Shear Reinforcement 1

[PowerRanger]

Hi Fellows

This seems a silly question.

I remember one times I read a book talk about the stirrup, stirrup not just use for shear reinforcement, also use for holding the compressive and tensile Reo. in position when bending (resist the compressive Reo buckle outside). And this is why the AS3600, 8.2.12 limit the max. spacing for the shear reinforcement.

Do my understand right? I just can't remember which book is talking about this.

Thx.

Marco

 

[dbuzz]

There are two clauses in AS 3600 regarding limits on the spacing on stirrups.

8.1.8.7 Restraint of compression reinforcement
Compression reinforcement required for strength in beams shall be adequately restrained by
fitments in accordance with Clause 10.7.3.

This clause, which refers to the requirements for the design of columns, limits the possibility that longitudinal bars in compression will buckle outwards. The maximum spacing for ties is 15d[sub]b[/sub] for single bars and 7.5d[sub]b[/sub] for bundled bars, which will generally be less than the spacing needed for shear reinforcement at midpsan.

8.2.12.2 Spacing
Shear reinforcement shall be spaced longitudinally not further apart than 0.5D or 300 mm,
whichever is less. Where V* ? ?Vu.min, the spacing may be increased to 0.75D or 500 mm,
whichever is less.

The maximum transverse spacing across the width of the member shall not exceed the lesser
of 600 mm and D.

This limit on the spacing of shear reinforcement is to ensure that a potential failure surface intersects one or more stirrups, reducing the concentration of compressive forces in the web strut.

Not to mention that that the stirrups also hold the longitudinal reinforcement together in a cage during the placement and hardening of concrete.