Static - Beam Element > A-12 (2D Frame with Rigid Offsets)

Objective

To verify the behavior of the rigid offsets

Problem Description

A portal frame [Ref 1] is clamped at point A and D as shown below. The columns are of rectangular size 200mm x 800mm. The beam is of rectangular size 200mm x 1000 mm. The beam is subjected to an uniform load 10 kN/m.

A-12 (2D Frame with Rigid Offsets)1

Finite Element Model

Model type: 2D Frame, without considering frame shear deformation.

The reference does not specify material specifically, so we will use concrete with fc = 3ksi.

A-12 (2D Frame with Rigid Offsets)2

Results

The following are the moment diagrams for modeling the structure with rigid offsets and without rigid offsets.

A-12 (2D Frame with Rigid Offsets)3

	ENERCALC 3D With Rigid Offsets	Ref 1
Beam Max Negative Moment	11.09 kN-m	11.23 kN-m
Beam Max Positive Moment	16.91 kN-m	16.9 kN-m
Moment Reactions at Supports	5.39 kN-m	5.43 kN-m

Comments

The results given by ENERCALC 3D are very close to the referenced values. The reference computes moment diagram manually using displacement method. There are noticeable differences between results with rigid offsets and those without.

Reference

[1]. Long & Bao, “Structural Mechanics”, pp296, People’s Educational Publishing House, China, 1983.