David A. Fanella is Senior Director of Engineering at the Concrete Reinforcing Steel Institute (dfanella@crsi.org).
Significant changes were made to the design and detailing requirements for special steel-reinforced concrete structural walls in the 2019 edition of Building Code Requirements for Structural Concrete (ACI 318-19) (hereafter referred to as ACI 318).
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Significant changes were made to the design and detailing requirements for special steel-reinforced concrete structural walls in the 2019 edition of Building Code Requirements for Structural Concrete (ACI 318-19) (hereafter referred to as ACI 318). According to ASCE/SEI 7-16, Minimum Design Loads and Associated Criteria for Buildings and Other Structures, special structural walls are required in buildings with bearing walls, building frames, and dual systems assigned to Seismic Design Category (SDC) D, E, or F.
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Requirements for the distribution of flexural reinforcement in two-way footings are given in Sections 13.3.2.2 and 13.3.3.3 of ACI 318-14, Building Code Requirements for Structural Concrete. For square footings, the reinforcement is to be distributed uniformly across the entire width of the footing in both directions. In the case of rectangular footings, the reinforcement must be distributed in accordance with the requirements in Section 13.3.3.3 of ACI 318-14, which are illustrated in Figure 1. Reinforcement in the long direction is uniformly distributed across the entire width. A portion of the reinforcement in the short direction is uniformly banded over the column with the remainder uniformly distributed outside of the band width. …
This article is the fourth in a series on recommended reinforcement details for cast-in-place concrete construction. Parts 1, 2 and 3 ran in June, July, and August 2019 of STRUCTURE. …
This article is the third in a series (STRUCTURE: Part 1 – June 2019, Part 2 – July 2019) on recommended reinforcement details for cast-in-place concrete construction. …
This article is the second in a series on recommended reinforcement details for cast-in-place concrete construction. The first article, on Two-Way Slabs, ran in the June 2019 issue of STRUCTURE. …
This article is the first in a series on recommended reinforcement details for cast-in-place concrete construction.
Two-way slabs are generally defined as suspended slabs where the ratio of the long to the short side of a slab panel is 2 or less. In two-way construction, load transfer is by bending in two directions. The main flexural reinforcement usually consists of two mats of reinforcing steel – a top mat and a bottom mat – that run predominately in the directions that are orthogonal and parallel to the rectangular grid of column lines. The bottom mat of reinforcement resists the positive bending moments at the critical sections in the span and is usually continuous over the entire slab area. …
The overall integrity and performance of a special moment frame, which is required in buildings assigned to Seismic Design Category (SDC) D, E, and F, is dependent on the behavior of the beam-column joints in the frames. …
