Taking a new approach to concrete

Conclusion
As a standard, ACI 562-13 represents the current structural engineering state of the art for evaluation and repair of existing concrete structures. It has evolved as the source for standard of care, or the quality of work expected of design professionals, in assessing existing concrete structures.

By understanding ACI 562, engineers and architects can improve the overall quality of concrete repairs while realizing significant benefits for contractors and owners. These knowledgeable concrete professionals can also educate project owners and municipalities about the new repair requirements that are becoming standard practice.

Building officials have already begun approving the use of ACI 562 on a case-by-case basis, and local jurisdictions can adopt the code directly. ACI 562 is also compatible with the International Existing Building Code (IEBC), and may be adopted as part of IEBC 2018.

 IS A STRUCTURAL EVALUATION ALWAYS REQUIRED?

Through a series of highlighted call-out boxes, the Guide to the Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings provides further explanation and references related to the provisions of American Concrete Institute (ACI) 562, Code Requirements for Evaluation, Repair, and Rehabilitation of Concrete Buildings. The following is an excerpt from a call-out box addressing structural evaluations:

ACI 562 does not require the licensed design professional (LDP) to perform a detailed structural evaluation in cases where the capacity of the structure is known. Consider the following scenarios when a structural evaluation would not be required.

Scenario #1: A beam at the lower level of a shopping center is impacted by an errant vehicle. The plans and available documents were reviewed as part of the preliminary evaluation and indicate the beam was designed to satisfy the required loading. Based on the LDP’s preliminary evaluation, the damage is limited to cracking and spalling of the concrete cover at a single beam location. There are no visible signs of damage to the existing reinforcement.

Based on these results, the LDP may proceed with the design of the repair without performing a more detailed structural assessment or structural analysis of the existing beam or structure.

Scenario #2: An LDP is retained to review the in-place condition of a parking garage and provide documents for repairs or maintenance. During the preliminary evaluation, the LDP learns the manager has recently started using de-icing salts on the ramps and parking areas. In addition to replacing failed sealant joints and performing other routine maintenance, the LDP is considering a coating or sealer for durability considerations of the salt-exposed deck. The preliminary evaluation performed by the LDP indicates the garage is in otherwise good structural condition with no signs of deterioration or structural deficiency. The LDP may proceed with the coating system design and durability repairs without performing a structural assessment or structural analysis of the existing deck or garage.

In this instance, additional assessment (for example, material sampling to determine chloride levels in the deck) is not required based on ACI 562, Chapters 6.1.2 and 6.1.3. A chain drag survey of the deck might be considered prior to performing coating repairs.

Jay H. Paul, SE, FACI, is a senior principal of Klein and Hoffman in Chicago, and has served the industry through numerous professional organizations including being past-president of the Structural Engineers Association of Illinois (SEAOI) and a past-chair of the American Concrete Institute (ACI) Committee 546 on concrete repair. Paul is currently a member of the International Concrete Repair Institute (ICRI) and ACI Committee 562 on evaluation, repair, and rehabilitation of concrete buildings. Recently, he chaired the review committee for the development of the Guide to the Code for Evaluation, Repair, and Rehabilitation of Concrete Buildings. He can be contacted at jayhpaul@comcast.net.

Gene R. Stevens, PE, SE, M. ASCE, is the chair of ACI 562, Subcommittee A and of the Structural Engineers Association of Colorado’s (SEAC’s) Existing Structures Committee. A principal with J. R. Harris & Company in Denver, Colorado, his focus includes the behavior and performance of members, systems, and structures, along with the investigation, evaluation, and assessment of existing concrete and wood buildings, and the design of repairs and rehabilitations for faulty construction, damage, and deterioration in existing structures. Stevens may be reached at gene.stevens@jrharrisandco.com.

Leave a Comment

7 comments on “Taking a new approach to concrete”

Leave a Comment

Comments

Your email address will not be published. Required fields are marked *