Structure Engineering notes for GATE and PSUs - part 5

Hello there,
How you doing? Here is the useful collection of one liners for the preparation for GATE and PSUs examinations.

• Intermediate vertical stiffeners in a plate girder need be provided if the depth of web exceeds 85t, where t is the thickness of the web.
• Bearing stiffeners in a plate girder is used to prevent buckling of web.
• The forces acting on the web splice of a plate girder are shear and bending forces
• Gantry girders are designed to resist lateral, longitudinal and vertical loads.
• Minimum spacing of vertical stiffeners is limited to d/3 where d is the spacing between flange angles.
• Bearing stiffeners are provided at the supports and at the points of application of concentrated loads.
• Rivets connected flange angles to cover plates in a plate girder are subjected to horizontal shear only.
• Maximum spacing of vertical stiffeners is 1.5d, where d is the distance between flange angles.
• The range of economical spacing of trusses varies from L/3 to L/5.
• The maximum permissible span of asbestos cement sheets is 1680 mm.
• Normally, the angle of roof truss with asbestos sheets should not be less than 30 degrees.
• To minimize the total cost of a roof truss, the ratio of the cost of truss to the cost of purlins shall be 2.
• Generally the purlins are placed at the panel points so as to avoid  bending moment in rafter.
• For the buildings having a low permeability, the internal wind pressure acting normal to the wall and roof surface is taken as  +-0.2 p, where p is the basic wind pressure.
• The relation between intensity of wind pressure p and velocity of wind V is taken as p is directly proportional to V^2.
• The live load for a sloping roof with slope 15 degree, where access is not provided to roof, is taken as 0.65 kN/m^2.
• The internal pressure co-efficient on walls for buildings with large permeability is taken as +-0.7.
• The basic wind speed is specified at a height 'h' above mean ground level in an open terrain. The value of 'h' is  10m.
• The risk co-efficient k1 depends on mean probable design life of structures and basic wind speed.
• The external wind pressure acting on a roof depends on slope of roof.
• Area of openings for buildings of large permeability is more than 20% of the wall area.
• As per IS: 800, the maximum bending moment for design of purlins can be taken as WL/10, where W is the total distributed load including the wind load on the purlins and L is centre to centre distance of supports.
• As per IS:875, for the purpose of specifying basic wind velocity, the country has been divided into 6 zones.
• The numbers of seismic zones into the country has been divided is 5.
• Minimum pitch provided in riveted steel tanks is 3.0d, where d is the diameter of rivet.

Reference: Civil Engineering objectives by S P Gupta and S P Gupta.

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