Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.
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www.concreteproducts.com January 2015 • 9 The contemporary use of structural concrete is a complex endeavor, requiring the skills, training, insights and experience of a broad range of professionals. These include designers, engineers, construction specifiers, insurers and code officials, as well as the general contrac- tors, subcontractors and construction personnel. The goal is to build the safest possible structures that incorpo- rate and reflect state-of-the-art knowledge and experience in the use of structural concrete. At the same time, on any assignment, all involved in the process strive to enhance the user experience, com- munity "look and feel," and overall value for investors and asset and property managers. A integral guide in achieving these ends is the American Concrete Institute's (ACI) "Building Code Requirements for Structural Concrete and Commentary," a Code that more than 22 nations incorporate in whole or in part into their Building Code requirements. ACI 318-14 In 2014, ACI published ACI 318-14, the first significant reorganiza- tion of the Code since the 1970s. Over the ensuing four decades, the Code has more than tripled in its provisions as knowledge and expe- rience with structural concrete advanced, especially in areas such as torsional strength, seismic design and detailing, integrity reinforce- ment, concrete exposure classes, strain-based strength reduction fac- tors and anchoring to concrete. After years of thorough research, including study groups and que- ries of industry professionals, it was determined a new Code would be easier to reference when designing the use of structural concrete. The reorganized ACI 318-14 needed to follow, as much as possible, the real-world design process, and better delineate the responsibilities of entities tasked with structural concrete design, specification and construction. To support this latter goal, ACI 318-14 includes a new chapter on Construction Documents and Inspection (Chapter 26), which will assist in the process of design to construction. Here, we review ACI 318-14's principles of organization, along with its imple- mentation and expected benefits. PRINCIPLES OF ORGANIZATION At its core, ACI 318-11, the previous Code, is built around the design and detailing of cast-in-place beams and columns. Most of these requirements are in chapters 7 through 12. In the reorganized ACI 318-14, the committee made the decision that ACI 318's content and requirements in use are the responsibility of the licensed design professional (LDP). Moreover, this more intu- itive version of 318 provides the designer with confidence that all provisions relevant to a particular design have been addressed. In 318-11, there was no internal road map to assure the user of having addressed all relevant provisions. When considering a common con- struction detail, the user had to refer to multiple chapters govern- ing issues like nominal flexure, axial length, nominal shear strength, strength reduction, tie spacing and bend details, or lap splices. As a result, the existing organization relied heavily on familiarity with the code, requiring visits to multiple chapters to design and detail mem- bers and make judgments on which provisions apply. In contrast, with its member-based organization, ACI 318-14 keeps the user within a given design chapter as much as possible. This means all design and detailing rules for each building member are provided within one chapter. Whether the member is cast-in-place or precast, or mildly reinforced or prestressed, all requirements for a particular member type are contained within the member chapter. When needed, specialty reference is made to a universal set of Tool- boxes that support the individual member chapters. IMPROVED ORGANIZATION The 27 chapters of ACI 318-14 can be grouped into six core sections: General; Systems; Members; Joints and Connections; The Toolbox; and, Construction. The General chapters include information on the scope, application and interpretation of the Code, notation and terminology, referenced standards, concrete design properties, and steel designed properties. The System chapters cover minimum requirements for structural systems. This includes a new chapter that clarifies the overall design and detailing requirements of reinforced concrete building structures; loads and load combinations; and, structural analysis, with a new sec- tion on requirements for a finite element analysis. A seismic chapter that addresses earthquake resistant structures, an area of increasing interest and importance, has been added as well. The Member chapters, the heart of the reorganized ACI 318-14, include One-Way Slabs; Two-Way Slabs; Beams; Columns; Walls; Dia- phragms (new); Foundations; and, Plain Concrete Members, as appro- priate. Each member chapter references all design and detailing pro- visions that apply to that member by way of uniform headings. The Joints and Connections chapters address beam-column and slab-column joints, connections between members, and anchoring to concrete. Continued on page 10 GUEST EDITORIAL BY RANDALL W. POSTON American Concrete Institute's ACI 318-14: A modern, accessible code platform