# Finite Element Method Questions and Answers – Three Dimensional Frames

This set of Finite Element Method Multiple Choice Questions & Answers (MCQs) focuses on “Three Dimensional Frames”.

1. What are three dimensional frames otherwise referred to as?
a) Space frames
b) Plane frames
c) Dynamic frames
d) Planar frames

Explanation: Three Dimensional frames are otherwise referred to as Space frames. These are very common in structural analysis while analyzing multistory buildings, automotive bodies etc. These members are not confined to any one singular frame.

2. Space frames have only 4 degrees of freedom.
a) True
b) False

Explanation: Every node of a space frame member has 6 degrees of freedom. Out of the 6, 3 degrees of freedom correspond to translational motion; whereas the other 3 degrees of freedom correspond to rotational motion of the space frame member.

3. Which of the following is not an example of a space frame member?
a) Bicycle frame
b) Automotive body
c) A simple bridge
d) Steel structures

Explanation: A simple bridge is not an example of a space frame member. This is because, the bridge element can be analyzed by taking into consideration any one of its plane. For all the other three elements, it is not possible to confine their members to a singular plane and perform respective analyses; hence they are space frame members.

4. Three different co ordinate systems are available in the three dimensional frame analysis library.
a) True
b) False

Explanation: The given statement is true. Every space frame member has 3 co ordinate systems; one global and two local. The local co ordinate systems correspond to element local and node local systems. Usually, the global co ordinate system matches with the local one; unless otherwise mentioned.

5. What are the co ordinate systems corresponding to Nodal loads, Diaphragm loads, and Member internal forces and displacements?
a) Element local, Nodal local, Global
b) Nodal local, Element local, Global
c) Global, Nodal local, Element local
d) Nodal local, Global, Element Local

Explanation: The given model data and corresponding co ordinate systems can be grouped as follows:
Nodal loads = Nodal local co ordinate system
Diaphragm loads = Global co ordinate system
Member internal forces and displacements = Element local co ordinate system
Note: Join free Sanfoundry classes at Telegram or Youtube

6. Which of the following is a load combination supported by the three dimensional frame analysis library?
a) Sum of odd squares method
b) Cube root sum of cubes method
c) Square root sum of squares method
d) Cube root sum of squares method

Explanation: The Square root sum of squares method (SRSS) is used for calculation of load elements in space frame members. The output segment of this procedure produces both positive and negative values for each joint of the frame under discussion. This is used exclusively for Modal analysis of space frame members.

7. What is the difference between grid construction and ordinary framing system?
a) Omni directional distribution of load

Explanation: The major difference in grid construction and ordinary framing system is in the distribution of load. In a grid construction, the load is distributed in all directions; whereas, in the ordinary framing system it is linearly distributed.

8. Which of the following is an advantage of space frame members?
a) Very short structures
b) Very tall structures
c) Heavy weight structures
d) Light weight structures

Explanation: Among the various advantages that a space frame member possesses, its light weight happens to be of utmost importance. This can be justified by the easy accommodation of the material in all three directions. The most predominant load transfer mechanism happens to be of the axial type (tension or compression).

Sanfoundry Global Education & Learning Series – Finite Element Method.