What is the minimum lap splice length for a horizontal member?

The minimum lap splice length for a horizontal member is based on the requirements defined by the design codes and standards for reinforced concrete. In many specifications, a common guideline indicates that lap splices for horizontal bars should be a specific multiple of the diameter of the reinforcing bars being used.

In this context, the choice indicating 40 times the diameter of the bar is correct because this length ensures that the reinforcing bars will be adequately bonded to transfer stress along the length of the splice. This is particularly important in horizontal applications where loads and structural conditions can vary significantly, necessitating sufficient overlap to maintain structural integrity and performance.

Using a lap length of 40 times the bar diameter helps accommodate factors such as the concrete cover, environmental conditions, and load requirements. It ensures that the splice can effectively carry the intended tensile and compressive loads without experiencing failure at the splice joint.

The other options, while they may represent valid splice lengths in specific circumstances, do not align with the standard minimum requirements for horizontal members as commonly outlined in structural design codes.