Concept on positioning of Columns
1) Comment on the layout of the framing plan concerning earthquake resistance in the two horizontal directions X or Y (dots are columns, lines depict beams). Look into aspects of symmetry, redundancy and bi-directional stiffness and ductility.
- The layout of the framing plan is Symmetric.
- A symmetrical well-distributed plan layout of structural elements is appropriate to achieve uniformity.
- The use of many, evenly distributed structural elements increases the redundancy of the structure, that is the structure becomes more reliable to resist the earthquake effects.
- In this plan, there might be a chance of arising plastic hinges. To calculate the limit load for finding the plastic hinge.
Limit load = 4MP/L
MP= Plastic moment
2) What are the possible sources of irregularity in the building shown here? Explain how, as an engineer, each of these irregularities should be dealt with.
- A building is said to be torsionaly irregular when the maximum horizontal displacements of any floor in the direction of the lateral force at one end of the floor is more than 1.5 times its minimum horizontal displacement at the far end of the same floor in that direction.
- In such a case the building configuration must be revised.
- Out of the many possible irregularities in building structures, the final structural design should, in absolute terms, avoid the two most dangerous irregular situations
1) Soft storeys
2) Extremely flexible Structure in torsion
- Both cases correspond to extremely irregular stiffness distributions: the former regarding the distribution in height/elevation with a very weak story and the latter regarding the distribution in plan, with the concentration of the stiffness at the center or at a corner.
3)
- There is no proper provision of redundancy in the vertical direction.
- Improper distribution of symmetry (or non-uniformity)
- Provision of the weak storey on left hand bay
- Improper placements of masonry infill wall