Structural Design Notes

STRUCTURAL DESIGN

Notes

Submitted by :

Tanya Pahwa

2K6/Arch./628

ASSIGN ON STEEL REINFORCEMENT

• What is the purpose of providing cover to the reinforcement? Give the value of clear cover for mild exposure conditions for slabs, beams, columns, footings.

• What is the difference between clear cover and effective cover to the reinforcement?

• What is the diff between overall depth and effec depth of an RCC beam. Why effec depth and not overall depth is adopted in the design of beams?

TABLE OF FLEXURE-REINFORCEMENT % FOR DOUBLY REINF SECTIONSTABLE OF FLEXURE-REINFORCEMENT % FOR DOUBLY REINF SECTIONS

WORKING STRESS METHOD M-20 CONC MIX

1. Explain the terms: One-way slab, 2-way slab, clear span, effective span, overall depth, aspect ratio, simply supported slabs, continuous slabs, cantilever slabs.

2. Give expressions for BM along short and long span of a simply supported slab of span lx=4m, ly=6m and loaded with a udl of w KN/m2.

Calc Mx and my if w=10 KN.m2.

3. Define Aspect Ratio. Explain why two-way slabs with aspect rate>=2.0 are generally designed as 1-way slabs?

4. Give general rules for detailing of reinforcement in RCC slabs.

5. Sketch typical 2-way slab, 2-way cont. slab, cantilever slabs.

• Rules for providing stirrups in beams:

– Dia. 8mm, 10mm, 12mm(rare). 2 or multilegged.

– Designed to resist shear force in beam members.

– As SF in a beam is max. at supports, spacing of stirrups is less at supports and increases at mid span.

– Max spacing of stirrups=0.75d; d=effec depth of beam

– For seismic areas, max spacing up to a distance of 2d from supports=d/4. For remaining portion of beam max spacing=d/2.