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Civil Structures
Quick questions on Stress, strain and Young's modulus: HSC Engineering Studies Civil Structures
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is definitions?Show answer
Stress is force per unit cross-sectional area:
What is stress-strain curves?Show answer
Ductile materials (mild steel, structural steel grades like 250 and 350) show a linear elastic region up to the yield point, a yield plateau, then strain hardening up to the ultimate tensile stress, then necking and fracture. Typical yield stress for grade 250 structural steel is 250 MPa; ultimate tensile strength is around 410 MPa.
What is application in civil structures?Show answer
Civil engineers use allowable stress well below the yield stress, dividing by a factor of safety of 1.5 to 3. Concrete is strong in compression (typical 32 MPa) but weak in tension (about 3 MPa), which is why it is reinforced with steel.
What is using diameter for area?Show answer
Cross-sectional area of a circular bar is , not .
What is treating concrete as ductile?Show answer
Concrete is brittle in tension. That is the entire reason for reinforced concrete: steel takes the tensile stresses.
What is reading Young's modulus from the wrong part of the curve?Show answer
is the slope of the elastic (initial linear) region only. Past yield the relationship is no longer linear. :::
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