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.

AIM:- To explain the layout of the framing plan concerning earthquake resistance in the two horizontal directions X or Y by looking into consideration such as aspects of symmetry, redundancy, bidirectional stiffness and ductility

INTRODUCTION:- Layout of the framing plan which is shown in figure above concerning earthquake in the two horizontal directions is going to be explained with step by step procedure.

EXPLANATION:- 

a) Symmetry of the in plan structural layout:- 

• Uniformity in plan is characterised by even distribution of the structural elements allowing short and direct transmission of the inertia fprces produced in the distributed mass of the building.
• Since the given plan layout of plan is symmetrical in nature hence the distribution of forces is uniformly distributed throughout the structures of the building which hlps in resisting the lateral forces.
• The structure is restrained to torsional rotation because of the minimum eccentricities developed between centre of mass and centre of stiffness

b) Redundancy:-

• The use of evenly distributed structural elements increases the redundancy of the structure 
• Redundancy allows a more favourable distribution of the action effects in the non linear range and widespread energy dissiption across the entire structure
• The structure  is evenly spaced in x direction hence it is more redundant in nature.
• The structure is somewhere evenly spaced in y direction but less connection between beam to column joints hence it is less redundant in nature.

c) Bi directional resistance and stiffness:-

• Horizontal sesismic force is by nature a bidirectional  phenomenon and thus the building structure must be able to resist horizontal actions in any direction
• The given force has an orthogonal in nature as well as symmetrical in nature hence it can transfer the forces evenly
• The structure is somewhere evenly spaced in y direction but less connection between beam to column joints hence it is less bi directional resistance.

d) Ductility:-

• Number of columns are more in X direction as compared to Y direction hence it is more stiffness and less ductile in nature  as compared to number of columns in Y directions.

RESULTS:- Layout of the framing plan which is shown in figure above concerning earthquake in the two horizontal directions has been explained

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.

AIM:- To explain the possible sources of irregularity in the building as shown in figure and also how to dealt with possibile irregularities.

INTRODUCTION:- Irregularity of the building is going to be explained along with possible steps how to deals with irregularity.

EXPLANATION:-

The possible sources of irregularity in the building as shown below:-

• Irregularity due to in plan flexibility
• Irregularity due to stiffness
• Soft story mechanism
• Irregularity due to elevation

a) As seen from the figure above, floor plans with L/d ratio are greater than 3 i.e. plan aspect ratio assumed to have significant in-plan flexibility. This can be minimise by adopting plan aspect ration must be less than 3

b) Height of the columns are differ drastically so it has to be properly maintained

c) Large opening has to restricted. This can be minimised by providing interior brick walls

d) This irregularity of building can be properly dealt with knowing of Indian codes such as IS 1893-2016 (Part-1)

RESULTS:- Irregularity of the building has been properly illustrated.

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).

EXPLANATION:-

Primary reason for collapse:-

a) Soft story mechanism:- Ground floor of the building is kept open. This may have resulted in soft story formation. As a result of it, it possess low stiffness

b) Improper mass distribution: Since the mass distribution is not proper in uniform because of the corridor is in midway between the two rooms

c) Improper dimension of beam sizes:- Beam sizes are not proper. As a result it is difficult to construct an  exterior wall of proper thickness

d) Improper structural framing:- Sructures are not been framed in a proper manner

e) Varying column dimension

RESULTS:-