For a continuous floor slab supported on beams, the ratio of end span length and intermediate span length, is

ANS:D - 0.9

1. Structural Efficiency: In certain cases, particularly for longer spans, maximizing the length of the intermediate span can lead to more efficient use of materials and reduced overall cost. By increasing the ratio of end span length to intermediate span length, the design can allocate more of the total span length to the intermediate spans, where the bending moments and shear forces are typically lower.
2. Load Distribution: Increasing the ratio of end span length to intermediate span length can help distribute loads more evenly across the floor slab and beams. By extending the end spans, the load transfer mechanism from the slab to the beams is adjusted, which may lead to a more balanced load distribution and reduced differential deflection between spans.
3. Stability Considerations: For longer end spans, providing additional length can enhance the stability of the floor system by reducing the susceptibility to lateral torsional buckling or other stability issues. This is particularly relevant for slender beams or when the floor system is subjected to lateral loads such as wind or seismic forces.
4. Architectural Constraints: The layout and configuration of the building may also influence the choice of span lengths. In some cases, architectural requirements or functional considerations may dictate longer end spans, leading to a higher ratio of end span length to intermediate span length.
5. Code Requirements: Building codes and design standards may impose limitations or provide recommendations on the maximum allowable ratio of end span length to intermediate span length based on structural performance and safety considerations. However, in certain situations where code requirements allow flexibility, a ratio of 0.9 may be justified based on engineering judgment and project-specific requirements.

Overall, while a ratio of 0.9 for the end span length to intermediate span length is less common compared to smaller ratios, it may be appropriate for specific structural configurations, loading conditions, and design objectives, as outlined above. Engineering judgment and careful consideration of various factors are essential in determining the optimal span lengths for a continuous floor slab supported on beams.