Truss Web Research Articles

Study on Structure-Borne Noise Characteristics of Long-Span Steel Truss Bridge in Urban Rail Transit

The application of long-span steel bridge in urban rail transit is becoming more and more extensive, but the structure-borne noise of steel bridge induced by passing train is also prominent. Research on the structure-borne noise problem of long-span steel bridge in urban rail transit has positive significance in promoting the sustainable development of steel bridge, and improving the quality of sound environment along rail transit. In this work, dynamic receptance principle, finite element method and statistical energy method are combined to establish the structure-borne noise prediction model of the long-span steel bridge, and the rationality and validity of the model are verified based on field measurement results. Based on the prediction model, the noise radiation characteristics of large-span steel truss bridge in urban rail transit are studied, and the following conclusions are drawn: The bridge deck has the strongest acoustic contribution ability, with the contribution rate of 33–44%, followed by the longitudinal web and transverse web, with the contribution rate of 23–30%, followed by the truss chord, with the contribution rate of 5–8%, and the truss web, longitudinal wing and transverse wing have weak contribution ability, with the contribution rate of less than 2%. The acoustic radiation efficiency of steel truss bridge components reaches its peak at the critical frequency, and the critical frequency is determined by the thickness of steel bridge plate components when the material parameters are fixed. Under ordinary track structures, the middle-to-high frequency noise distribution characteristics of large-span steel truss bridge structure are obvious. Damping pad floating slab track can effectively suppress the high-frequency noise of steel bridge, and the overall sound level can be reduced by about 11–14[Formula: see text]dB.

Bending Performance of a Prestressed Concrete Composite Girder Bridge with Steel Truss Webs

An experiment was conducted on a prestressed concrete (PC) composite girder bridge with steel truss webs to investigate its flexural performance. The mechanical characteristics and failure modes of a PC composite girder bridge with steel truss webs was clarified. Finite element (FE) analysis was carried out, and the influence of the girder height-to-span ratio and eccentric loading effect on the flexural performance of a composite beam bridge with a steel truss web was discussed. The method for calculating the cracking bending moment, the bending moment at the rebar yield stage, and the ultimate bending moment of a PC composite girder with steel truss webs was proposed. Key findings include that, in both the elastic and cracking elastic stages, the strain of the bottom and top conforms to the plane-section assumption. Throughout the loading process, there was no occurrence of joint failure or local buckling failure in the steel truss webs; the composite girder ultimately fails due to excessive deformation, indicating that the overall mechanical performance of the composite beam is good. The deflection and stress in the mid-span section decrease with an increasing height-to-span ratio, and there are significant impacts of eccentric loading on deflection and stress. Compared with the results of the FE analysis and test, the calculation methods of the cracking moment, reinforcement yield moment, and ultimate moment of PC composite girders with steel truss webs presented in this paper have a high accuracy.

Wind-Induced Response Analysis and Fatigue Life Prediction of a Hybrid Wind Turbine Tower Combining an Upper Steel Tube with a Lower Steel Truss

Based on the WindPACT-3MW wind turbine tower commonly used in wind power engineering, a finite element model (FEM) of a hybrid wind turbine tower combining an upper steel tube with a lower steel truss is designed and established. On this basis, a static optimization analysis, wind-induced vibration analysis, and fatigue life analysis of the hybrid tower structure are performed. The results show that under the same design parameters, the overall stiffness and static bearing capacity of the tower structure can be significantly improved by using subdivided truss webs, increasing the truss height as much as possible and increasing the width of the truss base appropriately. Under normal operation conditions, the response of the tower structure in the along-wind direction is significantly greater than the response in the crosswind direction, indicating that the aerodynamic thrust generated by the rotation of the blades is the main factor causing the wind-induced vibration of the tower structure. For the tower structure analyzed in this study, when considering the entire range of wind speeds from the cut-in wind speed to the cut-out wind speed, the fatigue life of the structure is 38.5 years.

Experimental study on eccentric compressive behavior of precast concrete double-faced superposed shear walls

With the growing application of prefabricated building structural systems, precast concrete double-faced superposed shear wall (PCDSSW) structures have gained increasing popularity in multi-story and high-rise buildings. However, limited research on the eccentric compressive performance of PCDSSWs could lead to severe consequences. To address this issue, this study conducted eccentric load tests on seven full-scale PCDSSW specimens with steel truss connectors and one full-scale cast-in-place reference specimen. The influence of various design parameters, including truss web diameter, trusses layout, connection locations and methods between steel trusses and distribution reinforcement on the eccentric compressive performance of PCDSSWs was analyzed and discussed. The results revealed that both cast-in-place and PCDSSW specimens exhibited similar failure modes characterized by large eccentric compression failure. PCDSSW specimens showed no noticeable laminated interface separation and can achieve the design objective of "comparable performance to cast-in-place". Moreover, the diameter of truss web reinforcement and the layout of steel trusses had minimal impact on the eccentric compression performance of PCDSSW. While employing welded connections could boost the load-bearing capacity and cracking stiffness of PCDSSW, it also led to a marginally faster stiffness degradation rate and reduced deformation capacity. Additionally, the existing design standards yield conservative predictions for the load-bearing capacity of PCDSSWs. Furthermore, the model proposed by GB 50010–2010 is advocated due to its reliability and accuracy.

Designing Truss in Architecture: Method and Applications Based on Clustering Algorithms and Principal Stress Lines

Rationally and effectively balancing the design objectives of architecture and structure is challenging owing to the limitations of existing truss design methods. Inspired by visual design principles, this study proposes a non-black-box, parametric, and integrated solution based on principal stress lines (PSLs). The idea is to mine the potential data features of PSLs by the clustering algorithm. Clustering the endpoints and equipartition points of PSLs is the core operation of this method. The clustering results are then used to reflect the geometric features and distribution characteristics of PSLs. For this purpose, the framework of two clustering algorithms (DBSCAN and K-means) is adapted with additional functions for sorting, screening, and counting the sample size of specific clusters. Moreover, combined with the layout pattern of linear elements, the truss web number, size, and layout are defined based on the clustering results. In addition, to verify the feasibility of form-finding results, the method is applied to a cantilever truss and two practical projects: Taishan Bridge and the Wing Stairway. Finally, the application potential of this method is demonstrated by comparing its conventional trusses under the same load and support conditions (materials used, maximum displacement, and maximum axial stress). • The proposed truss generation concept is initiated from structural performance, and at the same time is highly compatible with the architect’s design demand for visual presentation. • Compared to the other conventional structural optimization methods based on principal stress lines, the workflow of truss form evolving methodology provided in the paper is non-black-box and achieves parametric visualization in the whole designing process. • There are multiple parameters to control truss webs’ number, size, and layout pattern, which makes diversified outcomes of form generation possible to meet the different requirements of the designers. • The tensile and compression members in trusses can be distinguished to effectively select their cross-sectional sizes, which are important in the accurate demonstration of material properties for both architects and engineers.

Design and Calculation of PC Composite Rigid Frame Bridge with Variable Section Steel Truss Webs

Steel truss web prestressed concrete composite bridge has many advantages, such as light weight, clear stress, beautiful structure, convenient construction, etc., but it is still in its infancy in China. Taking Shuinianbao bridge of Yanchong high speed as an example, this paper introduces the design method of PC composite rigid frame bridge with variable cross-section continuous steel truss web, and analyzes the static calculation of the whole bridge in combination with the code, so as to provide design reference for the construction and development of PC composite bridge with variable cross-section steel truss web. The analysis results show that: the calculation results obtained after modeling according to the design size meet the design requirements. Under the condition of ultimate bearing capacity, the top plate obtains a more uniform maximum resistance, and the arch curve makes the internal force of the bottom plate relatively small. Under the combination of short-term load effect, the main tensile stress of the inclined section appears at the position close to the support and the middle span section of the top plate. The main tensile stress of the steel truss web member is the most different under the unfavorable load combination, the maximum tensile stress is greater than the compressive stress, and the maximum tensile stress occurs at 1/4 of the mid-span.

Bracing Applications for Improving the Earthquake Performance of Reinforced Concrete Structures

Braced frames, besides other structural systems, such as shear walls or moment resisting frames, have been a valuable and effective technique to increase structures performance against seismic loads. In wind or seismic excitations, diagonal members react as truss web elements which would afford tension or compression stresses. This study purposes at considering the effect of bracing diagonals on values of base shear and displacement of building. Two models were created and nonlinear pushover analysis has been implemented. Results show that bracing members enhance the lateral load performance of RC frames considerably. The purpose of this article is to study the nonlinear response of reinforced concrete Structures which contain Hollow Pipe Steel braces as the major structural elements versus earthquake loads. A five-storey reinforced concrete structure was selected in this study; two different reinforced concrete frames were considered. The first system was un-braced frame while the last one was braced frame with diagonal bracing. Analytical modelings of the bare frame and braced frame were realized by means of SAP 2000. The performances of all structures were evaluated using the nonlinear static analyses. From these analyses, the base shear and displacements were compared. Results are plotted in diagrams and discussed extensively and the results of the analyses showed that, the braced frame was seemed to capable of more lateral load carrying, had the high value for stiffness and lower roof displacement in comparison with bare frame.

Towards predicting the buckling and crushing strength of graded SA pine with high slenderness ratios

There is an apparent increase in failure of timber truss web members or compression chords. This paper seeks to reassess buckling of the compression chords with specific focus on web members. There are two possibilities for the seemingly lower buckling strength of web members, namely that the mean modulus of elasticity is a poor predictor of buckling strength where knots and other local changes in stiffness are concerned, and secondly that the actual crushing strength of the timber is lower than the design values. This paper will investigate both of these possibilities in order to achieve a safer approach to the design of timber compression members.

Performance of RC Asymmetrical Building With and Without Bracings by Linear Static and Time History Research

In asymmetrical Reinforce concrete (RC) buildings, the most effective and practical method of enhancing the seismic resistance and to reduce lateral displacement of the structures by combining bracings elements in the frame. Although past studies have focussed on the modelling of bracing elements, symmetric building models in linear analysis, there have been no detailed investigation on asymmetric structures under seismic excitation. Inclined elements (bracings) react as truss web elements which would bear compression or tension stresses. In present study a G+5 symmetrical RC bare frame, asymmetrical RC bare frame, asymmetrical RC frame incurred with different types of bracings such as X, V, inverted V, eccentric forward, eccentric back bracings at outer positions in all floors. Structural members of G+5 frame are designed as per the provisions of Indian seismic code IS: 1893 (Part-1)-2015. It was observed that maximum reduction both in X direction and Y-direction for x-type bracings in all models. It was observed that the maximum storey drift ratio of the structure under permissible limits as per the Indian seismic code IS: 1893 (Part-1)-2015 from linear static and dynamic analysis. From results obtained from linear static and dynamic analysis, the maximum forces in beams and columns reduced significantly X bracings in symmetric plan and asymmetric plan model

Behavior and design for component and system of cold-formed steel roof trusses

The experimental investigation of the behavior of cold formed steel (CFS) roof trusses does not offer a prior knowledge about either which member will fail first or the capacity of the whole truss. This research aims to investigate the overall behavior of CFS roof trusses using finite element analysis and to predict the failure location in the truss assembly and its cause by calculating the demand to capacity (D/C) ratios using Direct Strength Method (DSM) for each component of the truss and compare it with finite element results. Twelve trusses were examined under the same gravity load and boundary conditions to study the effect of span, the truss web pattern, and the cross section type of truss members on the ultimate strength of the truss.Results revealed that for longer spans, Fink truss configuration is better than Howe truss. The member with the maximum D/C ratio will be the first member to fail in FEA, so engineer can use D/C components' ratio instead of FEA to predict the first member to fail, the cause of failure, and truss capacity. The results of D/C ratio values showed that each truss was designed with high efficient critical components and highly variable D/C ratios, which increase the probability of producing an alternative load path to the loads that are carried by the failed truss members. The reliability of truss system is much greater than the reliability of any component as the truss system's D/C ratio calculated from FEA is always less than the maximum component's D/C ratio from the design.

Research on the Multidimensional Constraint Stability of Bridge Structure Modeling Based on Optimization Model

In this paper, we conduct research on the multidimensional constraint stability of bridge structure modeling based on the optimization model. The current internal and the external research results to the truss web structure, the high internode the aspect ratio and the stiffness of the middle truss brace of the truss web, deflection of composite beams of the impact of stress is a very important problem in the design of the bridge. Structural health monitoring is the use of the field of the non-destructive sensing technology, including the structural response, including structural system characteristics analysis, to achieve the purpose of monitoring structural damage or degradation. Under this basis, this paper proposes the new idea on the modelling and simulates the performance.

Seismic performance of reinforced concrete squat walls with embedded cold-formed and thin walled steel truss

To investigate the seismic performance of squat reinforced concrete (RC) walls with embedded cold-formed and thin walled (CFTW) steel truss, experimental and analytical studies were conducted. Four one-third scaled composite wall specimens were tested to failure subjected to cyclic load reversals under constant axial load. The experimental behaviors of test specimens including damage development process, load-deformation responses, stiffness degradation, energy dissipation capacity, failure pattern and ductility were discussed. Test results indicate that the embedded CFTW steel truss web braces can effectively avoid web concrete crushing and improve the energy dissipation capacity of shear walls with low aspect ratios, resulting in a more ductile failure pattern due to the failure of boundary elements. Nonlinear finite element analysis (FEA) on test specimens was carried out based on suggested modeling techniques and the accuracy of the numerical method was verified. Influences of critical parameters such as axial load ratio, amounts of embedded CFTW steel truss chord and web braces on the performance of the composite shear walls were further examined through comprehensive parametric analysis. It shows that the axial load ratio has a significant impact on the post-yielding behavior of composite shear walls. Good displacement ductility can be achieved under medium level of axial load ratio. Increasing the amount of embedded truss chord cannot significantly improve the performance of composite walls. The embedded truss web braces are noticeably beneficial to the energy dissipation capacity and ductility behavior of squat composite walls.

Seismic performance of steel and concrete composite shear walls with embedded steel truss for use in high-rise buildings

This paper studies the seismic behavior of steel and concrete composite shear walls with embedded steel truss, a crucial structural element for use in high-rise buildings. Three one-fourth scaled composite wall specimens with an aspect ratio of 1.0 were tested until to failure under reversed cyclic lateral load and constant axial load. The test parameters were the amounts of embedded truss chord and web brace. The behavior of the test specimens, including the damage formation, failure mode, hysteretic curve, stiffness and strength degradation, energy dissipation and ductility, were examined. Test results indicated that the embedded truss web braces affect significantly the hysteretic behavior of the composite walls in terms of lateral load capacity, energy dissipation and ductility, while the embedded truss chords can enhance the lateral load capacity. To further broaden the test results obtained, while searching for the optimal design, finite element (FE) models were validated against all the test results. Then 27 FE models that cover the practical ranges of axial load ratio, amount of embedded steel truss chord and web braces were adopted in a parametric analysis to investigate their effects on the wall performance. The results indicate that high axial load ratio is beneficial to initial stiffness and lateral load capacity, while adverse to energy dissipation capacity. Although increasing the volumetric ratio of embedded truss web brace can most effectively increase the lateral load capacity, a medium level about 1.59% is its optimum value for ensuring the critical seismic performance in terms of energy dissipation and ductility. In order to avoid the adverse effect on ductility behavior, the axial load ratio should be limited to the medium level, about 0.13 for the nominal value or about 0.30 for the design value.

Seismic behavior of high strength concrete composite walls with embedded steel truss

Experimental investigation was conducted on three 1:3 scaled high strength concrete composite wall (HSCCW) specimens with embedded steel truss with a medium aspect ratio (1.0–3.0) under cyclic load reversals and constant axial load, to examine the influences of steel usages of embedded truss chord and web brace on the overall seismic behavior of the specimens. The hysteretic characteristics, cracking pattern, failure modes and energy dissipation capacities of the specimens were discussed. Then parametric analysis was carried out on 27 numerical models based on verified finite element modeling techniques to thoroughly evaluate the influences of axial load ratio, steel ratio of embedded truss chord and volumetric ratio of embedded truss web brace on the overall seismic performance of HSCCW with embedded steel truss. Research results indicate that increasing the steel ratio of embedded truss chord can effectively improve the initial stiffness and lateral load carrying capacity. Although the volumetric ratio of embedded truss web brace has little influence on lateral strength, it is beneficial to the energy dissipation capacity of composite walls. Within the maximum allowable limit, higher axial load ratio can result in increased lateral load capacity and stiffness.

Seismic Fragility Assessment of Special Truss Moment Frames (STMF) Using the Capacity Spectrum Method

Fragility curves represent the probabilities that structural damages, under various levels of seismic excitation, will exceed the specified damage states by means of earthquake intensity damage relations. Conceptual aspects related to seismic vulnerability, damage and risk evaluation are discussed first, together with a short review of the most widely used possibilities for the seismic evaluation of structures. The capacity spectrum method starting from capacity and fragility curves is then discussed. The determination of capacity curves for buildings using a non-linear structural analysis tools is then explained, together with a simplified expeditious procedure allowing the development of fragility curves. Next, the seismic risk of the special truss moment frame (STMF) systems of Tehran, the capital of Iran, is analysed in this paper using the capacity spectrum method. The seismic hazard of the studied area is described by using the reduced 5%-damped elastic response spectra. Significant damage is obtained for mid-rise and high-rise special truss moment frames with a Vierendeel middle panel, because of the buckling and early fracture of truss web members. Special truss moment frames with an X-diagonal middle segment also show a low seismic capacity leading to significant expected damage.

Finite Element Analysis of Shear Lag Effect on Composite Girder with Steel Truss Webs

AbstractTo study the effect of shear lag on a composite girder with steel truss webs, a three-dimensional finite element (FE) model, using the ANSYS FE software, and a corresponding FE model of com...

Studies of In-Plane Ultimate Loads of the Steel Truss Web–RC Composite Arch

AbstractThis paper describes an experiment on the in-plane mechanical behaviors of the steel truss web–RC composite arch subjected to the unsymmetrical concentrated loads applied simultaneously at the 2/3 and 5/6 span points of the arch. The experimental results show that loads were transmitted as shear forces through the steel truss webs. The maximum measured strain in two steel tubes near the cross section at the 5/6 span point was less than the yield strain, and punching shear failure was observed at the loading sections. Using the experimental model, the authors developed and performed a finite-element simulation. They found that double N-shaped webs might be the most conducive to the stiffness and bearing capacity of the composite arches and require comparatively less steel. The critical wall thickness of the web tubes at which punching shear failure occurred was 3.5 mm for this arch model. Given the same wall thickness, the ultimate bearing capacity of the composite arch decreased as the incline ang...

波形鋼板ウェブ橋と複合トラス橋

波形鋼板ウェブ橋と複合トラス橋

Topology Optimization of Cable Truss Web for Prestressed Suspension Bridge

Topology Optimization of Cable Truss Web for Prestressed Suspension Bridge

Fatigue capacity of a new connection system for a prestressed concrete hybrid truss web girder

To replace a steel box bridge with construction of medium-span bridges in Korea, prestressed concrete box girder bridges with steel truss web members, also known as hybrid truss bridges (HTBs), are being considered as an alternative bridge type. The core technology of HTB is the connection joint that links the concrete slabs and steel truss pipes. Various construction companies in Japan have developed unique connection systems and applied them to real bridge constructions after verifying their performance through experimental evaluation. In this study, static fatigue tests of a hybrid truss girder have been performed to verify static and fatigue capacities of the newly proposed hinge-type connection system with circular ribs. Based on structural finite-element analysis simulations of the joint's fatigue test result, the simulation results proved that the proposed connection joint has sufficient fatigue capacity for structural application. Finally, it is expected that the hinge connection system with circular ribs developed in this study can be easily applied to real HTB bridge construction.