Early definition of construction tolerance expectations is an important step in the design process of a project. Designs should consider tolerances of all materials and systems for their integration into a constructable facility. This session presents case studies, best practices, and material tolerances for design strategies to best achieve a constructible structure.
(1) Review design considerations that generate a more constructable facility showcasing dramatic economic advantages to the project;
(2) Explain potential solutions to achieve a buildable facility, when current ACI 117 tolerances for multi-story structures are in severe conflict with other building systems such as elevators or exterior enclosure.
(3) Discuss research data on pavement depths which routinely exceed ACI 117 tolerances, without pavement failures and identify the other paving design parameters that may contribute to the success of the paving system;
(4) Identify critical, key components of a system such as void forms and focus on controlling these tolerances which in turn control our success.
Relevance of ACI 117 Vertical Tolerances for Tall Structures and Their Application
Presented By: Eric Peterson
Affiliation: Webcor Builders
Description: The ACI consensus-based standards, used for concrete structures, interact with many other disciplines and assemblies. Ideally, the consensus process would include acceptance or acknowledgement by other building system’s materials, producers, installers, and their organizations, resulting in a high degree of alignment of expectations across these various specialties. In the presenter’s experience many project specifications contain vertical tolerances which are more restrictive and different than those published by ACI Committee 117. Are the values currently reported in ACI-117, for vertical tolerances, right for tall structures, or is the fact that designers specify more restrictive tolerances an indication that the present tolerances do not satisfy the requirements of our Industry?
Planning for the Control of Construction Tolerances and Deflections
Presented By: Eamonn Connolly
Affiliation: James McHugh Construction Co.
Description: Engineers are designing increasingly thin, slender, flexible, and highly stressed structures. These systems are more prone to deflection and deformation issues than they have been in the past. Owners, architects, and design team members now have higher expectations of dimensional tolerances and finishes. This presentation the importance of the communication of anticipated construction tolerance and deflection criteria between all project team members and discusses common issues of conflicting modern specification requirements. Construction methodologies: including modeling, field layout and monitoring programs are also presented. Finally, a set of rational deflection and tolerance recommendations and best practices are introduced.
Evolving Tolerances of Elevator Shafts
Presented By: Chris Garcia
Affiliation: DPR Construction
Description: Changes to elevator specifications have driven the horizontal and vertical tolerances for the shafts to shrink, leading to constructability issues for the concrete structure and other building trades. The elevator construction schedule is often on the project critical path, so proper planning is important to achieving success and avoiding costly delays and rework. Fortunately, there are ways to mitigate these challenges with coordination between the General Contractor, design team and trade partners as well as utilization of published resources by ACI and ASCC. This presentation will include a comparison to the ACI 117 tolerances, a suggested process for resolving tolerance conflicts and responsibilities in terms of quality assurance and quality control.
Design for Constructability - The Art of Keeping-It-Simple
Presented By: Larry Karlson
Affiliation: PCL Constructors Inc.
Description: Constructability can include a vast assortment of ideas. The structural design can significantly impact the constructability of a building or structure. The art of Keeping-It-Simple (otherwise known as the KISS theory) can play a significant role in construction of structures. This presentation touches on some examples of keeping structures simple, thus resulting in reduced construction costs.
Design Tolerance Reality - How Tight Can We Really Measure Anyway
Presented By: William Paul
Affiliation: BKF Engineers, Inc.
Description: It is a folly to discuss tolerances and specification compliance without a reliable method to measure the work in question. This discussion, from a professional land surveyor's perspective, will cover the current state of the art of construction measurement equipment and techniques including total stations, unmanned aerial vehicles, laser scanners, GPS, automated monitoring, etc. An extremely tight tolerance is pointless without an accurate way to measure it. Our ability to measure tolerances must be accounted for in project specifications. Is this currently occurring?
Tolerances that Control Void Form Construction
Presented By: James Cornell
Affiliation: JN Cornell Associates, LLC
Description: Expansive soils in North America require unique methods of floor slab design and construction to overcome effects of shrinking and swelling of the soils. Creation of a void under the floor slab requires the floor slab be designed as an elevated structure. The applicable tolerances of an elevated slab need to be applied to the subgrade and void forms. Special tolerance considerations apply to the void formed slab to ensure its success and service life.