The minimum lap length for compression bars must be 12inches. The lap length for compression lap splice is calculated as per ACI 12.16.1 as Where, ld= development length, which is calculated as per ACI 12.2 ( Without taking into consideration the modification factor).The minimum lap length is 12 inches 3. As per ACI 318, the tension lap splices are classified into two classes Class A and Class B ( Table R12.5.2, ACI 318) for which the lap length are as follows: Hence, the lap splice, in this case, shows varied interaction depending on the concrete strength, grade of steel reinforcement, location, bar size ,and spacing. This hence results in a continuous line of reinforcement. In a tension lap, the force is transferred from the reinforcement bars to the concrete by the bond which in turn force back to the reinforcement. The lap splice length in tension reinforcement is calculated as per ACI 12.15. TABLE R12.15.Also Read: Methods of Splicing Reinforcement Bars 2. (b) one-half or less of the total reinforcement is spliced within the required lap length. Twice that required by analysis over the entire length of the splice and Table R12.15.2 presents the splice requirements in tabular form as presented in earlier code editions. Tensile bar stress Splice details Splice type 0. Table 10.7.5.2.2Tension lap splice class. Lap splices, mechanical splices, butt-welded splices, and end-bearing splices shall be permitted. R12.15.2 - The tension lap splice requirements of 12.15.1 encourage the location of splices away from regions of high tensile stress to locations where the area of steel provided is at least twice that required by analysis. Chapter 1 General Chapter 2 Notation and Terminology. (a) the area of reinforcement provided is at least Committee 318 considered suggestions from many sources, including ACI Committee 408, but has retained a two-level splice length primarily to encourage designers to splice bars at points of minimum stress and to stagger splices to improve behavior of critical details.ġ2.15.2 - Lap splices of deformed bars and deformed wire in tension shall be Class B splices except that Class A splices are allowed when: Thus, the Class C splice was eliminated although development lengths, on which splice lengths are based, have in some cases increased. The 1989 code contained several changes in development length in tension that eliminated many of the concerns regarding tension splices due to closely spaced bars with minimal cover. For staggered splices, the clear spacing is taken as the minimum distance between adjacent splices. R12.15.1(a) illustrates the clear spacing to be used. For splices in columns with offset bars, Fig. When multiple bars located in the same plane are spliced at the same section, the clear spacing is the minimum clear distance between the adjacent splices. The development length ld used to obtain lap length should be based on fy because the splice classifications already reflect any excess reinforcement at the splice location therefore, the factor from 12.2.5 for excess As should not be used. R12.15.1 - Lap splices in tension are classified as Type A or B, with length of lap a multiple of the tensile development length 1d. Where ld is calculated in accordance with 12.2 to develop fy without the modification factor of 12.2.5. R12.15 - Splices of deformed bars and deformed wire in tensionġ2.15.1 - Minimum length of lap for tension lap splices shall be as required for Class A or B splice, but not less than 12 in., where: 5 bars and smaller due to the potentially brittle nature of failure at these welds. The 1995 code limited these lower strength welds and connections to No. Therefore, lap welds of reinforcing bars, either with or without backup material, welds to plate connections, and end-bearing splices are allowed under certain conditions. R12.14.3.5 - The use of mechanical or welded splices of less strength than 125 percent of specified yield strength is permitted if the minimum design criteria of 12.15.4 are met. The 1995 code eliminated a requirement that the bars be butted since indirect butt welds are permitted by ANSI/AWS D1.4, although ANSI/AWS D1.4 does indicate that wherever practical, direct butt splices are preferable for No. See the discussion on strength in R12.14.3.2. The tensile strength requirement of 125 percent of specified yield strength is intended to provide sound welding that is also adequate for compression. R12.14.3.4 - A full welded splice is primarily intended for large bars (No.
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