{"title":"Advanced Composites for the Navy Waterfront Infrastructure","authors":"L. Malvar","doi":"10.14359/9996","DOIUrl":"https://doi.org/10.14359/9996","url":null,"abstract":"","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"128 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133126725","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}
Steel-concrete composite columns may be designed either by requirements of the American Concrete Institute Building Code ACI 318-99 or by the American Institute of Steel Construction Specifications for Load and Resistance Factor Design, 2nd Edition (1995). Each design standard is described for application to a concrete filled steel tube and to a concrete encased structural shape as each is designed for the same dimensional and service load conditions. These "standard" type column sections are used for the comparison, as the LRFD specification can be used directly only for such standard sections. The design exercise demonstrates that (a) the LRFD specification requires fewer computational steps and is therefore easier to apply, (b) the ACI rules tend to exaggerate the influence of slenderness, and (c) different but very similar results were obtained for the two methods applied to the same design problem.
{"title":"Should I Use ACI 318 or LRFD for Designing Composite Columns?","authors":"R. Furlong","doi":"10.14359/10001","DOIUrl":"https://doi.org/10.14359/10001","url":null,"abstract":"Steel-concrete composite columns may be designed either by requirements of the American Concrete Institute Building Code ACI 318-99 or by the American Institute of Steel Construction Specifications for Load and Resistance Factor Design, 2nd Edition (1995). Each design standard is described for application to a concrete filled steel tube and to a concrete encased structural shape as each is designed for the same dimensional and service load conditions. These \"standard\" type column sections are used for the comparison, as the LRFD specification can be used directly only for such standard sections. The design exercise demonstrates that (a) the LRFD specification requires fewer computational steps and is therefore easier to apply, (b) the ACI rules tend to exaggerate the influence of slenderness, and (c) different but very similar results were obtained for the two methods applied to the same design problem.","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130573122","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}
{"title":"Analytical Modeling of Through Beam Connection Detail","authors":"A. Elremaily, A. Azizinamini","doi":"10.14359/9995","DOIUrl":"https://doi.org/10.14359/9995","url":null,"abstract":"","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134614691","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}
This paper summarizes the assumptions and analyses used for developing the reliability-based design of reinforced concrete flexural and compression members. Based on data on the variability of concrete and reinforcing steel physical and dimensional properties, estimates were made of the variability of strength of reinforced concrete beams and columns. These data, plus statistical descriptions of loadings, were used in a first-order, second-moment probabilistic analysis to compute resistance factors. Two sets of resistance factors for reinforced concrete members subjected to flexural or combined axial load and flexure are discussed: (a) resistance factors compatible with the current American Concrete Institute (ACI) load factors specified in ACI 318-95 Section 9.2; and (b) resistance factors compatible with the American Society of Civil Engineers (ASCE) Standard 7-95 (ANSI A58-1) load factors included in ACI 318-95 Appendix C. This paper provides a direct comparison between the two sets of load and resistance factors that are now part of the ACI 318 safety criteria.
{"title":"Study of Structural Safety of Reinforced Concrete Flexural and Compression Members","authors":"S. Mirza","doi":"10.14359/10003","DOIUrl":"https://doi.org/10.14359/10003","url":null,"abstract":"This paper summarizes the assumptions and analyses used for developing the reliability-based design of reinforced concrete flexural and compression members. Based on data on the variability of concrete and reinforcing steel physical and dimensional properties, estimates were made of the variability of strength of reinforced concrete beams and columns. These data, plus statistical descriptions of loadings, were used in a first-order, second-moment probabilistic analysis to compute resistance factors. Two sets of resistance factors for reinforced concrete members subjected to flexural or combined axial load and flexure are discussed: (a) resistance factors compatible with the current American Concrete Institute (ACI) load factors specified in ACI 318-95 Section 9.2; and (b) resistance factors compatible with the American Society of Civil Engineers (ASCE) Standard 7-95 (ANSI A58-1) load factors included in ACI 318-95 Appendix C. This paper provides a direct comparison between the two sets of load and resistance factors that are now part of the ACI 318 safety criteria.","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133360775","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}
Using experimental data from previous tests and detailed analytical studies, the applicability of ACI and AISC standard techniques for concrete-filled tubular columns (CFTs) is evaluated. The test specimens include shorter and slender CFTs made with normal and high strength steel tubes filled with normal and high strength concrete. The focus of this paper is on rectangular and square tubes. To gauge the success of the code-based methods, the capacities are also computer by the fiber analysis techniques, along with a member level iteration algorithm for analyzing members with significant length. The results indicate that the ACI and AISC methods can yield substantially different capacities. In general, the capacities from the ACI method are reasonably close to those obtained from detailed analytical methods so long as normal strength tubes are used. Both the ACI moment method and AISC method are appropriate for slender CFTs although the ACI method tends to match the analytically calculated capacities more closely. Neither the ACI nor AISC method is applicable for CFTs made with high strength steel tubes as both techniques substantially underestimate the capacity of such columns. For CFTs with high strength steel tubes, it is more appropriate to assume that the steel tube fully yields when the capacity is developed. A revised version of the ACI standard method was developed by incorporating this assumption. The revised ACI method provides a fairly close estimate of the experimentally obtained capacities and those from detailed analysis.
{"title":"\"Comparison of ACI, AISC, and Basic Methods for CFTs\"","authors":"B. Shahrooz, W. Zhang","doi":"10.14359/9997","DOIUrl":"https://doi.org/10.14359/9997","url":null,"abstract":"Using experimental data from previous tests and detailed analytical studies, the applicability of ACI and AISC standard techniques for concrete-filled tubular columns (CFTs) is evaluated. The test specimens include shorter and slender CFTs made with normal and high strength steel tubes filled with normal and high strength concrete. The focus of this paper is on rectangular and square tubes. To gauge the success of the code-based methods, the capacities are also computer by the fiber analysis techniques, along with a member level iteration algorithm for analyzing members with significant length. The results indicate that the ACI and AISC methods can yield substantially different capacities. In general, the capacities from the ACI method are reasonably close to those obtained from detailed analytical methods so long as normal strength tubes are used. Both the ACI moment method and AISC method are appropriate for slender CFTs although the ACI method tends to match the analytically calculated capacities more closely. Neither the ACI nor AISC method is applicable for CFTs made with high strength steel tubes as both techniques substantially underestimate the capacity of such columns. For CFTs with high strength steel tubes, it is more appropriate to assume that the steel tube fully yields when the capacity is developed. A revised version of the ACI standard method was developed by incorporating this assumption. The revised ACI method provides a fairly close estimate of the experimentally obtained capacities and those from detailed analysis.","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131483158","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}
The behavior of concrete filled tube (CFT) columns made from high strength materials was investigated experimentally. The effects of the width-to-thickness (b/t) ratio, steel tube stress-strain characteristics, and axial load on the stiffness, strength, and ductility of CFT beam-columns and stub columns were studied. Twelve experiments, which included four stub tests (monotonic axial load) and eight beam-column tests (constant axial and monotonic axial load) and eight beam-column tests (constant axial and monotonic flexural load) were conducted. The CFT specimens were 305 mm square tubes, made from either conventional (A500 Grade-B) or high strength (A500 Grade-80) steel with nominal b/t ratios of 32 and 48. The CFT specimens were filled with high strength (104 MPa) concrete. Experimental results indicate that the concrete infill delays, the local buckling of the steel tube, and that for lower levels of axial load and smaller b/t ratios the steel confines the infill concrete, thus increasing its ductility. Comparison of the experimental results with predictions based on current code provisions indicates that the axial load capacity of the high strength CFT stub column specimens can be predicted with reasonable accuracy by superposition of the yield strength of the steel tube and 85% of the compressive strength of the concrete infill. The moment capacity of the high strength CFT beam-column specimens can be conservatively estimated using American Concrete Institute provisions for conventional strength CFT beam-columns. The initial and serviceability-level section flexural stiffness of these specimens was predicted with reasonable accuracy using the uncracked transformed and cracked transformed section properties, respectively. The experimental results indicate that the curvature ductility of a high strength CFT beam-column decreases significantly with an increase in the axial load or the b/t ratio of the steel tube.
{"title":"An Experimental Evaluation of High-Strength Square CFT Columns","authors":"A. Varma, J. Ricles, R. Sause, B. Hull, Le-wu Lu","doi":"10.14359/10005","DOIUrl":"https://doi.org/10.14359/10005","url":null,"abstract":"The behavior of concrete filled tube (CFT) columns made from high strength materials was investigated experimentally. The effects of the width-to-thickness (b/t) ratio, steel tube stress-strain characteristics, and axial load on the stiffness, strength, and ductility of CFT beam-columns and stub columns were studied. Twelve experiments, which included four stub tests (monotonic axial load) and eight beam-column tests (constant axial and monotonic axial load) and eight beam-column tests (constant axial and monotonic flexural load) were conducted. The CFT specimens were 305 mm square tubes, made from either conventional (A500 Grade-B) or high strength (A500 Grade-80) steel with nominal b/t ratios of 32 and 48. The CFT specimens were filled with high strength (104 MPa) concrete. Experimental results indicate that the concrete infill delays, the local buckling of the steel tube, and that for lower levels of axial load and smaller b/t ratios the steel confines the infill concrete, thus increasing its ductility. Comparison of the experimental results with predictions based on current code provisions indicates that the axial load capacity of the high strength CFT stub column specimens can be predicted with reasonable accuracy by superposition of the yield strength of the steel tube and 85% of the compressive strength of the concrete infill. The moment capacity of the high strength CFT beam-column specimens can be conservatively estimated using American Concrete Institute provisions for conventional strength CFT beam-columns. The initial and serviceability-level section flexural stiffness of these specimens was predicted with reasonable accuracy using the uncracked transformed and cracked transformed section properties, respectively. The experimental results indicate that the curvature ductility of a high strength CFT beam-column decreases significantly with an increase in the axial load or the b/t ratio of the steel tube.","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122968945","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}
Plastic mechanism of a structural frame system should be predetermined during design stage, and should be selected such as to achieve a desirable displacement ductility with smallest rotation demands in the plastic hinges. Development of plastic hinges in frame columns are usually associated with very high rotation demand and may result in a total structural instability. Formation of plastic hinges in beams is more favorable. However, formation of a plastic hinge at the face of a column may result in bond deterioration between the reinforcing bars and the surrounding concrete within the beam column joint. This paper introduces a new innovative steel-concrete composite frame system with controlled plastic mechanism. This frame system consists of steel tubed reinforced concrete (STRC) columns, and ordinary reinforced concrete beams with relocated plastic hinges. Beam plastic hinges are relocated by the use of straight-headed bars. The STRC column is an ordinary reinforced concrete column but transversely reinforced with light ordinary ties and a thin steel tube. Compared to concrete filled tube column (CFT), the steel tube of STRC column transfers no axial load, provides better confinement, and consequently, increases column ductility. In this paper, experimental investigation of two full scale STRC columns are two beams with and without headed bars are presented. Test results suggest that STRC columns and beams with relocated plastic hinge regions could offer a more ductile structural frame system for medium and high rise buildings in zones of high seismicity.
{"title":"Behavior of a New Steel-Concrete Hybrid Frame System","authors":"R. Aboutaha","doi":"10.14359/10010","DOIUrl":"https://doi.org/10.14359/10010","url":null,"abstract":"Plastic mechanism of a structural frame system should be predetermined during design stage, and should be selected such as to achieve a desirable displacement ductility with smallest rotation demands in the plastic hinges. Development of plastic hinges in frame columns are usually associated with very high rotation demand and may result in a total structural instability. Formation of plastic hinges in beams is more favorable. However, formation of a plastic hinge at the face of a column may result in bond deterioration between the reinforcing bars and the surrounding concrete within the beam column joint. This paper introduces a new innovative steel-concrete composite frame system with controlled plastic mechanism. This frame system consists of steel tubed reinforced concrete (STRC) columns, and ordinary reinforced concrete beams with relocated plastic hinges. Beam plastic hinges are relocated by the use of straight-headed bars. The STRC column is an ordinary reinforced concrete column but transversely reinforced with light ordinary ties and a thin steel tube. Compared to concrete filled tube column (CFT), the steel tube of STRC column transfers no axial load, provides better confinement, and consequently, increases column ductility. In this paper, experimental investigation of two full scale STRC columns are two beams with and without headed bars are presented. Test results suggest that STRC columns and beams with relocated plastic hinge regions could offer a more ductile structural frame system for medium and high rise buildings in zones of high seismicity.","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116624287","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}
A series of push-out tests of rectangular concrete-filled tubular columns (CFT) was recently conducted. The objective of this research program was to identify the shear transfer mechanisms between the infilled concrete and the steel tube and to determine a method for evaluating the capacity of the steel-concrete interface in a CFT column. The experimental variables investigated were the wall slenderness ratio (b/t) of the steel tube and the use of shear tab connections to apply axial load to the steel tube. The results of this study indicated that three mechanisms are responsible for shear transfer along the steel-concrete interface in a push-out specimen: adhesion to the concrete to the steel surface, friction, and wedging of the concrete core. The role of each mechanism in transferring shear between the concrete and steel in the CFT push-out specimen at various stages of load and slip is discussed. Design guidelines for shear transfer in rectangular CFT columns are presented, including a proposed bond strength equation and a recommended strength reduction factor for bond.
{"title":"Push-Out Behavior of Rectangular Concrete-Filled Steel Tubes","authors":"M. Parsley, J. Yura, J. Jirsa","doi":"10.14359/9998","DOIUrl":"https://doi.org/10.14359/9998","url":null,"abstract":"A series of push-out tests of rectangular concrete-filled tubular columns (CFT) was recently conducted. The objective of this research program was to identify the shear transfer mechanisms between the infilled concrete and the steel tube and to determine a method for evaluating the capacity of the steel-concrete interface in a CFT column. The experimental variables investigated were the wall slenderness ratio (b/t) of the steel tube and the use of shear tab connections to apply axial load to the steel tube. The results of this study indicated that three mechanisms are responsible for shear transfer along the steel-concrete interface in a push-out specimen: adhesion to the concrete to the steel surface, friction, and wedging of the concrete core. The role of each mechanism in transferring shear between the concrete and steel in the CFT push-out specimen at various stages of load and slip is discussed. Design guidelines for shear transfer in rectangular CFT columns are presented, including a proposed bond strength equation and a recommended strength reduction factor for bond.","PeriodicalId":282353,"journal":{"name":"SP-196: Composite and Hybrid Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124133888","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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