Default For Added Hinges Form

Choose to use Steel, Concrete, or User Defined default parameters for adding hinges to the model. If Steel or Concrete is selected, the program automatically generates suggested hinge properties. Those properties are typically based on ASCE 41-13 requirements. The list below briefly explains those hinge types.

Display the Default For Added Hinges form by clicking  the Define menu >Section Properties > Frame/Wall Nonlinear Hinge command to display the Define Frame/Wall Hinge Properties form; then click the Add New Property button.

Clicking the OK button displays the Hinge Property Data form. That form can be used to apply  those suggested hinge properties in hinge property definitions.

Note: Only Concrete Shear V2, Interacting P-M3, or Fiber P-M3 hinge types may be assigned to wall objects.

Click a type below for an explanation of the Steel and Concrete suggested hinge type.

• Steel Axial Hinge

  

   

  Steel Axial Hinge - Default Hinge Features:

  • Slope between points B and C is taken as 3% strain hardening

  • Hinge length assumption for Dy is the length of the member

  • Initial compression slope is taken to be the same as the initial tension slope

  • Points C, D and E are based on FEMA 273 Table 5.8, Braces in Tension

  • Points C’, D’ and E’ are based on FEMA 273 Table 5.8, Braces in Compression, Item C

• Concrete Axial Hinge

  

   

  Concrete Axial Hinge - Default Hinge Features:

  • Py = As fy

  • Pc = 0.85 Ac f’c

  • Slope between points B and C is taken as 10% total strain hardening for steel

  • Hinge length assumption for Dy is based on the full length

  • Point B, C, D and E based on FEMA 273 Table 5.8, Braces in Tension

  • Point B’ = Pc

  • Point E’ taken as 9Dy

• Steel Shear Hinge

  

   

  Steel Shear Hinge - Default Hinge Features:

  • Slope between points B and C is taken as 3% strain hardening

  • Dy = 0.01 radians per Note 3 in FEMA 273 Table 5.8

  • Points C, D and E based on FEMA 273 Table 5.8, Link Beam, Item a

• Concrete Shear Hinge

  

   

  Concrete Shear Hinge - Default Hinge Features:

  • Slope between points B and C is taken as 10% total strain hardening for steel

  • Vy = 2 As (f’c) ^ ½ + fy Asv d

  • Points C, D and E are based on ATC-40 Table 9.12, Item 2, average of the two rows labeled ”r;Conventional longitudinal reinforcement” and ”r;Conforming transverse reinforcement”

• Steel Moment Hinge and Steel P-M-M Hinge

  

   

  Steel Moment Hinge and Steel P-M-M Hinge - Default Hinge Features:

  • Slope between points B and C is taken as 3% strain hardening

  • qy based on FEMA 273, equation 5-1 and 5-2

  • Points C, D and E are based on FEMA 273 Table 5.4, for b / 2tf < 52 / (Fyc) ^ 1/2

  • P-M-M curve is for M3 (major moment) and is taken to be the same as the Moment curve in conjunction with the definition of Axial–Moment interaction curves.

• Concrete Moment Hinge and Concrete P-M-M Hinge

  

   

  Concrete Moment Hinge and Concrete P-M-M Hinge - Default Hinge Features:

  • Slope between points B and C is taken as 10% total strain hardening for steel

  • q = 0, since it is not needed

  • Points C, D and E are based on ATC-40, Table 9.6. The four conforming transverse reinforcing rows of the table are averaged.

  • My is based on reinforcement provided, otherwise it is based on minimum allowable reinforcement.

  • P-M-M curve is for M3 (major moment) and is taken to be the same as the Moment curve in conjunction with the definition of Axial–Moment interaction curves.

TIP: When the Default hinge property is used for a P-M2-M3 hinge type, the resulting hinge property must be assigned to a frame element with a material having steel or concrete design type. This allows the program to pick up certain design properties (yield stress, and so forth) for the element. If the frame element material design type is not steel or concrete, the program will display a message that the hinge property assignment cannot be made. If the material property for the associated frame element is STEEL, the ”Steel, ASCE 41-13 Equation 9-4” option is used, the expected yield strength is set to 1.0FY if FY £ 36 ksi or to 0.8FY if FY > 36 ksi, and the strain-hardening slope is set to 3% of the elastic slope . If the material property for the associated frame element is CONC, the ”Concrete, ACI 318-02 with phi = 1” option is used and the strain-hardening slope is set to 5% of the elastic slope. Hinge properties in ETABS define only the plastic behavior of the hinge. The elastic behavior of the frame element is determined by the frame section (and hence material properties) assigned to the element. Thus, the linear behavior of the structure is not changed by the assignment of hinges to the frame elements. The portions of the hinge load-deformation curve from A to B and from A to B’ are ignored by the program. After a hinge yields at point B, plastic deformation is determined by the curve B-C-D-E with all plastic deformation measured relative to B. Similarly, plastic deformation in the negative direction is measured relative to B’. The elastic slope of a hinge is actually given by the elastic stiffness of the element over the assumed length of the hinge. The strain-hardening slope is the slope of line BC.