Types of Ties for Concrete Rebar Reinforcement

Tie wire is used to hold rebar in place to ensure that when concrete is placed the bars do not shift out of position. Sixteen gauge wire is used to tie reinforcing bars. About 12 pounds (5.4 kg) of wire is required to tie an average ton of bars.

A number of different types of ties can be used with reinforcing bars; some are more effective than others. The illustration shows six types of ties that are identified according to the letters of the alphabet used to show individual ties.

* SNAP, OR SIMPLE, TIE. (view A) — The snap, or simple tie is simply wrapped once around the two crossing bars in a diagonal manner with the two ends on top. The ends are then twisted together with a pair of side cutters until they are very tight against the bars. Finally, the loose ends are cutoff. This tie is used mostly on floor slabs.


* WALL TIE. (view B) — The wall tie is made by taking one and one-half turns around the vertical bar, then one turn diagonally around the intersection. The two ends are twisted together until the connection is tight, then the excess is cut off. The wall tie is used on light vertical mats of steel.


* DOUBLE-STRAND SINGLE TIE. (view C) — The double-strand tie is a variation of the simple tie. It is favored in some localities and is especially used for heavy work.


* SADDLE TIE. (view D) — The wires of the saddle tie pass half way around one of the bars on either side of the crossing bar and are brought squarely or diagonally around the crossing bar. The ends are then twisted together and cut off.


* SADDLE TIE WITH TWIST. (view E) — The saddle tie with twist is a variation of the saddle tie.The tie wire is carried completely around one of the bars, then squarely across and halfway around the other, either side of the crossing bars, and finally brought together and twisted either squarely or diagonally across. The saddle tie with twist is used for heavy mats that are to be lifted by crane.


* CROSS, OR FIGURE-EIGHT, TIE. (view F) — The cross, or figure-eight, tie has the advantage of causing little or no twist in the bars.

Lapping reinforcement in concrete

All forms of steel reinforcement must be lapped in accordance with AS 2870 requirements. The overlaps should be held together with tie wire.
Trench mesh laps; Where trench maps are joined end to end, they need to be overlapped by at least 500 mm. Where they overlap at T or L intersections the overlap should be the width of the trench mesh

Reinforcing bar lap; Reinforcing bar laps need to be overlapped by at least 500 mm

Square mesh lap; Square mesh lap has to be overlapped by at least 225 mm

Are you looking for a easy way to calculate concrete materails

yd-mv.com has come up with a page that has the ability to do calculation for us. pages can calculate concrete volume, materials and cost, and the other page which can calculate beams reinforcement in bars and in Kilograms. it can also calculate the aprox budget your gonna need for the job. very useful when doing a BOQ.

according to engineer this page has been very useful to their customs.

the link for concrete volume and material is ; http://yd-mv.com/estimation.html
the link for reinforcement and material is ;http://yd-mv.com/steel%20calculation%20on%20beam.html

enjoy :-)

Monster Foundation

The 800-meter (1,827 feet) Burj Dubai will need the mother of all foundations to support a super-structure that is expected to weigh 500,000 tons. The tower will rest on a 3.7m-thick triangular frame foundation supported by 192 rounded steel piles or support cylinders measuring 1.5m in diameter and extending 50m (164 ft.) below the ground.

Bitumen coating on pile to educe skin friction

The settling soil imposes dragload on piles and may cause excessive settlement of pile foundation. The large magnitude of dragload may necessitate higher pile cross section and/or deeper pile penetration which increase the cost. The pile design must ensure that the dragload is accommodated without causing any structural distress and excessive settlement of pile. In the past various methods have been adopted to reduce the dragload depending upon the field condition. Coating the pile with bitumen is the most economical method for reducing the negative skin friction (Baligh et al., 1978).

The effectiveness of slip layer in reducing dragload depends on the characteristics of the pile, the type of soil strata through which pile passes and the properties of coating material itself. In case of fine grained soils, the shearing behavior depends on the average rate of soil settlement. In case of coarse grained soils, soil particles may penetrate into the coat during pile driving. The particle penetration may adversely affect the efficiency of coat in reducing the skin friction. The ideal coating material should have low viscosity to permit the slippage of soil surrounding the pile shaft and at the same time it should have adequate strength to adhere the pile shaft during storage and pile driving. The cost of coated pile can be much higher than that of uncoated pile (Briaud and Tucker, 1997).

The granular soil penetrates into coat during pile driving and may result in scrapping off the coat and higher skin friction. Therefore it is important to study the effectiveness of coating material in reducing the interface friction between pile material and granular soil. The selection of type of coat and thickness forms an important aspect of pile design for dragload mitigation and overall economy of the project. In the case of uncoated pile surface the frictional resistance is found to increase with the normal stress (or radial stress) whereas for the coated surface the frictional resistance is practically independent of the normal stress.