The 'influence line' for the support reaction RA of a simply supported beam at A has ordinate:
Choose the correct answer
Always 1.0 regardless of load position
(L-x)/L at distance x from A — linear from 1 at A to 0 at B
x/L at distance x from A
Constant 0.5 throughout
Correct Answer
B. (L-x)/L at distance x from A — linear from 1 at A to 0 at B
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IL for reaction RA of SS beam: when unit load is at distance x from A (span L): RA = (L-x)/L. So IL ordinate at A = 1.0, at B = 0, linear variation. When unit load at A: RA=1, RB=0. When load at B: RA=0, RB=1. To find max reaction: load placed where IL is maximum (= at A gives RA=1). Muller-Breslau: IL = deflected shape with support removed and unit settlement applied.
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