Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.38.6.671
H. Beiraghi, M. Hedayati
Seismic responses of RC core wall with two outriggers are investigated in this study. In the models analyzed here, one of the outriggers is fixed at the top of the building and the second is placed at different levels along the height of the system. Each of the systems resulting from the placement of the outrigger at different locations is designed according to the prescriptive codes. The location of the outrigger changes along the height. Linear design of all the structures is accomplished by using prescriptive codes. Buckling restrained braces (BRBs) are used in the outriggers and forward directivity near fault and far fault earthquake record sets are used at maximum considered earthquake (MCE) level. Results from nonlinear time history analysis demonstrate that BRB outriggers can change the seismic responses like force distribution and deformation demand of the RC core-walls over the height and lead to the new plastic hinge arrangement over the core-wall height. Plasticity extension in the RC core wall occurs at the base as well as adjacent to the outrigger levels. Considering the maximum inter-story drift ratio (IDR) demand as an engineering parameter, the best location for the second outrigger is at 0.75H, in which the maximum IDR at the region upper the second outrigger level is approximately equal to the corresponding value in the lower region.
{"title":"Optimum location of second outrigger in RC core walls subjected toNF earthquakes","authors":"H. Beiraghi, M. Hedayati","doi":"10.12989/SCS.2021.38.6.671","DOIUrl":"https://doi.org/10.12989/SCS.2021.38.6.671","url":null,"abstract":"Seismic responses of RC core wall with two outriggers are investigated in this study. In the models analyzed here, one of the outriggers is fixed at the top of the building and the second is placed at different levels along the height of the system. Each of the systems resulting from the placement of the outrigger at different locations is designed according to the prescriptive codes. The location of the outrigger changes along the height. Linear design of all the structures is accomplished by using prescriptive codes. Buckling restrained braces (BRBs) are used in the outriggers and forward directivity near fault and far fault earthquake record sets are used at maximum considered earthquake (MCE) level. Results from nonlinear time history analysis demonstrate that BRB outriggers can change the seismic responses like force distribution and deformation demand of the RC core-walls over the height and lead to the new plastic hinge arrangement over the core-wall height. Plasticity extension in the RC core wall occurs at the base as well as adjacent to the outrigger levels. Considering the maximum inter-story drift ratio (IDR) demand as an engineering parameter, the best location for the second outrigger is at 0.75H, in which the maximum IDR at the region upper the second outrigger level is approximately equal to the corresponding value in the lower region.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"38 1","pages":"671"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66590611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.39.3.261
Hongye Gou, Chang Liu, Ruihong Xie, Y. Bao, Lixiang Zhao, Q. Pu
In a railway bridge, the CRTS II slab ballastless track is subjected to interlayer connection failures, such as void under slab, mortar debonding, and fastener fracture. This study investigates the influences of interlayer connection failure on the safe operation of high-speed trains. First, a train-track-bridge coupled vibration model and a bridge-track deformation model are established to study the running safety of a train passing a deformed bridge with interlayer connection failure. For each type of the interlayer connection failure, the effects of the failure locations and ranges on the track irregularity are studied using the deformation model. Under additional bridge deformation, the effects of interlayer connection failure on the dynamic responses of the train are investigated by using the track irregularity as the excitation to the vibration model. Finally, parametric studies are conducted to determine the thresholds of additional bridge deformations considering interlayer connection failure. Results show that the interlayer connection failure significantly affects the running safety of high-speed train and must be considered in determining the safety thresholds of additional bridge deformation in the asset management of high-speed railway bridges.
{"title":"Running safety of high-speed train on deformed railway bridges with interlayer connection failure","authors":"Hongye Gou, Chang Liu, Ruihong Xie, Y. Bao, Lixiang Zhao, Q. Pu","doi":"10.12989/SCS.2021.39.3.261","DOIUrl":"https://doi.org/10.12989/SCS.2021.39.3.261","url":null,"abstract":"In a railway bridge, the CRTS II slab ballastless track is subjected to interlayer connection failures, such as void under slab, mortar debonding, and fastener fracture. This study investigates the influences of interlayer connection failure on the safe operation of high-speed trains. First, a train-track-bridge coupled vibration model and a bridge-track deformation model are established to study the running safety of a train passing a deformed bridge with interlayer connection failure. For each type of the interlayer connection failure, the effects of the failure locations and ranges on the track irregularity are studied using the deformation model. Under additional bridge deformation, the effects of interlayer connection failure on the dynamic responses of the train are investigated by using the track irregularity as the excitation to the vibration model. Finally, parametric studies are conducted to determine the thresholds of additional bridge deformations considering interlayer connection failure. Results show that the interlayer connection failure significantly affects the running safety of high-speed train and must be considered in determining the safety thresholds of additional bridge deformation in the asset management of high-speed railway bridges.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"39 1","pages":"261"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66591788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.39.2.201
Lei Guo, Jingfeng Wang, Tony Y. Yang, Wanqian Wang, Binggen Zhan
Currently, there is a lack of research in the design approach to avoid column wall failure in the concrete filled double skin steel tubular (CFDST) column-beam connections. In this paper, a finite element model has been developed and verified by available experimental data to analyze the failure mechanism of CFDST column-beam connections. Various finite element models with different column hollow ratios () were established. The simulation result revealed that with increasing the failure mode gradually changed from yielding of end plate, to local failure of the column wall. Detailed parametric analyses were performed to study the failure mechanism of column wall for the CFDST column-beam connection, in which the strength of sandwiched concrete and steel tube and thickness of steel tube were incorporated. An analytical model was proposed to predict the moment resistance of the assembled connection considering the failure of column wall. The simulation results indicate that the proposed analytical model can provided a conservative prediction of the moment resistance. Finally, an upper bound value of was recommend to avoid column wall failure for CFDST column-beam connections.
{"title":"Study and design of assembled CFDST column-beam connections considering column wall failure","authors":"Lei Guo, Jingfeng Wang, Tony Y. Yang, Wanqian Wang, Binggen Zhan","doi":"10.12989/SCS.2021.39.2.201","DOIUrl":"https://doi.org/10.12989/SCS.2021.39.2.201","url":null,"abstract":"Currently, there is a lack of research in the design approach to avoid column wall failure in the concrete filled double skin steel tubular (CFDST) column-beam connections. In this paper, a finite element model has been developed and verified by available experimental data to analyze the failure mechanism of CFDST column-beam connections. Various finite element models with different column hollow ratios () were established. The simulation result revealed that with increasing the failure mode gradually changed from yielding of end plate, to local failure of the column wall. Detailed parametric analyses were performed to study the failure mechanism of column wall for the CFDST column-beam connection, in which the strength of sandwiched concrete and steel tube and thickness of steel tube were incorporated. An analytical model was proposed to predict the moment resistance of the assembled connection considering the failure of column wall. The simulation results indicate that the proposed analytical model can provided a conservative prediction of the moment resistance. Finally, an upper bound value of was recommend to avoid column wall failure for CFDST column-beam connections.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"39 1","pages":"201"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66591875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.39.6.723
Yong Yang, Sun Dongde, Yicong Xue, Yunlong Yu, K. An, Chen Yang
This paper proposed an innovative RC column with encased prefabricated high-strength concrete filled steel tube core, and four RC columns with encased prefabricated high-strength CFST core and a RC control-column were tested under lateral low cyclic loading. All specimens were evaluated by the cracks developments, failure patterns, hysteretic behavior, skeleton curves, strength and stiffness degradation, ductility and energy dissipation capacity. The effects of stirrup ratio and welding studs of prefabricated CFST core were investigated in details. The experiment results indicated that compared with the RC control-column, the performances of RC columns with encased prefabricated high-strength CFST core, including the hysteretic behavior, strength degradation, ductility and energy dissipation, were significantly improved. Higher stirrup ratio of the RC column with encased prefabricated high-strength CFST core leaded to higher ductility and more satisfactory energy dissipation capacity, stiffness degradation. Studs could effectively combine prefabricated high-strength CFST core and surrounding concrete, which significantly increase the integrity of RC column with encased prefabricated high-strength CFST core. Based on the test results, a numerical model was established to further analyze the cyclic behavior of the test specimens, and the numerical results agreed well with the test results, which showed the feasibility for the further parametric study. Finally, on the basis of the plastic stress theory, a calculation model for seismic bending moment capacity of RC column with encased prefabricated high-strength CFST core was established, and the results obtained form the formulas showed good agreement with the experiments.
{"title":"Seismic performance of RC columns with encased prefabricated high-strength CFST core","authors":"Yong Yang, Sun Dongde, Yicong Xue, Yunlong Yu, K. An, Chen Yang","doi":"10.12989/SCS.2021.39.6.723","DOIUrl":"https://doi.org/10.12989/SCS.2021.39.6.723","url":null,"abstract":"This paper proposed an innovative RC column with encased prefabricated high-strength concrete filled steel tube core, and four RC columns with encased prefabricated high-strength CFST core and a RC control-column were tested under lateral low cyclic loading. All specimens were evaluated by the cracks developments, failure patterns, hysteretic behavior, skeleton curves, strength and stiffness degradation, ductility and energy dissipation capacity. The effects of stirrup ratio and welding studs of prefabricated CFST core were investigated in details. The experiment results indicated that compared with the RC control-column, the performances of RC columns with encased prefabricated high-strength CFST core, including the hysteretic behavior, strength degradation, ductility and energy dissipation, were significantly improved. Higher stirrup ratio of the RC column with encased prefabricated high-strength CFST core leaded to higher ductility and more satisfactory energy dissipation capacity, stiffness degradation. Studs could effectively combine prefabricated high-strength CFST core and surrounding concrete, which significantly increase the integrity of RC column with encased prefabricated high-strength CFST core. Based on the test results, a numerical model was established to further analyze the cyclic behavior of the test specimens, and the numerical results agreed well with the test results, which showed the feasibility for the further parametric study. Finally, on the basis of the plastic stress theory, a calculation model for seismic bending moment capacity of RC column with encased prefabricated high-strength CFST core was established, and the results obtained form the formulas showed good agreement with the experiments.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"39 1","pages":"723-736"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66593192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.40.1.087
Zhong Zhang, D. Zhou, Jiandong Zhang, H. Fang, Huixuan Han
In this study, an analytical model is developed for the analysis of transient temperature, displacements, and stresses in simply supported layered beams. The beam is suddenly heated from the top and bottom surfaces by external steady heat sources and is subjected to a mechanical load. The temperature in each layer is variable along the thickness and follows the one-dimensional (1-D) transient heat transfer equation. The Laplace transform approach is used to obtain the transient temperature field in the beam. The thermoelastic constants of the beam are temperature-dependent. Dividing every layer into a series of thin slices, the temperature and the thermoelastic constants for each slice can be considered uniform. The two-dimensional (2-D) thermoelasticity theory is adopted to derive the governing equations of displacements and stresses in each slice. The transfer matrix method is applied to obtain the displacement and stress solutions for the beam. As an example, the distributions of transient temperature, displacements, and stresses in a three-layer beam are studied. The effects of the temperature dependent thermoelastic constants on the mechanical behavior of the beam are discussed in detail.
{"title":"Transient analysis of layered beams subjected to steady heat supply and mechanical load","authors":"Zhong Zhang, D. Zhou, Jiandong Zhang, H. Fang, Huixuan Han","doi":"10.12989/SCS.2021.40.1.087","DOIUrl":"https://doi.org/10.12989/SCS.2021.40.1.087","url":null,"abstract":"In this study, an analytical model is developed for the analysis of transient temperature, displacements, and stresses in simply supported layered beams. The beam is suddenly heated from the top and bottom surfaces by external steady heat sources and is subjected to a mechanical load. The temperature in each layer is variable along the thickness and follows the one-dimensional (1-D) transient heat transfer equation. The Laplace transform approach is used to obtain the transient temperature field in the beam. The thermoelastic constants of the beam are temperature-dependent. Dividing every layer into a series of thin slices, the temperature and the thermoelastic constants for each slice can be considered uniform. The two-dimensional (2-D) thermoelasticity theory is adopted to derive the governing equations of displacements and stresses in each slice. The transfer matrix method is applied to obtain the displacement and stress solutions for the beam. As an example, the distributions of transient temperature, displacements, and stresses in a three-layer beam are studied. The effects of the temperature dependent thermoelastic constants on the mechanical behavior of the beam are discussed in detail.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"72 1","pages":"87"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66594276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.40.1.045
Habib Ghasemi Jouneghani, A. Haghollahi, Mohammad Talebi Kalaleh, S. Beheshti-Aval
Recently, the elliptic-braced moment resisting frame (ELBRF) which is a new lateral bracing system installed in the middle bay of the frame in the facade of buildings is introduced. This system not only prevents a solution for opening space problem in view of architectural aspects, but also improves the structural behavior. The main drawback of its using in view of numerical modeling in multistory buildings is lack of curved frame element in design and analysis software. To overcome this shortcoming, in this paper, for the first time, an equivalent element for elliptic brace is presented for ELBRF through a laboratory program and nonlinear finite element analysis, which will contribute to its accurate and easy modelling and design. To evaluate the hysteresis behavior of the equivalent element, an experimental test on a 1/2 scale was conducted for a single-story single-bay ELBRF specimen under cyclic quasi-static loading and the results were compared with those for the equivalent element in a story base model. Good agreement was observed between the experimental and analytical outcomes. The seismic demand analyses of ELBRF and frame with equivalent bracing system in 3, 5, 7, and 10 stories were carry out through different loading patterns in Nonlinear Static Pushover Analysis (NSPA) and Nonlinear Time History Analysis (NTHA) with 20 earthquake records using OpenSees software. Story drift, displacement, and story shear were evaluated. Relatively accurate estimations were achieved by NSPA in comparison with NTHA. Also, the seismic performance of the equivalent element for the ELBRF system against earthquake was examined and then response modification factor (R factor) was acquired. The values of 8.5 and 12.2 for the R factor were calculated at the ultimate and the allowable stress limit states, respectively.
{"title":"Nonlinear seismic behavior of elliptic-braced moment resisting frame using equivalent braced frame","authors":"Habib Ghasemi Jouneghani, A. Haghollahi, Mohammad Talebi Kalaleh, S. Beheshti-Aval","doi":"10.12989/SCS.2021.40.1.045","DOIUrl":"https://doi.org/10.12989/SCS.2021.40.1.045","url":null,"abstract":"Recently, the elliptic-braced moment resisting frame (ELBRF) which is a new lateral bracing system installed in the middle bay of the frame in the facade of buildings is introduced. This system not only prevents a solution for opening space problem in view of architectural aspects, but also improves the structural behavior. The main drawback of its using in view of numerical modeling in multistory buildings is lack of curved frame element in design and analysis software. To overcome this shortcoming, in this paper, for the first time, an equivalent element for elliptic brace is presented for ELBRF through a laboratory program and nonlinear finite element analysis, which will contribute to its accurate and easy modelling and design. To evaluate the hysteresis behavior of the equivalent element, an experimental test on a 1/2 scale was conducted for a single-story single-bay ELBRF specimen under cyclic quasi-static loading and the results were compared with those for the equivalent element in a story base model. Good agreement was observed between the experimental and analytical outcomes. The seismic demand analyses of ELBRF and frame with equivalent bracing system in 3, 5, 7, and 10 stories were carry out through different loading patterns in Nonlinear Static Pushover Analysis (NSPA) and Nonlinear Time History Analysis (NTHA) with 20 earthquake records using OpenSees software. Story drift, displacement, and story shear were evaluated. Relatively accurate estimations were achieved by NSPA in comparison with NTHA. Also, the seismic performance of the equivalent element for the ELBRF system against earthquake was examined and then response modification factor (R factor) was acquired. The values of 8.5 and 12.2 for the R factor were calculated at the ultimate and the allowable stress limit states, respectively.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"40 1","pages":"45"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66594495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.40.6.805
Barbaros Atmaca
The pleasing appearances, economic and easy construction of cable-stayed footbridges (CSFB) have made them one of the most preferred options for pedestrian traffic crossing over the highways. The basic structural members of CSFB can be sortable as a foundation, pylon, deck, and stay-cables. The stay-cable has an important role in the formation of structural integrity by ensuring that the deck and pylon work together with the help of proper post-tensioning forces (PTF) applied to them. In this study, it is aim to determine proper set of PTF with the help of the developed optimization process which provides to work together metaheuristic algorithm named Teaching-Learning-Based Optimization (TLBO) and Open Applicable Programming Interface (OAPI) properties of SAP2000 with codes created in MATLAB. In addition of this aim, the study also presents the importance of PTF for structural behavior of CSFB. TLBO algorithms use a randomly created initial population. The teacher phase and student phase are the main part of this algorithm. Five different proper sets of PTF are determined by using developed optimization process and the structural response such as displacement and internal forces of structural members of the selected CSFB compared with each other. Consequently, PTF directly affects the behavior of CSFB, as it ensures that displacements of deck and pylon remain between the acceptable limits, controls the distribution and magnitude of the internal forces for different load combinations. Furthermore, the evaluation of PTF might not have a single solution because CSFB are highly statically indeterminate so there are more different possible sets of PTFs that satisfy strength and serviceability requirements.
{"title":"Determination of proper post-tensioning cable force of cable-stayed footbridge with TLBO algorithm","authors":"Barbaros Atmaca","doi":"10.12989/SCS.2021.40.6.805","DOIUrl":"https://doi.org/10.12989/SCS.2021.40.6.805","url":null,"abstract":"The pleasing appearances, economic and easy construction of cable-stayed footbridges (CSFB) have made them one of the most preferred options for pedestrian traffic crossing over the highways. The basic structural members of CSFB can be sortable as a foundation, pylon, deck, and stay-cables. The stay-cable has an important role in the formation of structural integrity by ensuring that the deck and pylon work together with the help of proper post-tensioning forces (PTF) applied to them. In this study, it is aim to determine proper set of PTF with the help of the developed optimization process which provides to work together metaheuristic algorithm named Teaching-Learning-Based Optimization (TLBO) and Open Applicable Programming Interface (OAPI) properties of SAP2000 with codes created in MATLAB. In addition of this aim, the study also presents the importance of PTF for structural behavior of CSFB. TLBO algorithms use a randomly created initial population. The teacher phase and student phase are the main part of this algorithm. Five different proper sets of PTF are determined by using developed optimization process and the structural response such as displacement and internal forces of structural members of the selected CSFB compared with each other. Consequently, PTF directly affects the behavior of CSFB, as it ensures that displacements of deck and pylon remain between the acceptable limits, controls the distribution and magnitude of the internal forces for different load combinations. Furthermore, the evaluation of PTF might not have a single solution because CSFB are highly statically indeterminate so there are more different possible sets of PTFs that satisfy strength and serviceability requirements.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"40 1","pages":"805"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66596574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.41.1.137
Yunsheng Li, Q. Dai, Chaoxing Liu, Yanling Zhang
The curved composite box-girders (CBGs) with corrugated steel webs (CSWs) have been used widely in bridges due to their great advantages and the demand of the road alignment, but the curvature makes both the static and dynamic behaviors more complex. To research the free vibration performance of the curved CBGs with CSWs, 5 simply-supported test girders were designed with the span-to-radius ratio (n=L/R), the number of the cells of the box section, and the number of the diaphragms as parameters. The natural frequencies and mode shapes were measured in the experiment. The experimental results were compared with the numerical results using ANSYS software, and a satisfying agreement was obtained. The parametric analysis shows that for the curved CBG with CSWs, the vertical mode shapes are combined flexural and torsion, and the contribution of the torsional effects to the mode shapes and frequencies improve with the increase of n, which leads to a decrease in the vertical and lateral frequencies and increase in the torsional frequency. The corrugated angle of the steel web has little effect on the natural frequencies of the curved CBGs with CSWs. Increasing the thickness of the steel web and the number of the diaphragms can improve the torsional rigidity of the curved CBG with CSWs effectively; while the deck width has a great contribution on the lateral rigidity.
{"title":"Experimental research on free vibration of curved composite box-girders with corrugated steel webs","authors":"Yunsheng Li, Q. Dai, Chaoxing Liu, Yanling Zhang","doi":"10.12989/SCS.2021.41.1.137","DOIUrl":"https://doi.org/10.12989/SCS.2021.41.1.137","url":null,"abstract":"The curved composite box-girders (CBGs) with corrugated steel webs (CSWs) have been used widely in bridges due to their great advantages and the demand of the road alignment, but the curvature makes both the static and dynamic behaviors more complex. To research the free vibration performance of the curved CBGs with CSWs, 5 simply-supported test girders were designed with the span-to-radius ratio (n=L/R), the number of the cells of the box section, and the number of the diaphragms as parameters. The natural frequencies and mode shapes were measured in the experiment. The experimental results were compared with the numerical results using ANSYS software, and a satisfying agreement was obtained. The parametric analysis shows that for the curved CBG with CSWs, the vertical mode shapes are combined flexural and torsion, and the contribution of the torsional effects to the mode shapes and frequencies improve with the increase of n, which leads to a decrease in the vertical and lateral frequencies and increase in the torsional frequency. The corrugated angle of the steel web has little effect on the natural frequencies of the curved CBGs with CSWs. Increasing the thickness of the steel web and the number of the diaphragms can improve the torsional rigidity of the curved CBG with CSWs effectively; while the deck width has a great contribution on the lateral rigidity.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"41 1","pages":"137"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66597339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.41.1.001
X. Li, Wang Lianguang, B. Chen, Zhang Yaosheng
This paper proposes a NSTS (new steel tube slab) structure by connecting the longitudinal steel tubes with small steel tubes in transverse, in order to decrease the construction difficulty and improve the bearing capacity of existing NTR (new tubular roof) or STS (steel tube slab) structures. Experimental study on the bending performance and influences of following parameters are carried out: the connection type of the steel tube, the diameter and eccentricity of the small steel tube, and the thickness of the bottom steel plate. The results show that the NSTS members present progressive ductile flexural failure under concentrated load. The connection type has important effect on the mechanical behavior, and the bolts fixed T-shaped plate (B+T) connection method, which provides much higher bending stiffness, is proved to be the most reliable connection type. The increase of small steel tube diameter enhances the bending performance as expected, which also confirms the effectiveness of the B+T connection, while the tube eccentricity presents little impact on the bearing capacity. The bottom steel plate significantly improves the bearing capacity and stiffness and reduces the mid-span deflection. Furthermore, the bending capacity calculation method is proposed and the calculated values show good agreement with the test results. Also, the effect rules of the diameter-thickness ratio of the small tube, the length-diameter ratio of the member and the thickness variety of the bottom steel plate on the bending capacity of NSTS members are further investigated based on the proposed theoretical method.
{"title":"Bending performance of NSTS members based on steel tube connection","authors":"X. Li, Wang Lianguang, B. Chen, Zhang Yaosheng","doi":"10.12989/SCS.2021.41.1.001","DOIUrl":"https://doi.org/10.12989/SCS.2021.41.1.001","url":null,"abstract":"This paper proposes a NSTS (new steel tube slab) structure by connecting the longitudinal steel tubes with small steel tubes in transverse, in order to decrease the construction difficulty and improve the bearing capacity of existing NTR (new tubular roof) or STS (steel tube slab) structures. Experimental study on the bending performance and influences of following parameters are carried out: the connection type of the steel tube, the diameter and eccentricity of the small steel tube, and the thickness of the bottom steel plate. The results show that the NSTS members present progressive ductile flexural failure under concentrated load. The connection type has important effect on the mechanical behavior, and the bolts fixed T-shaped plate (B+T) connection method, which provides much higher bending stiffness, is proved to be the most reliable connection type. The increase of small steel tube diameter enhances the bending performance as expected, which also confirms the effectiveness of the B+T connection, while the tube eccentricity presents little impact on the bearing capacity. The bottom steel plate significantly improves the bearing capacity and stiffness and reduces the mid-span deflection. Furthermore, the bending capacity calculation method is proposed and the calculated values show good agreement with the test results. Also, the effect rules of the diameter-thickness ratio of the small tube, the length-diameter ratio of the member and the thickness variety of the bottom steel plate on the bending capacity of NSTS members are further investigated based on the proposed theoretical method.","PeriodicalId":51177,"journal":{"name":"Steel and Composite Structures","volume":"41 1","pages":"1"},"PeriodicalIF":4.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66597350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.12989/SCS.2021.41.2.279
Alireza Shamaei-Kashani, M. Shokrieh
In the present research, a novel analytical approach was developed to predict the bearing chord stiffness and the damage initiation bearing-load of single-lap composite bolted joints under medium strain rate loading. First, the elastic moduli, Poisson's ratio, and strength of a unidirectional composite ply at an arbitrary strain rate were predicted by available micromechanical equations. Then, the bearing chord stiffness of the joint at any arbitrary strain rate was predicted. For this purpose, the available spring-based model was modified. The strain-rate-dependent damage initiation bearing-load of the joint was predicted by using the moduli and the stress concentration factor of a pin-loaded unidirectional ply. Four types of single-lap joints with [-45/0/+45/90]s and [90/-452/+45]s layups with and without carbon nanofibers were tested at the strain rates of 0.0048 s-1, 0.36 s-1, and 0.89 s-1. The results of experiments showed that mechanical properties of single-lap composite bolted joints increased with increasing the strain rate. Also, employing carbon nanofibers has a significant effect on the mechanical properties of the joints. The predicted results in comparison with the conducted experimental data show good agreements.
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