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Needham & Associates Consulting Engineers Fort Wayne, IN - Overland Park, KS

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Presentation on theme: "Needham & Associates Consulting Engineers Fort Wayne, IN - Overland Park, KS"— Presentation transcript:

1 Needham & Associates Consulting Engineers Fort Wayne, IN - Overland Park, KS

2 Serviceability Design of Metal Buildings Or….Why is my customer so unhappy???Or….Why is my customer so unhappy??? What does a contractor need to know???What does a contractor need to know???

3 Your Speakers Jeff Needham, PrincipalJeff Needham, Principal –P.E., S.E in 20 states, started firm in 1989 in Fort Wayne –BS and MS from University of Kansas Andy Carter, PrincipalAndy Carter, Principal –P.E., S.E in 25 states, started in PEMB in 1968 –BS Virginia Military Institute, MS from Georgia Tech

4 What Does Needham and Associates Do? General Practice Structural/Civil EngineersGeneral Practice Structural/Civil Engineers Consultants to PEMB IndustryConsultants to PEMB Industry –Heavy Structures ( ex: large clear-spans, steel mills, special structures) –Hardwall Buildings ( ex: site-cast, tilt-up concrete)

5 Introduction Why consider serviceability (source of many problems and claims)Why consider serviceability (source of many problems and claims) Owner input (must have active input, common problem)Owner input (must have active input, common problem) Specific to structures useSpecific to structures use Easy to build in, difficult to repairEasy to build in, difficult to repair

6 Example of Breakdown in Serviceability Considerations Probably lack of communication between owner and contractorProbably lack of communication between owner and contractor Project in Terra Haute, INProject in Terra Haute, IN

7 Flammable Vapor Build-up in Insulation

8 Types of Serviceability Issues Deflections and Drift (primary focus of this talk)Deflections and Drift (primary focus of this talk) Expansion/ContractionExpansion/Contraction CamberCamber VibrationVibration CorrosionCorrosion Connection SlipConnection Slip

9 Responsibility for Determining Serviceability Requirements Generally not code issueGenerally not code issue Building manufacturers consideration only if informed by dealerBuilding manufacturers consideration only if informed by dealer Entity (Architect or Owner) specifying the building parameters specifies criteriaEntity (Architect or Owner) specifying the building parameters specifies criteria Serviceability criteria need owner agreement of requirements & costServiceability criteria need owner agreement of requirements & cost

10 Basic Deflection and Drift Ratios

11 Wall Considerations - Drift Metal walls usually have no real limitMetal walls usually have no real limit Masonry/tilt-up/precast wall vs. frame driftMasonry/tilt-up/precast wall vs. frame drift Base condition free to rotate - H/100Base condition free to rotate - H/100 Base condition fixed to rotate - H/200Base condition fixed to rotate - H/200 Do not use unreinforced masonry walls with PEMBDo not use unreinforced masonry walls with PEMB

12 Typical NEW PEMB Hardwall Buildings Designed for strict serviceability issuesDesigned for strict serviceability issues Load bearing wallsLoad bearing walls

13 Wall Considerations - Deflection Wainscot walls & framing aboveWainscot walls & framing above Total deflectionTotal deflection –sum of frame drift & girt deflection Spandrel Beam (single girt) L/240, but not more than 1.5 inchesSpandrel Beam (single girt) L/240, but not more than 1.5 inches Details to enhance compatibility of materials, allow for movementsDetails to enhance compatibility of materials, allow for movements

14 Special Considerations for Bridge Cranes Complex topicComplex topic Common drift limit H(eave ht)/200 under crane lateral loadCommon drift limit H(eave ht)/200 under crane lateral load Crane beam deflection L(bay)/600 for vertical deflectionCrane beam deflection L(bay)/600 for vertical deflection Crane beam deflection L(bay)/400 for horizontal deflectionCrane beam deflection L(bay)/400 for horizontal deflection

15 Typical Crane Installation Serviceability often controls design as opposed to strengthServiceability often controls design as opposed to strength Steel and weldment fatigue is a major serviceability issueSteel and weldment fatigue is a major serviceability issue Therefore, serviceability dictates costTherefore, serviceability dictates cost

16 Crane Serviceability Controls

17 References for Bridge Cranes CMAA Standard 74 (Single Girder TR and UH Cranes)CMAA Standard 74 (Single Girder TR and UH Cranes) CMAA Standard 70 (Double Girder TR Cranes )CMAA Standard 70 (Double Girder TR Cranes ) Call (704) to orderCall (704) to order About $40 eachAbout $40 each

18 CMAA Standards 70 and 74

19 Interior Partitions & Ceiling Considerations Suspended ceilings will telegraph roof deflectionsSuspended ceilings will telegraph roof deflections

20 Sprinkler Heads Indicate Deflection Common winter callbackCommon winter callback May or may not indicate a real problemMay or may not indicate a real problem

21 Interior Partitions & Ceiling Considerations Suspended ceilings will telegraph roof deflectionsSuspended ceilings will telegraph roof deflections NoticeableNoticeable –in large open offices –junctions of ceilings & interior walls

22 Typical Ceiling Problem

23 Interior Partitions & Ceiling Considerations Suspended ceilings will telegraph roof deflectionsSuspended ceilings will telegraph roof deflections NoticeableNoticeable –in large open offices –junctions of ceilings & interior walls Dont tie interior partitions to main framingDont tie interior partitions to main framing

24 Good and Bad Details Bad Good

25 Interior Partitions & Ceiling Considerations Suspended ceilings will telegraph roof deflectionsSuspended ceilings will telegraph roof deflections NoticeableNoticeable –in large open offices –junctions of ceilings & interior walls Dont tie interior partitions to main framingDont tie interior partitions to main framing Remember - Actual deflections are as much as 25% higher than calculations indicateRemember - Actual deflections are as much as 25% higher than calculations indicate

26 Roof Considerations L/Span deflectionsL/Span deflections

27 Comparison of L/Span Deflections L/180 on typical Z-purlinL/180 on typical Z-purlin –20 foot bay = 1.33 inches, 30 foot bay = 2 inches L/240 on typical roof bar joistL/240 on typical roof bar joist –30 foot bay = 1.5 inches less initial camber of 3/8 –Net deflection is 1.125, much less than Z-purlin Z-purlin deflection is magnified by purlin rollZ-purlin deflection is magnified by purlin roll

28 Purlin Deflection

29 Roof Considerations L/Span deflectionsL/Span deflections Purlin deflection at eaves and rakesPurlin deflection at eaves and rakes

30 Eave Deflection/Ice Dam

31 Roof Considerations L/Span deflectionsL/Span deflections Purlin deflection at eaves and rakesPurlin deflection at eaves and rakes Ponding, with low slope roofsPonding, with low slope roofs

32 Ponding Common failure type of joist roofs due to clogged drains, scuppersCommon failure type of joist roofs due to clogged drains, scuppers Can be caused by snow driftingCan be caused by snow drifting Design checks for stability failure are usually not required for slopes of 1/4/12 or greaterDesign checks for stability failure are usually not required for slopes of 1/4/12 or greater Stability checks may be required for slopes of 1/4/12 or greater if ice dams/snow drifts occur…Be Careful with this condition!Stability checks may be required for slopes of 1/4/12 or greater if ice dams/snow drifts occur…Be Careful with this condition!

33 Ponding Problem on 1/2 to 12 Slope

34 Roof Considerations L/Span deflectionsL/Span deflections Purlin deflection at eaves and rakesPurlin deflection at eaves and rakes Ponding, with low slope roofsPonding, with low slope roofs Panel distress & leakage caused by excessive purlin or frame deflections…this may be first clue of serviceability issuePanel distress & leakage caused by excessive purlin or frame deflections…this may be first clue of serviceability issue

35 Non-Deflection/Drift Serviceability Expansion/ContractionExpansion/Contraction Not usually an issue with all steel buildingNot usually an issue with all steel building Watch for adjacent structureWatch for adjacent structure Watch for collateral materials..tilt-up concrete especiallyWatch for collateral materials..tilt-up concrete especially

36 Non-Deflection/Drift Serviceability CamberCamber CorrosionCorrosion VibrationVibration Connection SlipConnection Slip

37 Summary MBMA states that is up to owner (or his agent) to identify all materials so that the metal building can be designed to be compatibleMBMA states that is up to owner (or his agent) to identify all materials so that the metal building can be designed to be compatible Know your owner/customerKnow your owner/customer Dont forget to program the job in the rush to start a design build jobDont forget to program the job in the rush to start a design build job Require that manufacturer meet AISC Steel Design Guide 3Require that manufacturer meet AISC Steel Design Guide 3

38 AISC Steel Design Guide 3 Call AISC Call AISC Price $16Price $16

39 Questions????

40 Thank You!...Needham & Associates Consulting Engineers 233 W. Baker St. Fort Wayne, IN W. Baker St. Fort Wayne, IN (219) (219) Santa Fe Dr. Overland Park, KS (913)


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