Pub Date : 2024-09-13DOI: 10.1016/j.istruc.2024.107281
Bond-slip behavior is a common failure mode in steel structures reinforced with fiber fabric. Premature debonding of the fiber fabric significantly impacts the effectiveness of steel structure reinforcement. In this study, a gripping anchor is proposed to enhance the reliability of the interface between fiber fabric and steel plates. Experimental investigations were conducted to analyze the influence of anchor bolt preload on the double shear joint between fiber fabric and steel plates. 41 specimens were prepared and tested to explore the effects of parameters such as bolt preload, anchor position, number and type of fiber fabric layers, and bond length on load-bearing capacity. Comparative analyses were conducted on failure modes, ultimate loads, and stress-strain distributions of the specimens. Experimental results indicate that the position of the anchor has a minimal impact on the ultimate bearing capacity of the specimen. However, anchors positioned closer to the joint end exhibit lower ductility upon failure. A novel predictive model was developed to characterize the bond-slip behavior of preload applied to carbon fiber fabric and steel plates. The theoretical model of the ultimate bearing capacity in the yield stage fits well with the experimental results of specimens with three layers of carbon fiber fabric, with a difference range of 0.34 % to 14.97 % compared to actual results. This indicates that the model has high accuracy in predicting stress-strain and bearing capacity.
{"title":"Influence of bolt preload of anchors on bond-slip behavior of fiber fabric-steel interface","authors":"","doi":"10.1016/j.istruc.2024.107281","DOIUrl":"10.1016/j.istruc.2024.107281","url":null,"abstract":"<div><p>Bond-slip behavior is a common failure mode in steel structures reinforced with fiber fabric. Premature debonding of the fiber fabric significantly impacts the effectiveness of steel structure reinforcement. In this study, a gripping anchor is proposed to enhance the reliability of the interface between fiber fabric and steel plates. Experimental investigations were conducted to analyze the influence of anchor bolt preload on the double shear joint between fiber fabric and steel plates. 41 specimens were prepared and tested to explore the effects of parameters such as bolt preload, anchor position, number and type of fiber fabric layers, and bond length on load-bearing capacity. Comparative analyses were conducted on failure modes, ultimate loads, and stress-strain distributions of the specimens. Experimental results indicate that the position of the anchor has a minimal impact on the ultimate bearing capacity of the specimen. However, anchors positioned closer to the joint end exhibit lower ductility upon failure. A novel predictive model was developed to characterize the bond-slip behavior of preload applied to carbon fiber fabric and steel plates. The theoretical model of the ultimate bearing capacity in the yield stage fits well with the experimental results of specimens with three layers of carbon fiber fabric, with a difference range of 0.34 % to 14.97 % compared to actual results. This indicates that the model has high accuracy in predicting stress-strain and bearing capacity.</p></div>","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142173052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-13DOI: 10.1016/j.istruc.2024.107258
The post-tensioned friction dissipating (PTFD) connection for steel frames has drawn significant attention from researchers due to its excellent seismic performance. A simplified numerical algorithm suitable for modeling the SMA strands is proposed. The simplified numerical model of the SMA-PTFD is established. Parametric analysis is performed based on hysteresis analysis and transient dynamic analysis to reveal the influence of SMA strands on the seismic performance of SMA-PTFD frames. The changing rule of seismic response of SMA-PTFD frames, along with the fmax for SMA strands and the Fmax for the friction device, is systematically investigated. The value of the objective function can be reduced by about 50 % when the fmax is increased from 1 kN to 13 kN. The fundamental frequency is 1.25 Hz for three analyzed conditions. The value of the second frequency is significantly affected by Fmax. The values of the second frequency are 1.5 Hz, 1.58 Hz, and 1.42 Hz. The characteristics of seismic response, including displacement and cable force, are deeply studied. The seismic response is also investigated in the frequency domain. The results presented in this work reveal the collaborative energy dissipation mechanism of the friction device and SMA strands.
用于钢框架的后张法摩擦消能（PTFD）连接因其卓越的抗震性能而备受研究人员的关注。本文提出了一种适用于 SMA 钢绞线建模的简化数值算法。建立了 SMA-PTFD 的简化数值模型。通过基于滞后分析和瞬态动力分析的参数分析，揭示了 SMA 钢绞线对 SMA-PTFD 框架抗震性能的影响。系统地研究了 SMA-PTFD 框架地震响应的变化规律，以及 SMA 钢绞线的 fmax 和摩擦装置的 Fmax。当 fmax 从 1 kN 增加到 13 kN 时，目标函数值可降低约 50%。在三种分析条件下，基频为 1.25 赫兹。第二频率值受 Fmax 的影响很大。次频率值分别为 1.5 Hz、1.58 Hz 和 1.42 Hz。深入研究了地震响应的特征，包括位移和索力。还在频域中对地震响应进行了研究。研究结果揭示了摩擦装置和 SMA 钢绞线的协同消能机制。
{"title":"Seismic performance of friction damped posttensioned steel frame equipped with SMA strands","authors":"","doi":"10.1016/j.istruc.2024.107258","DOIUrl":"10.1016/j.istruc.2024.107258","url":null,"abstract":"<div><p>The post-tensioned friction dissipating (PTFD) connection for steel frames has drawn significant attention from researchers due to its excellent seismic performance. A simplified numerical algorithm suitable for modeling the SMA strands is proposed. The simplified numerical model of the SMA-PTFD is established. Parametric analysis is performed based on hysteresis analysis and transient dynamic analysis to reveal the influence of SMA strands on the seismic performance of SMA-PTFD frames. The changing rule of seismic response of SMA-PTFD frames, along with the <em>f</em><sub>max</sub> for SMA strands and the <em>F</em><sub>max</sub> for the friction device, is systematically investigated. The value of the objective function can be reduced by about 50 % when the <em>f</em><sub>max</sub> is increased from 1 kN to 13 kN. The fundamental frequency is 1.25 Hz for three analyzed conditions. The value of the second frequency is significantly affected by <em>F</em><sub>max</sub>. The values of the second frequency are 1.5 Hz, 1.58 Hz, and 1.42 Hz. The characteristics of seismic response, including displacement and cable force, are deeply studied. The seismic response is also investigated in the frequency domain. The results presented in this work reveal the collaborative energy dissipation mechanism of the friction device and SMA strands.</p></div>","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-13DOI: 10.1016/j.istruc.2024.107283
The loess region in China, known for its high seismic activity and the extreme vulnerability of loess to earthquakes, presents a considerable threat to the seismic safety of underground structures, including subway stations. With the Xi'an Aerospace City subway station as the background, a subway station model was designed, and shaking table tests were conducted under various conditions to analyze the seismic damage and dynamic responses in this study. The study reveals the seismic vulnerable areas and dynamic response patterns of the subway station under different spectral earthquake actions. Simultaneously, a three-dimensional numerical modeling analysis accounting for soil-structure interaction, was conducted to explore the displacement response of the structure and soil. Results indicate a noticeable amplification effect on the acceleration of both the structure and the soil under seismic motion. The structure exhibits a suppressive effect on the acceleration amplification of the surrounding soil, diminishing with increasing seismic motion intensity. Different depths show varying differences in acceleration responses between the structure and adjacent soil. Structural strain responses and damage phenomena suggest that the central column is the seismic vulnerable area of the subway station. Additionally, the strain distribution of the structure exhibits a distinct spatial effect. The relative horizontal displacement between the structure and the soil follows certain patterns in the depth direction, with the structure experiencing smaller relative horizontal displacement than the soil under seismic action due to the constraining effect of surrounding soil on its displacement response. The experimental conclusions provide valuable reference points for the seismic design and analysis of subway station structures in loess regions.
{"title":"Shaking-table tests and numerical simulations study of subway stations in loess region","authors":"","doi":"10.1016/j.istruc.2024.107283","DOIUrl":"10.1016/j.istruc.2024.107283","url":null,"abstract":"<div><p>The loess region in China, known for its high seismic activity and the extreme vulnerability of loess to earthquakes, presents a considerable threat to the seismic safety of underground structures, including subway stations. With the Xi'an Aerospace City subway station as the background, a subway station model was designed, and shaking table tests were conducted under various conditions to analyze the seismic damage and dynamic responses in this study. The study reveals the seismic vulnerable areas and dynamic response patterns of the subway station under different spectral earthquake actions. Simultaneously, a three-dimensional numerical modeling analysis accounting for soil-structure interaction, was conducted to explore the displacement response of the structure and soil. Results indicate a noticeable amplification effect on the acceleration of both the structure and the soil under seismic motion. The structure exhibits a suppressive effect on the acceleration amplification of the surrounding soil, diminishing with increasing seismic motion intensity. Different depths show varying differences in acceleration responses between the structure and adjacent soil. Structural strain responses and damage phenomena suggest that the central column is the seismic vulnerable area of the subway station. Additionally, the strain distribution of the structure exhibits a distinct spatial effect. The relative horizontal displacement between the structure and the soil follows certain patterns in the depth direction, with the structure experiencing smaller relative horizontal displacement than the soil under seismic action due to the constraining effect of surrounding soil on its displacement response. The experimental conclusions provide valuable reference points for the seismic design and analysis of subway station structures in loess regions.</p></div>","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142173051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-13DOI: 10.1016/j.istruc.2024.107260
Plastic hinge formation in beams is the main energy dissipation mechanism in moment resisting frames, but its deformation capacity is limited by the strength deterioration after reaching the maximum moment. Such degradation is highly influenced by the onset of local buckling in the plastic hinge region once a significant portion of the cross-section has reached the yield stress. Numerical models developed to study this effect have shown good accuracy against experimental data, but with high computational costs and the need to calibrate several model parameters. This work proposes a numerical model of a beam plastic hinge that uses only one parameter to reproduce the hysteretic behavior under cyclic loading, degrading simultaneously stiffness and resistance with lower computational cost. The proposed model relies on the discretization of the beam cross-section using uniaxial bars with a prescribed geometric imperfection with buckling degrading strength capability spanning along an assumed plastic hinge length. The Euler-Bernoulli hypothesis is imposed at the ends of the plastic hinge region and elastic beam elements are used to model the beam outside this domain. The model is validated against experimental data from three cyclic loading connection tests reported in the literature. Results show that the model can accurately represent the response of the beam plastic hinge with a low computational cost by adjusting one single model parameter as well as the definition of the nominal information of the beam geometry and material properties, expected plastic hinge length, and standard fabrication tolerances.
{"title":"Numerical modeling of beam plastic hinges in steel moment resisting frames including local buckling and stiffness/strength degradation","authors":"","doi":"10.1016/j.istruc.2024.107260","DOIUrl":"10.1016/j.istruc.2024.107260","url":null,"abstract":"<div><p>Plastic hinge formation in beams is the main energy dissipation mechanism in moment resisting frames, but its deformation capacity is limited by the strength deterioration after reaching the maximum moment. Such degradation is highly influenced by the onset of local buckling in the plastic hinge region once a significant portion of the cross-section has reached the yield stress. Numerical models developed to study this effect have shown good accuracy against experimental data, but with high computational costs and the need to calibrate several model parameters. This work proposes a numerical model of a beam plastic hinge that uses only one parameter to reproduce the hysteretic behavior under cyclic loading, degrading simultaneously stiffness and resistance with lower computational cost. The proposed model relies on the discretization of the beam cross-section using uniaxial bars with a prescribed geometric imperfection with buckling degrading strength capability spanning along an assumed plastic hinge length. The Euler-Bernoulli hypothesis is imposed at the ends of the plastic hinge region and elastic beam elements are used to model the beam outside this domain. The model is validated against experimental data from three cyclic loading connection tests reported in the literature. Results show that the model can accurately represent the response of the beam plastic hinge with a low computational cost by adjusting one single model parameter as well as the definition of the nominal information of the beam geometry and material properties, expected plastic hinge length, and standard fabrication tolerances.</p></div>","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-07DOI: 10.1016/j.istruc.2024.107225
Liu Shaohui, Jiang Lizhong, Zhou Wangbao, Yan Wangji, Yu Jian, Ren Zhenbin, Xiao Jun
The deterioration of track surface smoothness after seismic action of the track-bridge system is a key factor influencing the post-seismic operating safety of high-speed trains. This study proposes a linear mapping relationship between seismic-induced irregularities and the operation performance of high-speed trains to simplify the calculation of the seismic-induced dynamic irregularity building upon the residual geometric irregularity. It introduces the concept of an equivalent coefficient for seismic-induced dynamic irregularities. Within the study context, the validity of this equivalent coefficient in the post-seismic operation performance analysis of high-speed trains on bridges is confirmed, taking into account the randomness of ground motions. In addition, the impact of ground motion intensity and the structural natural vibration period on the equivalent coefficient for seismic-induced dynamic irregularities is examined. The study findings revealed that the magnitude of seismic-induced residual geometric irregularities in the track-bridge system far exceeds that of dynamic irregularities induced by earthquakes. Damage to the track-bridge system under seismic action primarily presents as residual deformations, with stiffness degradation playing a secondary role. There is a significant correlation between the root mean square velocity of seismic-induced irregularities and the post-seismic operation level in high-speed trains. This correlation is a quantitative basis for establishing the equivalent coefficient of seismic-induced dynamic irregularities. Under identical peak ground acceleration (PGA) conditions, the equivalent coefficient for dynamic irregularities in the track-bridge system during NF (near-fault) earthquakes is considerably lower than that during MFF (mid-far-field) earthquakes. This underscores the notable impact of the velocity pulse effect on the equivalent coefficient of seismic-induced dynamic irregularities. An increase in ground motion intensity and the structural natural period leads to a rise in the equivalent coefficient of dynamic irregularities. Finally, the stiffness degradation effect in critical components of the track-bridge system shows greater sensitivity to the ground motion intensity and the structural natural period.
{"title":"Study on the equivalent coefficients of seismic-induced track dynamic irregularities based on post-seismic running performance","authors":"Liu Shaohui, Jiang Lizhong, Zhou Wangbao, Yan Wangji, Yu Jian, Ren Zhenbin, Xiao Jun","doi":"10.1016/j.istruc.2024.107225","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107225","url":null,"abstract":"The deterioration of track surface smoothness after seismic action of the track-bridge system is a key factor influencing the post-seismic operating safety of high-speed trains. This study proposes a linear mapping relationship between seismic-induced irregularities and the operation performance of high-speed trains to simplify the calculation of the seismic-induced dynamic irregularity building upon the residual geometric irregularity. It introduces the concept of an equivalent coefficient for seismic-induced dynamic irregularities. Within the study context, the validity of this equivalent coefficient in the post-seismic operation performance analysis of high-speed trains on bridges is confirmed, taking into account the randomness of ground motions. In addition, the impact of ground motion intensity and the structural natural vibration period on the equivalent coefficient for seismic-induced dynamic irregularities is examined. The study findings revealed that the magnitude of seismic-induced residual geometric irregularities in the track-bridge system far exceeds that of dynamic irregularities induced by earthquakes. Damage to the track-bridge system under seismic action primarily presents as residual deformations, with stiffness degradation playing a secondary role. There is a significant correlation between the root mean square velocity of seismic-induced irregularities and the post-seismic operation level in high-speed trains. This correlation is a quantitative basis for establishing the equivalent coefficient of seismic-induced dynamic irregularities. Under identical peak ground acceleration (PGA) conditions, the equivalent coefficient for dynamic irregularities in the track-bridge system during NF (near-fault) earthquakes is considerably lower than that during MFF (mid-far-field) earthquakes. This underscores the notable impact of the velocity pulse effect on the equivalent coefficient of seismic-induced dynamic irregularities. An increase in ground motion intensity and the structural natural period leads to a rise in the equivalent coefficient of dynamic irregularities. Finally, the stiffness degradation effect in critical components of the track-bridge system shows greater sensitivity to the ground motion intensity and the structural natural period.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The inadequate grouting performance in cross-river shield tunnels is primarily due to the insufficient bonding strength between the grouting material and the tunnel segments. In this study, a series of tests were conducted to compare foamed polymer and common grouting materials, focusing on the tangential bonding performance of the interface with tunnel segment concrete under varying humidity conditions. The applicability of polymer for treating leaks in cross-river shield tunnels was explored. The effects of polymer density, interfacial humidity, interfacial roughness, and normal stress on the shear strength of the polymer-concrete interface were investigated. A mathematical model reflecting the interface shear characteristics between polymer and concrete was established and validated. The test results have shown that, due to the fast reaction speed and high expansion rate, foamed polymer was found to be a feasible solution for addressing leakage in cross-river shield tunnels. Compared with common grouting materials, the density of foamed polymer is controllable, and the shear strength between foamed polymer and concrete segments is less affected by humid conditions. The minimum shear strength of the interface between foamed polymer and concrete is 1.2 MPa, while the maximum is 2.0 MPa. Foamed polymer can meet the needs of leakage treatment of cross-river shield tunnel. The interfacial shear strength between foamed polymer and concrete segments is directly proportional to the polymer density, interfacial roughness, and normal stress, and inversely proportional to the level of humid in the tunnel. The influence of various factors on interfacial strength is ranked as follows: polymer density > interfacial humidity > normal pressure > interfacial roughness. The residual error of linear regression mathematical model for the shear strength of interface between foamed polymer and segment concrete follows a normal distribution. The fitting results were proven to be accurate, allowing for the intuitive prediction of the quantitative relationship between shear strength and multiple influencing factors.
{"title":"Experimental studies on the interfacial shear characteristics between joint concrete and foamed polymer in cross-river shield tunnel","authors":"Yuke Wang, Sensen Zhou, Zhenyu Li, Dongbiao Li, Pengyu Yang, Yuyuan Chen","doi":"10.1016/j.istruc.2024.107241","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107241","url":null,"abstract":"The inadequate grouting performance in cross-river shield tunnels is primarily due to the insufficient bonding strength between the grouting material and the tunnel segments. In this study, a series of tests were conducted to compare foamed polymer and common grouting materials, focusing on the tangential bonding performance of the interface with tunnel segment concrete under varying humidity conditions. The applicability of polymer for treating leaks in cross-river shield tunnels was explored. The effects of polymer density, interfacial humidity, interfacial roughness, and normal stress on the shear strength of the polymer-concrete interface were investigated. A mathematical model reflecting the interface shear characteristics between polymer and concrete was established and validated. The test results have shown that, due to the fast reaction speed and high expansion rate, foamed polymer was found to be a feasible solution for addressing leakage in cross-river shield tunnels. Compared with common grouting materials, the density of foamed polymer is controllable, and the shear strength between foamed polymer and concrete segments is less affected by humid conditions. The minimum shear strength of the interface between foamed polymer and concrete is 1.2 MPa, while the maximum is 2.0 MPa. Foamed polymer can meet the needs of leakage treatment of cross-river shield tunnel. The interfacial shear strength between foamed polymer and concrete segments is directly proportional to the polymer density, interfacial roughness, and normal stress, and inversely proportional to the level of humid in the tunnel. The influence of various factors on interfacial strength is ranked as follows: polymer density > interfacial humidity > normal pressure > interfacial roughness. The residual error of linear regression mathematical model for the shear strength of interface between foamed polymer and segment concrete follows a normal distribution. The fitting results were proven to be accurate, allowing for the intuitive prediction of the quantitative relationship between shear strength and multiple influencing factors.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reinforced Concrete column and Steel beam (RCS) structural system has been extensively studied due to the effective use of concrete and steel material and cost efficiency. Bearing failure and constructability were two main issues of RCS joint in practical engineering. To improve these two deficiencies, the authors proposed a whole-section diaphragm type RCS joint. This study aimed to examine the impact of axial compression ratio and face bearing plate (FBP) thickness on the seismic behavior of the proposed joint. In this research, six RCS joint specimens were designed to achieve joint failure and tested under cyclic loading. Shear failure was identified as the typical failure mode. The results revealed that higher axial, compression ratio could lead to higher cracking loads, with improved load-carrying capacity, stiffness, and energy dissipation capabilities. Additionally, the joint bearing distortion reduced as the axial compression ratio increased. All specimens displayed spindle-shaped hysteresis loops while the specimen without axial compression exhibited pinching effect. The presence of parallel FBPs significantly improved the shear capacity. However, as the thickness of the parallel FBPs increased from 6 mm to 10 mm, the load-carrying capacity showed limited enhancement. Moreover, a comparative analysis of current calculation methods was conducted. The results demonstrated that the AIJ and CECS347:2013 formulas showed acceptable accuracy in predicting the joint shear strength. These findings validated the applicability of the existing methods for proposed composite joints, while the effect of the axial compression ratio required further evaluation.
{"title":"Seismic performance of new detailing RCS connection with different axial compression ratio and FBP thickness","authors":"Siyuan Feng, Yuchen Tao, Linlin Yuan, Zhenfen Jin, Weijian Zhao","doi":"10.1016/j.istruc.2024.107207","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107207","url":null,"abstract":"Reinforced Concrete column and Steel beam (RCS) structural system has been extensively studied due to the effective use of concrete and steel material and cost efficiency. Bearing failure and constructability were two main issues of RCS joint in practical engineering. To improve these two deficiencies, the authors proposed a whole-section diaphragm type RCS joint. This study aimed to examine the impact of axial compression ratio and face bearing plate (FBP) thickness on the seismic behavior of the proposed joint. In this research, six RCS joint specimens were designed to achieve joint failure and tested under cyclic loading. Shear failure was identified as the typical failure mode. The results revealed that higher axial, compression ratio could lead to higher cracking loads, with improved load-carrying capacity, stiffness, and energy dissipation capabilities. Additionally, the joint bearing distortion reduced as the axial compression ratio increased. All specimens displayed spindle-shaped hysteresis loops while the specimen without axial compression exhibited pinching effect. The presence of parallel FBPs significantly improved the shear capacity. However, as the thickness of the parallel FBPs increased from 6 mm to 10 mm, the load-carrying capacity showed limited enhancement. Moreover, a comparative analysis of current calculation methods was conducted. The results demonstrated that the AIJ and CECS347:2013 formulas showed acceptable accuracy in predicting the joint shear strength. These findings validated the applicability of the existing methods for proposed composite joints, while the effect of the axial compression ratio required further evaluation.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-07DOI: 10.1016/j.istruc.2024.107224
Qing He, Kangjie Ling, Guangxing Zhao, Xiaopeng Li, Dewen Liu, Shunzhong Yao, Min Lei, Weiwei Sun
The overall friction pendulum bearing (OFPB) is based on the traditional friction pendulum bearing (FPB) proposed as a kind of friction pendulum bearing using the whole large slide. The energy brought by the earthquake is consumed by the overall friction pendulum seismic isolation structure through its large displacement at the bottom. This study aims to analyze the response of the overall friction pendulum seismic isolation structure under earthquake action and to explore its seismic performance. Based on the principles of structural dynamics and the basic theory of finite elements, three models are established in this study using the finite element software ABAQUS: the non-isolated model, the traditional friction pendulum seismic isolation structure model, and the overall friction pendulum seismic isolation structure model. The study takes into account the confinement effects to ensure an accurate simulation of the structural response. Nine seismic waves (seven natural waves and two artificial waves) were selected for seismic time-history analysis. Subsequently, various overall friction pendulum parameters are studied. The results indicate that both traditional friction pendulum seismic isolation structures and overall friction pendulum seismic isolation can effectively reduce the roof acceleration, roof drift, floor acceleration, interstory drift ratio, base shear, and structural damage of the structure. The roof acceleration of the structure can be reduced by 15.78 % to 45.82 % and 45.24 % to 63.61 % by friction pendulum seismic isolation structures and overall friction pendulum seismic isolation structures, respectively. Similarly, the floor acceleration can be reduced by 11.25 % to 60.27 % and 45.24 % to 71.96 %, respectively. The maximum reduction in roof drift is 73.83 % and 74.59 %, the interstory drift ratio is 82.80 % and 83.59 %, and the base shear is 39.12 % and 80.00 %. A certain impact on the control of the structure is exerted by different friction pendulum parameters. The two kinds of isolation structures can play a significant role in earthquake isolation so that the structure can still maintain the elastic design range under the action of rare earthquakes. When facing earthquakes, the overall friction pendulum seismic isolation structure exhibits more significant seismic stability and seismic effect compared with the traditional friction pendulum seismic isolation structure.
{"title":"Seismic response analysis of overall friction pendulum bearing (OFPB) isolated structures","authors":"Qing He, Kangjie Ling, Guangxing Zhao, Xiaopeng Li, Dewen Liu, Shunzhong Yao, Min Lei, Weiwei Sun","doi":"10.1016/j.istruc.2024.107224","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107224","url":null,"abstract":"The overall friction pendulum bearing (OFPB) is based on the traditional friction pendulum bearing (FPB) proposed as a kind of friction pendulum bearing using the whole large slide. The energy brought by the earthquake is consumed by the overall friction pendulum seismic isolation structure through its large displacement at the bottom. This study aims to analyze the response of the overall friction pendulum seismic isolation structure under earthquake action and to explore its seismic performance. Based on the principles of structural dynamics and the basic theory of finite elements, three models are established in this study using the finite element software ABAQUS: the non-isolated model, the traditional friction pendulum seismic isolation structure model, and the overall friction pendulum seismic isolation structure model. The study takes into account the confinement effects to ensure an accurate simulation of the structural response. Nine seismic waves (seven natural waves and two artificial waves) were selected for seismic time-history analysis. Subsequently, various overall friction pendulum parameters are studied. The results indicate that both traditional friction pendulum seismic isolation structures and overall friction pendulum seismic isolation can effectively reduce the roof acceleration, roof drift, floor acceleration, interstory drift ratio, base shear, and structural damage of the structure. The roof acceleration of the structure can be reduced by 15.78 % to 45.82 % and 45.24 % to 63.61 % by friction pendulum seismic isolation structures and overall friction pendulum seismic isolation structures, respectively. Similarly, the floor acceleration can be reduced by 11.25 % to 60.27 % and 45.24 % to 71.96 %, respectively. The maximum reduction in roof drift is 73.83 % and 74.59 %, the interstory drift ratio is 82.80 % and 83.59 %, and the base shear is 39.12 % and 80.00 %. A certain impact on the control of the structure is exerted by different friction pendulum parameters. The two kinds of isolation structures can play a significant role in earthquake isolation so that the structure can still maintain the elastic design range under the action of rare earthquakes. When facing earthquakes, the overall friction pendulum seismic isolation structure exhibits more significant seismic stability and seismic effect compared with the traditional friction pendulum seismic isolation structure.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-09-07DOI: 10.1016/j.istruc.2024.107221
Xuehui You, Peng Wang, Qingxuan Shi, Chong Rong
Using ABAQUS software, a finite element analysis model is established to investigate the shear failure of reinforced concrete (RC) composed beams without stirrups using ultra-high performance concrete (UHPC) permanent formworks. The model accounts for the influence of steel fibers and the interaction between UHPC formwork and normal concrete on the shear performance. Based on the validation of the accuracy of the finite element model, the effects of section height, shear span ratio, and UHPC formwork thickness on the shear capacity, shear ductility, and nominal shear strength of the beams are studied. Additionally, the shear capacity gains of RC beam with UHPC formwork are compared to those of conventional RC beams. Finally, based on the simplified modified compression field theory (MCFT) and the truss-arch model, a method for calculating the shear capacity of RC beam with UHPC formwork is proposed. The research results indicate that the shear capacity of the beam increases with the increase in UHPC formwork thickness and section height, while it decreases with the increase in the shear span ratio. Shear ductility and nominal shear strength exhibit significant size effects. As the section height increases, both shear ductility and nominal shear strength decrease significantly. Increasing the shear span ratio and reducing the UHPC formwork thickness can mitigate the size effect of nominal shear strength. Compared to conventional RC beams, RC beams with UHPC formwork exhibit significantly higher shear capacity. However, as the section height increases, the gain in shear capacity gradually decreases. Finally, the proposed shear capacity calculation method shows good agreement with experimental values. The calculation process is relatively simple and can be used for engineering design
{"title":"Study on the influence of section dimensions on the shear performance of RC beam with UHPC formwork","authors":"Xuehui You, Peng Wang, Qingxuan Shi, Chong Rong","doi":"10.1016/j.istruc.2024.107221","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107221","url":null,"abstract":"Using ABAQUS software, a finite element analysis model is established to investigate the shear failure of reinforced concrete (RC) composed beams without stirrups using ultra-high performance concrete (UHPC) permanent formworks. The model accounts for the influence of steel fibers and the interaction between UHPC formwork and normal concrete on the shear performance. Based on the validation of the accuracy of the finite element model, the effects of section height, shear span ratio, and UHPC formwork thickness on the shear capacity, shear ductility, and nominal shear strength of the beams are studied. Additionally, the shear capacity gains of RC beam with UHPC formwork are compared to those of conventional RC beams. Finally, based on the simplified modified compression field theory (MCFT) and the truss-arch model, a method for calculating the shear capacity of RC beam with UHPC formwork is proposed. The research results indicate that the shear capacity of the beam increases with the increase in UHPC formwork thickness and section height, while it decreases with the increase in the shear span ratio. Shear ductility and nominal shear strength exhibit significant size effects. As the section height increases, both shear ductility and nominal shear strength decrease significantly. Increasing the shear span ratio and reducing the UHPC formwork thickness can mitigate the size effect of nominal shear strength. Compared to conventional RC beams, RC beams with UHPC formwork exhibit significantly higher shear capacity. However, as the section height increases, the gain in shear capacity gradually decreases. Finally, the proposed shear capacity calculation method shows good agreement with experimental values. The calculation process is relatively simple and can be used for engineering design","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The utilization of fly ash waste from thermal power stations as a value-added product and the search for alternatives to traditional fine aggregates in concrete production are indeed important steps toward addressing environmental concerns and promoting sustainable construction practices. Applying the geopolymerization technique in the manufacture of fine aggregates is proving to be one of the greatest methods to utilize the waste materials instead of employing them directly. In this study, Geopolymer Fly ash Fine Aggregate (GFFA) was manufactured by fly ash geopolymerization and introduced as a partial M-sand substitute in cement mortar to mitigate both challenges. Physical, chemical, and microstructural properties of GFFA were satisfactory to ensure its application in cement mortar and concrete. The addition of 30 % GFFA to the cement mortar resulted in higher compressive, tensile and flexural strength values of 14.086 %, 13.03 % and 13.36 % over control mix which is attributed from the increased calcium silicate hydrate (C-S-H) and sodium aluminosilicate hydrate (N-A-S-H) formation. Relationship between W/C ratio and compressive strength was derived and Abram constants have been obtained as 49.47 and 3.743 for 28th day. Relationships between split tensile strength, compressive strength and flexural strength were derived and were compatible with the previous studies.
{"title":"Characteristic study of geopolymer fly ash fine aggregate and its influence on partial replacement of M-sand in the strength properties of mortar","authors":"Rusna Kizhakkum Paramban, Kalpana Varatharajapuram Govindarajulu","doi":"10.1016/j.istruc.2024.107141","DOIUrl":"https://doi.org/10.1016/j.istruc.2024.107141","url":null,"abstract":"The utilization of fly ash waste from thermal power stations as a value-added product and the search for alternatives to traditional fine aggregates in concrete production are indeed important steps toward addressing environmental concerns and promoting sustainable construction practices. Applying the geopolymerization technique in the manufacture of fine aggregates is proving to be one of the greatest methods to utilize the waste materials instead of employing them directly. In this study, Geopolymer Fly ash Fine Aggregate (GFFA) was manufactured by fly ash geopolymerization and introduced as a partial M-sand substitute in cement mortar to mitigate both challenges. Physical, chemical, and microstructural properties of GFFA were satisfactory to ensure its application in cement mortar and concrete. The addition of 30 % GFFA to the cement mortar resulted in higher compressive, tensile and flexural strength values of 14.086 %, 13.03 % and 13.36 % over control mix which is attributed from the increased calcium silicate hydrate (C-S-H) and sodium aluminosilicate hydrate (N-A-S-H) formation. Relationship between W/C ratio and compressive strength was derived and Abram constants have been obtained as 49.47 and 3.743 for 28th day. Relationships between split tensile strength, compressive strength and flexural strength were derived and were compatible with the previous studies.","PeriodicalId":48642,"journal":{"name":"Structures","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142222165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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