Floor Openings in Two-Way Slabs-Detailing Corner-Reinforcing Bar Layout for Two-Way Slabs (PDF)

Detailing Corner-Reinforcing Bar Layout for Two-Way Slabs (PDF)

Pdf Summary

The article "Reinforcing Bar Layout for Two-Way Slabs" from Concrete International, November 2012, explores the reinforcement layout and detailing practices for two-way slabs. Two-way slabs are slabs with a ratio of long span to short span less than two, designed for flexure in more than one direction, usually orthogonal to a rectangular grid of column lines. These slabs require two mats of reinforcing steel: a continuous bottom mat for positive moments and temperature/shrinkage reinforcement and a top mat at supports for negative moments.<br /><br />The detailing methods emphasized in the article involve showing the actual layout of column and middle strips on a plan view, scheduling reinforcement in tables or directly on the plans, and indicating uniform reinforcement quantities across slabs with specified additional reinforcement. All methods underscore the need for clarity and constructibility, ensuring reinforcement is correctly positioned to facilitate accurate and efficient construction.<br /><br />Certain detailing practices are recommended for good results: indicating inner and outer layers of bars, properly designating column strip reinforcement as integrity steel, and ensuring reinforcement spacing is a multiple of main bars. Properly fitting hooks, managing punching shear through design adjustments or using higher-strength concrete, and clear differentiation of slab and beam reinforcement are highlighted as essential tasks.<br /><br />Avoiding small diameter bars in two-way slabs due to issues of displacement and bending is advised. The article concludes by reinforcing that practical field experience, constructibility, and clarity, alongside adherence to code requirements, are vital for successful concrete construction projects. The article leverages guidelines from ACI 318-11 and ACI 421.1R-08, offering insights into effectively detailing two-way slab reinforcement.

Keywords

two-way slabs

reinforcement layout

flexure design

constructibility

column strips

reinforcing steel

punching shear

ACI guidelines

detailing practices

concrete construction