Skip to main content
Soham Ortiz
Field Engineer
Asked a question last year

What is substitute frame method in structural design?

What is the substitute frame method in structural design?

Where am I?

In TheConstructor you can ask and answer questions and share your experience with others!

Lillian Holmes
Director of Public Works

As we know that the analysis of the multi-story building is consists of very complex loading calculations and time-consuming. So for approximate and quick analysis, the Subsitute method is used for analysis.

This method is used only for vertical loading conditions. The moments in the beam are assumed that are influenced by the loading on that floor alone.

In this method, we are dividing the whole multi-story building frame into a smaller frame, which is called an equivalent frame or substitute frame. These subframes are analyzing by the Moment Distribution Method.

Peter Smith
Heating and ventilation engineer


Substitute frame method is used for the analysis of complex structure I.e multi-storeyed building because analysis of multi-story building is very complicated and long calculations needed. Substitute frame method used for sudden analysis and gives approximate values.

The moment distribution method is used for the analysis of applied loads on the structure in the substitute frame method. This method is generally used to determine the vertical loads and horizontal loads. Vertical load is a combination of live load and dead loads

This method is applied only or vertical loads.

Dead loads include self-weight of slab column and beams which is analysed in substitute frame method.

In this method, the beams which are at floor level as well as the columns above the floor and below which are situated at the fixed far end will be e analysed. In some cases the bending moment is not distributed over the far end, thus the moment is computed independently at each floor and retained on that floor for further analysis.