![]() ![]() Find a library where document is available.It is considered that the results would also apply to the new 410Y grade reinforcing steel. Design details for lap splice fillet welds in the 1983 SAA Structural Steel Welding Code AS 1554, Part 3, Welding of Reinforcing Steel, which provide that the weld throat thickness be given by 0.25D, have been confirmed in the present work. Comparison of these experimental results with the design approach provided in the 1983 draft unified concrete structures code DE83046 indicates that the proposed design rules lead to a strength factor of approximately two for lap splice fillet welds. It is proposed that a weld lap length of 5D be adopted as a general rule in the specification of weld sizes. ![]() The LAP SPLICE is a ground- mounted breakaway. Other classes of electrode such as E4112 rutile and higher strength weld metal such as E4818 provide matching strength at a smaller lap size but this is not of any practical advantage. The simplest, easiest-to-use and most economical breakaway signpost system. Tensile tests on lap splice fillet welded joints in 410C grade reinforcing steels have shown that matching strength to full bar strength is achieved at a total fillet weld length of 5D where D is the nominal bar diameter for weld metal deposited by E4111 cellulose coated electrodes. To stay with the codes, we use this chart for every project.THE DESIGN STRENGTH OF LAP SPLICE FILLET WELDS IN REINFORCING STEEL - AWRA CONTRACT 64, AWRA DOCUMENT P4-23-83 Refer to your reinforcing chart for your particular project. It doesn’t mean a size minimum that is determined by the engineering load.įor the major part of the shell of a small dome, use #2 Rebar, 12" on center. So if we are using 2 1/2" of concrete, we cannot separate the bars more than 12" on center. The code states that bars cannot be separated more than five times the thickness of the concrete. Question: Why don’t we just spread the bars further apart? Answer: That works but does not meet code. The cost per pound will be more, but the cost per foot will be less. They can make deformed #2 bars that generally cost far less than #3 bars because #2 rebar weighs much less. But if you can’t find #2 or it costs as much as #3 and causes more hassle, use #3.Ĭompanies that furnish fence materials usually have #2 Rebar. We are instructing our engineers to utilize #2 Rebar where possible. But fortunately the Monolithic Dome is naturally such a perfect shape for strength that #2 Rebar works in many projects for which we previously used #3. Why is it hard to buy? Extremely little #2 Rebar is used because most concrete requires larger bars on many projects. It needs to be deformed it needs to be grade sixty it needs all these wonderful things, but it is hard to buy. The #2 Rebar is 2/8" or 1/4" in diameter. Rebar comes in various sizes: #2, #3, #4, #5, #6 etc. Rebar SizingĪt Monolithic, we also pay close attention to rebar sizing. We want to keep the laps in the clear so the concrete can wrap around them. So whenever possible, we do not overlap the rebar tightly against itself. Keeping these lapping locations away from sections with high flexural/shear stresses. If it does not touch, we do an 18" overlap.Ĭonsidering the cost of rebar, these are vast differences. What is Lap Length Using proper splicing techniques. With #4 Rebar, if the bar splice will touch we do a 44" overlap. The engineering world has come up with some numbers to use for bar splices. The two bar diameters provide space for the concrete to go in, around, and between the bars and actually increase the strength. So the recommended way is to bring the bars together and overlap them, but leave at least two bar diameters between the bars. If you touch the two bars together as they overlap, it becomes more difficult for the concrete to go in and around the rebar, and the splice is not considered as strong. When splicing rebar we bring one piece to the other, overlap it a distance, and spray it in place with concrete. So we recommend that you stay away from welding. In fact when I first started, we overlapped and welded the bars together.īut it turns out that unless you’re using A706 rebar – which is very expensive – welding the rebar is not allowed. For years and years, we just overlapped the rebar and tied the bars together. Monolithic’s recommended procedure for splicing rebar has changed. ![]()
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