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 most useful for link beams that support 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.
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\\ !Figure 1.png|align=right,border=1,width=350px,hspace=10,vspace=10! *Shear hinges* are modeled to account for inelastic shear behavior. Shear hinges are most useful for link beams which resist lateral load, and do not support gravity load. When gravity load is present, a recommendation is to replace distributed loading with equivalent concentrated loading at element [joints|kb:Joint]. 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 the lateral loading applied between hinge locations. Gravity load must be carried during [nonlinear|kb:Nonlinear] analysis. {new-tab-link:http://www.csiberkeley.com/}CSI{new-tab-link} [_Analysis Reference Manual_|doc:Analysis Reference Manual] 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 proceed toward more ductile response mechanisms. |