Question
Download Solution PDFAs per IS code, calculate the negative moment coefficient in the case of the two-way slab, if the positive moment coefficient is 0.3.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcepts:
Moment coefficient:
As per IS code method of two-way slab design with continuous edges, the positive moment coefficient is ¾ times of corresponding negative moment coefficient.
As per IS code method of two-way slab design with discontinuous edges, the negative moment coefficient is 0.
Note:
Coefficient Method for design of two–way slab
The coefficient method employs tables of moment coefficients for different slab edge conditions. The conditions are based on elastic analysis but inelastic redistribution is accounted for as well.
According to the coefficient approach, the slab is divided into the middle strip and column strip in each direction. The width of the latter is equal to one-quarter of the panel width whereas the width of the former is one-half the panel width.
Calculation:
Given data
The positive moment coefficient = 0.3
As per IS code method of two-way slab design with continuous edges,
the positive moment coefficient is ¾ times of corresponding negative moment coefficient.
The negative moment coefficient
= \(0.3 \times 4 \over 3\) = 0.4
Hence, according to the given options, the correct answer is 0.45.
Important Points
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 |
\(-\left( {\frac{{{w_l}}}{9} + \frac{{{w_d}}}{{12}}} \right){L^2}\) |
Last updated on May 19, 2025
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