Tham khảo tài liệu 'bruhn - analysis and design of flight vehicles structures episode 1 part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | A5. 6 BEAMS SHEAR AND MOMENTS The load of 1000 at 45 and applied at point Er will be referred to point E the centerline of beam. Fig. d shows the reaction at E due to the load at S . The reaction at B should also be referred to the beam centerline. Fig. shows the beam with the applied loads at points c 0 E F and Br . Figs. 18 and 19 show the axial load vertical shear and bending moment diagrams under the beam loading of Fig. . Fig. -500 lb. Fig. I 0 Axial Load Dia. lb. The shear diagram is determined In the same manner as explained before. The applied external couples do not enter Into the vertical shear calculations. The bending moment diagram can be calculated by taking the algebraic sum of all couples and moments of all forces lying to the one side of a particular section. If It Is desired to use the area of the shear diagram to obtain the bending moments it is necessary to add the couple moments to the shear areas to obtain the true bending moment. For example the bending moment just to the left of point E will be equal in magnitude to the area of the shear diagram between c and E plus the sum of all applied couple moments between c and E but not Including that at E. To illustrate the calculations are - - 500 X 5 X 10 4578 in. lb. from area of shear diagram . 3000 - 4000 - 1000 in. lb. from sum of couple moments . Thus bending moment at E 4578 - 1000 -3578 in. lb. left The bending moment at Epỉght will equal that at Eleft pl113 the couple moment at E or 3578 707 4285 in. lb. The student should realize that when couple moments are applied to a beam It Is possible to have maximum peak moments without the Vertical Shear passing through zero. To Illustrate this fact consider the beam of Fig. namely a simple supported beam with an externally applied couple moment of 10 In. lb. magnitude at point c the center point of the beam. The shear and bending moment diagrams are as Indicated and a maximum bending .
