Buildings must be constructed in accordance with which design method as permitted?

The correct answer is that buildings must be constructed in accordance with all the design methods listed, including strength design, load and resistance factor design, and allowable stress design. Each of these design approaches has its own principles and applications that have been recognized for ensuring structural integrity and safety in building construction.

Strength design is focused on ensuring that structures can support expected loads without failure, taking into account different material strengths and load combinations. Load and resistance factor design incorporates safety factors into the design process, allowing for a more nuanced approach that mitigates risks due to uncertainties in load estimations and material properties. Allowable stress design, on the other hand, emphasizes the limits of stress that materials can safely withstand, offering a simpler methodology, especially for less complex structures.

By incorporating each of these methods, building codes and design standards provide flexibility and options for engineers and architects, allowing them to choose the most suitable design methodology for the specific needs of a project while fulfilling safety and performance criteria. This comprehensive approach helps adapt to various conditions and material types, ultimately contributing to the resilience and sustainability of buildings.