[PDF] Compression And Tension Lap Splices In Reinforced Concrete Members Subjected To Inelastic Cyclic Loading eBook

Author : Mouhamad Youssef Mansour
Publisher :
Page : 214 pages
File Size : 20,28 MB
Release : 1994
Category : Concrete construction
ISBN :

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A tension lap splice is a common and necessary detail in reinforced concrete construction. A noncontact lap splice also called spaced splice, is a structural detail in reinforced concrete that provides continuity to the reinforcement by overlapping the ends of the steel without the bars touching. The subject of bar spacing in tension lap splices is addressed in the ACI Building Code and Commentary. Section 12.14.2.3 of the code states that "bars spliced by noncontact lap splices in flexural members shall not be spaced transversely farther than one-fifth the required lap splice, nor 6inches". The current provision limiting the spacing of noncontact lap splices was based on experience as well as on limited research performed before 1971. The objective of this study is to perform wider scope research on slab specimens to check the requirements of the ACI Building Code and provide recommendations. Slab specimens were designed to include three bars in tension, spliced at the center of the span. The splice length was selected so that the bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. The slabs were loaded in positive bending with the splice in a constant moment region. The materials used in the experimental program were typical of those used in current construction practices. The main variable was the center-to-center spacings of bars in each splice.

Author : Ahmad Ali Rteil
Publisher :
Page : 306 pages
File Size : 10,22 MB
Release : 2002
Category :
ISBN :

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The deterioration of reinforced concrete structures is increasingly becoming a serious problem facing the infrastructure worldwide. To prolong the service life of existing structures, fiber reinforced polymer (FRP) sheets are being used. On the other hand, research reported in the literature indicates that a mechanism should exists which would confine the tension lap splices in high strength concrete (HSC) in order to have a more ductile failure and to increase the capacity of the lap splice. The main objective of this research is to assess the effect of FRP wraps in improving the serviceability and ultimate response of bond-critical regions in reinforced concrete members. The lack of research reported in the literature on the effect of the FRP wraps on bond strength makes this study significant. Moreover, the research will provide important design information that facilitates the introduction of FRP into design codes and encourage the use of this new technology. To meet the objective, 10 full-scale high strength concrete beam specimen were tested. Each beam was designed with 20-mm bars spliced in a constant moment region at midspan. The variables were: FRP type (glass or carbon), number of layers of FRP (1 or 2), and the configuration of FRP wraps placed in the splice region. Results of the study indicated that FRP wraps have similar effects to those of steel fibers and transverse steel reinforcement in confining the splices in HSC beam specimen. The brittle mode of failure is modified to a more ductile one. More bar lugs along the spliced bars are allowed to participate in the stress transfer between steel and concrete, and the average splitting bond strength is increased. Finally, a new index, Ktr, f, accounting for the presence and amount of FRP confining tension lap splices in HSC beams was proposed.

Author : William F. Vanaskie
Publisher :
Page : 121 pages
File Size : 43,96 MB
Release : 1978
Category : Epoxy resins
ISBN :

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For the past 30 years an area of major concern to engineers has been the strength of spliced reinforcement in reinforced concrete construction. This investigation used an epoxy emulsion to form a polymer-portland-cement concrete (PPCC), which was cast around tension lap splices in reinforced concrete beams. The beams, with varying length of lap splice, were tested with the splice located in a constant moment zone. The results showed that the strength of the splice can be increased by as much as 50 percent in ultimate load carrying capacity by use of the PPCC. Calculations also indicate that the required development length of the reinforcing steel in the PPCC is approximately one-half of that in ordinary concrete. These conclusions do not reflect, however, the physical properties of the material. Although the test beams acted favorably, the tensile strength of the PPCC at age seven days was 602 psi (42.3 Kg/sq cm), which was only a 3 percent increase over the cement concrete. However, the average bond stress was calculated to have an average increase of 200 psi over the cement concrete. The PPCC exhibited a failure pattern which allowed the ductility of the member, even at short splice lengths, to be superior to that of the control beams. The investigation indicates that this type of construction can readily be adapted to field use without additional costs in labor and with a savings in time and steel over other types of polymer modified concrete. (Author).