As per IS: 800-1984, the lacings of compression member shall be propo...
Lacing can be designed to resist a total transverse shear at any point in the member equal to 2.5% of axial force in the member. This shear shall be divided among lacing systems in parallel planes.
Hence the correct answer is option C.
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As per IS: 800-1984, the lacings of compression member shall be propo...
Compression Member Lacings as per IS: 800-1984
Introduction:
IS: 800-1984 is the Indian standard code of practice for general construction in steel. It provides guidelines and specifications for the design, fabrication, and erection of steel structures. In the case of compression members, such as columns and struts, lacings are provided to resist transverse shear forces.
Definition of Transverse Shear:
Transverse shear is the force that acts perpendicular to the longitudinal axis of a member. In compression members, transverse shear forces can arise due to eccentric loading, wind or seismic loads, or imperfections in the member.
Proportioning of Lacings:
According to IS: 800-1984, the lacings of a compression member should be proportioned to resist a total transverse shear 'S' equal to at least 2.5% of the axial load.
Explanation:
The axial load in a compression member refers to the load acting along its longitudinal axis. Lacings are provided to prevent the buckling or lateral instability of the compression member under the influence of transverse shear forces.
The code specifies that the total transverse shear 'S' should be resisted by the lacings. This means that the lacings should be designed to carry the transverse shear force acting on the compression member. The value of 'S' is expressed as a percentage of the axial load.
According to the code, the minimum value of 'S' is 2.5% of the axial load. This means that the lacings should be proportioned to resist a transverse shear force equal to 2.5% of the axial load.
The choice of 2.5% is based on the experience and knowledge of the behavior of compression members under transverse shear forces. It ensures that the lacings are designed to provide adequate resistance against lateral instability and buckling.
Therefore, the correct answer is option 'C' - 2.5% of the axial load.
Conclusion:
IS: 800-1984 provides guidelines for the proportioning of compression member lacings to resist transverse shear forces. The lacings should be designed to resist a total transverse shear equal to at least 2.5% of the axial load. This ensures the stability and safety of the compression member.