Week 3 Challenge
Q1) EFFECTIVE LENGTH DETERMINATION
It is length between the points of contraflexure of a buckled column. It depends upon the support conditions. It depends upon end condition height of column and does not depends upon span of beam it supports.
Height of column is 10 m and it is effectively restrained in mid height in one direction (in Z direction) but free to move in other direction (Y direction). Bottom of column is Fixed and top of column is Free.
>i) A BRACED FRAME AND SHEAR WALL
Theoretical value : 0.5L = 0.50*10= 5m
Recommended value : 0.65L = 0.65*10= 6.5m
>ii) UNBRACED FRAME WITH PINNED BASE
Theoretical value : 2L = 2*10= 20m
Recommended value : 2L = 2*10= 2m
>iii) UNBRACED COLUMN WITH FIXED BASE
Theoretical value : 0.7L = 0.70*10= 7m
Recommended value : 0.8L = 0.8*10= 8m
Q2) Axial strength determination of a column
Column made up of Hot rolled ISMB 300 with flange cover plate of 200x12 mm on each flange having length of beam as 3 m.
The bottom of the column is Fixed and Top as Roller (Rotation Fixed, translation free).
Yield strength of material fy= 250 N/mm^2
The radius of gyration as the imaginary distance from the centroid at which the area of cross-section is imagined to be focused at a point in order to obtain the same moment of inertia.
k= `root`I/m = 8.1mm
Slenderness ratio = L/r = 30
kL/r of section computed is limited value.
DESIGN STRENGTH Pd assumptions:
DL, LL = 180
WL EL = 250
Tie in roof truss or bracing system = 350
Column Lacing = 145
Built up section elements = 50
Q3) DESIGN Circular tube strut member
2 m long tubular strut member to carry factored axial load of 400 kN.
Assume the ends of the member are simply supported
The yield strength fy=210 Mpa
Q4) Design of laced column
A single laced column made up of two channels back to back of 10 m height to carry factored axial load of 1000kN.
The lacings are bolted.
Q5) Design of battened column
A battened column made up of two channels back to back of 5 m height to carry factored axial load of 2000kN.
The Battens are welded.
