Conceptual design of a building with columns and shear walls

1 aim:-

The building shown, 20 × 35 m in plan, has columns on a 5 × 5 m grid and shear walls (with dimensions shown in m, 250 mm in thickness) in three alternative arrangements, (a), (b), (c), all with the same total cross-sectional area of the shear walls. Compare the three alternatives, taking into account the restraint of floor shrinkage, the lateral stiffness and the torsional one with respect to the vertical axis, the vertical reinforcement required for the same total flexural capacity at the base, the static eccentricity, the system’s redundancy, foundation systems, architectural constraints etc.

ans:-

sr no	fig1	fig.2	fig.3
1) restarin  of  floor shrinkage	full restraints AT ALL  corners	cornres are left free but restraints along the edge	non unifrom restrints
2) the lateral stiffness	compertively lower lateral stiffness in both x and y direcation	unifromly and compartively higher lateral stiffness  in both x and y dircation	non unifrom lateral stifness in both x and y dircation
3)torsion with respect ton vertical axis	corenrrs wall provide more resisitnce to tiwst	edge wall provide good resistnce to wist	irregular wall provide very poor resistnce to twist
4) vertical rainforcement for similer base capacity	wall are sub to nomial flexural  moment and heavy twisting moment	wall are sub to nomial  twisting moment	wall are sub to heavy flexural  moment and  twisting moment
statice eccentricity	structurally symmetical	structurally symmetical	structurally  un-symmetical
5) system s redundancy	unifrom placement of lateral load support in both the axes	unifrom placement of lateral load support in both the axes	concentrede latera load support in both the axes
6) foundation system	due to l shaped wallthe geomenetry of foundation and its design will be crictical	wall are in line .easy to fix the geomentry and design of foundation	wall are in line  & concentered.easy to fix the geomentry foundation but critical to desgin

2)-aim-

Discuss the suitability for earthquake resistance of the moment resisting framing plan of a three-storey building depicted here (cross-sectional dimensions in cm), the eccentricity of the centre of mass (as centroid of floor plan) to the centre of stiffness (from the moments of inertia of the columns) are shown. Suggest an alternative. Also, is there torsional flexibility? Are the two fundamental translational modes of vibration larger than the fundamental torsional mode of vibration. Discuss qualitatively.

ans-

ecenticity- the longer the distance between center of mass and  center of stiffness, the hogher torsional moment of the building.as per the given plan ecentricity, the building is subjected to higher trosionalmoment (torsional flexibility )in both x and y direcation.

strong beam weak column possibilty:- the size of columns majorly mentioned as 25*25 cm but all the beams have much deeper section 50 cm. inertia of beamis vaisally higher than coulmn .if the column reinforcmet is adequatelty greter than that beam wr are ok and sinces we do not have the rainforcement detail this is doubtful its recommended to have slight bigger size for column

3)-A multi-storey building with basement, with a quadrilateral (non symmetrical floor plan) plan as, has interior columns in an irregular (not in a grid) pattern in plan that serves architectural and functional considerations. Partition walls and interior beams supporting the slab have different layout in different stories. However, there is no constraint to the type, location and size of the lateral force resisting components and sub-systems on the perimeter. Proposals are to be made and justified for the choice of the lateral-load-resisting system and its foundation.

ANS-

FLOOR PLAN- THE FLOOR PLAN OF BUILDING is not either unifrom or symmentric so naturally any lateralload induced in the floor will not have 100% influenece in same direcation. difenitley a speecial lateral load resisting system for these torsionalmoments should be accommodated.

Random intrnal column-since the intrnal coulmn are randomly they are unable to transfer latderal loade efficentlyand can notacchived desirable building responces. so we have to assum and design those column for only gravity lods.

floor to floor varriation in partition wall and beam-partion wall provied an importance mass control in a building and beam play key role an shear transfer floor to beam.all this elemnts are not inoder.so heavy distrition and distributionof lateral lods will happen.