For a tension member plate of width b and thickness t with staggered rivet holes, what is the correct expression for the net sectional area A_net in terms of staggered pitch p, gauge distance g, number of holes n, number of gauge spaces m, and rivet diameter d?
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AA_net = b*t − n*d*t + (p^2 / (4g))*m*t
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BA_net = b*t − n*d*t
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CA_net = b*t − (n−1)*d*t
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DA_net = b*t − n*d*t − (p^2 / (4g))*m*t
Answer
Correct Answer: A_net = b*t − n*d*t + (p^2 / (4g))*m*t
Explanation
Introduction / Context:In riveted tension members, gross area is reduced by rivet holes. For staggered pitch, some strength is regained due to the zig-zag path. IS:800 specifies an effective net area formula considering both direct hole deduction and staggered layout benefit.
Given Data / Assumptions:
- b = plate width
- t = plate thickness
- n = number of rivet holes in zig-zag line
- m = number of gauge spaces in zig-zag line
- d = gross diameter of rivet hole
- p = staggered pitch
- g = gauge distance
Concept / Approach:Gross area = b*t. Hole deductions = n*d*t. Staggered arrangement adds a term (p^2 / (4g)) * m * t to account for the zig-zag path.
Step-by-Step Solution:Start with gross area: A_g = b*tDeduct holes: n*d*tAdd stagger correction: (p^2 / (4g)) * m * tNet area: A_net = b*t − n*d*t + (p^2 / (4g)) * m * t
Verification / Alternative check:Matches IS:800 and standard design handbooks for staggered connections.
Why Other Options Are Wrong:
- b*t − n*d*t: ignores staggered benefit
- b*t − (n−1)*d*t: incorrect deduction
- Negative stagger term: physically impossible
Common Pitfalls:Using clear hole diameter instead of gross; forgetting to add stagger term; mixing up m (spaces) vs n (holes).
Final Answer:A_net = b*t − n*d*t + (p^2 / (4g))*m*t