• Login
No Result
View All Result
Civil Construction
  • Contact us
  • Home
    • About us
      • Privacy Policy
  • Civil General
  • Structural design
    • Preliminary design
    • Detailed design
  • News
    • Entertainment
    • Misc
    • Trending
  • Contact us
  • Home
    • About us
      • Privacy Policy
  • Civil General
  • Structural design
    • Preliminary design
    • Detailed design
  • News
    • Entertainment
    • Misc
    • Trending
No Result
View All Result
Civil Construction
No Result
View All Result
Home Civil General

Torsion in building

civiltej by civiltej
August 7, 2020
in Civil General
1
torsion in building
0
SHARES
1.9k
VIEWS
Share on FacebookShare on Twitter

Table of Contents

  • Torsion in building structure:
    • Torsional stiffness:
    • Torsional Irregularity:
    • Behavior of structure under torsion:
      • Cause of torsion in building structure:
        • 2. Unequal Mass distribution
        • 3. Infill walls
        • 4. Position of Staircase or opening
    • Calculation of torsion in building:
      • Torsional failure:

Torsion in building structure:

Torsion is the condition of being twisted or turned. Torsion in building structure is defined as the deformation or the stress developed in the building when one end of a member/structure is twisted in one direction and other end is held motionless or twisted in opposite direction or also in same direction but with less magnitude.

torsion in building
Fig: Architectural twisted building
source: posted by Abdullah khan in Instagram

Torsional stiffness:

The torsional stiffness KT of a member is defined as the torsional moment T required to produce a unit angle of twist.

KT = T/Ѳ = GJ/L

T/J = GѲ/L = Ⴀt,max/R

Ⴀt,max = TR/J

Where,

J = Polar MOI of cross sectional

G = Shear modulus = E / 2(1 + μ)

E = Young’s modulus of elasticity

μ = poisson’s ratio

L = length of a member

For a rectangular section subjected to pure torsion, the maximum shear occur at the middle of the wider (or longer) side D and given by,

Ⴀt,max = T/ (K b2 D)

Where,

K b2 D = polar or torsional section modulus

b and D are the shorter and longer sides of the rectangular section, respectively

K = torsion constant

The value of k depend upon the ratio D/b and given in table:

Table: Variation of coefficient k with the ratio D/b

D/b1.01.52.02.53.04.05.06.08.010.0> 10
K0.20.230.240.250.260.280.290.290.300.310.33

Torsional Irregularity:

Normally, a well-proportioned building does not twist about its vertical axis, when a) the stiffness distribution of the vertical elements resisting lateral loads is balanced in plan accordance to the distribution of mass in plan at each storey level and b) the floor slab is stiff in their own plane, happens when its plan aspect ratio is less than 3.

A building structure is said to be torsional irregular when 1) the maximum horizontal displacement of any floor in the direction of the lateral force at one end of the floor is more than 1.5 times its minimum horizontal displacement at the far end of the same floor in that direction; and 2) the natural period corresponding to fundamental torsional mode of oscillation is more than those of first two translational modes of oscillation along each principle plan directions.

In torsional irregular building, when the ratio of maximum horizontal displacement at the end corner of the building and the minimum horizontal displacement at the other end corner of the building is,

  1. In the range of 1.5 – 2.0

a) the building configuration should be revised to ensure that the natural period of fundamental torsional mode of oscillation shall be smaller than those of the first two translation modes along each of the principle plan directions, and then

b) three dimensional dynamic analysis method shall be adopted; and

2. More than 2.0, the configuration of the building shall be revised.

This provision is based on the IS code mentioned in 1893 (part 1) : 2016

Behavior of structure under torsion:

torsion in building
Fig: twisted building due to unequal lateral force distribution

Cause of torsion in building structure:

  1. Reentrant Corner

A building is said to have a re-entrant corner in any plan direction, when its structural configuration in plan direction, when its structural configuration in plan has projection of size greater than 15% of its overall plan dimension in that direction.

torsion in building
Fig: Effect of torsion in reentrant corner of structure
source:https://www.awc.org
2. Unequal Mass distribution

The building having heavy mass in one area that other than other end the building may undergo torsional moment. For example, if the one side of a building has library, heavy instrument/devices and other end has very low mass, then the heavy end side undergoes more deflection than that of least mass.

3. Infill walls

The presence of infill wall in some area and absence in some area also cause torsion on building. It is almost similar to unequal mass distribution.

4. Position of Staircase or opening

The opening should be left in the slab for the casting of stairs. Opening in slabs results in flexural diaphragm behavior, and hence the lateral force is not shared by frames and/or vertical members in proportional to their lateral translational stiffness. A building is said to have discontinuous in their in-plane stiffness, when floor slabs have cut-outs or openings of area more than percent of the full area of the floor slab

Calculation of torsion in building:

The torsion in building is found out by measuring the distance between the center of mass and center of rigidity.

The max. Limit that the difference of center of mass rigidity can be is d > 20% of w, where w = width of building on that axis.

Torsional failure:

The failure of the building by torsion is severe so it is better to avoid it by revising the plan configuration. Three dimensional dynamic analysis method should be adopted to analyze the torsional effects.

ALSO READ:

SHEAR WALL

BASE SHEAR

Previous Post

Hanging Column or Floating Column

Next Post

Segregation

civiltej

civiltej

Next Post
segregation

Segregation

Comments 1

  1. Atlas_2022 says:
    11 months ago

    This paper discusses the origins of torsion and its effect on the response of structures with a focus on the contribution of experimental data. The fact that torsion increases the stresses in structures, augmenting strain and damage during earthquakes, was confirmed in the 19. Over the years, the torsional response of structures has mainly been analysed through numerical studies, because few buildings are equipped with translational sensors, and even fewer are equipped with rotational sensors. This is likely to change as building instrumentation becomes more widespread and new generations of rotational sensors are developed. Therefore, this paper focusses on a number of scientific questions concerning the rotational response of structures during earthquakes and the contribution of experimental data to the understanding of this phenomenon. Since the 19 and the emergence of earthquake engineering as a distinct field of engineering sciences, earthquake design for civil engineering structures has been concerned with the dynamic response induced by earthquakes. Analysis of a structure s dynamic response is primarily motivated by the desire of earthquake engineers to reduce the consequences and losses of earthquakes; this is achieved by a conservative compromise involving the engineering simplification of current state-of-the-art scientific knowledge. For engineering seismologists, the analysis of strong ground motion is also motivated by the need to produce response spectra for design purposes via numerical or analytical methods, integrating the complexity of earthquake ground motion. Designing a building under seismic loading becomes extremely complicated, as this objective encompasses all the complexities inherent to seismic loading and the transfer of design loads to the structure, considering different scientific aspects that are sometimes closely related.

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Recommended

Owning a Horse: Training Tips for New Horse Owners

Owning a Horse: Training Tips for New Horse Owners

6 days ago
How Long Should I Wait Before Sealing My New Pavers?

How Long Should I Wait Before Sealing My New Pavers?

6 days ago

Trending

Ala Vaikunthapurramuloo Hindi dubbed Download Filmyzilla 720p

Ala Vaikunthapurramuloo Hindi dubbed Download Filmyzilla 720p

11 months ago
numerical of one-way slab design

Numerical of One-way slab

3 years ago

Popular

Ala Vaikunthapurramuloo Hindi dubbed Download Filmyzilla 720p

Ala Vaikunthapurramuloo Hindi dubbed Download Filmyzilla 720p

11 months ago
numerical of one-way slab design

Numerical of One-way slab

3 years ago
design of primary beam supporting secondary beam

Design of primary beam supporting secondary beam

3 years ago
example of two-way slab design

Example of two-way slab

3 years ago
Design of raft foundation

Design of Raft Foundation

3 years ago

Category

  • Automobile
  • Business
  • Career
  • Civil General
  • construction
  • Detailed design
  • Entertainment
  • Family
  • Furniture
  • Home
  • Internet
  • Misc
  • Pet
  • Preliminary design
  • Structural design
  • Tech
  • Tips
  • Uncategorized

Follow Us

  • Contact us
  • Terms and Conditions
  • Privacy Policy

Copyright © 2022 All Rights Reserved | Powered by Civiltej

No Result
View All Result
  • Contact us
  • Home
    • About us
      • Privacy Policy
  • Civil General
  • Structural design
    • Preliminary design
    • Detailed design
  • News
    • Entertainment
    • Misc
    • Trending

Copyright © 2022 All Rights Reserved | Powered by Civiltej

Welcome Back!

Login to your account below

Forgotten Password?

Create New Account!

Fill the forms bellow to register

All fields are required. Log In

Retrieve your password

Please enter your username or email address to reset your password.

Log In