Maximum bending Moment and Maximum Shear Stress Question

[coolguy16]

Is the maximum bending moment and maximum shear stress an absolute value? For example, when drawing out a bending moment diagram say if I get -400 kNm at one point and 300 kNm at a different point. If these values are the maximum/minimum points on my diagram would 400 kNm be considered as a maximum bending moment? Does the same method apply for shear force also?

Thanks

 

[PhanthomJay]

You wouldn't want to design a uniform beam for +300 moment when you have a -400 moment, so in that sense, use the absolute value for the max. But plus and minus moments tell you about the curvature of the beam (concave or convex) so you can't just ignore the signage . Same for shear in terms of using the larger magnitude if you are looking for the max

 

[coolguy16]

Ok perfect. Thanks so much.