This column discusses a PCI research and development project that pertains to the precast concrete workhorse: the headed-stud connection.
本专栏讨论了一项PCI研究和开发项目，该项目与预制混凝土主力:头钉连接有关。
{"title":"Headed-stud connections","authors":"D. Meinheit, A. Osborn","doi":"10.15554/pcij68.1-05","DOIUrl":"https://doi.org/10.15554/pcij68.1-05","url":null,"abstract":"This column discusses a PCI research and development project that pertains to the precast concrete workhorse: the headed-stud connection.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67575518","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}
William B. Rich, Christopher S. Williams, R. Frosch
Deterioration of the end regions of prestressed concrete bridge girders is commonly observed in the field when girders are exposed to chloride-laden water that has leaked through failed expansion joints. Because the deterioration is often localized to the end regions of the girders, reliable repair techniques can provide a means to extend girder service life, avoiding the need for immediate superstructure replacement. To evaluate different repair methods and identify key design considerations for end region repair, shear tests to failure were conducted on prestressed concrete girders extracted from a decommissioned superstructure. Three repair systems were evaluated: an externally bonded fiber-reinforced-polymer (FRP) system, a near-surface-mounted FRP system, and a concrete end block. Only the externally bonded FRP system successfully restored both the strength and initial stiffness of the girder. Although the other two methods were not successful, the tests on the repaired girders highlight important factors that must be considered when designing repairs or conducting further research. The tests also demonstrate that end region deterioration can cause significant (> 40%) reductions in strength, underscoring the importance of addressing such deterioration observed in the field.
{"title":"Investigation of repair techniques for deteriorated end regions of prestressed concrete bridge girders","authors":"William B. Rich, Christopher S. Williams, R. Frosch","doi":"10.15554/pcij68.2-02","DOIUrl":"https://doi.org/10.15554/pcij68.2-02","url":null,"abstract":"Deterioration of the end regions of prestressed concrete bridge girders is commonly observed in the field when girders are exposed to chloride-laden water that has leaked through failed expansion joints. Because the deterioration is often localized to the end regions of the girders, reliable repair techniques can provide a means to extend girder service life, avoiding the need for immediate superstructure replacement. To evaluate different repair methods and identify key design considerations for end region repair, shear tests to failure were conducted on prestressed concrete girders extracted from a decommissioned superstructure. Three repair systems were evaluated: an externally bonded fiber-reinforced-polymer (FRP) system, a near-surface-mounted FRP system, and a concrete end block. Only the externally bonded FRP system successfully restored both the strength and initial stiffness of the girder. Although the other two methods were not successful, the tests on the repaired girders highlight important factors that must be considered when designing repairs or conducting further research. The tests also demonstrate that end region deterioration can cause significant (> 40%) reductions in strength, underscoring the importance of addressing such deterioration observed in the field.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67575340","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}
D. Jung, T. Kang, D. J. Lee, Sanghee Kim, J. LaFave
The seismic performance of a ductile rod system for exterior precast concrete beam-to-column connections was experimentally evaluated. Five full-scale precast concrete beam-to-column subassemblies connected with ductile rods were fabricated, considering various aspects (ductile rod size, prestressing, and flexural/shear capacities). Lateral cyclic loading tests were conducted for the precast concrete connections along with two monolithic reinforced concrete connections. Despite their relatively lower lateral stiffness, most precast concrete connections showed sufficient moment capacities with peak moments at approximately 3% to 4% interstory drifts. The prestressing tendons were effective at enhancing moment and shear strengths of the precast concrete connections, as well as in reducing slip of the ductile rods. The precast concrete specimens generally showed satisfactory seismic performance, fulfilling acceptance criteria specified by the American Concrete Institute. The test results demonstrated that careful considerations are required in the design of ductile rods and high-strength threaded bars to induce stable flexural responses of the precast concrete connections.
{"title":"Seismic performance of a ductile rod exterior connection system for precast concrete industrial buildings","authors":"D. Jung, T. Kang, D. J. Lee, Sanghee Kim, J. LaFave","doi":"10.15554/pcij68.1-03","DOIUrl":"https://doi.org/10.15554/pcij68.1-03","url":null,"abstract":"The seismic performance of a ductile rod system for exterior precast concrete beam-to-column connections was experimentally evaluated. Five full-scale precast concrete beam-to-column subassemblies connected with ductile rods were fabricated, considering various aspects (ductile rod size, prestressing, and flexural/shear capacities). Lateral cyclic loading tests were conducted for the precast concrete connections along with two monolithic reinforced concrete connections. Despite their relatively lower lateral stiffness, most precast concrete connections showed sufficient moment capacities with peak moments at approximately 3% to 4% interstory drifts. The prestressing tendons were effective at enhancing moment and shear strengths of the precast concrete connections, as well as in reducing slip of the ductile rods. The precast concrete specimens generally showed satisfactory seismic performance, fulfilling acceptance criteria specified by the American Concrete Institute. The test results demonstrated that careful considerations are required in the design of ductile rods and high-strength threaded bars to induce stable flexural responses of the precast concrete connections.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67575390","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}
Connecting or anchoring reinforcing steel to structural steel plate or shapes using fillet welds is a common detail in precast concrete construction. However, there is currently no guidance on the effects of skewing the reinforcing bar with respect to the plate. This paper reports findings from a study of the effects of a skewed reinforcing bar on both the effective weld area and the overall connection strength. Thirty-two samples of reinforcing bars welded to steel plates at various skew angles were fabricated and tested in tension to failure. These results were compared with an analysis based on the instantaneous center of rotation method presented in the American Welding Society’s Structural Welding Code—Steel (AWS D1.1-20). Recommendations are presented to revise the Structural Welding Code—Reinforcing Bars (AWS D1.4) to account for the effect of skewed reinforcing bars welded to structural steel plate or shapes.
{"title":"Fillet welding of skewed reinforcing steel to steel plate","authors":"E. Pratt","doi":"10.15554/pcij68.1-04","DOIUrl":"https://doi.org/10.15554/pcij68.1-04","url":null,"abstract":"Connecting or anchoring reinforcing steel to structural steel plate or shapes using fillet welds is a common detail in precast concrete construction. However, there is currently no guidance on the effects of skewing the reinforcing bar with respect to the plate. This paper reports findings from a study of the effects of a skewed reinforcing bar on both the effective weld area and the overall connection strength. Thirty-two samples of reinforcing bars welded to steel plates at various skew angles were fabricated and tested in tension to failure. These results were compared with an analysis based on the instantaneous center of rotation method presented in the American Welding Society’s Structural Welding Code—Steel (AWS D1.1-20). Recommendations are presented to revise the Structural Welding Code—Reinforcing Bars (AWS D1.4) to account for the effect of skewed reinforcing bars welded to structural steel plate or shapes.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67575401","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}
Hannah D. Kessler, K. Conway, L. Redmond, G. Pataky
A design method for precast concrete buckling-restrained braced frames with traditional gusset plate connections has not yet been codified. In addition, experimental data for this novel system are lacking. The primary objectives of this research were to design and experimentally test a partial system under representative seismic loads and to determine the applicability of the uniform force method (UFM) for connection interface force distribution. A quasi-static cyclic test was performed on a scaled, partial system. Experimental results showed that the UFM alone does not accurately predict interface forces for this system because the method does not account for frame action. Results also showed that there is some change in column base fixity as the frame undergoes larger horizontal displacements. This was the first U.S. laboratory test on a scaled, partial version of this system. Development of a codified design method would require further testing to determine an appropriate interface force distribution and quantify the change in column base fixity.
{"title":"Design and cyclic testing of a gusset plate connection for precast concrete buckling-restrained braced frames","authors":"Hannah D. Kessler, K. Conway, L. Redmond, G. Pataky","doi":"10.15554/pcij68.2-03","DOIUrl":"https://doi.org/10.15554/pcij68.2-03","url":null,"abstract":"A design method for precast concrete buckling-restrained braced frames with traditional gusset plate connections has not yet been codified. In addition, experimental data for this novel system are lacking. The primary objectives of this research were to design and experimentally test a partial system under representative seismic loads and to determine the applicability of the uniform force method (UFM) for connection interface force distribution. A quasi-static cyclic test was performed on a scaled, partial system. Experimental results showed that the UFM alone does not accurately predict interface forces for this system because the method does not account for frame action. Results also showed that there is some change in column base fixity as the frame undergoes larger horizontal displacements. This was the first U.S. laboratory test on a scaled, partial version of this system. Development of a codified design method would require further testing to determine an appropriate interface force distribution and quantify the change in column base fixity.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67575485","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}
{"title":"Evolution of the L-shaped spandrel beam","authors":"A. Osborn, G. Klein","doi":"10.15554/pcij68.2-06","DOIUrl":"https://doi.org/10.15554/pcij68.2-06","url":null,"abstract":"","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67576146","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}
{"title":"Precast, prestressed concrete products for infrastructure","authors":"Stephen J. Seguirant, R. Miller","doi":"10.15554/pcij68.3-05","DOIUrl":"https://doi.org/10.15554/pcij68.3-05","url":null,"abstract":"","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67576236","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}
Zoe N. Lallas, Matthew J. Gombeda, Flavia Mendonca
This paper presents a comprehensive review of existing research examining the effects of supplementary cementitious materials on age-dependent concrete properties with the most profound implications for precast concrete production. The review covers the physical and chemical properties of selected types of supplementary cementitious materials, concrete mixture proportions, concrete curing methods, testing procedures, and test results related to the fresh properties and strengths of a range of concrete mixtures. Although the use of supplementary cementitious materials in precast concrete products is common, the detailed information provided in this paper may facilitate more widespread use of these materials to enhance concrete properties and comply with sustainability initiatives.
{"title":"Review of supplementary cementitious materials with implications for age-dependent concrete properties affecting precast concrete","authors":"Zoe N. Lallas, Matthew J. Gombeda, Flavia Mendonca","doi":"10.15554/pcij68.6-01","DOIUrl":"https://doi.org/10.15554/pcij68.6-01","url":null,"abstract":"This paper presents a comprehensive review of existing research examining the effects of supplementary cementitious materials on age-dependent concrete properties with the most profound implications for precast concrete production. The review covers the physical and chemical properties of selected types of supplementary cementitious materials, concrete mixture proportions, concrete curing methods, testing procedures, and test results related to the fresh properties and strengths of a range of concrete mixtures. Although the use of supplementary cementitious materials in precast concrete products is common, the detailed information provided in this paper may facilitate more widespread use of these materials to enhance concrete properties and comply with sustainability initiatives.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982781","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 describes research on the behavior of precast, post-tensioned concrete rocking systems with a proposed new type of external rotational friction damper. The proposed damper takes advantage of geometrical arrangement with small initial angle (less than 20 degrees) to amplify the relative rotations due to the unique gap opening mechanism that occurs in the joints of these systems. These relative rotations, which take place on friction surfaces between metallic friction plates, contribute to the energy dissipation and force capacity of the system by means of rotational friction. The novelty of the proposed damper stems from the amplification effect, which provides substantial energy dissipation capacity even in small drift demands. In this study, a numerical model was developed and verified with experimental results. This numerical model was used to analyze unbonded, post-tensioned beam-column subassemblies and frames with and without the proposed damper tested to develop the force-displacement relations. The analysis results indicate that the proposed damper would effectively dissipate seismic energy and increase force capacity.
{"title":"Experimental and numerical study of a motion amplification mechanism to enhance the seismic energy-dissipation capacity of precast, post-tensioned concrete rocking systems","authors":"Ahmet Ata Kulaksizoglu, Cetin Yilmaz, Cem Yalcin","doi":"10.15554/pcij68.6-02","DOIUrl":"https://doi.org/10.15554/pcij68.6-02","url":null,"abstract":"This paper describes research on the behavior of precast, post-tensioned concrete rocking systems with a proposed new type of external rotational friction damper. The proposed damper takes advantage of geometrical arrangement with small initial angle (less than 20 degrees) to amplify the relative rotations due to the unique gap opening mechanism that occurs in the joints of these systems. These relative rotations, which take place on friction surfaces between metallic friction plates, contribute to the energy dissipation and force capacity of the system by means of rotational friction. The novelty of the proposed damper stems from the amplification effect, which provides substantial energy dissipation capacity even in small drift demands. In this study, a numerical model was developed and verified with experimental results. This numerical model was used to analyze unbonded, post-tensioned beam-column subassemblies and frames with and without the proposed damper tested to develop the force-displacement relations. The analysis results indicate that the proposed damper would effectively dissipate seismic energy and increase force capacity.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982812","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}
Fatigue strength, relaxation, and creep rupture strength of carbon-fiber-reinforced polymer (CFRP) strands were evaluated experimentally, and their impact on bridge beam design was investigated. The long-term relaxation of CFRP strands was evaluated by loading CFRP test specimens under different environmental conditions and monitoring prestress loss over time. Creep rupture strength of CFRP strands after 1 million hours of sustained stress exposure was predicted by loading and monitoring CFRP test specimens under a range of sustained stress levels for an extended time. The fatigue strength of CFRP strands was established by cyclically loading CFRP test specimens using different stress amplitudes. In addition, and as a benchmark for fatigue evaluation, low-relaxation steel and stainless steel strand test specimens were prepared and cyclically loaded within the fatigue test matrix. Test results showed that fatigue strength of CFRP strands is superior to that of low-relaxation steel and stainless steel prestressing strands. In addition, the one-million-hour relaxation loss of CFRP strands is approximately 2% for a wide range of initial stress levels. Furthermore, the one-million-hour creep rupture strength is at least 88% of the average tensile strength of the strands. Extended exposure to environmental conditions did not seem to affect the tensile capacity of CFRP strands.
{"title":"\"Evaluating fatigue, relaxation, and creep rupture of carbon-fiber- reinforced polymer strands for highway bridge construction\"","authors":"N. Grace, M. Mohamed, Mena Bebawy","doi":"10.15554/pcij68.3-01","DOIUrl":"https://doi.org/10.15554/pcij68.3-01","url":null,"abstract":"Fatigue strength, relaxation, and creep rupture strength of carbon-fiber-reinforced polymer (CFRP) strands were evaluated experimentally, and their impact on bridge beam design was investigated. The long-term relaxation of CFRP strands was evaluated by loading CFRP test specimens under different environmental conditions and monitoring prestress loss over time. Creep rupture strength of CFRP strands after 1 million hours of sustained stress exposure was predicted by loading and monitoring CFRP test specimens under a range of sustained stress levels for an extended time. The fatigue strength of CFRP strands was established by cyclically loading CFRP test specimens using different stress amplitudes. In addition, and as a benchmark for fatigue evaluation, low-relaxation steel and stainless steel strand test specimens were prepared and cyclically loaded within the fatigue test matrix. Test results showed that fatigue strength of CFRP strands is superior to that of low-relaxation steel and stainless steel prestressing strands. In addition, the one-million-hour relaxation loss of CFRP strands is approximately 2% for a wide range of initial stress levels. Furthermore, the one-million-hour creep rupture strength is at least 88% of the average tensile strength of the strands. Extended exposure to environmental conditions did not seem to affect the tensile capacity of CFRP strands.","PeriodicalId":54637,"journal":{"name":"PCI Journal","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67575772","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：