Common Parameter Created Edited

# Definition of Frame

## Function

• Select the structural frame type (braced/unbraced) with respect to the global X- and Y-directions. Select the auto-calculation option for the effective buckling length factors for column members.

## Call

From main menu, select [Design] tab > [Design Input Data] > [Design Parameters] > [Definition of Frame]

## Input

The following dialog box is used to enter the data:

### Definition of Frame

Define the type of structural frame.

X-Direction of Frame
Select Unbraced | Sway or Braced | Non-sway frame in the global X-direction (Default = Unbraced | Sway).

Y-Direction Frame
Select Unbraced | Sway or Braced | Non-sway frame in the global Y-direction (Default = Unbraced | Sway).

### Auto Calculate Effective Length Factors

Select if the effective buckling length factors are to be automatically calculated.

Auto calculation procedure for effective length factor

Auto calculation procedure for effective length factor

(1) Calculate the stiffness, S (=EI/L), of the members which are connected to the 'Member a' as shown in the figure 1 below. If the joint of the flexural member is fixed or hinged as shown in the figure 2 below, the stiffness, S, is modified as below.

Fixed joint: S = (1/1.5)* EI/L

Hinge: S= (1/2.0)* EI/L

Where,

E: Modulus of elasticity

I: Moment of inertia of section

L: Span length of flexural member measured from center to center of joints

(2) Calculate Ψ and Ψ. Ψ is the ratio of Σ(EI/lc) of compression members and Σ(EI/l) of flexural members in a plane at one end of a compression member. As shown in the figure 3 below, if the end of the compression member is fixed or hinged, Ψ is taken as 1 or 10 respectively. If the compression member is not connected to any flexural member, Ψ is taken as 1000.

(3) Calculate the solution, X, in the stability equation below.

Braced / Nonsway frames

Unbraced / Sway frames

Where, Ψ: Ratio of Σ(EI/lc) of compression members to Σ(EI/l) of flexural members in a plane at one end of a

compression member.

(4) Calculate the effective length factor, K

Reference: "Steel structures" (1982), Ballio and Mazzolani

### Design Type

3D : Calculate the forces for and design all the members.

X-Z Plane : Calculate the forces for and design all the members parallel with X-Z Plane.

Y-Z Plane : Calculate the forces for and design all the members parallel with Y-Z Plane.

X-Y Plane : Calculate the forces for and design all the members parallel with X-Y Plane.

: Enter the selection and close the dialog box.

: Do not enter the selection and close the dialog box.

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