As per IS : 800, the thickness of slab base is given by
Where A and B are larger and smaller projections respectively of plate beyond column, W is the pressure on the underside of base and Fb is permissible bending stress in slab bases.
If 20 mm rivets are used in lacing bars, then the minimum width of lacing bar should be
Minimum width of lacing bars in riveted connection should be as follows:
diameter (mm) 22 20 18 16
Width of lacing bars (mm) 65 60 55 50
Lacing bars in a steel column should be designed to resist
The lacing of compression members should be designed to resist a transverse shear, V = 2.5% of axial force in the member.
For single lacing system on two parallel faces, the force (compressive or tensile) in each bar,
For double lacing system on two parallel planes, the force (compressive or tensile) in each bar,
The channels or angles in the compression chords of the steel truss girder bridges are turned outward in order to increase
Which one of the following pairs is correctly matched?
An electric pole 5 m high is fixed into the foundation. It carries a wire at the top and is free to move sideways. The effective length of the pole is
It is equivalent to a compression member whose one end is fixed against rotation and position and the other and neither restrained against rotation nor fixed in position in the direction perpendicular to wire. So effective length = 2L = 10 m.
In the direction of wire, the pole is hinged at wire end so effective length = 0.8L = 4.0 m.
For a compression member having the same effective length about any cross-sectional axis, the most preferred section from the point of view of strength is
Lesser the value of λ (greater radius of gyration r), the column can take more load. Maximum radius of gyration is obtained when material is farthest from centroid. Therefore box section is best.
The slenderness ratio of lacing bars should not exceed
Which one among the following is the correct ratio of effective length to actual length of a discontinuous angle strut, if ends are welded?
For single angle discontinuous,
(i) One rivet or bolt - Effective length is the distance between the centres of end fastenings
(ii) Two or more rivets or welding - Effective length is 0.85 times the distance between node points.
In a gusseted base, when the end of the column is machined for complete bearing on the base plate, the axial load is assumed to be transferred to the base plate
If the column ends and gusset materials are not faced/machined for complete be a ring, the fasteners are designed for the total forces to be transferred. If they are faced/machined for complete bearing, 50% of the forces are transferred directly by the column and 50% through the fasteners