Near-field (NF) and far-field (FF) ground motion records were used to develop seismic fragility curves at different damage states for a multi-span reinforced concrete bridge using incremental dynamic analysis (IDA). The use of different methods for the prediction of the fragility curves, including truncated IDA, was also investigated. The results indicated that the median spectral acceleration causing different states of earthquake damage was lower for the NF records than for the FF records. In other words, the studied bridge was more vulnerable when subjected to NF records. The significantly larger probabilities of failure at different damage states, especially at the bar buckling damage state, for the case of NF records was attributed to the significantly larger variability of the results compared with the case of FF records. The results also showed that the probability of failure at different damage levels was relatively low for the case of the FF ground motions. It was also found that truncated IDA could be used to predict the fragility curves with sufficient accuracy for the cases studied.
{"title":"Seismic fragility analysis of concrete bridges subjected to far- and near-field records","authors":"Hamid Reza Ebrahimi Motlagh, Payam Tehrani","doi":"10.1680/jstbu.20.00284","DOIUrl":"https://doi.org/10.1680/jstbu.20.00284","url":null,"abstract":"Near-field (NF) and far-field (FF) ground motion records were used to develop seismic fragility curves at different damage states for a multi-span reinforced concrete bridge using incremental dynamic analysis (IDA). The use of different methods for the prediction of the fragility curves, including truncated IDA, was also investigated. The results indicated that the median spectral acceleration causing different states of earthquake damage was lower for the NF records than for the FF records. In other words, the studied bridge was more vulnerable when subjected to NF records. The significantly larger probabilities of failure at different damage states, especially at the bar buckling damage state, for the case of NF records was attributed to the significantly larger variability of the results compared with the case of FF records. The results also showed that the probability of failure at different damage levels was relatively low for the case of the FF ground motions. It was also found that truncated IDA could be used to predict the fragility curves with sufficient accuracy for the cases studied.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135845698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of biaxial compressive loading on hollow steel box column (HSBC) and concrete-filled steel box column (CFSBC) sections wrapped with low-modulus carbon-fibre-reinforced polymer (CFRP) was studied. The CFSBC and HSBC sections were simulated using Abaqus finite-element software and validated using available experimental data. Biaxial compressive loading was considered for different eccentricities (i.e. eccentricity to depth ratio (e/D) ratio of zero to 0.32). The results indicated that, for CFRP-wrapped HSBCs at low eccentricity (e/D = 0.08), compact and non-compact sections were effective at carrying higher load, while a slender section was effective for concentric loads. For the CFRP-wrapped CFSBCs, compact and non-compact sections were effective for all the eccentric loads (e/D = 0–0.32). It was also found that the low-modulus CFRP layer wrapping the CFSBC sections had no significant effect on strength. An empirical relationship was developed based on trend analysis, which gives the load-carrying capacity of any section. For the CFSBC sections, axial compression–uniaxial moment (P–M) interaction curves are presented to validate the simulation results under biaxial loading.
{"title":"Non-linear analysis of CFRP-wrapped steel box sections under biaxial load","authors":"Pramod Tiwari, Kranti Jain, P. Emani","doi":"10.1680/jstbu.22.00161","DOIUrl":"https://doi.org/10.1680/jstbu.22.00161","url":null,"abstract":"The effect of biaxial compressive loading on hollow steel box column (HSBC) and concrete-filled steel box column (CFSBC) sections wrapped with low-modulus carbon-fibre-reinforced polymer (CFRP) was studied. The CFSBC and HSBC sections were simulated using Abaqus finite-element software and validated using available experimental data. Biaxial compressive loading was considered for different eccentricities (i.e. eccentricity to depth ratio (e/D) ratio of zero to 0.32). The results indicated that, for CFRP-wrapped HSBCs at low eccentricity (e/D = 0.08), compact and non-compact sections were effective at carrying higher load, while a slender section was effective for concentric loads. For the CFRP-wrapped CFSBCs, compact and non-compact sections were effective for all the eccentric loads (e/D = 0–0.32). It was also found that the low-modulus CFRP layer wrapping the CFSBC sections had no significant effect on strength. An empirical relationship was developed based on trend analysis, which gives the load-carrying capacity of any section. For the CFSBC sections, axial compression–uniaxial moment (P–M) interaction curves are presented to validate the simulation results under biaxial loading.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87751180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hanady Almahmood, A. Ashour, D. Figueira, G. Yıldırım, A. Aldemir, M. Şahmaran
The results of an experimental investigation of a new dry connection for reinforced concrete slab elements are presented. Seven full-scale slabs were tested; one slab was monolithic and used as a control specimen, while the other six were assembled using top and bottom steel plates joined by steel bolts with high tensile strength. Two connection scenarios were investigated – a simple bolted connection and a connection with a shear key. The parameters studied were the use of stirrups at the connection section, the step size of the shear key, the bolt diameter and the number of bolts. The test results showed that using a shear key at the assembled section in demountable slabs was more efficient than the simple bolted connection, providing higher flexural stiffness, greater load capacity and less deflection. However, increasing the shear key step size improved the flexural performance of the demountable slabs. In addition, adding stirrups in the assembled section enhanced the flexural stiffness and the total load capacity of the demountable slabs. Predictions of the moment capacity and deflection of the demountable slabs showed reasonably good agreement with the experimental results but, to be generalised, additional calibrated data from experiments are required.
{"title":"Demountable reinforced concrete slabs using dry connections","authors":"Hanady Almahmood, A. Ashour, D. Figueira, G. Yıldırım, A. Aldemir, M. Şahmaran","doi":"10.1680/jstbu.22.00151","DOIUrl":"https://doi.org/10.1680/jstbu.22.00151","url":null,"abstract":"The results of an experimental investigation of a new dry connection for reinforced concrete slab elements are presented. Seven full-scale slabs were tested; one slab was monolithic and used as a control specimen, while the other six were assembled using top and bottom steel plates joined by steel bolts with high tensile strength. Two connection scenarios were investigated – a simple bolted connection and a connection with a shear key. The parameters studied were the use of stirrups at the connection section, the step size of the shear key, the bolt diameter and the number of bolts. The test results showed that using a shear key at the assembled section in demountable slabs was more efficient than the simple bolted connection, providing higher flexural stiffness, greater load capacity and less deflection. However, increasing the shear key step size improved the flexural performance of the demountable slabs. In addition, adding stirrups in the assembled section enhanced the flexural stiffness and the total load capacity of the demountable slabs. Predictions of the moment capacity and deflection of the demountable slabs showed reasonably good agreement with the experimental results but, to be generalised, additional calibrated data from experiments are required.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75795654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper discusses web slenderness effects on the flexural behaviour of epoxy adhesive-bonded compound normal and high-strength steel beams. The compound beams were simply supported and consisted of an I-section connected, on its top flange, to a channel section via an epoxy adhesive. A nonlinear 3D finite element modelling study has been performed using ABAQUS software for the analysis of the beams. The nonlinear finite element modelling was verified against tests on compound steel beams having different cross-sections. An extensive parametric study was carried out using the finite element modelling to study the effects of the change in web slenderness, cross-section geometries, beam lengths and steel strengths on the flexural behaviour of compound steel beams. The failure moments predicted from the finite element modelling were compared with the design moments predicted from the European code for steel beams in flexure. It is shown that the Code, generally, overestimated the design failure moments for most of the epoxy adhesive-bonded compound steel beams investigated in this study. In addition, reliability analysis was performed to assess the reliability of the design rules of the code. Generally, it is found that the European Code is unconservative and statistically unreliable for the epoxy adhesive-bonded compound beams investigated in this study.
{"title":"Web slenderness effects on flexural behaviour of compound normal and high-strength steel beams","authors":"E. Ellobody","doi":"10.1680/jstbu.22.00113","DOIUrl":"https://doi.org/10.1680/jstbu.22.00113","url":null,"abstract":"This paper discusses web slenderness effects on the flexural behaviour of epoxy adhesive-bonded compound normal and high-strength steel beams. The compound beams were simply supported and consisted of an I-section connected, on its top flange, to a channel section via an epoxy adhesive. A nonlinear 3D finite element modelling study has been performed using ABAQUS software for the analysis of the beams. The nonlinear finite element modelling was verified against tests on compound steel beams having different cross-sections. An extensive parametric study was carried out using the finite element modelling to study the effects of the change in web slenderness, cross-section geometries, beam lengths and steel strengths on the flexural behaviour of compound steel beams. The failure moments predicted from the finite element modelling were compared with the design moments predicted from the European code for steel beams in flexure. It is shown that the Code, generally, overestimated the design failure moments for most of the epoxy adhesive-bonded compound steel beams investigated in this study. In addition, reliability analysis was performed to assess the reliability of the design rules of the code. Generally, it is found that the European Code is unconservative and statistically unreliable for the epoxy adhesive-bonded compound beams investigated in this study.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79363866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents the results of an extensive investigation carried out to better understand the seismic resilient features of Kath-Kuni structures that is mainly timber-laced dry masonry construction prevalent in the Himachal Pradesh region of India. The research comprised field reconnaissance surveys through rapid visual screening to understand the structural configuration. Thereafter, laboratory testing was conducted to evaluate the mechanical properties, joint characteristics, and interfacial resistance of timber and stones. Results from the field survey highlighted that the symmetrical geometry, the use of lintels above openings, and the corner interlocking were the major contributors to increase the seismic resilience of the buildings. Laboratory testing conducted on wooded joints present in the walls namely dowel and double-dovetail joints indicated the importance of connection conditions in increasing the shearing capacity. Besides, the shearing capacity was also dependent on the overburden pressure indicating the least capacity of connection at the top portion of the wall and the highest capacity at the bottom portion of the wall. The interface of timber and stones contributed to further increasing the shearing capacity of the walls. The output of this research is the first insight into the mechanical behaviour of joints of the Kath-Kuni structure.
{"title":"Kath Kuni architecture: field investigations and material characterisation","authors":"A. Sharma, Ashutosh Kumar, V. Sarhosis","doi":"10.1680/jstbu.22.00080","DOIUrl":"https://doi.org/10.1680/jstbu.22.00080","url":null,"abstract":"This study presents the results of an extensive investigation carried out to better understand the seismic resilient features of Kath-Kuni structures that is mainly timber-laced dry masonry construction prevalent in the Himachal Pradesh region of India. The research comprised field reconnaissance surveys through rapid visual screening to understand the structural configuration. Thereafter, laboratory testing was conducted to evaluate the mechanical properties, joint characteristics, and interfacial resistance of timber and stones. Results from the field survey highlighted that the symmetrical geometry, the use of lintels above openings, and the corner interlocking were the major contributors to increase the seismic resilience of the buildings. Laboratory testing conducted on wooded joints present in the walls namely dowel and double-dovetail joints indicated the importance of connection conditions in increasing the shearing capacity. Besides, the shearing capacity was also dependent on the overburden pressure indicating the least capacity of connection at the top portion of the wall and the highest capacity at the bottom portion of the wall. The interface of timber and stones contributed to further increasing the shearing capacity of the walls. The output of this research is the first insight into the mechanical behaviour of joints of the Kath-Kuni structure.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90971222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, accelerated bridge construction (ABC) has led to substantial application of precast post-tensioned segmental (PPS) bridge piers. However, PPS piers are not widely used in high-seismicity regions due to their low energy-dissipation capacity. To address this deficiency, this research work examines a series of Shape Memory Alloy (SMA) concrete composite PPS piers. Nonlinear static and dynamic analyses are performed on experimentally validated Finite Element (FE) models of the SMA concrete composite piers, and the results are compared with those without SMA bars. It is found that length, area, and post-tensioning ratio of the SMA bars affect the energy dissipation capacity of the piers, and an optimal design of the bars is required to reach the highest energy dissipation possible. The effects of the SMA bars on the frequency response functions of the piers are investigated for the first time in this study, and it is shown that, unlike the piers without SMA bars, the sub-harmonics and super-harmonics are not seen in the response of the SMA concrete composite piers, mainly for the drift responses. Further, the SMA concrete composite piers experience a significant reduction in the drift responses compared to those without SMA.
{"title":"Modelling nonlinear dynamic behaviour of rocking bridge piers with shape memory alloys","authors":"Sedef Kocakaplan, Ehsan Ahmadi, M. Kashani","doi":"10.1680/jstbu.22.00219","DOIUrl":"https://doi.org/10.1680/jstbu.22.00219","url":null,"abstract":"In recent years, accelerated bridge construction (ABC) has led to substantial application of precast post-tensioned segmental (PPS) bridge piers. However, PPS piers are not widely used in high-seismicity regions due to their low energy-dissipation capacity. To address this deficiency, this research work examines a series of Shape Memory Alloy (SMA) concrete composite PPS piers. Nonlinear static and dynamic analyses are performed on experimentally validated Finite Element (FE) models of the SMA concrete composite piers, and the results are compared with those without SMA bars. It is found that length, area, and post-tensioning ratio of the SMA bars affect the energy dissipation capacity of the piers, and an optimal design of the bars is required to reach the highest energy dissipation possible. The effects of the SMA bars on the frequency response functions of the piers are investigated for the first time in this study, and it is shown that, unlike the piers without SMA bars, the sub-harmonics and super-harmonics are not seen in the response of the SMA concrete composite piers, mainly for the drift responses. Further, the SMA concrete composite piers experience a significant reduction in the drift responses compared to those without SMA.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79486758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Matloub, Sara S. Hassan, Ibrahim S. Hussein, A. Yousef
Lateral torsional buckling, that pronounced for the case of laterally unrestrained compression flange, reduces the moment capacity of steel I-girders. To recover this weakening, the approach is to replace the conventional plate flange with a rectangular tube which has higher lateral stiffness thus valuable against lateral buckling. At the same time, web openings in this section are introduced to enable passing of services but causing strength reduction. Girders with tubular flange plus web openings are yet not discussed in publications. In this paper, FEM is performed to fill this gap studying different web and flange slenderness classifications as well as parameters such as size of web openings, spacing, and location. The results for solid web are found more comparable to EC than AISC, enabling good prediction of the flexural capacity. By introducing web openings, the flexural capacity is reduced by 10%-20%, closer to the higher side for large opening diameters located near the compression flange. The oval shape of the openings has less reduction strength while the square is unfavorable. Tubular flange girders, even if perforated, proves its flexural strength enhancement and considerable reduction of the material than the plate flange girders. This section behaves better regarding the carbon emissions.
{"title":"Flexural strength of steel girders with perforated web and tubular compression flange","authors":"A. Matloub, Sara S. Hassan, Ibrahim S. Hussein, A. Yousef","doi":"10.1680/jstbu.23.00010","DOIUrl":"https://doi.org/10.1680/jstbu.23.00010","url":null,"abstract":"Lateral torsional buckling, that pronounced for the case of laterally unrestrained compression flange, reduces the moment capacity of steel I-girders. To recover this weakening, the approach is to replace the conventional plate flange with a rectangular tube which has higher lateral stiffness thus valuable against lateral buckling. At the same time, web openings in this section are introduced to enable passing of services but causing strength reduction. Girders with tubular flange plus web openings are yet not discussed in publications. In this paper, FEM is performed to fill this gap studying different web and flange slenderness classifications as well as parameters such as size of web openings, spacing, and location. The results for solid web are found more comparable to EC than AISC, enabling good prediction of the flexural capacity. By introducing web openings, the flexural capacity is reduced by 10%-20%, closer to the higher side for large opening diameters located near the compression flange. The oval shape of the openings has less reduction strength while the square is unfavorable. Tubular flange girders, even if perforated, proves its flexural strength enhancement and considerable reduction of the material than the plate flange girders. This section behaves better regarding the carbon emissions.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87807129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
At present, there are only a few studies on the application of coal gangue concrete to structural components. To study the moment-curvature relationship of steel fibre-reinforced coal gangue concrete beams, a simplified calculation method was proposed in this study. The equations were optimised based on current design codes, including theoretical calculations of flexural stiffness, crack width and spacing, cracking moment and ultimate moment. Calculated results were compared with experimental results to verify that the cracking moment and ultimate moment of the beams were slightly lower than those of natural concrete beams. However, the cracking moment, flexural stiffness and ductility of coal gangue concrete beams was increased by incorporating steel fibres. Increasing the rebar ratio also significantly improved the load-carrying capacity but reduced ductility. The calculated values for moment-curvature were close to the experimental values, proving the optimised calculations have a high accuracy and are applicable to predicting the bending behaviour of steel-fibre-reinforced coal gangue concrete beams. This paper provides a theoretical basis for subsequent related research.
{"title":"Theoretical analysis of the moment-curvature relationship of coal gangue concrete beams","authors":"B. Cai, Kaiyi Li, F. Fu","doi":"10.1680/jstbu.22.00066","DOIUrl":"https://doi.org/10.1680/jstbu.22.00066","url":null,"abstract":"At present, there are only a few studies on the application of coal gangue concrete to structural components. To study the moment-curvature relationship of steel fibre-reinforced coal gangue concrete beams, a simplified calculation method was proposed in this study. The equations were optimised based on current design codes, including theoretical calculations of flexural stiffness, crack width and spacing, cracking moment and ultimate moment. Calculated results were compared with experimental results to verify that the cracking moment and ultimate moment of the beams were slightly lower than those of natural concrete beams. However, the cracking moment, flexural stiffness and ductility of coal gangue concrete beams was increased by incorporating steel fibres. Increasing the rebar ratio also significantly improved the load-carrying capacity but reduced ductility. The calculated values for moment-curvature were close to the experimental values, proving the optimised calculations have a high accuracy and are applicable to predicting the bending behaviour of steel-fibre-reinforced coal gangue concrete beams. This paper provides a theoretical basis for subsequent related research.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89606615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sustainable Seismic Design (SSD) is the first step toward next-generation earthquake engineering. SSD of Mixed Multiple Seismic Systems (MMSS), where more than one earthquake-resisting structure (ERS) are used, is one of the challenging structural engineering issues. Seismic Sustainability (SS) implies survivability during and after the earthquake, preceded by Post-Earthquake Realignment and Repairs (PERR). Purpose-specific MMSS are ideally suited for SSD. However, contemporary codes address neither sequences nor failure mechanisms of the earthquake-resisting structures of MMSS. The difference between conventional design and SSD is their approach to expected behavior during and after earthquakes. Earthquakes are, natural and dynamic occurrences, whereas PERR is a manual and static process. SSD does not favor unreal detailing nor oversimplifying assumptions; it is a multifaceted effort that involves realistic structural analysis and planned manual operations. In this context, design implies operability with a view to PERR and requires a change from damageability assessment, and Performance-Based Seismic Design (PBSD), to Performance Control (PC) and Reparability Based Design (RBD), including development of new analytic tools and purpose-specific details. The current paper presents graphical solutions and theoretical principles that help achieve practical SSD for MMSS. These new techniques may be utilized for practical reliability, economy, and environmental protection.
{"title":"Limit state design of resilient earthquake resisting systems","authors":"M. Grigorian, Siavash Sedighi, Hadi Mohammadi","doi":"10.1680/jstbu.22.00202","DOIUrl":"https://doi.org/10.1680/jstbu.22.00202","url":null,"abstract":"Sustainable Seismic Design (SSD) is the first step toward next-generation earthquake engineering. SSD of Mixed Multiple Seismic Systems (MMSS), where more than one earthquake-resisting structure (ERS) are used, is one of the challenging structural engineering issues. Seismic Sustainability (SS) implies survivability during and after the earthquake, preceded by Post-Earthquake Realignment and Repairs (PERR). Purpose-specific MMSS are ideally suited for SSD. However, contemporary codes address neither sequences nor failure mechanisms of the earthquake-resisting structures of MMSS. The difference between conventional design and SSD is their approach to expected behavior during and after earthquakes. Earthquakes are, natural and dynamic occurrences, whereas PERR is a manual and static process. SSD does not favor unreal detailing nor oversimplifying assumptions; it is a multifaceted effort that involves realistic structural analysis and planned manual operations. In this context, design implies operability with a view to PERR and requires a change from damageability assessment, and Performance-Based Seismic Design (PBSD), to Performance Control (PC) and Reparability Based Design (RBD), including development of new analytic tools and purpose-specific details. The current paper presents graphical solutions and theoretical principles that help achieve practical SSD for MMSS. These new techniques may be utilized for practical reliability, economy, and environmental protection.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78963212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most design codes assume the nonlinear seismic performance of structures using response reduction/modification factor (R). The R factor is sensitive to a variety of factors in terms of overall ductility and over-strength. This research assesses the actual R factor for vertical irregularity cases for RC bare buildings with moment-resisting frames (MRF) systems. Also, this research derives a significant relationship between R values and identified vertical irregularity index calculated from relative stiffness between adjacent stories. Three-dimensional numerical models are carried out for the soft story and setback irregularity scenarios using ETABS. Modal pushover analysis (MPA) is selected to obtain the inelastic seismic capacity. The obtained results demonstrate that vertical irregular buildings have weak inelastic seismic capacities compared to regular one. So, the response modification factor (R) should be scaled down before the design stage by 15% to 40% for single and combined vertical irregularity scenarios. Structures with a combined asymmetric setback with a soft ground story experience the worst R factor. Also, R factors are sensitive to the identified vertical irregularity index (Vtm) that has 80% regression percent. So, it may be used to specify the allowable vertical irregularity ratio, location, and combination for each seismic zone.
{"title":"Response modification factor evaluation for vertical irregular MRF buildings","authors":"M. M. Ahmed, M. Abdo, W. Mohamed","doi":"10.1680/jstbu.22.00146","DOIUrl":"https://doi.org/10.1680/jstbu.22.00146","url":null,"abstract":"Most design codes assume the nonlinear seismic performance of structures using response reduction/modification factor (R). The R factor is sensitive to a variety of factors in terms of overall ductility and over-strength. This research assesses the actual R factor for vertical irregularity cases for RC bare buildings with moment-resisting frames (MRF) systems. Also, this research derives a significant relationship between R values and identified vertical irregularity index calculated from relative stiffness between adjacent stories. Three-dimensional numerical models are carried out for the soft story and setback irregularity scenarios using ETABS. Modal pushover analysis (MPA) is selected to obtain the inelastic seismic capacity. The obtained results demonstrate that vertical irregular buildings have weak inelastic seismic capacities compared to regular one. So, the response modification factor (R) should be scaled down before the design stage by 15% to 40% for single and combined vertical irregularity scenarios. Structures with a combined asymmetric setback with a soft ground story experience the worst R factor. Also, R factors are sensitive to the identified vertical irregularity index (Vtm) that has 80% regression percent. So, it may be used to specify the allowable vertical irregularity ratio, location, and combination for each seismic zone.","PeriodicalId":54570,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Structures and Buildings","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82423866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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