Search Results (48)

This study investigates the structural performance of a novel composite space truss deck system as an alternative to the conventional steel box girder in cable-stayed bridges. Using the Suez Canal Bridge as a benchmark, comprehensive linear and nonlinear finite element analyses were performed to evaluate the global behavior of both deck configurations under dead, live, wind, and temperature loads. The proposed system consists of a three-dimensional square-on-square truss acting compositely with a 25 cm reinforced concrete slab, designed to optimize stiffness and material efficiency. The results revealed that the composite space truss deck achieved a 5–7% reduction in mid-span deflection under live loading and a 6% increase in torsional rigidity compared with the steel box girder, while maintaining comparable self-weight (490 kg/m² versus 480 kg/m²). The influence of geometric nonlinearity was moderate, 6.56% for the space truss and 1.64% for the box girder, whereas temperature variations of ±30 °C induced up to a 25.3% change in mid-span deflection, highlighting the space truss’s higher thermal sensitivity. Parametric analyses demonstrated that increasing the truss depth from 2.5 m to 4.0 m enhanced global stiffness by 15%, and using lightweight concrete reduced mid-span deflection by 30%. Overall, the composite space truss system offers superior stiffness-to-weight efficiency, substantial steel savings (two-thirds less), and competitive construction economy, establishing it as a promising solution for medium- and long-span cable-stayed bridges. Full article

The application of steel–concrete composite structures in the pylons of long-span cable-stayed bridges can effectively address the issue of insufficient structural stiffness. Shear connectors are critical load-transfer components in steel–concrete composite segments, where they are typically arranged to ensure coordinated force transmission between steel and concrete. The stud–PBL composite shear connector, as a novel type of connector, has been implemented in engineering practice. However, the collaborative load-bearing performance between studs and PBL connectors remains unclear. Most shear connectors operate within the elastic stage during service, making their elastic stiffness a key evaluation metric. Based on the Winkler elastic foundation beam theory, plane strain theory, and the spring series–parallel model, this study derives the elastic stiffness calculation formulas for stud shear connectors and PBL shear connectors, respectively. The primary focus of this study was the single-layer stud–PBL composite shear connector within the steel–concrete composite section of bridge pylons. Embedded push-out tests were designed and conducted, comprising three main categories and eight subcategories. The load–slip curves for the three types of shear connectors were generated, and the stiffness calculation formula for the stud–PBL composite shear connector was verified through finite element analysis. The comparative push-out tests and finite element simulations demonstrate that the theoretical formula proposed in this study can effectively analyze the elastic stiffness of three types of shear connectors. The elastic stiffness of composite shear connectors can be regarded as the superposition of the elastic stiffness of studs and PBL shear connectors. Compared with single shear connectors, composite shear connectors exhibit superior elastic stiffness and shear resistance, meeting the application requirements of steel–concrete composite bridge pylons. The research findings provide a theoretical basis for the optimal design of shear connectors in large-span cable-stayed bridge composite pylons. Furthermore, the established formula has broad applicability. Full article

Cable-stayed suspension hybrid bridges (CSSHBs) integrate the advantages of cable-stayed bridges and suspension bridges into a highly rigid structure. However, due to their hybrid nature, the static performance of CSSHBs is highly sensitive to various factors, presenting significant challenges for parameter analysis and scheme comparison during design. This study presents a new live load effects analysis strategy for the hybrid bridge with varied structural parameters. The methodology expands the application scenarios of variable parameter influence line (IL) analysis. It solves structural live load responses based on the area of influence lines with the same sign and constructs a “parameter variation-structural response” diagram. Simultaneously, it extracts critical live load cases, enabling designers to adjust parameters during the conceptual design phase based on calculation results from a limited number of load cases. The 690 m Tuwan Bridge is used as the benchmark model for the case study. The study first investigates the characteristics of its influence lines, followed by parametric studies. Results indicate that when the main girder stiffness is increased by a factor of 100, the deflection at the mid-span section and the cable force amplitude of the side hanger are reduced by 53% and 81%, respectively. And increasing the sag-to-span ratio proves effective in mitigating live load effects. Finally, the structural static responses under three critical load cases are analyzed to comprehensively validate the proposed analytical strategy. Full article

Designing long-span cable-stayed bridges in high seismic hazard zones presents significant challenges due to their flexible structural systems, the influence of multi-support excitation, and the need to control large displacements while limiting seismic demands on critical components. These difficulties are further amplified in regions with complex geology and for bridges required to maintain high levels of post-earthquake serviceability. This study develops a low-damage seismic design approach for long-span cable-stayed bridges and demonstrates its application in the New Panama Canal Bridge. Probabilistic seismic hazard assessment and site response analyses are performed to generate spatially varying ground motions at the pylons and side piers. The pylons adopt a reinforced concrete configuration with embedded steel stiffeners for anchorage, forming a composite zone capable of efficiently transferring concentrated stay-cable forces. The lightweight main girder consists of a lattice-type steel framework connected to a high-strength reinforced concrete deck slab, providing both rigidity and structural efficiency. A coordinated girder–pylon restraint system—comprising vertical bearings, fuse-type restrainers, and viscous dampers—ensures controlled stiffness and effective energy dissipation. Nonlinear seismic analyses show that displacements of the girder remain well controlled under the Safety Evaluation Earthquake, and the dampers and bearings exhibit stable hysteretic behaviours. Cable tensions remain within 500–850 MPa, meeting minimal-damage performance criteria. Overall, the results demonstrate that low-damage seismic performance targets are achievable and that the proposed design approach enhances structural control and seismic resilience in long-span cable-stayed bridges. Full article

This study aims to analyze the wind-induced effects and vibration control of a long-span cable-stayed bridge with a steel truss girder under strong marine wind conditions during its maximum single-cantilever state. During the cantilever construction stage of cable-stayed bridges, the reduction in structural stiffness and damping may lead to excessive wind-induced responses, affecting construction accuracy and safety. Focusing on a newly constructed sea-crossing railway cable-stayed bridge with a steel truss girder and a main span of 364 m, this research utilizes field-measured data and finite element simulations to analyze the buffeting responses of the bridge in the maximum single-cantilever state during construction. The vibration suppression effects of different wind-resistant measures are compared, and we propose an economical and efficient vibration mitigation solution. The results indicate that using the turbulent field parameters and unit aerodynamic admittance function recommended in JTG/T 3360-01—2018 Wind-resistant Design Specification for Highway Bridges leads to conservative in predictions regarding the buffeting responses, and this approach can be used in the preliminary design of large-span bridges. The measured turbulent field parameters can effectively estimate the bridge buffeting responses, especially in the transverse direction. Measuring wind speeds at the bridge site is crucial for the rational design and construction of cable-stayed bridges in strong marine wind environments. The effectiveness of vibration reduction decreases in the order of temporary piers, inclined struts, tuned mass dampers, and wind-resistant cables. The inclined strut scheme achieved vibration reductions of 84.45% in the transverse direction and 68.17% in the vertical direction, slightly lower than those of the auxiliary pier scheme (89.04% and 85.47%). However, the installation of temporary piers during the construction of a sea-crossing bridge would significantly increase construction costs, whereas the inclined strut scheme requires only temporary steel structures near the main tower and piers without substantially increasing the construction workload. Therefore, the inclined strut scheme is recommended as an effective and economical vibration control measure for large-span sea-crossing cable-stayed bridges. Full article

High-pier partially cable-stayed bridges, with their significant pier heights and relatively low structural stiffness and stability, experience pronounced vehicle–bridge coupling effects during vehicle transit, influencing their dynamic response and safety. This study developed a co-simulation analysis program using easy language and ANSYS to investigate the dynamic behavior of a prestressed concrete five-tower partially cable-stayed bridge under vehicle–bridge interaction, considering factors such as vehicle speed, bridge deck grade, and cable force. The research findings indicate that a reduction in bridge deck grade leads to increases in peak dynamic responses and impact factors, with the dynamic amplification factor showing a deteriorating trend across all cross-sections. Structural responses fluctuate with vehicle speed and exhibit sensitivity to speed variations, with the maximum response observed at a speed of 80 km/h. Adjusting cable forces can reduce the impact factor: a 5% change in cable tension causes the mid-span impact factor to drop sharply from 0.38 to 0.04, a substantial decrease of 89.5%. The structural system can exert an impact on the impact factor by as much as several times: while the dynamic displacement and bending moment of the fixed system are smaller than those of the continuous beam system, its impact factor is as high as 4.22 times that of the continuous beam system. Additionally, dynamic responses are closely related to the position of the fixed bearing, with responses near the fixed bearing being reduced. Notably, the maximum impact factors of critical sections all exceed the 0.05 limit specified in the code for this type of bridge, with values of 0.54 at the mid-span, 0.91 at the pier top, and 0.43 at the tower top anchor zone. This indicates that the provisions regarding dynamic amplification factors in the current code are inappropriate for such bridges. The difference in impact factors between bridge components can reach 2.12 times, this indicates that specific impact factors should be assigned to individual components to achieve an optimal balance between safety and economic performance. Full article

Cable force distribution in cable-stayed bridges critically impacts structural safety and efficiency, yet traditional optimization methods struggle with unconventional designs due to nonlinear mechanics and computational inefficiency. This study proposes a hybrid approach combining Response Surface Methodology (RSM) and Multi-Objective Particle Swarm Optimization (MOPSO) to overcome these challenges. RSM constructs surrogate models for strain energy and mid-span displacement, reducing reliance on finite element analysis, while MOPSO optimizes Pareto solution sets for rapid cable force adjustment. Validated through an engineering case, the method reduces the main girder’s max bending moment by 8.7%, mid-span displacement by 31.2%, and strain energy by 7.1%, improving stiffness and mitigating stress concentrations. The response surface model demonstrates prediction errors of 0.35% for strain energy and 5.1% for maximum vertical mid-span deflection. By synergizing explicit modeling with intelligent algorithms, this methodology effectively resolves the longstanding efficiency–accuracy trade-off in cable force optimization for cable-stayed bridges. It achieves over 80% reduction in computational costs while enhancing critical structural performance metrics. Engineers are thereby equipped with a rapid and reliable optimization framework for geometrically complex cable-stayed bridges, delivering significant improvements in structural safety and construction feasibility. Ultimately, this approach establishes both theoretical substantiation and practical engineering benchmarks for designing non-conventional cable-stayed bridge configurations. Full article

Insufficient structural stiffness is a key technical challenge that restricts the increase in span of multi-tower cable-stayed bridges. In order to clarify the application effect of crossing cables in long-span, multi-tower cable-stayed bridges, theoretical analysis and the finite element method were used to study the influence of the cable sag effect on the longitudinal constraint stiffness of crossing cables. The longitudinal constraint stiffness formula of the crossing cable was modified by introducing the equivalent elastic modulus to consider the cable sag effect. Based on the stiffness formula, the influence of the main span, initial stress of the crossing cable, and the ratio of the crossing cable area on its restraining effect was analyzed. The finite element model of a three-tower cable-stayed bridge with main span length of 1000 m and 1500 m is established to verify the accuracy of the formula, and the influence of the number of crossing cables and the tower height on the restraining effect of crossing cables is explored. The research results indicate that as the main span length increases, the location of maximum restraining stiffness of crossing cables moves closer to the mid span; increasing the area of crossing cables connected to the mid tower can effectively suppress the deviation of the tower. In addition, increasing the main span length will reduce the restraining effect of the crossing cables, while changes in the height of the towers do not affect the enhancement effect of the crossing cables on structural rigidity. Full article

Previous studies have demonstrated that two representative passive control devices, including inertial mass dampers (IMDs) and negative stiffness dampers (NSDs), exhibit superior control performance in single-mode vibration control of stay cables. However, observations in recent years have increasingly reported rain–wind-induced multi-mode vibrations of stay cables on actual bridges. Therefore, it is of considerable significance to investigate the control effectiveness of the two representative passive dampers in mitigating multi-mode cable vibrations. For this reason, this study presents a comparative study of the IMD and NSD for the multi-mode vibration control of stay cables. The mechanical models of typical IMDs and NSDs are first introduced, followed by the numerical modeling of the two cable-damper systems using the finite difference method. Subsequently, the effectiveness of three multi-mode optimization strategies is comprehensively assessed, and the most effective strategy is selected for the optimal design of the IMD and NSD. Finally, the effectiveness of the control of the IMD and NSD in suppressing harmonic, white noise and wind-induced multi-mode vibrations of a 493.72 (m) long ultra-long cable is systematically evaluated. The numerical results indicate that the NSD significantly improves the cable damping ratios for multiple vibration modes as its negative stiffness coefficient increases, while IMD performs well only within a small inertia coefficient. Moreover, the NSD outperforms the IMD in suppressing multi-mode cable vibrations induced by harmonic, white noise and wind excitations. Full article

Conducting health monitoring on entire large-scale structures is challenging. Compared to non-critical regions, local damage in critical regions significantly impacts the overall structural performance, with even minor damage posing a threat to structural safety. Therefore, identifying the critical regions of a structure is essential to enable prioritized and focused monitoring, evaluation, and management. This paper proposes a method for identifying critical regions in cable-stayed bridges based on dynamic eigensensitivity analysis. The method integrates the sensitivity of multi-order eigenvalues and eigenvectors with respect to elemental stiffness parameters, designating regions with high sensitivity values as critical. The results demonstrate that the midspan region of the main girder, the longest stay cable, and the junctions between the upper, middle, and lower bridge towers and the foundation are identified as critical regions in a cable-stayed bridge. These findings are consistent with established engineering experience. The proposed critical region identification method holds significant potential for improving the efficiency of health monitoring and assessment, as well as optimizing the allocation of manpower and material resources. Full article

This study investigates the construction methodology of large-span cable-stayed tensioned metal thin-sheet structures, introducing the “integrated enclosure and load-bearing” design concept. By applying in-plane prestress, the out-of-plane stiffness of the metal thin sheet is effectively enhanced, enabling it to simultaneously serve as an enclosure and a load-bearing component. Through experimental studies and finite element analysis, the study systematically examines the effects of various construction methods on internal forces and displacements. The tensioning of back cables is identified as the safest and most efficient construction method. Subsequently, through simulations of a three-span structure and tensioning forming tests, the research examines displacement, stress, and cable force distribution patterns, demonstrating that increases in the tensioning level result in corresponding increases in sheet surface stress, cable forces, and displacements. The structure exhibits a concave middle section, upward curvatures at both ends, and outward-leaning end columns. Structural members with lower cable forces show minimal impact on displacement and are therefore identified as suitable targets for design optimization. This study offers a theoretical foundation and practical engineering insights to guide the optimization of design and construction for cable-stayed tensioned metal thin-sheet structures. Full article

To suppress large vibrations of the cable in cable-stayed bridges, it is common to install transverse dampers near the end of the cable. This paper focuses on the cable-damper system; based on the dynamic stiffness method, an accurate dynamic analysis method considering cable parameters, damper parameters, and cable forces is proposed. First, a mechanical analysis model is established which is closer to the cable with a transverse damper installed in the bridge. The model considers the cable bending stiffness, sag, inclination angle, cable force, damper stiffness, damping coefficient, and damper installation height. Then, the characteristic frequency equation of the cable-damper system is established, and a solution method that combines the initial value method and Newton–Raphson method is proposed. This method is confirmed to provide more accurate frequency analysis for the cable-damper system. Finally, using this method, the effect of the damper parameters on the dynamic characteristics of the system is investigated. Full article

The hybrid cable-stayed and suspension (HCSS) bridge is known for its stability and cost-effectiveness, with significant application potential. This study examined the static performance of an HCSS bridge with a 1440 m main span. A finite element model (FEM) was developed to assess key parameters, such as the span-to-rise ratio, cable-to-hanger ratio, pylon stiffness, steel–concrete interface, and cable stiffness. Through FEM analysis and parameter optimization using the zero-order and first-order optimization methods in an ANSYS module, key design variables were optimized. The results show that an inappropriate span-to-rise ratio negatively impacts mid-span girder forces, while increasing the cable-stayed area enhances the overall stiffness. Main cable stiffness plays a crucial role in load-bearing and deformation control. Significant force differences were observed between stay and hanger cables, with axial force in the main girder increasing from the side span to the pylon under dead load. Bending moments in the transition region varied widely under combined loads. Optimizing parameters, such as the span-to-rise and cable-to-hanger ratios, significantly improved the mechanical performance of HCSS bridges, offering valuable insights for future designs. Full article

The evaluation of bridge safety is closely related to structural stiffness, with dynamic characteristics and displacement being key indicators. Displacement is a significant factor as it is a physical phenomenon that bridge users can directly perceive. However, accurately measuring displacement generally necessitates the installation of displacement meters within the bridge substructure and conducting load tests that require traffic closure, which can be cumbersome. This paper proposes a novel method that uses wireless accelerometers to measure ambient vibration data from bridges, extracts mode shapes and natural frequencies through the time domain decomposition (TDD) technique, and estimates static displacement under specific loads using the flexibility matrix. A field test on a 442.0 m cable-stayed bridge was conducted to verify the proposed method. The estimated displacement was compared with the actual displacement measured by a laser displacement sensor, resulting in an error rate of 3.58%. Additionally, an analysis of the accuracy of displacement estimation based on the number of measurement points indicated that securing at least seven measurement points keeps the error rate within 5%. This study could be effective for evaluating the safety of bridges in environments where load testing is difficult or for bridges that require periodic dynamic characteristics and displacement analysis due to repetitive vibrations, and it is expected to be applicable to various types of bridge structures. Full article

The bridge influence line can effectively reflect its overall structural stiffness, and it has been used in the studies of safety assessment, model updating, and the dynamic weighing of bridges. To accurately obtain the influence line of a bridge, an Empirical and Variational Mixed Modal Decomposition (E-VMD) method is used to remove the dynamic component from the vehicle-induced deflection response of a bridge, which requires the preset fundamental frequency of the structure to be used as the cutoff frequency for the intrinsic modal decomposition operation. However, the true fundamental frequency is often obtained from the picker, and the testing process requires the interruption of traffic to carry out the mode decomposition. To realize the rapid testing of the influence lines of bridges, a new method of indirectly identifying the operational modal frequency and deflection influence lines of bridge structures from the axle dynamic response is proposed as an example of cable-stayed bridge structures. Based on the energy method, an analytical solution of the first-order frequency of vertical bending is obtained for a short-tower cable-stayed bridge, which can be used as the initial base frequency to roughly measure the deflection influence line of the cable-stayed bridge. The residual difference between the deflection response and the roughly measured influence line under the excitation of the vehicle is operated by Fast Fourier Transform, from which the operational fundamental frequency identification of the bridge is realized. Using the operational fundamental frequency as the cutoff frequency and comparing the influence-line identification equations, the empirical variational mixed modal decomposition, and the Tikhonov regularization to establish a more accurate identification of the deflection influence line, the deflection influence line is finally identified. The accuracy and practicality of the proposed method are verified by real cable-stayed bridge engineering cases. The results show that the relative error between the recognized bridge fundamental frequency and the measured fundamental frequency is 0.32%, and the relative error of the recognized deflection influence line is 0.83%. The identification value of the deflection influence line has a certain precision. Full article