{"title":"Tensile Strength of GFRP Bars Under Sustained Loading in Concrete Beams","authors":"C. Bakis, T. Boothby, R. Schaut, C. Pantano","doi":"10.14359/14902","DOIUrl":"https://doi.org/10.14359/14902","url":null,"abstract":"","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"238 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121311490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: This paper deals with the effectiveness of a new triaxially braided ductile Fiber Reinforced Polymer (FRP) fabric for flexural strengthening of continuous reinforced concrete beams. The tested continuous beams had two spans strengthened in flexure along their positive and negative moment regions and loaded with a concentrated load at the middle of each span. One beam was not strengthened and was tested as a control beam. The behaviors of the beams strengthened with the new fabric were investigated and compared with the behaviors of similar beams strengthened using a commercially available carbon fiber sheet. The responses of the beams were examined in terms of deflections, strains, and failure modes. The beams strengthened with the new fabric showed greater ductility than those strengthened with the carbon fiber sheet. The new fabric provided reasonable ductility due to the formation of plastic hinges that allowed for the redistribution of moment between the positive and negative moment zones of the strengthened continuous beam. Redistribution of the moment enabled the full utilization of the strength of the beam at cross sections of maximum positive and negative bending moments.
{"title":"Innovative Triaxially Braided DuctileFRP Fabric for Strengthening Structures","authors":"N. Grace, W. Ragheb, G. Abdel‐Sayed","doi":"10.14359/14828","DOIUrl":"https://doi.org/10.14359/14828","url":null,"abstract":"Synopsis: This paper deals with the effectiveness of a new triaxially braided ductile Fiber Reinforced Polymer (FRP) fabric for flexural strengthening of continuous reinforced concrete beams. The tested continuous beams had two spans strengthened in flexure along their positive and negative moment regions and loaded with a concentrated load at the middle of each span. One beam was not strengthened and was tested as a control beam. The behaviors of the beams strengthened with the new fabric were investigated and compared with the behaviors of similar beams strengthened using a commercially available carbon fiber sheet. The responses of the beams were examined in terms of deflections, strains, and failure modes. The beams strengthened with the new fabric showed greater ductility than those strengthened with the carbon fiber sheet. The new fabric provided reasonable ductility due to the formation of plastic hinges that allowed for the redistribution of moment between the positive and negative moment zones of the strengthened continuous beam. Redistribution of the moment enabled the full utilization of the strength of the beam at cross sections of maximum positive and negative bending moments.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"90 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116844229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: Recent world events have illustrated that the sustainability of buildings to blast loads is an ever increasing issue. Many older buildings contain unreinforced masonry (URM) infill walls. Due to their low flexural capacity and their brittle mode of failure, these walls have a low resistance to out-of-plane loads, which includes blast loads. As a result, an effort has been undertaken to examine retrofit methods that are feasible to enhance their out-of-plane resistance. The use of externally bonded and near surface mounted (NSM) Fiber Reinforced Polymer (FRP) laminates and rods have been proven to increase the out-of-plane load capacity. This paper investigates the out-of-plane behavior of URM walls strengthened with FRP subjected to static and blast loading and the capability of developing continuity between the FRP strengthening material and the surrounding reinforced concrete (RC) frame system. There were two phases to this research study. Phase I evaluated strengthened URM walls’ out-of-plane performance using static tests. Two strengthening methods were utilized, including the application of glass FRP (GFRP) laminates to the wall’s surface and the installation of near surface mounted (NSM) GFRP rods. In both methods, the strengthening material was anchored to boundary members above and below the wall on some of the specimens in the research program. The effects of bond pattern, and the effects of FRP laminate strip width were also investigated in this phase. Phase II involved the field blast testing of two walls to dynamically study the continuity detail for laminates and verify the results obtained in Phase I. The development of continuity between the FRP materials and the surrounding framing system is one approach to improving the blast resistance of URM infill walls.
{"title":"Out-of-Plane Static and Blast Resistance of UnreinforcedMasonry Wall ConnectionsStrengthened with FRP","authors":"P. Carney, J. Myers","doi":"10.14359/14835","DOIUrl":"https://doi.org/10.14359/14835","url":null,"abstract":"Synopsis: Recent world events have illustrated that the sustainability of buildings to blast loads is an ever increasing issue. Many older buildings contain unreinforced masonry (URM) infill walls. Due to their low flexural capacity and their brittle mode of failure, these walls have a low resistance to out-of-plane loads, which includes blast loads. As a result, an effort has been undertaken to examine retrofit methods that are feasible to enhance their out-of-plane resistance. The use of externally bonded and near surface mounted (NSM) Fiber Reinforced Polymer (FRP) laminates and rods have been proven to increase the out-of-plane load capacity. This paper investigates the out-of-plane behavior of URM walls strengthened with FRP subjected to static and blast loading and the capability of developing continuity between the FRP strengthening material and the surrounding reinforced concrete (RC) frame system. There were two phases to this research study. Phase I evaluated strengthened URM walls’ out-of-plane performance using static tests. Two strengthening methods were utilized, including the application of glass FRP (GFRP) laminates to the wall’s surface and the installation of near surface mounted (NSM) GFRP rods. In both methods, the strengthening material was anchored to boundary members above and below the wall on some of the specimens in the research program. The effects of bond pattern, and the effects of FRP laminate strip width were also investigated in this phase. Phase II involved the field blast testing of two walls to dynamically study the continuity detail for laminates and verify the results obtained in Phase I. The development of continuity between the FRP materials and the surrounding framing system is one approach to improving the blast resistance of URM infill walls.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116298560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: The use of externally-bonded FRP plates and sheets to strengthen existing reinforced concrete structures is now widely recognized. However, a primary concern that still discourages the use of FRPs in some cases is their assumed susceptibility to fire. While recent studies have demonstrated that the overall performance of appropriately designed and insulated FRP-strengthened reinforced concrete members is satisfactory, the specific behavior of FRP materials at high temperature and after exposure to high temperature remains largely unknown, particularly for externallybonded FRP strengthening systems. As a first step in an effort to learn more about the high temperature properties of these systems, an initial series of tests is presented to study the high temperature residual properties of externally-bonded carbon and glass FRP systems for concrete. Axial tension tests, single-lap bond tests, thermogravimetric analysis, and differential scanning calorimetry are all used to elucidate high temperature residual performance. The potential consequences of these initial results for the fire-safe design of FRP-strengthened reinforced concrete members are discussed.
{"title":"High Temperature Residual Properties of Externally-Bonded FRP Systems","authors":"S. Foster, L. Bisby","doi":"10.14359/14891","DOIUrl":"https://doi.org/10.14359/14891","url":null,"abstract":"Synopsis: The use of externally-bonded FRP plates and sheets to strengthen existing reinforced concrete structures is now widely recognized. However, a primary concern that still discourages the use of FRPs in some cases is their assumed susceptibility to fire. While recent studies have demonstrated that the overall performance of appropriately designed and insulated FRP-strengthened reinforced concrete members is satisfactory, the specific behavior of FRP materials at high temperature and after exposure to high temperature remains largely unknown, particularly for externallybonded FRP strengthening systems. As a first step in an effort to learn more about the high temperature properties of these systems, an initial series of tests is presented to study the high temperature residual properties of externally-bonded carbon and glass FRP systems for concrete. Axial tension tests, single-lap bond tests, thermogravimetric analysis, and differential scanning calorimetry are all used to elucidate high temperature residual performance. The potential consequences of these initial results for the fire-safe design of FRP-strengthened reinforced concrete members are discussed.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126627548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: Externally bonded FRP has been established as the technology of choice to strengthen RC beams. Researchers and practicing engineers have recently developed design guidelines for FRP strengthening. However, the current state of the art flexural design procedure suggests an iterative process. No earlier efforts have been devoted to develop direct strength design equations on the failure mode of FRP rupture that can facilitate structural calculations. This study develops exact and approximate sets of closed form equations to design singly and doubly reinforced strengthened rectangular sections that fail by FRP rupture. Comparisons with reported experimental strength data indicate excellent agreement. A comprehensive parametric study has yielded a simple linear regression equation that has an almost perfect statistical correlation and is equally applicable in cases of analysis and design. Comparison between the exact solution and the regression equation confirms the accuracy of the latter. The latter is used in a design example.
{"title":"Closed Form Design Equations for Strengthened Concrete Beams: FRP Rupture","authors":"N. Hatami, H. Rasheed","doi":"10.14359/14912","DOIUrl":"https://doi.org/10.14359/14912","url":null,"abstract":"Synopsis: Externally bonded FRP has been established as the technology of choice to strengthen RC beams. Researchers and practicing engineers have recently developed design guidelines for FRP strengthening. However, the current state of the art flexural design procedure suggests an iterative process. No earlier efforts have been devoted to develop direct strength design equations on the failure mode of FRP rupture that can facilitate structural calculations. This study develops exact and approximate sets of closed form equations to design singly and doubly reinforced strengthened rectangular sections that fail by FRP rupture. Comparisons with reported experimental strength data indicate excellent agreement. A comprehensive parametric study has yielded a simple linear regression equation that has an almost perfect statistical correlation and is equally applicable in cases of analysis and design. Comparison between the exact solution and the regression equation confirms the accuracy of the latter. The latter is used in a design example.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122024676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: Despite significant theoretical advances in the use of concrete-filled fiber reinforced polymer (FRP) tubes (CFFT), research on their shear behavior has been few and limited. Current method of shear analysis of CFFT beams relies on Bernoulli beam theory, which utilizes the basic assumption of linear strain distribution across the depth. Most recently, the use of modified compression field theory was suggested to improve the shear analysis of CFFT beams. The approach, however, is not applicable to the disturbed or D-regions of a beam, such as those in a deep CFFT beam. Therefore, this study adopted the strut-and-tie model to predict the shear strength of deep CFFT beams. The model is validated against test results for a CFFT beam with a shear-spanto-depth ratio of 1. A parametric study is then carried out to assess the shear criticality of CFFT beams. The study showed that shear failure would only be critical for beams with shear span less than their depth. High strength concrete was also found to improve capacity of CFFT beams. However, a judicious selection of concrete strength and fiber architecture with different proportions of shear and flexural capacities of the tube could help optimize the use of materials.
{"title":"Shear Strength Prediction of Deep CFFT Beams","authors":"I. Ahmad, Zhenyu Zhu, A. Mirmiran, A. Fam","doi":"10.14359/14882","DOIUrl":"https://doi.org/10.14359/14882","url":null,"abstract":"Synopsis: Despite significant theoretical advances in the use of concrete-filled fiber reinforced polymer (FRP) tubes (CFFT), research on their shear behavior has been few and limited. Current method of shear analysis of CFFT beams relies on Bernoulli beam theory, which utilizes the basic assumption of linear strain distribution across the depth. Most recently, the use of modified compression field theory was suggested to improve the shear analysis of CFFT beams. The approach, however, is not applicable to the disturbed or D-regions of a beam, such as those in a deep CFFT beam. Therefore, this study adopted the strut-and-tie model to predict the shear strength of deep CFFT beams. The model is validated against test results for a CFFT beam with a shear-spanto-depth ratio of 1. A parametric study is then carried out to assess the shear criticality of CFFT beams. The study showed that shear failure would only be critical for beams with shear span less than their depth. High strength concrete was also found to improve capacity of CFFT beams. However, a judicious selection of concrete strength and fiber architecture with different proportions of shear and flexural capacities of the tube could help optimize the use of materials.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128168035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: Although fiber reinforced polymer (FRP) composites are increasingly being used in civil infrastructure applications, there is still a lack of well documented data and understanding regarding their long-term performance especially under combined exposure to environmental conditions and sustained load. This paper presents the results of an investigation into synergistic effects of hygrothermal exposure and sustained strain on pultruded E-glass/vinylester composites. It is seen that effects of increasing strain levels can be significant and can lead to changes in damage mechanisms, especially in conjunction with moisture uptake. High strains in combination with moderate to elevated temperatures resulted in substantially more catastrophic failure than elevated temperatures in combination with lower strains. These effects were noted in tension and short-beam-shear modes, and overall deterioration was corroborated by moisture uptake, Dynamic Mechanical Thermal Analysis (DMTA) and Fourier Transform Infrared Spectroscopy (FTIR) investigations.
{"title":"Durability Assessment of Combined Environmental Exposure and Bending","authors":"C. Helbling, V. Karbhari","doi":"10.14359/14900","DOIUrl":"https://doi.org/10.14359/14900","url":null,"abstract":"Synopsis: Although fiber reinforced polymer (FRP) composites are increasingly being used in civil infrastructure applications, there is still a lack of well documented data and understanding regarding their long-term performance especially under combined exposure to environmental conditions and sustained load. This paper presents the results of an investigation into synergistic effects of hygrothermal exposure and sustained strain on pultruded E-glass/vinylester composites. It is seen that effects of increasing strain levels can be significant and can lead to changes in damage mechanisms, especially in conjunction with moisture uptake. High strains in combination with moderate to elevated temperatures resulted in substantially more catastrophic failure than elevated temperatures in combination with lower strains. These effects were noted in tension and short-beam-shear modes, and overall deterioration was corroborated by moisture uptake, Dynamic Mechanical Thermal Analysis (DMTA) and Fourier Transform Infrared Spectroscopy (FTIR) investigations.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125983582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: Unreinforced masonry (URM) walls are prone to failure when subjected to out-of-plane loads caused by seismic loads or high wind pressure. Fiber Reinforced Polymers (FRP) in the form of laminates or grids adhesively bonded to the masonry surface with epoxy or polyurea based resins; or FRP bars used as Near Surface Mounted (NSM) reinforcement bonded to the masonry using epoxy or latex modified cementitious pastes, have been successfully used to increase flexural and/or shear capacity of URM walls. However, the practical application of FRPs to strengthen masonry structures is only limited to few research projects due to the limited presence of specific design guidelines. This paper describes provisional design guidelines for the FRP strengthening of masonry walls subject to out of plane loads. The proposed design methodology offers a first rational attempt for consideration by engineers interested in out-of-plane upgrade of masonry walls with externally bonded FRP systems.
{"title":"Design Guidelines for Masonry Structures: Out of Plane Loads","authors":"N. Galati, E. Garbin, G. Tumialan, A. Nanni","doi":"10.14359/14837","DOIUrl":"https://doi.org/10.14359/14837","url":null,"abstract":"Synopsis: Unreinforced masonry (URM) walls are prone to failure when subjected to out-of-plane loads caused by seismic loads or high wind pressure. Fiber Reinforced Polymers (FRP) in the form of laminates or grids adhesively bonded to the masonry surface with epoxy or polyurea based resins; or FRP bars used as Near Surface Mounted (NSM) reinforcement bonded to the masonry using epoxy or latex modified cementitious pastes, have been successfully used to increase flexural and/or shear capacity of URM walls. However, the practical application of FRPs to strengthen masonry structures is only limited to few research projects due to the limited presence of specific design guidelines. This paper describes provisional design guidelines for the FRP strengthening of masonry walls subject to out of plane loads. The proposed design methodology offers a first rational attempt for consideration by engineers interested in out-of-plane upgrade of masonry walls with externally bonded FRP systems.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128281231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: This research program was initiated to examine the feasibility of assessing the blast-resistant capacity of reinforced concrete (RC) slabs using the displacement based design (DBD) method. In order to achieve this objective, five RC slabs were tested under real blast loads in the out-of-plane direction. One of the slabs was used as the control unit to establish a baseline for comparison in terms of performance for the other four slabs, which were strengthened with fiber reinforced polymer (FRP) and steel fiber reinforced polymer (SRP). The explosive charge weight and stand-off distance required to impose a given damage level were predicted by the DBD method. Test results showed that the blast loads were effectively estimated and the damage levels observed from the field tests correlated well with the predicted levels. In addition, test results corroborated that the blast-resistant capacity of RC slabs can be effectively increased by strengthening using FRP composites. The main conclusion that can be drawn from these tests using improvised explosive devices (IDE) is that RC slabs retrofitted on both sides have a higher blast resistance capacity than those slabs retrofitted only on one side. This paper discusses these experimental results along with the analysis steps used to predict the blast charge and standoff distance to impose a given damage level.
{"title":"Retrofit for Blast-Resistant RC Slabs with Composite Materials","authors":"Binggeng Lu, Pedro F. Silva, A. Nanni, J. Baird","doi":"10.14359/14897","DOIUrl":"https://doi.org/10.14359/14897","url":null,"abstract":"Synopsis: This research program was initiated to examine the feasibility of assessing the blast-resistant capacity of reinforced concrete (RC) slabs using the displacement based design (DBD) method. In order to achieve this objective, five RC slabs were tested under real blast loads in the out-of-plane direction. One of the slabs was used as the control unit to establish a baseline for comparison in terms of performance for the other four slabs, which were strengthened with fiber reinforced polymer (FRP) and steel fiber reinforced polymer (SRP). The explosive charge weight and stand-off distance required to impose a given damage level were predicted by the DBD method. Test results showed that the blast loads were effectively estimated and the damage levels observed from the field tests correlated well with the predicted levels. In addition, test results corroborated that the blast-resistant capacity of RC slabs can be effectively increased by strengthening using FRP composites. The main conclusion that can be drawn from these tests using improvised explosive devices (IDE) is that RC slabs retrofitted on both sides have a higher blast resistance capacity than those slabs retrofitted only on one side. This paper discusses these experimental results along with the analysis steps used to predict the blast charge and standoff distance to impose a given damage level.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"150 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133888749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Synopsis: A study on glass FRP-bonded RC beams subjected to sustained loading under tropical weathering is reported. Beams were observed for long-term deflections and cracking due to sustained loading over different periods of time, after which they were unloaded and subsequently tested to failure. Beams subjected to outdoor tropical weathering for six months showed 8% larger deflections and 15% larger crack widths compared to those kept under ambient laboratory condition. Under accelerated weathering in a chamber, similar increase in deflections and crack widths were observed. Also, after six months of accelerated weathering, the ultimate flexural strength was about 17% and 12% less for beams bonded with uniand bi-directional glass FRP laminates, respectively, compared to the un-weathered reference beams. The failure mode changed from concrete crushing to FRP rupture with weathering period, indicating the deterioration of FRP laminates. The effect of weathering was more detrimental in the presence of sustained loads.
{"title":"GFRP-Bonded RC Beams under Sustained Loading and Tropical Weathering","authors":"M. Saha, K. Tan","doi":"10.14359/14899","DOIUrl":"https://doi.org/10.14359/14899","url":null,"abstract":"Synopsis: A study on glass FRP-bonded RC beams subjected to sustained loading under tropical weathering is reported. Beams were observed for long-term deflections and cracking due to sustained loading over different periods of time, after which they were unloaded and subsequently tested to failure. Beams subjected to outdoor tropical weathering for six months showed 8% larger deflections and 15% larger crack widths compared to those kept under ambient laboratory condition. Under accelerated weathering in a chamber, similar increase in deflections and crack widths were observed. Also, after six months of accelerated weathering, the ultimate flexural strength was about 17% and 12% less for beams bonded with uniand bi-directional glass FRP laminates, respectively, compared to the un-weathered reference beams. The failure mode changed from concrete crushing to FRP rupture with weathering period, indicating the deterioration of FRP laminates. The effect of weathering was more detrimental in the presence of sustained loads.","PeriodicalId":151616,"journal":{"name":"SP-230: 7th International Symposium on Fiber-Reinforced (FRP) Polymer Reinforcement for Concrete Structures","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132407418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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