In low- to mid-sized structures, it's often unnecessary and uneconomical to follow a design code that encompasses all structures. The added design costs needed to prepare thorough studies that effectively utilize materials aren't justified in low-rise buildings. For low- to mid-sized structures, designing for expediency in construction, rather than efficiency in structural design, reduces total construction cost. Simplified designs usually yield members that are more conservative than required by code, but savings due to the ease of construction should offset additional material costs. All simplified design procedures comply with provisions of Building Code Requirements for Reinforced Concrete (ACI 318-89, revised 1992) using appropriate load factors and strength reduction factors. A few general rules:
- Choose member depth to control deflection.
- Size member to resist bending moment.
- Select moment reinforcement.
The article also includes ten tips for economical detailing of reinforcement, and design decisions that reduce formwork costs.