Jacobs
25 - 01 Oct 2025
Match-Cast Segmental Joints
Estimated Time: 4–5 min quiz | PDH/CPD: 1.0 hr | Difficulty: Intermediate
Question
A match-cast segmental joint experiences a shear force of 2,500 kN. The joint has 4 shear keys, each with an effective area of 0.15 m². If the concrete compressive strength is 50 MPa, what is the average shear stress in the keys, and is this within typical design limits?
Shear keys transfer loads through bearing and friction. The calculated stress of 4.2 MPa is well within the typical design limit of 0.2f'c (10 MPa), ensuring adequate safety margin for joint performance.
Calculation:
Total effective area = 4 keys × 0.15 m² = 0.60 m²
Average shear stress = 2,500 kN ÷ 0.60 m² = 4,167 kN/m² = 4.2 MPa
Typical limit = 0.2f'c = 0.2 × 50 = 10 MPa ✓
Learning Resources:
ACI 343R-95, Chapter 13 - Segmental joint design and shear key requirements
fib Bulletin 81 (2017), Section 4.5 - Match-cast joint construction and quality control
VSL Post-Tensioning Systems Manual - Segmental construction joint details