Q1: According to I.S. : 456 specifications, the safe diagonal tensile stress for M 150 grade concrete, is

ANS:A - 5 kg/cm²

In reinforced concrete structures, diagonal tension stresses can develop due to various loading conditions, such as bending, shear, and torsion. Diagonal tensile stresses occur along diagonal planes within the concrete elements, particularly at regions where there is a concentration of shear forces. These stresses can lead to the formation of diagonal cracks in the concrete. The Indian Standard IS 456:2000 "Plain and Reinforced Concrete - Code of Practice" provides guidelines and specifications for the design and construction of concrete structures in India. This code specifies various parameters, including the permissible stresses for different grades of concrete. For M150 grade concrete, which is a commonly used concrete grade in construction, the IS 456 standard typically specifies a safe diagonal tensile stress of 5 kg/cm². This value is determined based on factors such as the compressive strength of the concrete, its tensile strength, and the desired level of safety for the structure. The choice of a safe diagonal tensile stress is crucial in ensuring the structural integrity and durability of reinforced concrete members. By limiting the diagonal tensile stress to a safe level, designers can prevent the formation and propagation of diagonal cracks, which could compromise the performance and safety of the structure over time. Designers must consider various factors, such as the type of loading, structural geometry, and material properties, when determining the safe diagonal tensile stress for a particular concrete grade. Additionally, local building codes and project specifications may influence the selection of permissible stresses to ensure compliance with regulatory requirements and construction standards. Overall, the safe diagonal tensile stress specified in IS 456 for M150 grade concrete reflects a balance between structural safety, serviceability, and material performance, aiming to ensure the robustness and longevity of reinforced concrete structures in India.