Concept on positioning of Columns
Ques:1
As per the framing plan given the structure seems a good earthquake resistance since the arrangement of the columns are even and the length in both x and y axis are not much differ.
Looking into aspects of symmetry, redundancy and bi-directional stiffness and ductility
Aspects of Symmetry
The importantance of symmetry in the plan is that the good symmertical plan will achieve good uniformity. In this plan the column is arranged in a uniform manner so the stiffness of the structure is also good. So the structure in this plan has a good symmetrical aspect.
Redundancy
The uniformity distributed structural elements increases the redundant of the structure.The redundancy of the structure is more important because this more redundant will of the structure will provide more reliable to resist the structure from sesismic action. In this strcture the Uniformity of the column and beam are good so that the distribution of the seismic load from x and y direction could widely spread energy to the entire structure so that the structure could be more reliable.
Bi-directional Stiffness
The bidirectional Stiffness can be achieved in plan of orthoganol Structural pattern of the structures in which it could direct the seismic action from any side of the stuctures. In this case the structue is not orthogonal and there are also some offsets on plan. So the Bi-directional Stiffness is comparitivly less in which the corner or the offset would gain more horizontal force and equal stiffness is not possible.
Ductility
Obtaining of large deformation without failing of structure is the ductility of the structure. Depends on the height and the Storey height on equal level the elasticity of the structure is made. Depends on the eleasticity the ductility can be determined. In this strcture the uniformity is made in a perfect manner. So the Direction of seismic force can be resticted by the structure which could be ductile.
Ques:2
In this building given Soft Storey irregularity is noticed.
The marked portion shows the absence of shear wall in the mid floor level
As an engineer point of view
From the marked portion there are 6 level of structure above the marked portion. So that the mass of the strcture above the marked portion will definetly be high. Also below the marked portion there are four levels where the marked portion is not directly attached to the foundation.
In this case the the marked portion would attain high tortional force which tends to soft story irregularity. Also if the marked portion heigth is quiet larger than the above level height then definity this would achieve soft story failure.
Since the lateral stiffness is less than that of the level above of the marked portion it leads to stiffness irregularity.
In this case Shear walls can be provided which helps to resist stiffness irregularity.
Ques:3
Ground Floor of the building is open and the right side in-filled
Storey 2 to 4 have one rows filled with room and the remaing is cooridor. The two shorter span side is in-filled
the upper left corner is staircase.
These are the featues of the building.In this case of building if the seismic force acts on the structures the results obtaining are
Since the Ground floor of the building is open except the right end and the remaining 3 story have rooms at one end the mass of the structure is high at one large side(let assume at the bottom of the plan).
The stiffness of the structure would fail in this case. Also the ductility wont withstand. In this case soft story failure could attain at the bottom of the plan. So that the Bottom side of the column(in plan) could attain since the mass of the structure acta at the bottom side of the plan.
In the staircase area at the top left corner remain which would not fail in seismic reaction due to the correct infill
The structure on the bittom portion of the plan fails as stoft story failure in seismic reaction due to the lack of infill.
This could attain with staircase area withstand.