We do not recommend the use of shear hinges at both ends of any member. For example, when shear hinges are used at both ends of a horizontal beam and one of the hinges fails, this begins to reduce the load in this hinge towards zero and it begins to transfer the member gravity load to the other hinge. Since all gravity loads must be carried, this would result in a failure of the second hinge. However, it is not possible for both hinges to fail and still support gravity load! So the analysis cannot continue.
Shear hinges are modeled to account for inelastic shear behavior. Shear hinges are most useful for when applied to link beams that support , which resist lateral load , not gravity load.
During pushover analysis, the program is allowed to increase and decrease the magnitude of the lateral load according to the capacity of the structure. However, gravity load must be carried at all times. If it cannot be redistributed, then the analysis cannot continue.
If you really must use shear hinges, then we recommend that you remove the gravity load from the beams and replace it with joint loads at the columns joints.
Another important thing to consider is that when the shear capacity is exceeded, there is no further useful information that can be obtained from the initial model. The capacity of these shear connections should be increased, so modifying the model accordingly and then re-analyzing the structure to find the next weak spot would be the next recommended analysis stepand do not support gravity load. When gravity load is present, users are recommended to replace distributed loading with equivalent loads concentrated at either element end.
Another recommendation is to avoid placing shear hinges at either end of a member. Only one shear hinge is necessary. Once a shear hinge begins yielding, capacity begins decreasing, and load is redistributed. If a second hinge then fails, the member will no longer be able to transfer lateral load applied between hinge locations. Gravity load must be carried during nonlinear analysis. CSI Software will stop analysis if gravity load cannot be redistributed.
When using shear hinges, please keep in mind that once shear capacity is exceeded, the model will not provide any further useful information. There is no sense in continuing with analysis since shear connections must be modified. Once shear capacity is increased, analysis may then proceed toward more ductile response mechanisms.