How do you prevent torsion in a building?

In order to minimize the overall torsion, it is imperatively necessary to reduce the distance between the centre of mass (CM) and centre of stiffness (CS) in the design stage.

What is torsion in a building?

Torsion is the state of strain in a material that has been twisted by an applied torque. It will occur whenever a structural element is subject to a twisting force. Torsion develops shear stresses and is equivalent to tension and compression at right angles.

How the torsional forces are created in the building?

Torsion is created when the centre of mass (CM) and the centre of rigidity or resistance (CR) in the building do not coincide – the distance between these two points is referred to as torsion eccentricity. Torsional effects can develop only in buildings with rigid diaphragms.

How does torsion affect a building?

Torsional effects may significantly modify the seismic response of buildings, and they have caused severe damage or collapse of structures in several past earthquakes. In ductile structures, the main consequence of floor twist is an unequal demand of lateral displacements in the elements of the structure.

What causes torsion mechanics?

The torsion, or twist, induced when torque is applied to a shaft causes a distribution of stress over the shaft’s cross-sectional area. (Note that this is different from tensile and compressive loads, which produce a uniform stress over the object’s cross-section.)

What is eccentricity in building?

The design eccentricity is a function of the structural eccentricity, which is defined as the distance between the cen- ter of rigidity at a level and the resultant of all lateral forces at that level.

What is torsion in structures under what configurations a building structure suffers torsion during a seismic action?

According to the authors, torsion is caused due to the eccentricity between center of mass and center of stiffness. Behavior of a multi-storey building during strong earthquake motion depends on structural configuration.

What is torsional irregularity in building?

Recent codes have defined torsional irregularity as the condition where the maximum story drift, including accidental torsion, at one end of the structure transverse to an axis is more than 1.2 times the average of the story drifts at the two ends of the structure.

What is torsional irregularity?

Torsional irregularity is a kind of plan irregularity and it occurs due to the eccentricity between the centre of mass (CM) and the centre of resistance (CR). The seismic load acts at the mass-centre of the structure while the resisting force acts at the centre of resistance of the structure.

How is torsion induced in reinforced concrete?

Torsion may be induced in a reinforced concrete member in various ways during the process of load transfer in a structural system. In reinforced concrete desi commonly used to refer to two different torsion -inducing situations. Torsion when encountered in reinforced concrete members usually occurs in combination with flexure shear.

How does torsion arise in a structure?

Torsion may arise in structures due to primary or secondary actions. Primary torsion arises when the structure has no other options to resist the external loads but a twist. In this case, the only way to resist the torsion due to the external load is by the strength of the materials.

How can we avoid torsion in a building?

In most of the cases it’s difficult to avoid. However, these are the few ways i have found. Maintaining symmetry in buildings. It should be better to avoid change in direction of forces within a frame. Cantilevers should not intersect. Finally, designing the structural members to withstand torsional forces/moments as per standard codes.

When to neglect torsional stiffness of reinforced concrete members?

For this reasons, the code (CL.40.1) permits the designer to neglect the torsional stiffness of reinforced concrete members at the structural analysis stage itself, so that the need for detailed design for torsion in such cases does not arise at the design stage.