SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely最新文献

{"title":"Contribution of Concrete between Cracks at Inelastic Steel Strains and Conclusions for the Optimization of Bond","authors":"R. Eligehausem, J. Ožbolt, U. Mayer","doi":"10.14359/5872","DOIUrl":"https://doi.org/10.14359/5872","url":null,"abstract":"The bond betweem reinforcement and concrete should ensure high structural stiffness and small cracks in the serviceability limit state, generate small splitting forces and allow full utilization of the reinforcement ductility in the ultimate limit state. While bond behavior at service load and splitting behavior has been investigated intensively, bond behavior at large inelastic steel strains is not known very well. Therefore, in this paper the contribution of concrete between cracks at inelastic steel strains is investigated numerically based on a rational mechanical model and using realistic constitutive materials laws. The model predictions agree rather well with a large number of tst results. According to the results of the parametric study, after steel yielding the ratio of mean steel strain to the steel strain at the crack is mainly influenced by the reinforcement percentage and the shape of the steel stress-strain curve. It is much lower than at service load. Due to this lower ratio of mean steel strain to steel strain at the crack, the rotation capacity of plastic hinges and this the structural ductility is reduced significantly and may be very low if reinforcement with low ductility is used. Therefore an optimization of bond seems to be necessary. Corresponding extensive numerical and experimental studies are under way in Germany.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"132 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114202807","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":"A Dilatational-Interface Model for Bond","authors":"J. Cox","doi":"10.14359/5873","DOIUrl":"https://doi.org/10.14359/5873","url":null,"abstract":"A bond model is presented that uses an interface idealization of the bond phenomena and incorporates dilation to characterize the wedging effect of splitting failures, it may provide an approach for characterizing the observed experimental response of bond specimens in a form that can be used to better understand the progressive failure of complicated structural components. Using the mathematical framework of plasticity theory, the model is defined to characterize the effects of damage in the region near the bar. The form of the model is based upon experimental results that include a variation of the confinement stress; thus, the model fully couples the tangent and normal response so that it: (1) exhibits a sensitivity to the confinement stress and (2) produces longitudinal cracking in models of bond specimens. Validation problems based on experiments from several research groups are considered to highlight the strengths and weaknesses of the model. The model reproduces the experimental data with acceptable accuracy using a single calibration, but the results also suggest that the limitations of the interface idealization merit further investigation.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123863829","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":"Bond Studies of Reinforcing Bars in Silica Fume Concrete","authors":"B. Hamad, M. S. Itani","doi":"10.14359/5890","DOIUrl":"https://doi.org/10.14359/5890","url":null,"abstract":"This paper reports on research in progress conducted at the American University in Beirut to evaluate the effect of silica fume on bond and anchorage of reinforcement in high performance concrete (HPC) structures. The program includes testing the effect of a wide range of variables on the bonded strength of beam bar splices and bars anchored in pullout specimens. Results of the first phase of the research program have been analyzed. Ten beam specimens were tested. Each beam was designed to include two bars in tension, spliced at the center of the span. The splice length was selected so that bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. The beams were loaded in positive bending with the splice in a constant moment region. The variables used were the percentage replacement of cement by silica fume and the casting position. Test results indicated that replacement of 5 to 20 percent of the cement by an equal weight of silica fume resulted in an average 8 percent reduction in bond strength regardless of casting position.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"199 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115014239","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":"Confinement Role in Anchorage Capacity","authors":"E. Giuriani, G. Plizzari","doi":"10.14359/5877","DOIUrl":"https://doi.org/10.14359/5877","url":null,"abstract":"In the present paper, the role of the confining forces both on bond capacity and on splitting crack opening under service loads is shown. In particular, theoretical relationship between the transverse reinforcement area, the bond strength, the splitting crack opening and the stirrup stress are presented. The theoretical predictions are contrasted with some experimental results and a discussion on the values provided by building codes is presented. The results show the strong influence of transverse reinforcement whose confining force is expressed by the stirrup index of cinfinement, which governs bond behavior and is suitable for design. The comparison with several experimental results showed a good agreement between theory and tests. Adequate values are also required to control splitting crack opeining under service loads. For common amounts of transverse reinforcement, the splitting crack opening can be larger than one half of the flexural crack, which could be unacceptable for structural durability.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"217 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122089531","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":"Bond Slip of Bridge Column Reinforcement Anchored in Cap Beams","authors":"S. Sritharan, J. Ingham, M. Priestley, F. Seible","doi":"10.14359/5883","DOIUrl":"https://doi.org/10.14359/5883","url":null,"abstract":"Until recently, bridge design specifications in California permitted longitudinal column reinforcement to be terminated in monolithic cap beam/column joints with straight bar development not extending fully up the joint height. Since the development length could be construed not to comply with ACI 318 requirements, it was suspected that the anchorage length provided for the column bars was insufficient to develop the full moment capacity of the column at the joint interface. considering that this detailing was widely used in bridges in California an experimental investigation was initiated at the University of California, San Diego, where response of a bridge knee joint incorporating as-built reinforcement details was examined under simulated seismic loading. Following inadequate performance of the test unit, the behavior of the knee joint was investigated based on the experimental readings, giving consideration to bond slip of the longitudinal column reinforcement. The response of the test unit indicated that the bond conditions developed when anchoring the longitudinal reinforcement of circular bridge columns is unlike that developed along the beam reinforcement anchored into building joints.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134379927","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":"Bond and Splitting: A Vexing Question","authors":"P. Gambarova, G. Rosati, C. Schumm","doi":"10.14359/5871","DOIUrl":"https://doi.org/10.14359/5871","url":null,"abstract":"Splitting does always occur in some way prior to bond failure, in the form of either partial splitting (quite often undetected) or full splitting, the latter beng the subject of several recent papers, owing to the importance of cover splitting in R/C elements. Starting from the test results on fully-split specimens (like those by the authors on special specimens having a fabricated crack) it is possible to formulate suitable bond stress-confinement stress relationships. These models can be introduced into the limit-analysis models developed lately for the description of partial splitting up to the onset of full splitting and bar pull-out in short anchorages. In this way, a linkage between the bar-concrete pressure (studied here thoughjt a limit-analysis elastic-cohesive model) and the bond stress is estabhlished, in order to evaluate the ultimate bond capacity and to investigate the transition from a splitting-type failure to a pull-out failure. At the same time, such important topics as concrete tensile strength and fracture energy, crack cohesion and localization, concrete cover and bar diameter, fiber content and external pressure can be incorporated into the model. A set of diagrams showing the bond capacity and crack number/opening/penetration versus concrete cover is presented, and the design implications of both the theoretical and experiments results are discussed.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116347760","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":"Bond of FRP Reinforcement in Concrete: A State-of-the-Art in Preparation","authors":"R. Tepfers","doi":"10.14359/5891","DOIUrl":"https://doi.org/10.14359/5891","url":null,"abstract":"The Comite Euro-International du Beton (CEB) has set up under its Commission 2 \"Material and Behavior Modelling\" a Task Group TG 2/5 \"Bond Models\" with terms of reference to write a State-of-the-Art report. Chapter 8 in the report will deal with bond of non-metallic reinforcement, FRP. The work has been started using the Japanese State-of-the-Art knowledge presented. Now research experience is added. The bond concept elaborated for steel rebars is used to interpret the action of the FRP rods/bars. The different bond influencing factors are discussed also for FRP rods/bars. Comparison is performed with steel rebars. The bond of FRP rod/bar depend on more parameters than bond of steel. Variables of interest are form of rod/bar section, type of surface deformations and treatment, modulus of elasticity, Poissons ratio etc. Therefore it is appropriate to use the known bond action of deformed steel rebars in its different stages as a reference, when investigating the bond performance of FRP rods/bars.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133920131","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":"Evaluation of Bond Performance in Reinforced Concrete Structures","authors":"S. Mccabe, S. Pantazopoulou","doi":"10.14359/5870","DOIUrl":"https://doi.org/10.14359/5870","url":null,"abstract":"The increasing significance of performance-based criteria in modern structural design has motivated new considerations in bond design of conventional reinforcing steels, relating to more reliable assessment of both the demand and the supply side of the anchorage/development design problem. Accurate identification of the required anchorage lengths needed to ensure strain compatibility, by proper consideration of the conditions affecting bond, is necessary to limit slippage of the steel relative to the concrete. While minimum development lengths calculated by designers imply that the bar is fully anchored, it is well established by experimental observation that in practice there is always some bar slip. Recent research results from around the world provide the basis for improved understanding of the effects on bond performance of critical parameters such as confinement, spacing, and material properties. Much of this work has been empirical in nature and the applicability of empirical design expressions in calculations is limited. Nonlinear finite element calculations and other sophisticated analysis requires more information as to how bond failure proceeds than simply an upper limit. This paper will summarize the available information that exists both within North America through ACI within the CEB as to the viable approaches and philosophies that can be applied to the bond problem. The range of application of the various techniques will be identified as will limitations and needs for more research.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133518310","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":"Overview of Research to Improve the Development Characteristics of Reinforcing Bars","authors":"D. Darwin, J. Zuo, M. Tholen","doi":"10.14359/5882","DOIUrl":"https://doi.org/10.14359/5882","url":null,"abstract":"The results of the first major reevaluation of reinforcing bar geometry in the United states in nearly 50 years is described. The study involves experimental and analytical efforts designed to broaden the understanding of factors that control bond strength, improve the development characteristics of reinforcing bars, and develop practical design expressions that more accurately represent development and splice strength than exisiting expressions. The research has established that deformation pattern has little effect on the bond strength of uncoated bars that are not confined by transverse reinforcement. Deformation pattern, however, as represented by the relative rib area, does have a major effect on the bond strength of bars that are confined by transverse reinforcement. Increases in relative rib area, obtained with either higher ribs, closer ribs, or a combination thereof, result in an improved bond strength for confined bars. The study has also established limits on how closely ribs can be placed without resulting in pullout failure. High relative rib area bars provide a reduction in development/splice length of 20 percent for all coated bars, independent of the presence or absence of confining transverse reinforcement. Based on the experimental work, expressions are developed that accurately characterize development/splice strength. The resulting design expressions are accurate for compressive strengths between 2500 and 16,000 psi (17 and 110 MPa). The most accurate representation of the effect of transverse reinforcement on bond strength include parameters that account for the number of transverse reinforcing bars that cross the developed/spliced bar, the area of transverse reinforcement, the number of bars developed or spliced at one location and the relative rib area, and size of the developed/spliced bar. The yield strength of the transverse reinforcement does not play a measurable role. Practical comparisons illustrate reductions in splice lengths of 20 percent for conventional bars and 30 percent for high relative rib area bars to current requirements in ACI 318-95.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121294448","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":"Performance of Concrete Bridge Decks and Slabs Reinforced with Epoxy-Coated Steel Under Repeated Loading","authors":"H. Hasan, D. Cleary, J. Ramirez","doi":"10.14359/5886","DOIUrl":"https://doi.org/10.14359/5886","url":null,"abstract":"This experimental study addresses the performance of reinforced concrete slabs containing epoxy-coated reinforcement subjected to high-cycle/low stress range repeated loading typical of those encountered in bridge decks. The behavior under repeated load indicated that epoxy-coated reinforcement does not significantly increase deflections despite the larger bar slip associated with wider cracks. The wider cracks do increase the potential for increased amount of corrosive agent at the level of the rop mat of reinforcement in bridge decks. The average bond strength ratios of coated to uncoated specimens support a proposed single modification factor of 1.35 for specimens with lower cover.","PeriodicalId":273104,"journal":{"name":"SP-180: Bond and Development of Reinforcement - A Tribute to Dr. Peter Gergely","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1996-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129338202","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}