introducing sei &asce 37-02 design loads on structures during construction

8/18/2019 Introducing SEI &ASCE 37-02 Design Loads on Structures During Construction

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codes & standardsIntroducing SEI/ASCE 37-02 Design Loadson Structures during ConstructionWhat the engineering professional should know…By Cris Subrizi, PE, Alan Fisher, PE, John S. Deerkoski, PE

26 STRUCTURE magazine • March 2004

Are more structures failing during construction, or does it just seem like there are? What, if anything, is being or could be done to reverse this trendWhose problem is it? How does the recently issued SEI/ASCE Standard 37-02, “Design Loads on Structures During Construction” fit into thiissue, and what future efforts should be made? It is hoped that this article will initiate a wider dialog in the structural engineering community aboudesign engineers and their role in designing structures for loads encountered during the construction period.

Origin of SEI/ASCE 37-02It had long been recognized that there was

a “hole” in the structural design-constructionprocess. There have been no standardizeddefinitions of loads that should be used in thedesign and/or checking of structures during theirconstruction phases. The new standard, SEI/ ASCE 37-02, Design Loads on Structures DuringConstruction is intended to plug that hole.

Current design codes and standards are mostlysilent on the subject of construction loads, or givesuch general statements as “Proper provisions shallbe made for stresses . . . during erection . . . of thebuilding” and “Adequate temporary bracing shallbe provided to resist wind loading . . . during theerection and construction phases.” The questions,of course, are: what is adequate and what areproper provisions? The answers often depend on who gives them: the designer, the contractor, theowner, or the building official.

The development ofSEI/ASCE 37 was precededby a survey of several structural design andconstruction related organizations and practicingengineers. All participants endorsed the idea ofdeveloping guidelines or a consensus standard fordesign loads on structures during construction.

The group recognized that a set of standardizedconstruction loads could contribute substantiallyto the mitigation of construction failures(See Figure 1). It would call attention to the needfor serious design for the construction process,and would specify reasonable guidance on themagnitudes of expected construction loads. It

would provide a common “language” just as othercodes and standards do for completed structuresduring their service lives.

In October 1987, ASCE’s Board of Directorsapproved the development of a new ASCEStandard for Design Loads on Structures DuringConstruction. A committee of ninety-sixpeople, representing a cross section of industryprofessionals and stakeholders, was formed andorganized into six subcommittees: Purpose andScope, Loads and Load Combinations, Dead and

Live Loads, Construction Loads, Lateral EarthPressures, and Environmental Loads.

After fourteen years of thoughtful developmentand debate, observing ANSI rules and proceduresthat included public balloting, the document waspublished in early 2002 as SEI/ASCE 37-02 .Now we have industry-wide guidance on designloads for temporary structures and permanent

structures during their construction phases.The intent is that “The design loads shall provide

for a level of safety of partially completed structures,and temporary structures used in construction, thatis comparable to the level of safety of completedstructures.” The Standard’s provisions, however,are not intended to account for loads caused bygross negligence and error.

While specifying the design loads for temporaryconstructions, the Standard does not specify who is responsible for the design. Roles andresponsibilities during the design-constructionprocess are defined by state laws and the contractseffective among the involved parties.

Like the standards for permanent constructithis standard is applicable to both Design-BBuild (DBB) and Design-Build (DB) projdelivery. In the DBB method, the way which the standard is used is expected to vaccording to the requirements of the authorhaving jurisdiction. Considering that the Sin a DBB arrangement can only postulate me

and methods without the benefit of controllthem during construction, the standard does nat first appear to be a useful addition to the SEtoolbox. This raises the question; what does standard mean to them?

What the practicing SERshould know about the standard…The use of SEI/ASCE 37 as an extension

the widely-used SEI/ASCE 7, Minimum DesLoads for Buildings and Other Structures , is meto enhance the SER’s ability to evaluate structu

issues which occur during the construction pha

Figure 1 SEI/ASCE 37 is a new tool to aid engineers avoid failures such as this.

(Photo courtesy of Wiss, Janney, Elstner Assoc.)



STRUCTURE magazine • March 2004

The SER should evaluate with the client whetherthe contract should enforce special structuralengineering requirements on the contractor forthe construction phase.

When SEI/ASCE 37 is referenced as the designload specification, there is substantial reductionin the potential for misunderstanding as tomagnitudes of the loads accounted for during thevarious phases of the construction.

Since this is a new standard, intended to apply

to a broad user base, it is clear that some specificsections of the standard may deviate from currentpractice (e.g., practice as expressed in Section2.3.3 Overturning and Sliding and Section-6.5 Earthquake). These provisions should bereviewed carefully and may warrant specificcomment in the contract documents.

Who is responsible to evaluate thestructure during its construction life?

The document is a load standard, not a designstandard that defines analysis methods or otherstructural design tasks. How an engineer uses theloads or evaluates strength and stability is a matterof her/his professional practice.

In the DBB arrangement, the SER and theclient should discuss whether explicit analysis

during the construction phase of the structureis to be the SER’s concern or if it is to be left tothe contractor.

If the SER must perform the evaluation, SEI/ ASCE 37 will be helpful in the development ofthe base case construction scheme. This scheme will illustrate howSEI/ASCE 37 was used in theevaluation, a process that is analogous to finaldesign plans developed based on traditionalload standards.

Two realities need to be considered: first, theSER in a Design-Bid-Build arrangement will nothave complete knowledge of means and methods

and, secondly, the freedom to innovate is integralto the competitive bid process. Consideringthese, it is certain that the base design will not beall inclusive and will likely change. However, it isnot a wasted effort to consider such a base design,since its existence will provide a clear benchmarkto better define the scope of the project to be bid,as well as facilitate the management of contractorinnovation.

The base design can include engineeringevaluations of the erection sequence for stressor stability concerns; structural design ofconstruction means and methods, such as

excavation support and access scaffolding; andstructural evaluation of special loadings, such asstacked materials or special equipment that mayimpose loads in excess of the service-life designduring construction.

The outcome of this discussion with the clientmay be that there are no special concerns, there areconcerns that can be addressed on the documentsor there are concerns that the SER should address.

Does use of ASCE 37-02 requiremodification to DBB specifications

and drawings? What goes inthe specifications? What goes

on the drawings?Modifications to the drawings and

specifications will be dependent upon whetherthe local jurisdiction explicitly considers theconstruction life of the structure.

If the owner does not wish to explicianalyze the construction phase, then itanticipated that the specifications would neto clarify for the bidder what, if any, engineerneeds to be considered in the bid, and to defithe mechanism to review the engineeriperformed by the Contractors StructuEngineer (CSE) during construction.

SEI/ASCE 37 facilitates these check abalance mechanisms with a standard “languafor loads, providing the transparency needto confirm that things are on the right traand providing a benchmark for evaluati

alternate means and methods. Definitiondesign loads should not stifle innovation construction.

It is expected that ASCE 37-02 loads and locombinations, when used, will be recordedthe contract drawings within a context. Tcontext is important considering the transienature of construction. As a result depictionassembly sequences appears to be an effect way of conveying the context of design loa Also useful would be the identification of lorestrictions and seasonal work limitatio As a result, these plans could prove usefulthe event of future retrofit, rehabilitation adisassembly.

What does the standard mean to thSER involved with DB project

delivery? Or to the CSE workingwithin the context of DBB delivery

The existence of the load standard meathat engineers designing for contractors whave a common “language” for design loaThis benchmark will promote transparen

in design level communications between contractor and the owner’s reviewers.The arrangement of the standard is sensit

to the fact that the nature of engineering construction is dynamic; as a result it mbe best thought of as a “thinking” standaLoads are provided for situations customof the construction phase. Commentaryalso provided that discuss the context of thloads and issues that could be encountered the engineer during design.

What Is SEI/ASCE 37?

Scope “This standard addresses partially completedstructures and temporary structures used during

construction.”

Purpose“To provide minimum design load requirements

during construction for buildings and otherstructures.”

ObjectiveTo establish design loads, load combinations

and safety factors to be used in the analysis anddesign of structures during transient stages ofconstruction, as well as temporary structures usedin construction operations.

What Is New?“The construction loads, load combinations

and load factors herein account for the often shortduration of loading, and for the variability of

temporary loads.”

Level of Safety“The design loads shall provide for a level

of safety of partially completed structures, andtemporary structures used in construction, thatis comparable to the level of safety of completedstructures.”

Design Responsibility“The standard does not specify who theresponsible party is for the design of temporarystructures or temporary supports or for thetemporary use of incomplete structures.”

Alternate Standards“When a construction loading is covered in adocument, acceptable to the authority having jurisdiction, written to address a specific materialor method of construction, the more applicabledocument shall be permitted to be followed.”

Benefits of Standardized Construction Loads

- A Constructors View Point

Standardization provides a “common language for

construction phase loads, this should cut confusion

Standardized construction loads offer aopportunity to improve practice.

- A Constructors View PoinIt is in the Owner’s best interest for the SE

to create a design that considers a structurconstruction phase.

This will reduce the incidence of failures b placing the level of safety during construction at pawith that of the rest of the structures life cycle.

Continued on next p



28 STRUCTURE magazine • March 2004

Recognizing that many of these issues are tobe resolved by reaching a consensus with theauthority having jurisdiction, the commentaryis provided to form the base needed to developthe design rather than being definitive.

The “Bottom Line”There was a time in the last century when

professional engineers and contractors wereone-in-the-same. Projects were brought tocompletion by a single design/build entity. For

decades now, the delivery method has beendifferent. There has been separation betweenthe designers and the builders of major works.

Perhaps this separation has, in part,contributed to construction failures. Underpresent practice, there can be confusion andmisunderstanding between the intent of theSER and the practice of the contractor. Therealso has been little authoritative load-definitionguidance for engineers serving contractors.

SEI/ASCE 37 is intended to be a tool for thecollaboration of professionals in DB contractsand for clarity and safety in the constructionprocess in both DB and DBB delivery methods. A component of the successful evolution – andperhaps in general improvement in structuralsafety during construction – could be a moreactive participation of the SER in the construction

The authors have been active committee members during the 15 years of ASCE 37-02 development. Cris Subri

is a Supervising Engineer with Parsons Brinckerhoff Quade & Douglas, Inc., San Francisco, CA. Alan Fisher, P

is Chief Structural Engineer at Cianbro Corporation, Portland, ME. John Deerkoski, PE is the Principal of John

Deerkoski & Associates, Warwick, NY, and is the subcommittee chairman responsible for Chapter 4.0 Constructio

Loads. The authors would like to recognize the contribution of Robert T. Ratay, SEI/ASCE 37 Standard Commit

Chairman, and Donald O. Dusenberry and John F. Duntemann Sub-Committee Chairs.

process, either through a direct role or throughmore comprehensive reviews of constructionactivities. This potential to efficiently improvesafety during construction will be realized ifindustry professionals avail themselves of newtools, such as this standard, to foster the evolutionof engineering and construction practice andsafety at all stages of the design, construction, anduse of built works.

In recent years, the delivery method has

begun an evolution that takes it back towardits prior form. DB contracts are designed tofoster efficiency and safety in both the designand construction phases. Such relationshipsbring together professionals from both arenas;professionals that have had institutional arms-length relationships in recent years.

As with any standard, SEI/ASCE 37 is aliving document; it depends on input fromits users and those impacted by its use. Theauthors encourage the reader to take part inthe support of this new standard.!

Further ReadingDetailed discussions of the background

purpose and content of the standard can b

found in the following series of four paper

published in the Proceedings of the 2003SE ASCE Structures Congress , May 29-31, 2003

Seattle, WA, and in Forensic Engineering

Proceedings of the Third Congress , ASCE

October 19-21, 2003, San Diego, CA.

• SEI/ASCE 37-02 Design Loads on Structures During Construction Standard – Background, Purpose and Scope , by Robert T. Ratay;

• Loads and Load Combinations in SEI/ASCE 37-02 , by John F. Duntemann

• Construction Loads in SEI/ASCE 37-02 ,

by John S. Deerkoski;

• Environmental Loads in SEI/ASCE 37-02 by Donald O. Dusenberry.

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