FRAME ANALYSIS By: Mohammad Soffi bin Md. Noh Introduction In the design of RC structures based on BS 8110 it has to analyse the structure subjected to all probable combinations of loads, considering the ultimate limit state. Once the bending moment, shear force etc. were obtained, reinforcements can be designed according to the standard. Generally, three dimensional wide frame analysis is the most accurate method to analyse the frame building. 3-D frame is complex and need to be carried out using relevant computer software. Clause 3.2.1.1 BS 8110: Part 1: 1997 states that the analysis may be simplified appropriately sub-frame. Hence there are 3 levels sub-frames: Complete sub-frame Simplified sub-frame Simplified sub-frame at point BFC 3172 Reinforced Concrete Design 2
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FRAME ANALYSISBy:
Mohammad Soffi bin Md. Noh
Introduction
� In the design of RC structures based on BS 8110 it has to analyse the structure subjected to all probable combinations of loads, considering the ultimate limit state.
� Once the bending moment, shear force etc. were obtained, reinforcements can be designed according to the standard.
� Generally, three dimensional wide frame analysis is the most accurate method to analyse the frame building.
� 3-D frame is complex and need to be carried out using relevant computer software. Clause 3.2.1.1 BS 8110: Part 1: 1997 states that the analysis may be simplified appropriately sub-frame.
� Hence there are 3 levels sub-frames:� Complete sub-frame
� Simplified sub-frame
� Simplified sub-frame at point
BFC 3172
Reinforced Concrete Design 2
Method of Frame Analysis
1) Complete sub-frame
BFC 3172
Reinforced Concrete Design 2
The frame consists of all beams at each level with columns top and bottom of beams.
Moments at columns and beams are tabulated by analyzing the complete sub-frame.
Method of Frame Analysis
2) Simplified sub-frame
BFC 3172
Reinforced Concrete Design 2
The frame consists of a selected beam with columns and neighbouringbeams at both sides of selected beam.
Method of Frame Analysis
3) Simplified sub-frame at point
BFC 3172
Reinforced Concrete Design 2
The frame consists of a selected point or node with columns at top andbottom, and neighbouring beams coming into the point.
Analysis of Braced Frame
� A building is saying as braced frame when the horizontal loadings are resisting by the shear walls or bracing.
� The analysis of braced frame is only considered for the vertical loads which are dead and imposed load.
� For the combination of dead load and imposed load, the following loading patterns are considered:� All spans loaded with maximum
dead plus imposed loads� Alternate spans loaded with
maximum dead load and imposed load and all other spans loaded with minimum dead load