RM Bridge, inside OpenBridge Designer, has three possible solutions for designing with cracked concrete in the tensile zone in composite structures with continuous steel girders and concrete reinforced slabs. The combination of both, Reload and No tens, allows for redistributing stresses of tension partial elements of composite elements to the other partial elements of the composite element. As a linear method it creates, just at the cross-section level, an elastic redistribution performed with Action ReloadLc, or ReloadSup, and there is no change in the analyzed structure stiffness. In this case, for the redistribution, the program assumes a complete stiffness loss of the respective partial elements when the split normal force is a tension.
- Reload: Actions ReloadLc, or ReloadSup can be found at the Analyzer\Schedule\Schedule Actions\Actions\Calculations\Static and are used to reload the load or superposition file and redistribute them into the cross-section planes resulting in new internal forces that are now considering the concrete cracked tension zones.
- No tens: The Elements could be selected at Analyzer\Structure\Elements\Checks with the Class as No tens, meaning that it cannot carry tensile forces and the redistribution is needed for those elements. Normal Class Partial Elements, on the other hand, can carry tensile forces.
Hint: A partial stiffness loss, for example, a redistribution from concrete to reinforcement due to cracking, can only be simulated by defining the reinforcement as a separate partial element of the composite section, and not as a reference set in the concrete section. However, stress redistribution due to cracked concrete can also be calculated by using the action FibII.
More information can be found in the specific FAQ/Demo example: