G.17.4.2.1.5 Define Pushover Hinges Properties and Acceptance Criteria

At the beginning of the analysis user needs to define properties (Refer Section 1.3) and acceptance criteria for all pushover hinges. The program includes several built-in default hinge properties that are based on FEMA 356 tables 1.6.1 (Table 5-6 Pg 5-40 of FEMA 356) and 1.6.2 (Table 5-7 Pg 5-44 of FEMA 356) for steel structures.

While generating default in-built hinge properties following points have been considered.

Columns in axial tension in braced frame with negligible moment - It is considered as deformation-controlled action as per Table 5-7 Pg 5-44 of FEMA 356. Mz and My moment are negligible.
Columns in axial compression in braced frame with negligible moment - It is considered as force-controlled action as per Table 1-5-1 of FEMA 356. Mz and My moment are negligible.
Columns in axial tension in braced and moment frame with moment - As per FEMA 356 Pg 5-17, for steel columns under axial tension or combined axial tension and bending shall be considered deformation controlled. It will simply act as beam.
Columns in axial compression in braced and moment frame with moment - As per FEMA 356 Pg 5-17, for steel columns under combined axial compression and bending stress, the column shall be considered deformation-controlled for flexural behavior, force-controlled for compressive behavior. i.e.
1. if Fx / Pcl <= 0.5 consider deformation-controlled
2. if Fx / Pcl > 0.2 and Fx / Pcl <= 0.5 consider deformation-controlled
3. if Fx / Pcl > 0.5 consider force-controlled
where Fx is axial compressive force and Pcl is lower bound compressive strength of column. (Refer Section 1.6.1 for detail).
Beams in axial tension in braced frame with negligible moment - It is considered as deformation-controlled action as per Table 5-7 Pg 5-44 of FEMA 356. Mz moment is negligible.
Beams in axial compression in braced frame with negligible moment - It is considered as force-controlled action as per Table 1-5-1 of FEMA 356. Mz moment is negligible.
Beams in axial compression and tension in moment and braced frame with moment - It is considered as deformation-controlled action as per Table 5-6 Pg 5-40 of FEMA 356.
Braces in axial tension and compression in braced frame - It is considered as deformation-controlled action as per Table 5-7 Pg 5-44 of FEMA 356. For braces in compression out-of-plane is considered.

Please note that while generating built-in hinge properties in STAAD.Pro, the following components are not considered:

Column panel zones
Fully restrained moment connections
Partially restrained moment connection
EBF
Steel plate shear walls

If any member has releases, the effect in member nonlinear stiffness is considered to be same as that for linear member stiffness.

Parent topic: G.17.4.2.1 Performing Pushover Analysis

Related tasks	Related reference
M. To manually define and assign hinges	TR.37.7.5.1 User-Defined Hinge Property TR.37.7.5.2 Assignment of Hinge Property to the Members Define Hinge Property tab

Define Acceptance Criteria

The performance of a structure and its components is defined by the acceptance criteria to provide desirable information for evaluation or retrofit. It refers to the specific limiting values for the deformations and loadings, for deformation-controlled and force-controlled components respectively, which constitute for acceptable seismic performance. Following three criteria are there:

Immediate Occupancy (IO): The post earthquake structural damage state in which only very limited structural damage has occurred. The basic vertical and lateral force resisting systems of the building retain nearly all of their pre-earthquake characteristics and capacities. The risk of life-threatening injury from the structural failure is negligible
Life Safety (LS): The post earthquake damage state in which significant damage to the structure may have occurred but in which some margin against either total or partial structural collapse remains.
Collapse Prevention (CP): The post earthquake structural damage state in which the building’s structural system is on the verge of experiencing partial or total collapse.

The program considers only moment hinge for beam and column for steel structures. If you do not define hinge properties, the program will consider built-in default hinge properties based on FEMA 356.These automatic hinge properties include both moment and axial hinge.