![]() See Notes on Soft Metric Reinforcing Bars on of this report. Code Eq in Section includes the effects of several of the major variables: * Due to equipment limitations, the notation, L d, is used throughout this report for the tension development length of a straight bar rather than ACI 318 s script ell. Section This section presents a general approach in which particular values of concrete cover and bar spacing as well as the amount of transverse reinforcement is taken into account. If the structural member is a beam or a column, another consideration is the amount of stirrups or ties being provided throughout the distance L d. Concrete cover and clear spacing of the bars are compared with the limiting values under the Conditions heading of Table 1. The applicable expression is based on: Bar size expressions are given for #10 through #19 bars, and for #22 bars and larger. Use of Section requires selection of the applicable expression from the four expressions given in Table 1. ![]() The expressions for calculating L d are reproduced in Table 1. Section This section provides a short-cut approach for calculating L d. Therefore, discussion of Sections and in ACI is the thrust of this report. This reference to the 1989 Code was removed in Commentary Section R12.2 of the 2002 Code. This report discusses the provisions in ACI Several examples are presented to demonstrate application of the two procedures for calculating L d ACI Building Code Under ACI, as with the 19 Codes, the Architect/Engineer has a choice of two procedures for calculating L d, which are presented in Code Sections and There were actually three acceptable procedures in the 19 Codes, because Commentary Section R12.2 in those Code editions sanctioned the use of the provisions in the 1989 Code. No technical revisions were introduced in the 1999 edition or in the current 2002 edition, i.e., the provisions for calculating L d in the 2002 Code are the same as those in the 19 Codes. These variables include: Bar size Yield strength of the bar Compressive strength of the concrete Lateral spacing of the bars Concrete cover Bar position other bar or top bar Type of concrete normal-weight or lightweight aggregate Uncoated or epoxy-coated bars Since the 1971 Code, major changes were made to the provisions for calculating L d in the 19 editions. Provisions in Chapter 12 of the Code attempt to account for the many variables affecting the tension development length, L d *, of a straight bar. The concept of development length of reinforcing bars was introduced in the 1971 ACI Building Code. The ACI Code cites Structural Welding Code Reinforcing Steel (ANSI/AWS D1.4-98) as the standard for welding reinforcing bars. Further information on mechanical splices is presented in the CRSI publication, Reinforcement Anchorages and Splices, 4th Ed., Commentary Section R3.5.2 of the Code discusses welded splices. Regarding Item (i), provisions in other parts of the Code include performance requirements for mechanical and welded splices. The basic premise is the anchorage length or embedment length must be equal to or greater than the required tension development length of the bar. A reinforcing bar must be embedded or anchored a sufficient distance or length in concrete so the bar will be capable of developing its design strength. Anchorage length can also be called embedment length. ![]() Two items, 1.2.1(h) and 1.2.1(i), are concerned with anchorage and splicing of reinforcement: (h) Anchorage length of reinforcement and location and length of lap splices (i) Type and location of mechanical and welded splices of reinforcement This report focuses on Item (h), i.e., on determining tension development lengths and tension lap splice lengths of reinforcing bars. ![]() 1 ENGINEERING DATA REPORT NUMBER 51 Tension Development and Lap Splice Lengths of Reinforcing Bars under ACI A SERVICE OF THE CONCRETE REINFORCING STEEL INSTITUTE Introduction Section in the 2002 ACI Building Code lists 13 items that must be shown on design drawings or in project specifications. ![]()
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