Needham & Associates Consulting Engineers

1. Needham & AssociatesConsulting Engineers Fort Wayne, IN - Overland Park, KS http://www.needhamassoc.com

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

3. Jeff 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, Principal P.E., S.E in 25 states, started in PEMB in 1968 BS Virginia Military Institute, MS from Georgia Tech Your Speakers

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

5. Introduction • Why consider serviceability(source of many problems and claims) • Owner input (must have active input, common problem) • Specific to structure’s use • Easy to build in, difficult to repair

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

7. Flammable Vapor Build-up in Insulation

8. Types of Serviceability Issues • Deflections and Drift (primary focus of this talk) • Expansion/Contraction • Camber • Vibration • Corrosion • Connection Slip

9. Responsibility for Determining Serviceability Requirements • Generally not code issue • Building manufacturer’s consideration only if informed by dealer • Entity (Architect or Owner) specifying the building parameters specifies criteria • Serviceability criteria need owner agreement of requirements & cost

10. Basic Deflection and Drift Ratios

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

12. Typical NEW PEMB Hardwall Buildings • Designed for strict serviceability issues • Load bearing walls

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

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

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

16. Crane Serviceability Controls

17. References for Bridge Cranes • CMAA Standard 74 (Single Girder TR and UH Cranes) • CMAA Standard 70 (Double Girder TR Cranes ) • Call (704) 552-8644 to order • About $40 each

18. CMAA Standards 70 and 74

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

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

21. Interior Partitions & Ceiling Considerations • Suspended ceilings will telegraph roof deflections • Noticeable • in large open offices • junctions of ceilings & interior walls

22. Typical Ceiling Problem

23. Interior Partitions & Ceiling Considerations • Suspended ceilings will telegraph roof deflections • Noticeable • in large open offices • junctions of ceilings & interior walls • Don’t tie interior partitions to main framing

24. Good and Bad Details Bad Good

25. Interior Partitions & Ceiling Considerations • Suspended ceilings will telegraph roof deflections • Noticeable • in large open offices • junctions of ceilings & interior walls • Don’t tie interior partitions to main framing • Remember - Actual deflections are as much as 25% higher than calculations indicate

26. Roof Considerations • “L/Span” deflections

27. Comparison of L/Span Deflections • L/180 on typical Z-purlin • 20 foot bay = 1.33 inches, 30 foot bay = 2 inches • L/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 roll”

28. Purlin Deflection

29. Roof Considerations • “L/Span” deflections • Purlin deflection at eaves and rakes

30. Eave Deflection/Ice Dam

31. Roof Considerations • “L/Span” deflections • Purlin deflection at eaves and rakes • Ponding, with low slope roofs

32. Ponding • Common failure type of joist roofs due to clogged drains, scuppers • Can be caused by snow drifting • Design 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!

33. Ponding Problem on 1/2 to 12 Slope

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

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

36. Non-Deflection/Drift Serviceability • Camber • Corrosion • Vibration • Connection 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 compatible • Know your owner/customer • Don’t forget to “program” the job in the rush to start a design build job • Require that manufacturer meet AISC “Steel Design Guide 3”

38. AISC “Steel Design Guide 3” • Call AISC 800-644-2400 • Price $16

39. Questions????

40. 233 W. Baker St.Fort Wayne, IN 46802 (219)420-3400 8417 Santa Fe Dr. Overland Park, KS 66212 (913)385-5300 Thank You!...Needham & AssociatesConsulting Engineers http://www.needhamassoc.com