dynamic response of horizontally curved bridges under heavy vehicle loads. Most of the main factors that affect the bridge dynamic response due to moving vehicles are considered. An improved 3D grid model, based on commercial software ANSYS Mechanical APDL, is developed for the analysis of curved bridges following the 3D shear-flexibility grillage analyzing method. A simplified numeric method, considering the effect of random road roughness and its velocity term, is developed for solving the interaction problem. With the model and numerical method presented, a series of parametric studies are conducted to study the curved bridge dynamic interaction. Based on the investigation of determining factors of curve bridge dynamic interaction, the expression of the upper-bound envelop for impact factors of maximum deflection is given with different surface conditions and highway speed limits as a function of bridge fundamental frequency or bridge central angle. A study is conducted on comparing these empirical equations and serval other major design codes, comments and suggestions are then made based on the discoveries. [ABSTRACT FROM AUTHOR]

The seismic response of curved concrete bridges is complex because of the geometric irregularity and induced planar rotation of the deck, which can magnify the displacement of the deck and deformation of the bearings. To control the planar rotation and thus the seismic response of the curved bridge, an orthogonally separated isolation system (OSIS) is proposed, which consists of the upper and lower isolation parts. With this, the planar relative displacement of the common isolation system is decomposed into the relative displacement of the upper part in one direction and the relative displacement of the lower isolation part in the orthogonal direction. Therefore, the planar rotation can be restrained and the seismic demand of the isolation bearing is decoupled. The analytical models of a curved bridge and the OSIS are established in OpenSees. A suite of 118 ground motions, of which 80 are ordinary and 38 are pulse-like, is selected as input with 24 different angles of incidence so as to consider the seismic variation. Nonlinear dynamic time-history analyses of the two models are conducted to evaluate the effectiveness of the OSIS. The results show that the OSIS can effectively decrease the deck displacement, the bearing deformation and the pier column shear force, especially under the ground motions with higher intensities, while the shear force increases slightly on the abutment. [ABSTRACT FROM AUTHOR]

Lead Rubber Bearings (LRBs) represent one of the most widely employed devices for the seismic protection of structures. However, the effectiveness of the same in the case of curved bridges has not been judged well because of the complexity involved in curved bridges, especially in controlling torsional moments. This study investigates the performance of an LRB-isolated horizontally curved continuous bridge under various seismic loadings. The effectiveness of LRBs on the bridge response control was determined by considering various aspects, such as the changes in ground motion characteristics, multidirectional effects, the degree of seismic motion, and the variation of incident angles. Three recorded ground motions were considered in this study, representing historical earthquakes with near-field, far-field, and forward directivity effects. The effectiveness of the bi-directional behavior considering the interaction effect of the bearing and pier was also studied. The finite element method was adopted. A sensitivity study of the bridge response related to the bearing design parameters was carried out for the considered ground motions. The importance of non-linearity and critical design parameters of LRBs were assessed. It was found that LRBs resulted in a significant increase in deck displacement for Turkey ground motion, which might be due to the forward directivity effect. The bi-directional effect is crucial for the curved bridge as it enhances the displacement significantly compared to uni-directional motion.

Based on bearing friction slip performance, the influence of vehicle load on lateral slip of curved bridge was analyzed. Taking the vehicle running on the simply supported curved girder bridge as an example, a theoretical analysis of the vehicle-bridge system was carried out to control the friction slip of the bearing, and the theoretical formula for controlling the friction slip of the bearing under the vehicle load was obtained, which can be used to guide the route design and operation control. [ABSTRACT FROM AUTHOR]

Under the action of an earthquake, the piers of urban curved bridges are usually subjected to compression, bending and torsion due to the geometric irregularity and with low and moderate shear-span ratio. To explore the seismic performance of piers under combined actions, this paper made a theoretical analysis on the seismic performance of four circular RC columns under combined action with low and moderate shear-span ratio through experimental research. Taking the shear-span ratio and torsion-bending ratio as the main variables, cyclic bending loading and combined cyclic bending and torsion loading were carried out on the columns, respectively. The results showed that the increase of torsional effect and shear effect will increase the failure height of the piers and weaken the energy dissipation capacity and bearing capacity. Through the extraction of characteristic points in the test data, the relationship between force, displacement and torsion-bending ratio of columns with shear-span ratio below 4 was fitted. The bending and shear restoring force models of columns with spiral stirrups and small torsion-bending ratio were established. Moreover, based on the variable angle truss theory, the concrete improvement coefficient β was introduced, and the formula of torsional bearing capacity of columns under combined actions with low and moderate shear-span ratio was deduced. Compared with the test data, when the value of β was taken as 1.1, the proposed formula could be well applied to the calculation of bearing capacity of piers with torsion-bending ratio below 0.2 under combined actions with low and moderate shear-span ratio. [ABSTRACT FROM AUTHOR]

This paper proposes a three-dimensional dynamic model for high-speed railway trains moving over curved bridges considering the transition curves, circular curves, and superelevation. Key features of this study are to consider the nonlinear geometrical relationships and creep relationships between the wheels and rail, for which the interactive iterative numerical algorithms are developed based on the equations of vertical displacement and rolling of wheelset, and the torsional resonance conditions of the vehicle–bridge system are verified. The results show that the torsional vibration will cause amplification on vertical dynamic response of the beam on the outside edge of the curve. The deficient/surplus superelevation plays an important role in the lateral and torsional angular displacements of the bridge, and the peak of the torsional resonance response can be reduced by adjusting the practical superelevation of the curve. The variations of wheel–load reduction rate and derailment coefficient in the curve section are positively correlated to the deficient/surplus superelevation. The curve radius is the key factor affecting the wear and fatigue of wheel–rail, and when the curve radius is greater than 7000 m, the wear and fatigue can be significantly reduced. Running at a deficient superelevation level can also reduce the wear and fatigue. [ABSTRACT FROM AUTHOR]

To study the influence of near-fault and far-field (FF) ground motions on a curved girder bridge, a 1:10 scale curved bridge shaking table test model was constructed. Three types of ground motions, namely, near-fault pulse (NP), near-fault non-pulse (NN), and FF ground motions, were selected and employed in the test model. The test results indicated that the seismic response of the curved bridge in the excitation of NP ground motion is significantly higher than that in the excitation of NN and FF ground motions, and is destructive to the curved bridge. The displacement of the curved bridge has spatial characteristics in the excitation of NP ground motions. The rotation generated by the curved bridge is easy to cause bearing shedding or girder falling at the low pier. The amplification of pier height increases the displacement response at the high pier.

Curved pedestrian bridges are important urban infrastructure with the desired adaptability to the landscape constraints and with aesthetic benefits. Pedestrian bridges feature thin cross-sections, which provide sufficient load capacities but lead to low natural frequencies that make the bridges susceptible to vibration under pedestrian excitation. This study investigates the lateral vibration of a curved bridge with a small radius down to 20 m, proposes an approach to mitigate the lateral vibration of bridges with large curvatures using distributed multiple tuned mass dampers (MTMD), and conducts in-situ bridge tests to evaluate the vibration mitigation performance. The lateral vibration was investigated through in-situ tests and finite element analysis as well as the code requirements. The key parameters of the distributed MTMD system were improved by strategically selecting the mass ratio, bandwidth, center frequency ratio, and damper number. The results showed that the curved bridge was subjected to significant lateral vibration due to the coupling of torque and moment, and the recommended design parameters for the studied bridge were derived, i.e., the total mass ratio is 0.02, bandwidth is 0.15, center frequency ratio is 1.0, and damper number is 3. The proposed approach effectively improves the deployment of MTMD for lateral vibration control of the curved bridge. The field tests showed that the vibration was reduced by up to 82% by using the proposed approach.

Because of the irregular geometries, earthquake-induced adjacent curved bridge pounding may lead to more complex local damage or even collapse. The relevant research is mainly concentrated on the numerical analysis which lack experimental verification and discussion by changing of structural parameters. In this paper, a scaled three-dimensional numerical model of a curved bridge is established based on 3D contact friction theory for investigating the uneven distribution of pounding forces at the expansion joint of the bridge. Shaking table tests were carried out at first on a curved bridge to validate the numerical model. A series of parametric studies were then conducted to examine the impacts of the radius of curvature and longitudinal slope of the superstructure of the curved bridge on its seismic pounding response. The results show that the maximum pounding force first increases and then decreases as the radius of curvature increases, but that it decreases monotonically with the growth of the longitudinal slope. These results suggest that controlling the radius of curvature and the longitudinal slope of the superstructure of the bridge can reduce the localized high stress that is induced by seismic pounding. Also, the unevenly distributed pounding forces can significantly increase the relative radial displacement of the bridge's deck corners, although the relative tangential displacement may decrease. It is thus necessary to adopt effective anti-pounding measures to prevent the superstructure of the bridge from being unseated. [ABSTRACT FROM AUTHOR]

A viaduct is an important structural form in intercity railway networks, and the curved bridge is inevitable in railway line network planning. When the vehicles cross through the curved bridge, the transverse load experienced by the bridge is much larger than that of the straight bridge due to the centrifugal forces. Therefore, in the bridge resonance analysis, in addition to the vertical moving vehicle load, it is also imperative to consider the radial vehicle load. In order to systematically analyze the dynamic impact factor (or dynamic load allowance) and resonance conditions of the curved intercity railway viaduct, a numerical model is developed. The reliability of the proposed model is assessed by comparing it with the existing literature. Taking the curved viaduct of Zhengzhou-Xuchang railway as a case study, the theoretical resonance velocity, dynamic impact factor, and dynamic time-history response under resonance velocity are calculated. The parameters of different spans, curve radius, and speeds are analyzed, and the reasonable ranges of bridge natural vibration frequency are determined.

Curved multi-frame box-girder bridges with hinges are widely used in the United States due to the large spanning capacity, construction simplification and construction cost economy. This type of bridge frequently has the characteristics of column height asymmetry, adjacent bridge frames vibrating discrepancy. The combination of curved shape and random seismic excitation angles could aggravate the irregularity of the structural seismic response. In this study, an OpenSees model is established for an example bridge, and the hinge is taken as a key component to observe. The impacts of seismic excitation angles and column height layouts on fragility are investigated through the comparison of the fragility curves. The conclusions list the most unfavorable seismic excitation angles corresponding to the fragilities of bridge system, plug-type concrete elements in hinges, hinge restrainers, columns, abutment bearings as well as the secondary components, respectively. The symmetrical column height layout is proved to be beneficial to mitigate the damage risks of restrainers in intermediate hinges and reduce the fragility of the bridge system. This study can provide a reference for the rapid assessment of the fragile position and damage degree of bridges through structural configuration and shape, as well as the seismic excitation angle.

This article proposes an analytical modeling approach for seismic evaluation of curved prestressed concrete (PSC) bridges using alternative restraint materials. The approach was applied to a simply supported, curved PSC I-girder bridge subjected to a suite of ground motions. Along with analyzing the response of the bridge without Shape Memory Alloy (SMA), the bridge was retrofitted with SMA components and restraints to reduce its response and both results were compared. SMA components used included dowels in the bearing pad, restraints connecting the girders to the abutments, and piles with SMA characteristics. Results indicated that the SMA components reduced seismic response, and specifically the deformations of the SMA bridge were up to 80% lower than the non-SMA bridge. [ABSTRACT FROM AUTHOR]

Experimental programme was carried out to investigate the flexural behaviour of horizontally curved composite I-girder decks subjected to Iraqi Standard bridge live loads. This program included fabricating and testing five scaleddown, simply supported, curved bridge models, 3 m in central span length. Each model included four steel girders, with 175 mm girder spacing for the first two models, which had curvature (L/R) of 0.2 and 0.3, respectively. The other three models had 200 mm girder spacing, with curvature of 0.1, 0.2 and 0.3, respectively. The applied loads were equivalent to the self-weight and superimposed dead load to achieve that of the full scale designed bridge plus one of the Iraqi bridge live load cases (Lane, Military loading: composed of tracked vehicles class 100 and wheeled vehicles class 100) sequentially. The experimental results revealed that the Iraqi Wheeled load case controlled the behaviour of most of the bridge models; all the girder deflections were below the permissible AASHTO LRFD 2012 limit. The longitudinal mid-span bottom flange girder strain was less than the girder yield strain and the maximum longitudinal mid-span concrete strain at the top surface was (469 micro-strains) which was lower than the ultimate concrete strain of (3000 micro-strains). The deflection and the longitudinal girder strains increased with the increasing curvature, whereas the girder spacing exerted only a very slight effect.

Based on the rigid–flexible coupling method, an original scheme for the dynamic analysis of the vehicle–bridge interaction between suspended monorail trains and horizontally curved bridges is proposed. Considering the compression deformation and contact model of walking tire and guiding tire, the geometric and mechanical coupling relationships between vehicle and bridge are studied, and the dynamic equations of suspended monorail vehicle–bridge interaction are derived. A vehicle–curved bridge coupling vibration system is established according to transformable relationship between the local coordinate system and the global coordinate system in SIMPACK. Considering a curved bridge under passage of suspended monorail vehicles as an example, the influences of critical system parameters, such as the superelevation, vehicle speed, and bridge curve radius, on the dynamic responses of vehicles and the curved bridge are explored. It is shown that the direction of the yawing moment of the front bogie is in accordance with the turning direction of the vehicle, while the yawing moment of the rear bogie is in the opposite direction. The superelevation has great influence on the lateral guiding force and vertical walking force of vehicle, and vehicle speed is a key factor to the running safety of suspended monorail vehicle. In addition, the curve negotiation ability of vehicle is better with the increase in bridge curve radius. [ABSTRACT FROM AUTHOR]

In such curved sections, parameters of a track-bridge system have significant influences on the dynamic performance of the vehicle, track and bridge. Based on two-stage technique, 3D dynamic behaviors of a curved track-bridge system under heavy-haul train are simulated. The stochastic parameters to which the dynamic responses are sensitive are extracted by means of factorial experimental design, and the response surface methodology is adopted to study the influence of each sensitive random parameter on the probability of the failure of system, and the reliability of track-bridge structure in curved sections can then be evaluated. The results show that 1) the damping ratio and elastic modulus of bridge, and the interaction of the thickness of ballast bed and the elastic modulus of beam concrete are the key parameters affecting the reliability of track-bridge system; 2) when the radius of the curved section is less than 800 m, the lateral failure probability of the track-bridge system is increased rapidly; 3) maintaining good track quality can effectively improve the reliability of the track-bridge system; and the heavy-haul bridge designed according to the 30t standard can satisfy the requirements for the operation of train with 35t axle load. [ABSTRACT FROM AUTHOR]

This study presents a new hybrid method to develop seismic fragility curves for horizontally-curved steel I-girder bridges using Artificial neural network and logistic regression methods. The approach for developing fragility curves based on the assumption that engineering demand parameters follow the lognormal distribution for calculating the probability of damage occurrence. A sufficient number of input data including a set of earthquake ground motion records and macro-structural parameters together with the output data resulting from nonlinear structural analyses was assigned to neural network structure to achieve satisfactory approximations of responses. Logistic regression statistical method was used to determine the probability of occurrence or non-occurrence of limit states for earthquake ground motion parameters and structural characteristics. In this study, based on the estimation of engineering demand parameters, the proposed method is compared with the neural network method, simplified mathematical model and analytical method. The nonlinear time history analysis of three dimensional horizontally curve bridges were performed using the OpenSEES software. The statistical results indicate the accuracy and efficiency of the predicted limit state occurrence of the proposed method at a low computational cost. Comparison of fragility curves using the mentioned methods represent a proper estimation for slight, moderate, extensive and collapse limit states at different levels of seismic intensity. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The collapses of curved bridges are mainly caused by the damaged columns, subjected to the combined loadings of axial load, shear force, flexural moment and torsional moment, under earthquakes. However, these combined loadings have not been fully investigated. This paper firstly investigated the mechanical characteristics of the bending-torsion coupling effects, based on the seismic response spectrum analysis of 24 curved bridge models. And then 9 reinforced concrete (RC) and circular column specimens were tested, by changing the bending-tortion ratio (M/T), axial compression ratio, longitudinal reinforcement ratio and spiral reinforcement ratio, respectively. The results show that the bending-torsion coupling effects of piers are more significant, along with the decrease of girder curvature and the increase of pier height. The M/T ratio ranges from 6 to 15 for common cases, and influences the crack distribution, plastic zone and hysteretic curve of piers. And these seismic characteristics are also influenced by the compression ratio, longitudinal reinforcement ratio and spiral reinforcement ratios of piers. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The difficulty in curved bridge design lies in the eccentricity. Eccentricities break the regularity and make it difficult to resist horizontal loads. However, relatively stable and robust performance can still be achieved through properly aligned eccentricity. This paper used the controllability-related concepts, the controllability Grammians and Hankel singular values (HSVs), to study the impact of eccentricities on the seismic performance of curved bridges. An analytical model was expressed by second order differential equations with rigid deck assumption. Six eccentricity cases: three different radii (resulting in different center of mass (CM)), three different bearing arrangements (resulting in different center of stiffness (CS)), and variable earthquake directions (resulting in different moment arms) were strategized for research. Analyses showed that effects of eccentricities (offsets of CS from CM) can be extensively interpreted by controllability indices. Proper eccentricity may “reach” and thus “control” the responses better and decrease the coupling effects, counteract the unfavorable excitation effects, and make the bridge less sensitive to excitation changes. In this sense, regularity or stability could be somewhat re-established through design. Time history analyses confirmed the results.