improving structural drawings

8/13/2019 Improving Structural Drawings

1/10STRUCTURE magazine May 2006

Communication and coordinationbetween the architect and engineerare essential for improving structuraldrawings for masonry construction.Errors, omissions and conicts, whichcan lead to additional costs, are oftencaused by a lack of coordinationbetween the architectural plans andspecications and the structural

drawings. Structural steel framedbuildings with masonry cavity walls seem to

generate the most problems.Structural drawings for masonry construction

have improved in recent years, thanks to increasedtechnical literature written and distributed frommasonry organizations. This article will reviewthe most important items that have emerged

from these communications, as well as those thathave come from actual review by International

Masonry Institute (IMI) staff.

1

Figure 2: Column penetrates wall cavity

Figure 3B: Column and spaces are protected bymembrane ashing

Figure 1: Steel Column within CMU backup

Communication and coordination between the architect andengineer are essential for improving structural drawings for masonry

construction. Errors, omissions and conicts, which can lead toadditional costs, are often caused by a lack of coordination betweenthe architectural plans and specications and the structural drawings.Structural steel framed buildings with masonry cavity walls seem togenerate the most problems.

Structural drawings for masonry construction have improvedin recent years, thanks to increased technical literature written anddistributed from masonry organizations. This article will review the

most important items that have emerged from these communicatias well as those that have come from actual review by InternatMasonry Institute (IMI) staff.

Structural Steel Frame ColumnsMany times, the structural engineer does not consider the exte

masonry wall conguration when designing and locating column

beams. The location of structural steel columns can interfere adjacent masonry wall consttion. Failure to provide a waresistant or waterproof baat columns that penetrate ithe masonry cavity is a comproblem. New energy codes require air and vapor barriersfurther complicate these sitions. Developing the prodetails for these conditionsquires a special coordinabetween the architect and

structural engineer.The detail shown in Figuillustrates a successfully descolumn and masonry interfThe CMU cavity wall bac

has a clearanc3 to 4 inchesfront of the cumn. This allothe backup walbe continuous a

when dampprooor waterproo

forms a moistresistant barrierequired by buing codes. A ctrol joint is creaby the separaof the masoand steel. Eneers and architshould always i

ImprovingStructural

DrawingsforMasonry

ConstructionBy Richard Filloramo

Figure 3A: Unprotected column

Fillers and sealantare difcult to use



Figure 4: Do NOT penetrate ashing with ties and anchors at steelcolumns when anchor spacing requirements are maintained

Figure 7: Columns with reproong or voids

A Add rigid material B If needed, add metalstrips or anchors

cate when a separation space (usually 1 inch) is required between steelcolumns and masonry. It is also important to indicate concrete llaround the column base to support the CMU backup wall.

The detail shown in Figure 2 and the photos in Figure 3 illustrateconditions where the column penetrates the masonry cavity by 1inch. Although this can be remedied by installing full-height ash-ing membrane over the exterior column, it does add cost to theproject. Without proper coordination between the architect andstructural engineer, this condition often goes unnoticed, leading towater penetration into the building.

In Figure 2 , the membrane is adhered to the column and onto theadjacent CMU. This application protects the column, and the spacebetween the column and the CMU backup, from air leakage and waterpenetration. Always specify the manufacturers recommendations forwall preparation, primers, adhesives, and laps.

Locate adjustable veneer ties within 2 or 4 inches of the columns.Do not specify and indicate ties on structural or architectural drawingsthat pierce the ashing membrane with anchors from the steel column(Figure 4 ). This only increases the potential for water penetration andair leakage. Ties are not required at the column if the adjustable tiesare maintained at the required horizontal spacing. Although manyprojects specify ties spaced 16 inches vertically and horizontally, the

MSJC code permits 16- x 24-inch spacing for masonry veneeris best to leave the spacing at 16- x 16-inches to allow for toleraand eld conditions, but to accept 24-inch spacing at columns other locations if necessary. Always check local codes for anchtie requirements. If the distance between adjustable ties exceeinches or the required design distance, additional detailing is requContact IMI for information.

Insulation with a thickness of 1 or 1 inches can be installed the column membrane to provide a continuous layer of insulaas a thermal break. This is an example of the versatility of thinch drainage wall (Figures 5 and 6) with the 2 : -inch air space 4: -inch cavity. For the condition where the column projects 1 iinto the cavity, the 1 inch insulation still ts and leaves a 2-incspace. Compressible llers or mineral wool can be placed betweecolumn and the CMU to further insulate the area. Engineers musfamiliar with these architectural masonry wall congurations. columns projecting greater than 1 inch into the cavity will requirreduction of either the insulation or the air space, and will reqspecial detailing.

It should be noted that cavities can exceed the code maximum42 inches, and typically do, as long as calculations are performethe anchors. IMI has performed this study and the results are avaifrom IMI.

Figure 5: Drainage wall brick veneer/CMU back-up

BrickVeneer 2 : AirSpace

2 RigidInsulation

CMUBack-Up

Damp-proofng

Eye & JoinReinforcing

Figure 6: 16-inch drainage wall brick veneer/CMU back-up

continued next



Figure 10: Good Detail


B Add anchorsif required

A Add studs andexterior sheathing

If the open web of a steel column faces the cavity, or if a largespace remains, it must be in-lled with masonry, insulation or someother rigid material to provide support for the vertical membranewaterproong. This also applies to columns with reproong (Figures7, 8 and 9 ). Once again, do not indicate ties on the steel column thatpenetrate the ashing.

Column ties to CMU backup ( shown in Figure 1) are only required if

the wall spans horizontally. Most exterior walls span vertically and areattached to the structure above (Figure 10 ). These ties, if not required,only interfere with column wraps, reproong, insulation and otherconstruction, making the detail difcult to build. Engineers andarchitects should work together to eliminate these ties when notrequired since substantial cost savings can be realized.

Structural Steel BeamsStructural engineers must consider the position, size, and location

of structural steel beams since they will affect the moisture-controlsystems with adjacent masonry construction.Figures 11 and 12 illustrate how the lack of water-resistant protection can lead toair leakage and water penetration within the building. It is best tomaintain a continuous wall plane of CMU backup at beams as shownin Figure 10 . There must be at least 4 inches of clear space from theexterior face of the CMU backup units to the beam web to installthe CMU ller. Full 3-inch (actual size) solid units are available fortight conditions since 2-inch soap units may not provide adequatesupport for the veneer when required. If there is not sufcient beamspace to provide support for CMU backup, an alternate detail shouldbe used as shown inFigure 13.

To improve structural drawings, engineers need to consider mascoursing heights when indicating the location of bond beams. Bbeams should not be located directly below a steel beam unlesbeam is offset to provide at least 4 inches of clear space on one sipouring the grout into the bond beam. Notice in Figures 14 andthat the bond beam is located one course below the beam, but thespace to pour the grout. In most cases, the bond beam will be loctwo courses below the beam, as shown inFigure 10 and FigureSince beam heights and depths will vary (Figure 17 ), it may be eafor the structural drawings to include a notation for locating bbeams a minimum of 4 inches below and a maximum of 12 incbelow beams, unless there is access for grouting.

In most CMU details, a clear space, usually about 1 inch, isopen between the bottom of the steel beam and the top coursCMU to provide for deection (Figure 18 ). If required, enginshould indicate this on the drawings. The resulting space in all demust be covered with a exible water-resistant barrier. A compreller with a facing can be used if it is compatible with the Cdampproong. Mortar is sometimes used if the CMU extends bey

the beam and does not contact the beam, and if movement cancompensated within the beam.

Figure 11: Poor Detail

The lack ofwater resistantprotectionleads to waterpenetration




Figure 12: Moisture protection at steel beams. Poor Detail - the lackof water resistant protection leads to water penetration

Figure 13: Good Detail

Figure 14: Locate bond beam directly under steel beam only if there room to grout from the exterior side. Maintain 1-inch space and useslotted angles or bolts

Other Items of ImportanceEngineers should highlight plans by cross hatching the exact location

and length of shear walls. The elevation and section for these wallsshould be clearly indicated on the plan and be differentiated from non-structural masonry walls. A good example is shown inFigure 19 . Inthis actual project, Glastonbury Elementary School, Macchi Engineersclearly indicates reinforcing requirements and has coordinated withMoser Pilon Nelson Architects on the architectural drawings.

A common mistake, usually found on the masonry structuraldrawing, is an elevation titled Typical Masonry Wall Reinforcing. Inmost cases, this causes confusion for the bidders. The drawings shouldclearly indicate reinforcing for structural walls, exterior walls andinterior walls. Interior walls in moderate and low seismic risk categoriesgenerally do not require vertical reinforcing.Figures 20 and 21 fromMacchi Engineers drawings are excellent, efcient and cost effectiveexamples that indicate masonry partition wall requirements.

Masonry NotesStructural drawings usually have a page dedicated to masonry d

and notes. It is essential to coordinate these notes with the archispecications. A common error, which causes great confusioinconsistency in CMU strength requirements. The architectspecication will call for CMU to conform to ASTM C-90 with acompressive strength of 1900 psi. This will yield an fm of 1500 based on MSJC 2002, Section 1.4.B, 2b, Table 2. If the project requhigher strength CMU for shear walls, rewalls or loadbearing wthe architect and engineer should be clear and consistent in indica

where these units are required. The engineer is required by codindicate the CMU strength, as well as the intended fm. The contracmay achieve the required design strength using lower strength bloprism testing.

Self adheredor spraymembraneover exteriorshething and

steel studs

Dampproong

continued on next

The architect and engineer also need to communicate on specied density of the CMU. The weight of the masonry wallaffect the structural design. In some areas, lightweight CMU (125 pcf ) CMU are used. Lightweight Chave many advantageous characteristics and should be investifor use on projects. Contact IMI for more information.

The project requirements for masonry inspection and testingthe responsibility of the engineer. The engineer must clearly idethe type and frequency of testing, as is required by the code anddesign. It is essential that architectural specications and enginerequirements are closely coordinated.


5/10



References1. Masonry Standards Joint Committee (MSJC) Building

Code Requirements for Masonry Structures(ACI 530-02/ASCE 5-02/TMS 402-02),Specications for Masonry Structures (ACI 530.1-02/ASCE6-02/TMS 602-02) and Commentaries.

2. International Masonry Institute Detailing MasonryConstruction Educational Series

3. International Masonry Institute IMI Technical Briefs onMasonry Construction

4. ASTM C 90-05 Standard Specications for LoadbearingConcrete Masonry Units

see next page for gures 19, 20

Figure 18: Steel beam

Cover spacewith selfadheringmembrane incavity

Maintain 1space and useslotted anglesfor deection

Figure 17

Richard Filloramo is Area Director of MarketDevelopment and Technical Services for the International Masonry Institute New England Region ConnecticutOfce. He has more than 28 years of experience in themasonry industry. Mr. Filloramo is a member of the

Masonry Standards Joint Committee, the code writingbody responsible for the Masonry 530 Code. Mr. Filloram

has been involved with the design, construction andinspection of more than 5,000 building projects.



Figure 19: Drawings courtesy of Macchi Engineers, Moser Pilon Architects for Glastonbury Elementary School, Connecticut

Example of shearwall indicated on thestructural drawings

with elevation.



WALL HEIGHT & TYPE(SEE NOTE 7)

VERTICALREINFORCING REMARKS

EXTERIOR WALLS ALL WALLS SEE SECTIONS

GROUT VOIDSSOLID @

REINFORCINGSEE NOTE 5

INTERIOR WALLS ALL WALLSNO VERTICALREINFORCING

REQUIREDSEE NOTES 2, 3, 4

Figure 20: A good example to indicate masonry partition wall requirements. Drawings courtesy of Macchi Engineers, Moser Pilon Architects for GlasElementary School, Connecticut see next page for Figure 21a an

@

@



Figure 21a: Interior partition connection details. Drawings courtesy of Macchi Engineers, Moser Pilon Architects for Glastonbury Elementary School

@

@


10/10

Figure 21b: Interior partition connection details. Drawings courtesy of Macchi Engineers, Moser Pilon Architects for Glastonbury Elementary Schoo

@

@

improving structural drawings

Documents