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ESTIMATING METAL REINFORCEMENT
Steel Bars
• Steel is the most widely used reinforcing materials for almost all types of concrete construction.
• It is an excellent partner of concrete in resisting both tension and compression stresses.
• Steel is ten times stronger than concrete in resisting compression loads.
• Steel is 100 times stronger than concrete in resisting tensile stresses.
• The design of concrete assumes that concrete and steel reinforcement acts together in resisting load and likewise to be in a state of simultaneous deformation.
BAR SPLICE, HOOK AND BEND
• In estimating reinforcing bars, one has to consider the additional length for the hook, the bend and the splice whose length varies depending upon the limitations as prescribed by the National Building Code.
Types of reinforcement Minimum splice length
Tension Bars 25 x bar size + 150 mm
Compression Bars 20 x bar size + 160 mm
• Example: determine the length of splice joint for a 16mm and 20 mm steel bars under the following conditions:
• Tensile reinforcement of a beam• Compressive reinforcement of a column
Various type of metal reinforcements that an estimator should be familiar
with:
• Concrete hollow block reinforcement• Footing reinforcements• Post and column reinforcements• Beam and girder reinforcements• Floor slab reinforcements
Reinforcement of CHB
• Could be determined in three ways:• Direct counting method• Area method• Unit block method
• From figure 3-6, determine the number of • 10x20x40 cm CHB• Vertical reinforcements spaced at 80 cm• Horizontal reinforcement at every 3 layers.• (use 6m commercial length for steel bars)
TIE WIRE FOR CHB REINFORCEMENT
• Tie wire refers to gauge no. 16 galvanized iron wire popularly known as GI tie wire.