Please help me solve this problem neatly with explanations! I do not know how to
ID: 1711697 • Letter: P
Question
Please help me solve this problem neatly with explanations! I do not know how to get this started! Thank you so much!
3. Consider the following frame: M1 wb= 1.5 km wi-2k/ft M2 am 24" deep 14" wide (isolated rect. beam) 19-0" umns- 14" by 14" Unfactored Moments End Moment (M 288 in-k Mid-span Moment (M) Dead 198 in-k 384 in-k Live 264 in-k 18-0 M2 6 kips M2 Exploded Moment Diagram M2 684 in-k Draw the moment envelop for the beam considering the following load combinations: U = 1.4D U=1.2D + 1.6L 2, 3, U = 1.2D + 1.0L + 1.0W Which load combination controls for the following locations: a) Midspan positive moment b) End of beam negative moment c) End of beam positive moment Consider that the wind can blow from either direction.Explanation / Answer
Let us determine design positive moment at midspan
momenrt at midspan due to dead load = D=198 k-in
moment at midspan due to live load = L=264 k-in
moment at midspan due to wind load = 0
Design moment per compination 1.4D = 1.4*198 = 277.2 k-in
Design moment per combination 1.2D+1.6L = (1.2*198)+(1.6*264) = 660 k-in
Design moment per combination 1.2D+1L+1W = (1.2*198)+264+0 = 501.6 k-in
Therefore design moment of midspan = 660 k-in
Let us determine design negative moment at beam end
moment at beam end due to dead load = D=-288 k-in
moment at beam end due to live load = L=-384 k-in
negative moment at beam end due to wind load = -684 k-in
Design moment per compination 1.4D = 1.4*(-288) = -403.2 k-in
Design moment per combination 1.2D+1.6L = (1.2*-288)+(1.6*-384) =-960 k-in
Design moment per combination 1.2D+1L+1W = (1.2*-288)+-384+-684 = -1413.6 k-in
Therefore negative design moment of beam end = -1413.6 k-in
Let us determine design positive moment at beam end
moment at beam end due to dead load = D=-288 k-in
moment at beam end due to live load = L=-384 k-in
positive moment at beam end due to wind load = 684 k-in
Design moment per compination 1.4D = 1.4*(-288) = -403.2 k-in
Design moment per combination 1.2D+1.6L = (1.2*-288)+(1.6*-384) =-960 k-in
Design moment per combination 1.2D+1L+1W = (1.2*-288)+-384+684 = -45.6 k-in
Therefore positive moment doesn't develop at beam end for any given load combination