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CONSTRUCTION LIVE SNOW OR WINDa DEAD + LIVE

Roof members:

Supporting plaster ceiling

Supporting nonplaster ceiling

Not supporting ceiling

Roof members supportingmetal roofing:

l / 360

l / 240

l / 180

l / 150

l / 360

l / 240

l / 180

-

l / 240

l / 180

l / 120

l / 60

Floor Members l / 360 - l / 240Exterior walls and interiorpartitions:

With brittle finishes

With flexible finishes

Secondary wall memberssupporting metal siding

-

-

-

l / 240

l / 120

l / 90

-

-

-(a) The wind load is permitted to be taken as 0.7 times the component and claddingloads for the purpose of determining deflection limits herein.

Roof slopes can be directed to drains by sloping the structure, using taperedinsulation, sloping fill, or by using a combination of these methods. Roof drains,gutters or scuppers are located at the low points. As the NRCA notes, from time totime, roof drainage points do not wind up at roof low points and can cause problemsfor the structure.

It at first seems logical that roof drains should be located at mid-span or mid-bay totake advantage of the low point created by deflection. The elevation of this low pointis, however, very difficult to control and can easily be negated by camber (such asmember curvature not requested but naturally occurring nonetheless) or upwarddeflection due to patterned loading in continuous designs.

If, on the other hand, drain points are located at columns, more control is possible.Within the limits of fabrication and erection tolerances, columns are known points ofrelative elevation. To ensure proper drainage to a low point at a column, themaximum deflection in the zone around the column must result in elevations thatremain higher than the drain. This criterion must be used to set elevations of supportsradiating from the low point.

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Crane RunwaysCrane runways must also be controlled for vertical deflections. Such deflections areusually calculated without an increase for vertical impact. The deflection limits forvarious crane types and classes are given below.

Top running cranes: CMAA Classes A, B and C: Span divided by 600 (CMAA, 1999) CMAA Class D: Span divided by 800 CMAA Classes E and F: Span divided by 1000 (AISE, 2003)

Underhung and monorail cranes: CMAA Classes A, B and C: Span divided by 450

Note: Underhung cranes with more severe duty cycles must be designed withextreme caution and are not recommended.

AIST Technical Report No. 13 (AIST, 2003) also provides deflection limits for cranerunway girders. They are established based on the Class of Mill Building, A throughD as follows:

Class A Buildings Span divided by 1000 Class B Buildings Span divided by 1000 Class C Buildings Span divided by 600 Class D Buildings Span divided by 600

Mechanical EquipmentMechanical equipment for buildings generally consists of piping, ductwork, exhausthoods, coils, compressors, pumps, fans, condensers, tanks, transformers, switchgear,etc. This equipment can be dispersed throughout the building, collected intomechanical rooms and/or located on the roof in the form of pre-engineered packageunits. The key feature of this equipment is that it represents real loads as opposed tocode specified uniform loads, which may or may not ever exist in their full intensity.Because of this, a degree of extra attention should be applied to the control ofdeflections as they relate to mechanical equipment.

This is especially true where the mechanical equipment loads are the predominantpart of the total loads on a given structure. Special Attention should be given to thetilting and racking of equipment, which, if excessive, could impair the function of theequipment and to differential deflection, which could deform or break interconnectingpiping or conduits. While the actual deflection limits on each project should becarefully reviewed with the mechanical engineers and equipment suppliers, it can bestated that buildings designed to the standard span divided by 150 to 240 for roofsand span divided by 360 for live loads have generally performed well.

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Table 3.1Serviceability Considerations � Metal Roofing

ROOFINGTYPE

STRUCTURALELEMENT DEFORMATION RECOMMENDATION LOADING

EXPANSIONJOINTS

HORIZONTALMOVEMENT

100� TO 200�MAXIMUM THERMAL

ROOF SLOPE 1 / 2 IN. PER FOOTMINIMUM DRAINAGE

PURLIN VERTICALDEFLECTION

L / 150*MAXIMUM SNOW LOAD

METAL ROOFSTHROUGH

FASTENER TYPE

PURLIN VERTICALDEFLECTION POSITIVE DRAINAGE DL + 0.5 S

DL + 5 PSF

EXPANSIONJOINTS

HORIZONTALMOVEMENT

150� TO 200�MAXIMUM THERMAL

ROOF SLOPE 1 / 4 IN. PER FOOTMINIMUM DRAINAGE

PURLIN VERTICALDEFLECTION

L / 150MAXIMUM SNOW LOAD

METAL ROOFSSTANDING SEAM

PURLIN VERTICALDEFLECTION POSITIVE DRAINAGE DL + 0.5 S

DL + 5 PSF

Note: The data originally published by AISC in Design Guide No. 3 for Through Fastened Roofs in Table 3.1 containedan error, which has been corrected here, shown underlined.

Table 3.2Serviceability Considerations - Skylights

DEFORMATION RECOMMENDATION LOADING

SKYLIGHT FRAMERACKING

1 / 4 IN.GASKETED MULLIONS DL + LL

SKYLIGHT FRAMERACKING

1 / 8 IN.FLUSH GLAZING DL + LL

DEFLECTIONNORMAL TO

GLAZINGL / 300 1 IN. MAXIMUM DL + LL

1 + 2± 1 / 8 IN. 25 DEGREES

DL + LL

1 + 2± 5 / 16 IN.

25 < < 45 DEG.DL + LL

1 + 2± 1 / 2 IN. 45 DEGREES

DL + LL

3 - 4L1 / 240 1 / 2 IN.

MAXIMUMDL + LL

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Table 3.3Serviceability Considerations � Cladding

CLADDINGSUPPORT

TYPE

STRUCTURALELEMENT DEFORMATION RECOMMENDATION LOADING

METAL PANELS /BARE FRAME

DRIFTPERPENDICULAR

TO WALLH / 60 TO H / 100

MAXIMUM 10 YEAR WIND

METAL PANELS /GIRTS

HORIZONTALDEFLECTION

L / 120MAXIMUM 10 YEAR WIND

METAL PANELS /WIND COLUMNS

HORIZONTALDEFLECTION

L / 120MAXIMUM 10 YEAR WIND

PRECAST WALLS /BARE FRAME

DRIFTPERPENDICULAR

TO WALLH / 100

MAXIMUM 10 YEAR WIND

UNREINFORCEDMASONRY WALLS /

BARE FRAME

DRIFTPERPENDICULAR

TO WALL1 / 16 IN. CRACKBASE OF WALL 10 YEAR WIND

REINFORCEDMASONRY WALLS /

BARE FRAME

DRIFTPERPENDICULAR

TO WALLH / 200

MAXIMUM 10 YEAR WIND

MASONRY WALLS /GIRTS

HORIZONTALDEFLECTION

L / 240 1.5 IN.MAXIMUM 10 YEAR WIND

MASONRY WALLS /WIND COLUMNS

HORIZONTALDEFLECTION

L / 240 1.5 IN.MAXIMUM 10 YEAR WIND

MASONRY WALLS /LINTEL

VERTICALDEFLECTION

L / 600 0.3 IN.MAXIMUM DL + LL

FOUNDATION

MASONRY WALLS /LINTEL ROTATION 1 DEGREE

MAXIMUM DL + LL

PRE-ASSEMBLEDUNITS / COLUMNS

RELATIVESHORTENING

1 / 4 IN.MAXIMUM 0.5 LL

COLUMNPRE-ASSEMBLED

UNITS / BAREFRAME

RACKING H / 500 10 YEAR WIND

CURTAIN WALLS /BARE FRAME RACKING H / 500 10 YEAR WIND

CURTAIN WALLS /SPANDRELS

VERTICALDEFLECTION

3 / 8 IN.MAXIMUM

DL PRIOR TOCLADDING

CURTAIN WALLS /SPANDRELS

VERTICALDEFLECTION

L / 480 5 / 8 IN.MAXIMUM TOTAL DL

CURTAIN WALLS /SPANDRELS

VERTICALDEFLECTION

L / 360 1 / 4 - 1 / 2 IN.

MAXIMUM0.5 LL

SPANDREL

CURTAIN WALLS /SPANDRELS

VERTICALDEFLECTION

L / 600 3 / 8 IN.MAXIMUM

DL INCL.CLADDING

WEIGHT

Note: A limit of height divided by 100 can be used for reinforced masonry walls / bare frame if a hinge type base can beemployed.

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Table 3.4Serviceability Considerations � Ceilings & Partitions

FINISHTYPE

STRUCTURALELEMENT DEFORMATION RECOMMENDATION LOADING

PLASTEREDCEILING ROOF MEMBER VERTICAL

DEFLECTIONL / 360

MAXIMUM0.5 LL OR

50 YEAR SNOW

ROOF MEMBER VERTICALDEFLECTION

L / 240MAXIMUM

0.5 LL OR50 YEAR SNOWNON-PLASTERED

CEILINGFLOOR BEAM /

GIRDERVERTICAL

DEFLECTIONL / 360 1 IN.

MAXIMUM DL

FRAME HORIZONTALMOVEMENT

H / 500MAXIMUM 10 YEAR WIND

ROOF MEMBER VERTICALDEFLECTION

3 / 8 IN. TO 1 IN.MAXIMUM

0.5 LL OR50 YEAR SNOW

PARTITION

FLOOR BEAM /GIRDER

VERTICALDEFLECTION

L / 360 3 / 8 IN. TO1 IN., MAXIMUM 0.5 LL

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Table 3.5Serviceability Considerations - Equipment

EQUIPMENTTYPE

STRUCTURALELEMENT DEFORMATION RECOMMENDATION LOADING

RUNWAYSUPPORTS

TOTAL INWARDMOVEMENT

1 /2 IN.MAXIMUM

LL OR50 YEAR SNOW

RUNWAYSUPPORTS

TOAL OUTWARDMOVEMENT

1 IN.MAXIMUM SNOW

RUNWAY BEAM HORIZONTALDEFECTION

L / 400MAXIMUM CRANE LATERAL

RUNWAY BEAMCMAA �A�, �B� & �C�

VERTICALDEFLECTION

L / 600MAXIMUM

CRANE LATERALSTATIC LOAD

RUNWAY BEAMCMAA �D�

VERTICALDEFLECTION

L / 800MAXIMUM

CRANE LATERALSTATIC LOAD

TOP RUNNINGCRANES

RUNWAY BEAMCMAA �E� & �F�

VERTICALDEFLECTION

L / 1000MAXIMUM

CRANE LATERALSTATIC LOAD

TOP RUNNINGCAB OPERATED BARE FRAME DRIFT AT RUNWAY

ELEVATIONH / 240 1-IN.

MAXIMUMCRANE LATERALOR 10 YR. WIND

TOP RUNNINGPENDANT

OPERATEDBARE FRAME DRIFT AT RUNWAY

ELEVATIONH / 100 1-IN.

MAXIMUMCRANE LATERALOR 10 YR. WIND

UNDERHUNGCRANE

RUNWAY BEAMCMAA �A�, �B� & �C�

VERTICALDEFLECTION

L / 450MAXIMUM

CRANEVERTICAL

JIB CRANE BOOM VERTICALDEFLECTION

H / 225MAXIMUM

CRANEVERTICAL

BARE FRAME DRIFT H / 500MAXIMUM 10 YEAR WIND

MACHINE /SHEAVE BEAMS

VERTICALDEFLECTION

L / 1666MAXIMUM DL + LLELEVATORS

MACHINE /SHEAVE BEAMS

SUPPORTSVERTICAL

DEFLECTIONH / 1666

MAXIMUM DL + LL

Note: The data originally published by AISC in Design Guide No. 3 for Table 3.5 contained an error, which has beencorrected here, shown underlined. In the original guide the serviceability considerations for Top Running CabOperated Cranes and Top Running Pendant Operated Cranes were inadvertently switched.