Cloumn Struts
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P1 P1 Department of Civil Engineering, ISM Dhanbad Structural Analysis-I Practical Manual Behaviour of Columns Aim of the Experiment: To study behaviour of different types of columns and find Euler’s buckling load for each case. Apparatus: Column Buckling Apparatus, weights, scale, vernier calliper. Theory: If compressive load is applied on a column, the member may fail either by crushing or by buckling depending on its material, cross section and length. If member is considerably long in comparison to its lateral dimensions, it will fail by buckling. If a member starts deflecting in lateral direction then the member leads to failure with small increase in load. The load at which the member just buckles is called as buckling load. The buckling load, as given by Euler, can be found by using following expression. P=π 2 EI ❑ l eff 2 Where, E = Modulus of Elasticity = 2 x 10 5 N/mm 2 for steel. I = Moment of inertia of column section. l eff = Effective length of column. The effective lengths for the different end conditions of the column, Both ends fixed: l eff = L/ 2Both ends pinned: l eff = L Different support conditions for
description
Behaviour of Columns; lab manual
Transcript of Cloumn Struts
P1P1
Department of Civil Engineering, ISM DhanbadStructural Analysis-I Practical Manual
Behaviour of Columns
Aim of the Experiment: To study behaviour of different types of columns and find Euler’s buckling load for each case.
Apparatus: Column Buckling Apparatus, weights, scale, vernier calliper.
Theory: If compressive load is applied on a column, the member may fail either by crushing or by buckling depending on its material, cross section and length. If member is considerably long in comparison to its lateral dimensions, it will fail by buckling. If a member starts deflecting in lateral direction then the member leads to failure with small increase in load. The load at which the member just buckles is called as buckling load. The buckling load, as given by Euler, can be found by using following expression.
P=π2 EI
❑leff2
Where,E = Modulus of Elasticity = 2 x 105 N/mm2 for steel.I = Moment of inertia of column section.leff = Effective length of column.
The effective lengths for the different end conditions of the column,
Both ends fixed: l eff = L/ 2Both ends pinned: l eff = L
One end fixed and the other pinned: l eff = L/√2One end fix and other end free
Different support conditions for the columns:
Effective Length (leff) = L/2 Effective Length (leff) = L
Department of Civil Engineering, ISM DhanbadStructural Analysis-I Practical Manual
Procedure:
1. Apply the load axially at the column end and increasing it gradually. At certain Loading, the
columns buckle which gives the buckling load.
2. For the column where one end is fixed and other completely free on roller, it shall be ensured
that rollers are well greased and before noting the load, the base is to be tapped lightly.
3. Note the buckling load for each of the four columns having different boundary conditions.
4. Calculate the theoretical effective lengths and thus buckling loads by the expressions given
above and compare them with the experimental values.
Observations:
Width of strip (b) =
Thickness of strip (t) =
Length of strip (L) =
Moment of inertia (I) = bt³/12 =
Observation table:
P
P
Effective LengthLeff=L
√2Effective Length Leff=2L
Department of Civil Engineering, ISM DhanbadStructural Analysis-I Practical Manual
Sl.No
.End Conditions
Critical Load Effective Length
Theoretica
l
Experimenta
l
Theoretica
l
Theoretica
l
1 Both ends fixed
2 Both ends pinned
3 One end fixed and the other end
pinned
4 One end fixed and the other end
free
Conclusions:
