Bending and Tying Rebars PDF

CTECH213 Bending rebars 9th October, 2017 Hooks and bends Parts of the bar bend  How to bend and cut rebars Bending and cutting rebar (steel concrete reinforcing bars) is often necessary when building structural reinforcement for concrete work. It is an easy to work with ma...

CTECH213 Bending rebars 9th October, 2017 Hooks and bends Parts of the bar bend  How to bend and cut rebars Bending and cutting rebar (steel concrete reinforcing bars) is often necessary when building structural reinforcement for concrete work. It is an easy to work with material that is commonly used in landscaping, art, and other projects where metal that is fairly easy to bend is required. Common rebar is sold by its diameter in 1/8th inch increments (meaning "#4" rebar is 1/2 inch in diameter).  Rebar up to #4 can often be bent and cut by hand. Larger diameter rebar is not typically used outside commercial or industrial concrete work and usually requires specialised equipment such as hydraulic shears and benders.  1. Have the correct equipment Rebar can be sharp and is heavy, and can create sparks when being cut. Always wear eye protection, sleeved shirts, long pants, gloves, and sturdy boots when handling rebar.  2. Set up a workspace Rebar comes in very long rods (typically 8–20 foot and up to 40 foot in length). Due to its length, tendency to be covered with mill scale or rust, and overall weight rebar is usually best handled in a large open area with few obstructions. Cutting rebar often creates very hot sparks so make sure the area is clear of flammable materials. The rust and sparks from rebar can ruin clothing so wear something sturdy and old.  3. Measure carefully Taking into account the overall length, any overlap (where you might tie it to another piece), and especially the curves can be a bit tricky. You may find that the first few times you bend and cut a piece of rebar it is shorter or longer than you had intended. This is often due to a failure to account for the length of the rebar through the curve. It can be tricky but you'll get the hang of it. Rebar is very easy to mark with wax crayon (if you'd like waterproof marking) or chalk (often handy in art projects where you'd like the marks to wipe off).  4. Cut your rebar Cutting rebar can be done easily with a metal cutting hacksaw blade. You can also use a reciprocating saw, portable bandsaw, or grinder equipped with a blade suitable for cutting "mild steel". Rebar tends to want to roll around when being cut, therefore it is often necessary to step on the bar or have an otherwise steady hold while cutting it. Cut rebar is always hot and/or sharp. Use gloves and caution.  5. Bending rebar 1/2” (1.3cm) or smaller Bending rebar is all about leverage. Place the rebar on the ground. Using a long metal pipe with a large enough internal diameter, place the rebar into the pipe stopping about six inches from the point you'd like to start the bend. Place your foot 6 to 12 inches (15.2 to 30.5 cm) back from where you'd like to bend. Pressing firmly down with your foot, raise the bar off the ground until the bar bends to the angle you'd like. It is often necessary to bend a piece a little at a time if you are trying to get an exact bend Plan View Beam and Column Tying Rebar  Tying Rebars Rebar is used for strength in foundations, walls and other structures that call for reinforced concrete, and the size, placement, overlap schedule and bending requirements are generally specified by the engineer or architect. The ties, or methods of joining, are commonly left to the steel installer, because the ties themselves do not add strength or structural integrity to the finished product.  Different kinds of ties, like sailing knots, are used based on contractor preference, and partially on the rigidity required. A stronger tie is used on vertical reinforcements if the steel contractor uses the form itself to reach upper levels. Tying rebar is generally done with the help of a metal hooking tool, or a simple pair of pliers that can also cut the wire tie if necessary. Each tool allows the bending, pulling and twisting of the thin wire ties to be accomplished as quickly and efficiently as possible. Different Types of Ties  1. Snap Tie The most common “knot” is a single tie, and is accomplished simply by wrapping the wire once around the joint, twisting it a couple of turns and either snapping it off or possibly cutting the long end of the wire. It is the type of tie most often used for horizontal surfaces, such as reinforced concrete foundations, and the rebar rests on chairs, cushions or pads to keep it elevated above the dirt.  2. Wrap and Snap A variation of the single is used to tie horizontal members to vertical supports in a way that prevents them from sliding down. Just as it sounds, the wire is wrapped around both members, then tied at one side and snapped clean.  3. Saddle Tie Sometimes called the “U” tie, this is just a bit more complicated than the others, and in some regions it is the preferred method. It is somewhat similar to a square knot, rather than forming a diagonal binding across the bar.  4. Wrap and Saddle A one and a half loop around the steel adds a bit more security and rigidity, but it is finished the same as the standard saddle tie.  5. Figure Eight Tie This is an alternative to the Wrap and Snap, and is a very secure tie for vertical reinforcement.  Which Tie is right for you? Ironworkers, like any other construction trade, have their own preferences, and as long as they conform to standard practices, all are sanctioned by engineers, architects and inspectors. Some use a single spool of wire that they manually cut into required lengths as needed. Others prefer a string of preformed ties, each one ready to be used as is. The same is true of tools used to cut, bend, shape and trim the reinforcing steel.  Steel bars today, either raw or coated, are also used for a variety of home and backyard purposes. Artists, furniture makers, and Do-It-Yourselfers have all discovered trendy and useful items to produce from common rebar. If you have a portable welder, a lot of imagination and some free time, it might be worth investigating.  Rebar tying tools You can use preformed ties or a single spool of tie wire that allows you to cut the lengths of wire you need as you them. A pair or pliers or a metal hooking tool can help you bend, pull, and twist the tie wire. The pliers can also cut the tie wire if needed. If you are going to be tying a significant amount of rebar, however, you should invest in a reliable rebar tier – this investment can help reduce the risk of injury and help you work faster.