- 2080 Chaitra · 6 marks
ILD for SF and BM at C of beam
Short answer
Using influence lines, bending moment at C is -190 kN m (hogging). Shear force is -67.5 kN just left of C and +70 kN just right of C.
Determine the shear force and bending moment at C in the given loaded beam using ILD. Take EI constant throughout the beam. [Figure: beam with hinge A at the left and a roller support C; AB = 2 m, BC = 2 m, then D, E, F at 1 m each; 40 kN load at B, 5 kN/m UDL over the portion around C to E, 60 kN load at F at the free end. Details partly unclear.]
Assumptions (figure partly unclear): beam –– is supported by a hinge at and a roller at ( m, span m), with an overhang ––– of 3 m (1 m each). Loads: 40 kN at ; 5 kN/m UDL from to (2 m); 60 kN at (free end). The section is taken at the support .
Reactions (for checking)
: kN; kN (uplift).
ILD for bending moment at C
Load at distance from . For , (the load is carried directly by the supports). For , (hogging).
A o---B-----o C---D---E---F
ILD(M_C): 0 0 0 -1 -2 -3
ILD for shear at C
Just left of C: ordinate for (so at and as the load approaches ); for the overhang ( at , at , at ).
Using ordinates: UDL area from to , so
Just right of C: ordinate 0 for loads on the span, and 1 for loads on the overhang:
Check by statics: kN and kN.
Answer: kN m (hogging); kN just left and kN just right of .
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Cantilever ILD for SF and BM at C · Theory of Structures I, chapter 5
- Arch: reactions, BM, thrust and shear at D by ILD · Theory of Structures I, chapter 6
- ILD at mid-span: BM and SF under given loads · Theory of Structures I, chapter 5
- Suspension 120 m: UDL on left half, SF and BM at 30 m · Theory of Structures I, chapter 7 · asked 2×
- Overhang beam ILD for shear force at C · Theory of Structures I, chapter 5
- ILD: RA, RB, SF and BM at C · Theory of Structures I, chapter 5
- ILD: bending moment at fixed support, 10 m beam · Theory of Structures II, chapter 4
- ILD: moment at support B, fixed-propped beam · Theory of Structures II, chapter 4
- ILD: bending moment at B, two-span beam · Theory of Structures II, chapter 4
- ILD: moment at middle support, two-span beam · Theory of Structures II, chapter 4