Useful Resources for the Serviceability of Concrete Slabs
Engineers are often more familiar with strength provisions for concrete slabs, but building codes require adequate strength and serviceability. Excessive cracking and sloping or bouncy floors can be a nuisance and render a building unusable for its intended purpose. Thus, engineers should be familiar with the available resources providing guidance for serviceability issues above and beyond the basic requirements in the building code.
In the February 2022 SEU Session, Dave Adams, PE, SE, from BWE, Inc., presented Serviceability for Concrete Slabs. Dave covered a variety of topics addressing serviceability of slabs including strategies for improving the performance of concrete, short- and long-term deflections, the influence of reinforcement on potential cracking, prestressed tendon layout, and the effects of floor vibrations.
Throughout the presentation, Dave offered resources to learn more about serviceability of concrete slabs and to find additional design examples for reference. Most of the presentation was based on guidelines in our usual Design Codes, such as 2018 International Building Code, ACI 318-14 Building Code Requirements for Structural Concrete, and ASCE/SEI 7-16 Minimum Design Loads and Associated Criteria for Buildings and Other Structures. But many other resources are available to provide further guidance for serviceability which tends to get less coverage in the main Design Codes.
Since mix design and placement can greatly affect the performance of concrete slabs, Dave noted that ACI 209R Prediction of Creep, Shrinkage, and Temperature Effects in Concrete Structures offers guidance for the practicing engineer on concrete mix designs and how to plan for serviceability concerns. ACI SP-20, Causes, Mechanisms, and Control of Cracking in Concrete is another useful document to prevent excessive short- or long-term cracks in concrete slabs along with 224R-01 Control of Cracking in Concrete Structures.
Two excellent resources that offer a detailed understanding of prestressed concrete member deflections are the PCI Design Handbook and Deflections of Prestressed Concrete Members from the ACI Journal Proceedings, V60, No.12, 1963. Also, Dave recognized the ACI Journal Proceedings V6, No, 6, from June 1963 Load-Balancing Method for Design and Analysis of Prestressed Concrete Structures by T.Y. Lin. This article is useful for learning more about determining acceptable tendon profiles for prestressed concrete and the load balancing method based on elastic prestressed concrete beam theory.
For vibration control of concrete slabs, engineers can refer to AISC Design Guide 11: Floor Vibrations Due to Human Activity and Design Guide for Vibrations of Reinforced Concrete Floor Systems from CRSI. Vibration issues are often subjective, but they can have important ramifications on the usefulness of concrete floors for a variety of activities.
Some of these resources are available free of charge, and others are available for purchase, but all of these materials are helpful to eliminate serviceability concerns in concrete slabs.