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The design process using STM involves five major steps described below. These steps are illustrated in Figure 7 using the design example of a dapped-ended beam.
1. |
Define the boundaries of the D-Region and determine the boundary forces (the ultimate design forces) from the imposed local and sectional forces. |
2. |
Sketch the truss, determine the equivalent boundary forces, and solve for the truss member forces. |
3. |
Select reinforcing or prestressing steel to provide the necessary tie capacity and ensure that this reinforcement is properly anchored in the nodes. |
4. |
Evaluate the dimensions of the struts and nodes such that the capacity of all struts and nodes is sufficient to carry the truss member forces. |
5. |
Provide distributed reinforcement to ensure ductile behavior of the D-Region. |
Since equilibrium of the truss with the boundary forces must be satisfied (step 2) and stresses everywhere must be below the limits (step 3 and 4), one can see that the STM is a lower-bound (static or equilibrium) method of limit analysis.
Figure 7 The Major Steps in STM Design Process
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