Rules of Thumb for STM Design

Rules of Thumb for STM Design

1. At the interface of a B-region and a D-region, ensure the internal forces and moment within the B-region is applied correctly to the D-region.

2. A tie must be located at the centroid of the reinforcement that carries the tie force 

3. The angle between a strut and a tie entering the same node must not be less than 25°

4. Minimize the number and lengths of ties 
Minimize the number of vertical ties between a load and a support -> use the least number of truss panels possible while still satisfying the 25° rule.

5. The STM must be in external and internal equilibrium

6. Ensure proper reinforcement detailing -> an STM is only as good as the details.

7. Make reasonable, conservative assumptions and simplifications when necessary

8. Make everything as simple as possible, but not simpler.

1. B 영역과 D 영역의 경계에서 B 영역 내의 내부 힘과 모멘트가 D 영역에 올바르게 적용되는지 확인합니다.

2. 타이는 타이 힘을 전달하는 보강재의 중심에 위치해야 합니다. 

3. 스트럿과 타이가 같은 노드에 들어가는 각도는 25° 이상이어야 합니다.

4. 타이의 수와 길이 최소화하기 
하중과 지지대 사이의 수직 타이 수 최소화 -> 25° 규칙을 충족하면서 가능한 최소 수의 트러스 패널 사용

5. STM은 외부 및 내부 평형 상태여야 합니다.

6. 적절한 철근 상세설계 확인 -> STM은 철근 상세만큼만 우수합니다.

7. 합리적이고 보수적인 가정을 하고 필요한 경우 단순화합니다.

8. 모든 것을 가능한 한 단순하게 만들되, 더 단순해서는 안 됩니다.
 
 
출처: TxDOT Project 5-5253-01-P2
Strut-and-Tie Model(STM) Examples for Bridges

C.S. Williams D.J. Deschenes o. Bayrak