Concept on positioning of Columns
- CONCEPT OF POSITIONING OF COLUMNS :
- QUESTION : 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.
- ANSWER :
- COMMENTS ON THE LAYOUT OF THE FRAMING PLAN IS GIVEN BELOW :
- SYMMETRY :
- if we split the plan vertically half and horizontally half it look like as a mirror . so we conclude the given plan is symmetric in x and y direction .
- REDUNDANCY :
- Redundancy in x direction :
- if we see the plan the column in x direction is more than in y direction . also more space in x direction , except top and bottom column .
- the redundancy at the top and bottom is less as compair to middle part in the x direction .
- Redundancy in Y direction :
- if we see the plan the column in y direction are comparatively less but having evenly spaced .
- the structure in y direction is redundant but comparitively less to x direction .
- BI-DIRECTIONAL STIFFNESS :
- The column in horizontial direction are connected to stright beam if any lateral load in x direction which are passing from left to right direction of the building , we see that path is stright there was less or no possibility of the force diversion.
- but in y direction the column is not connected to stright beam so , the lateral load passing through south side of the building get diverted into the opposite direction that is east nd west direction to reach at a next bey .
- therefore major force diversion is take place with sesmic force in y direction .
- the framing plan is weak with respect to bi-directional stiffness in y direction .
- DUCTILITY :
- We see that more column in x direction than y direction it will results in higher stiffness in x direction . that reduce ductiliy in x axis.
- we see that the x force is easly passes through one bay to another bay . but y force is doing more strugle for passing .
- the given floor plan is more ductile in y direction than x direction
- QUESTION : 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.
- ANSWER :
- SOURCES OF PSSIBLE OF IRREGULARITY IN THE BUILDING EXPLAIN BELOW :
- 1. VERTICAL IRREGULARITY
- 2. SOFT STORY
- 3. SLOPY BASE
- VERTICAL IRREGULARITY :
- This irregularity is cross checked with refreance to IS-1893-2016 table 6 - serial no (iii)
- we see in above picture at the bottom the floor plan area is large and then area is reduced as per height is increased .
- SOFT STORY :
- If we look at the 6th floor where concorved opening space is provided
- there was no partition wall is provided that leads with plastic hinged formation at the column .
- this irregulrity is cross checked with reference to IS-1893-2016 FIG 4A
- checked this and then design properly .
- SLOPY BASE :
- In picture looking to right side we see slopy base at a one side . that leads to significient variations in the stiffness .
- the few levels are subjected to soft story mechanism .
- this irregularity is cross checked with refrance to IS- 1893-2016 FIG 5E.
- QUESTION : 3
-
A 4-storey hotel building has an open ground floor for the restaurant. Story 2 to 4 have one row of rooms along each long side in plan, separated by a corridor. The two short sides of the perimeter are fully in-filled in all storeys, except for certain openings at the ends of the corridor at storeys 2 to 4 and along the right-hand side of the ground floor. There is a staircase near the upper left-hand corner, with straight flights between landings at floor levels and in-between floors. Cross-section dimensions are written next to the member no. in meters.
-
Comment on the features of the structural design and of the layout of infills which are important for earthquake resistance and seismic performance. How do they relate to the almost full collapse of this building (the extreme left-hand bay with the staircase survived, as well as one long-side façade in the rear end, and the frame along the right-hand side in plan).
- ANSWER :
- Looking toward the plain we see that it consist of one way slabs , beam and columns in the structural plan.
- the reinforced concrete beam is provided in x direction .
- no beams are provided in y direction thats way structure is failure .
- we see at bottom floor looking open at may lead soft story failure mechanism acting in the building .
- as per the given instructions, the middle portion is the corridor which means that portion has no mass as compaired to other sides having room and which results in greter mass , due to this irregularity building may collaps.