A Beginner's Guide to Structural Mechanics/Analysis

Qualitative Influence Lines

(c) 2026, T. Bartlett Quimby

Section IL.6

Homework Problems

Last Revised: 02/18/2026

Solutions to Homework Problems: BGSMA_IL_HWSolutions.pdf

Problem IF.1: For each of the beams shown in Figures IF 6.1-6.4, sketch the influence lines for

1. Each Reaction
2. Shear on each span
3. Moment at the middle of each span
4. Moment at each support

Figure IF 6.1: Simply Supported Single Span Beam

Figure IF 6.2: Simply Supported Beam with One Cantilever End

Figure IF 6.3: Simply Supported Beam with Two Cantilever Ends

Figure IF 6.4: Simply Supported Three Span Continuous Beam

Problem IF.2: For each of the beams shown in Figures IF 6.1-6.4, sketch the unique loading diagrams for maximum positive and negative effect for the locations specified below, assuming a uniformly distributed live load.

1. Each Reaction
2. Shear on each span
3. Moment at the middle of each span
4. Moment at each support