Question

The positive bending moment coefficient at the middle of the end-span of a continuous one way slab is
1. \(\left( {\frac{{{w_l}}}{{10}} + \frac{{{w_d}}}{{12}}} \right){L^2}\)
2. \(\left( {\frac{{{w_l}}}{9} + \frac{{{w_d}}}{{10}}} \right){L^2}\)
3. \(\left( {\frac{{{w_l}}}{{12}} + \frac{{{w_d}}}{{16}}} \right){L^2}\)
4. \(\left( {\frac{{{w_l}}}{9} + \frac{{{w_d}}}{{12}}} \right){L^2}\)

Answer 1

Correct Answer - Option 1 : \(\left( {\frac{{{w_l}}}{{10}} + \frac{{{w_d}}}{{12}}} \right){L^2}\)

Concept

 w_L= Live load

w_d = Dead load

As per Table 12 of IS-456:2000, the bending moment coefficients for dead and live load are given below:

Location	BM Coefficients for dead load	BM Coefficients for Live load	Bending moment
Middle of end span	1/12	1/10	\(\left( {\frac{{{w_l}}}{{10}} + \frac{{{w_d}}}{{12}}} \right){L^2}\)
Interior support of end span	-1/10	-1/9	\(-\left( {\frac{{{w_l}}}{9} + \frac{{{w_d}}}{{10}}} \right){L^2}\)
Middle of intermediate span	1/16	1/12	\(\left( {\frac{{{w_l}}}{{12}} + \frac{{{w_d}}}{{16}}} \right){L^2}\)
Interior support of intermediate span	-1/12	-1/9	\(-\left( {\frac{{{w_l}}}{9} + \frac{{{w_d}}}{{12}}} \right){L^2}\)

 

∴ Option 1 is correct