Q1: Lapped splices in tensile reinforcement are generally not used for bars of size larger than

ANS:D - 36 mm diameter

1. Mechanical Properties: As the diameter of the reinforcement bars increases, the mechanical properties also change. Larger diameter bars tend to have higher tensile strength and stiffness. This increased strength can make it more challenging to create effective lapped splices due to the higher forces involved.
2. Concrete Cover: In reinforced concrete structures, there is a requirement for a minimum cover of concrete over the reinforcement bars to protect them from corrosion and to provide fire resistance. With larger diameter bars, achieving adequate concrete cover becomes more difficult, especially at the spliced region. Inadequate cover can lead to durability issues and potential structural vulnerabilities.
3. Spacing Considerations: Lapped splices require a certain length of overlap between two bars to ensure effective transfer of forces. With larger diameter bars, the required overlap length also increases. This can lead to congestion issues within the concrete member, affecting the workability of concrete during placement and complicating the construction process.
4. Construction Challenges: Handling and maneuvering larger diameter bars during construction can be more difficult and labor-intensive. Lapping such bars adds to the complexity of construction, requiring careful placement and alignment to ensure the integrity of the spliced region.
5. Structural Integrity: Effective lapped splices rely on the bond between the reinforcement bar and the surrounding concrete. With larger diameter bars, achieving adequate bond strength becomes more critical. Factors such as concrete quality, compaction, and curing become even more crucial to ensure proper bond development.
6. Alternative Splicing Methods: For larger diameter bars, alternative splicing methods such as mechanical splices or welded splices are often preferred. These methods offer advantages such as improved efficiency, reduced congestion, and better control over splice lengths compared to lapped splices.

Overall, while lapped splices are a commonly used method for connecting reinforcement bars in smaller diameter applications, their effectiveness diminishes for larger diameter bars due to the aforementioned reasons. Hence, it is generally recommended to use alternative splicing methods for bars larger than 36 mm in diameter in reinforced concrete structures.