High Rise Structures - Fe Analysis

High Rise Structures

Assignment 1

1. Introduction

This assignment aims to use FE analysis to perform a system which is constituted by a floor panel and two band beams. All these elements are assumed to be simply supported. Four different kinds of load combinations are required to be analyzed by Strand 7 to find the presentations of deflection, stress and moments.

2. Modelling Approach

• Unit

• Grid Size

[pic 1]

• Meshing

• Using the quad4 elements,9 elements deep and 100 elements long, to define the two beams. 45 elements deep and 100 elements long to define the panel.
• Mesh all the elements for size of .[pic 2]

• Element types

• Assign property type 1 to the panel and type 2 to the two band beams.

• Materials and Geometrical properties

Note: change the Modulus of these two material to 37100 Mpa.

• Restraints

• The system is assumed as simple supported, so only the rotation on Y direction is not restricted.
• Restraints are applied along the right edge and left edge of the system.

[pic 3]

• Loads and load combinations

• Assign self-weight to Load Case 1
• Assign dead load to Load Case 2 (face load on both plant and beams)
• Assign live load to Load Case 3 (face load on both plant and beams)
• Apply the four load case combinations as below.

[pic 4]

• Analysis type

• Solve the model as Linear Static
• Open the results file
• Settle the factor of Displacement Scale to 10%
• Get the results (displacement, stress and moment) of the four load case combinations by apply the Results Settings as below.

3. Results and Discussions

• Deflection

• The contour plots for deflection due to the four load case combinations are similar. Therefore, only the plot of combination 4 is shown below.

[pic 5][pic 6]

• The deflection is increasable from the edge to the middle (both the plant and beams).
• The deflection gets larger as the load increase. Since the combination 4 is considered as a long-term load (considering the creep and shrinkage factor), it has the max deflection.

• Stress

• The four contour plots for Stress on XX or YY direction are similar. Therefore, only plots of combination 4 are shown below.
• The stress changed from compression in the middle to the tension at the edges on XX direction.
• The stress on beams at YY direction nearly is 0 and only tension at the boundary. But on the plant, it is compression in the middle and nearly 0 at edge.

[pic 7][pic 8]

• The stress graph of XX direction (+Z & -Z) shows that commonly the top of the structure is under compression while the bottom is under tension.

[pic 9][pic 10]

• The stress graph of YY direction (+Z & -Z) shows that due to the different depth of plant and beams, the stress is concentrative at the boundary which may lead to the fatigue cracks.

[pic 11][pic 12]

• Moment

• The four contour plots for Moment on XX or YY direction are similar. Therefore, only plots of combination 4 are shown below.

[pic 13][pic 14]

• The plots show that most moment occur at the boundary of the beams.
• The moment graph of XX direction is more significant than YY direction, so the system bends primarily around X axis.
• The moment graph of YY direction shows that the moment on the plant is nearly 0, mostly occur at the boundary of the beams.

[pic 15][pic 16]