L02: Beam with Elastic Supports✔

A two-span beam is supported at an interior point by a column and with yielding elastic supports at the two exterior points. The beam is continuous and the column is pin-connected to the beam.

The beam is subjected to a vertical point load and the column is subjected to a horizontal point load. Determine the deflections and reactions.



The 2D model consists of 6 joints, 3 beam elements and 2 spring elements. This is a plane frame analysis. The translational displacement in Global Y-direction and rotations about Global X and Z-directions can be deleted from the analysis. The joints 1, 4 and 6 are fixed supports.


The material property data is given:

Modulus of Elasticity = 30,000,000 psi

and sectional property data:

Area = 0.125 ft2
Izz = 0.263 ft4 for beams
Area = 0.175 ft2
Izz = 0.193 ft4 for columns


The spring constant for the springs is given as:

k = 1200 kip/ft


The member loads applied on beams are:

P = -15 kips on beam # 2 @ mid-span in Global Y
P = -5 kips on beam #3 @ mid-span in Global X


Linear static analysis with one load case is performed.


Tested Features

App

Object Link: https://openbrim.org/objid65tv28lznd34ie4efzje1.project

Library

Object Link: https://openbrim.org/objidi4segrgj8hdgrq97j7q0w.libobj


Sources

  • Beaufait, F.W., et al., "Computer Methods of Structural Analysis," Prentice-Hall, 197-210.
  • LARSA 4D

Result Comparison

Output Parameters

Independent

(Beaufait)

LarsaOpenBrIM

Percent Difference

(Larsa vs Independent)

Percent Difference

(OpenBrIM vs Independent)

U2 (x10^-3 ft)0.0130.0130.0130%0%
U3 (x10^-3 ft)0.0130.0130.0130%0%
U5 (x10^-3 ft)0.0130.0130.0130%0%
V2 (x10^-3 ft)0.0210.0210.021-0.017%0%
V3 (x10^-3 ft)-0.002-0.002-0.0020%0%
V5 (x10^-3 ft)-0.058-0.058-0.0580.004%0%
R2 (x10^-3 rad)0.0000.0000.0000%0%
R3 (x10^-3 rad)-0.000-0.0000.0000%0%
R5 (x10^-3 rad)0.0000.0000.0000%0%
Reaction V @ Joint 1 (kip)-2.1-2.144-2.1442.095%2.052%
Reaction H @ Joint 4 (kip)-5.0-5.0-5.00%0%
Reaction V @ Joint 4 (kip)11.311.36011.3600.531%0.531%
Reaction M @ Joint 4 (kip)-360-360-3600%0%
Reaction V @ Joint 6 (kip)5.85.78455.8-0.267%0%

U denotes the displacement in horizontal direction and V denotes the displacement in vertical direction. R is the rotation. Reaction V is the vertical force at the support joint and Reaction H is the horizontal force. Reaction M is the support moment.