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Analysis Methods for Buildings Frames

analysis methods for building frames

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Building frames can be analyzed by various methods such as force method, displacement method, and approximate method. The method of analysis to adopt depends upon the types of frame, its configuration (portal bay or multi-bay) in multi-storied frame and degree of indeterminacy.

Building frames are the most common structural form that is encountered practically. Commonly, the building frames are designed in such a way that the beam-column joints stay rigid. A typical example of a building frame is the reinforced concrete multistory frames.

Analysis Methods for Buildings Frames

1. Force Method

2. Displacement Method

This method requires writing the unknown displacements in terms of the loads using the load-displacement relationship. After that, solving the equilibrium equation for these displacements.

After the determination of displacements, the unknown loads are determined from the compatibility equations. All displacement methods follow this general procedure. In displacement method, three methods which are closely related to each other are presented:

2.1 Slope Deflection Method

 2.2 Moment Distribution Method

2.3 Direct Stiffness Method

3. Approximate Methods

Approximate analysis is useful in determining (approximately) the forces and moments in the different members and in coming up with preliminary designs. Based on the preliminary design, a more detailed analysis can be conducted and then the design can be refined.

Approximate analysis is conducted by making realistic assumptions about the behavior of the structure. For analysis of frames subjected to vertical loads, points of inflection are used whereas portal method or cantilever method is used for frames subjected to horizontal loads

3.1 Portal Method

Assumptions made in portal method include:

Fig. 1: Portal Method

3.2 Cantilever Method

The basic assumption of the method are:

3.3 Points of Inflection Method

Fig. 2: Approximate Method (Points of Inflection Method)

4. Kani’s Method

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