INTRODUCTIONA lintel is a structural member placed over an opening

in a wall. In the case of a brick masonry wall, lintels mayconsist of reinforced brick masonry, brick masonry arches,precast concrete or structural steel shapes. Regardlessof the material chosen for the lintel, its prime function is tosupport the loads above the opening, and it must bedesigned properly. To eliminate the possibility of structur-al cracks in the wall above these openings, the structuraldesign of the lintels should not involve the use of "rule-of-thumb" methods, or the arbitrary selection of structuralsections without careful analysis of the loads to be carriedand calculation of the stresses developed. Many of thecracks which appear over openings in masonry walls aredue to excessive deflection of the lintels resulting fromimproper or inadequate design.

This Technical Notes presents the considerations tobe addressed if structural steel lintels are to be used. Italso provides a procedure for the structural design ofthese lintels. For information concerning reinforced brickmasonry lintels, see Technical Notes 17H and for brickmasonry arches, see Technical Notes 31, 31A and 31CRevised.

CONSIDERATIONS

GeneralWhen structural steel lintels are used, there are sev-

eral considerations which must be addressed in order tohave a successful design. These include loading, type oflintel, structural design, material selection and mainte-nance, moisture control around the opening, provisions toavoid movement problems and installation of the lintel inthe wall.

TypesThere are several different types of structural steel lin-

tels used in masonry. They vary from single angle lintelsin cavity or veneer walls, to steel beams with plates insolid walls, to shelf angles in brick veneer panel walls.Most building codes permit steel angle lintels to be usedfor openings up to 8 ft 0 in. (2.4 m). Openings larger thanthis are usually required to have fire protected lintels.

Loose Angle Lintels. Loose angle lintels are used inbrick veneer and cavity wall constructions where the lintelis laid in the wall and spans the opening. This type of lin-tel has no lateral support. Figure 1a shows this condition.

Combination Lintels. In solid masonry walls, singleloose angle lintels are usually not capable of doing thejob. Therefore, combination lintels are required. Thesecombination lintels can take many forms, from a clusteringof steel angles, such as shown in Figs. 1b and 1c, to acombination of steel beam and plates, as shown in Figs.1d and 1e.

Angle Lintels - In solid masonry walls, it is usually sat-isfactory to use multiple steel angles as a lintel. Theseangles are usually placed back to back, as shown in Figs.1b and 1c.

Steel Beam/Plate Lintels - In solid walls with large super-imposed loads, or in walls where the openings are greaterthan 8 ft 0 in. (2.4 m), it may be necessary to use lintels com-posed of steel beams with attached or suspended plates, asshown in Figs. 1d and 1e. This permits the beam to be fullyencased in masonry, and fire-protected.

Shelf Angles. In panel walls systems, the exteriorwythe of brickwork may be supported by shelf anglesrigidly attached to the structural frame. These shelfangles, in some cases, also act as lintels over openings inthe masonry. This condition is shown in Fig.1f.

Reissued*May 1987

31BREVISEDTechnical Notes

on Brick ConstructionBrick Industry Association 11490 Commerce Park Drive, Reston, Virginia 20191

STRUCTURAL STEEL LINTELS

Abstract: The design of structural steel lintels for use with brick masonry is too critical an element to be left to“rule-of-thumb" designs. Too little concern for loads, stresses and serviceability can lead to problems.Information is provided so that structural steel lintels for use in brick masonry walls may be satisfactorilydesigned.

Key Words: beams (supports); brick; buildings; deflection; design; lintels; loads (forces); masonry; struc-tural steel; walls.

*Originally published in Nov/Dec 1981, this Technical Notes has been reviewed and reissued.

DesignThe proper design of the structural steel lintel is very

important, regardless of the type used. The design mustmeet the structural requirements and the serviceabilityrequirements in order to perform successfully. Designloads, stresses and deflections will be covered in a latersection of this Technical Notes.

MaterialsThe proper specification of materials for steel lintels is

important for both structural and serviceability require-ments. If materials are not properly selected and main-tained, problems can occur.

Selection. The steel for lintels, as a minimum, shouldcomply with ASTM A 36. Steel angle lintels should be atleast 1/4 in. (6 mm) thick with a horizontal leg of at least 31/2 in. (90 mm) for use with nominal 4 in. (100 mm) thickbrick, and 3 in. (75 mm) for use with nominal 3 in. (75mm) thick brick.

Maintenance. For harsh climates and exposures,consideration should be given to the use of galvanizedsteel lintels. If this is not done, then the steel lintels willrequire periodic maintenance to avoid corrosion.

Moisture ControlProper consideration must always be given to mois-

ture control wherever there are openings in masonrywalls. There must always be a mechanism to channel theflow of water, present in the wall, to the outside.

Flashing and Weepholes. Even where galvanizedor stainless steel angles are used for lintels in cavity andveneer walls, continuous flashing should be installed overthe angle. It should be placed between the steel and theexterior masonry facing material to collect and divertmoisture to the outside through weepholes. Regardlessof whether flashing is used, weepholes should be provid-ed in the facing at the level of the lintel to permit theescape of any accumulated moisture. See TechnicalNotes 7A for further information on flashing and weep-holes.

Movement ProvisionsBecause of the diversity of movement characteristics

of different materials, it is necessary to provide for differ-ential movement of the materials. This is especially trueat locations where a number of different materials cometogether. Technical Notes 18 Series provides additionalinformation on differential movement.

Expansion Joints. Expansion joints in brick masonryare very important in preventing unnecessary and unwant-ed cracking. There are two types of expansion jointswhich will need to be carefully detailed when lintels areinvolved: vertical and horizontal.

Vertical - Vertical expansion joints are provided to per-mit the horizontal movement of the brick masonry. Wherethese expansion joints are interrupted by lintels, theexpansion joint should go around the end of the lintel andthen continue down the wall.

Fig. 1Types of Structural Steel Lintels

2

Concentrated Loads. Concentrated loads frombeams, girders, or trusses, framing into the wall above theopening, must also be taken into consideration. Suchloads may be distributed over a wall length equal to thebase of the trapezoid and whose summit is at the point ofload application and whose sides make an angle of 60deg with the horizontal. In Fig. 2b, the portion of the con-centrated load carried by the lintel would be distributedover the length, EC, and would be considered as a par-tially distributed uniform load. Arching action of themasonry is not assumed when designing for concentratedloads. Again, if stack bonded masonry is used, horizontaljoint reinforcement must be provided to assure this distrib-ution.

StressesAfter the loads have been determined, the next step

in the design of the lintel is the design for stresses.Which stresses need to be checked will depend upon thetype and detailing of the lintel.

Flexure. In a simply supported member loadedthrough its shear center, the maximum bending momentdue to the triangular wall area (ABC) above the openingcan be determined by:

Mmax = WL

6where:Mmax = maximum moment (ft---lb)

W = total load on lintel (lb)L = span of lintel, center to center of end bearing (ft)

As an alternative, the designer may wish to calculate anequivalent uniform load by taking 2/3 of the maximumheight of the triangle times the unit weight of the masonryas the uniform load across the entire lintel. If this is done,the maximum bending moment equation becomes:

Mmax = wL2

8where:w = equivalent uniformly distributed load per unit

of length (lb per ft).

To this bending moment should be added the bendingmoment caused by the concentrated loading, if any.Where such loads are located far enough above the lintelto be distributed as shown in Fig. 2b, the bending momentformula for a partially distributed uniform load may beused. Such formulae may be found in the " Manual ofSteel Construction," by the American Institute of SteelConstruction (AISC). Otherwise, concentrated load bend-ing moments should be used.

The next step is the selection of the required section.The angle, or other structural steel shape, should beselected by first determining the required section modu-lus. This becomes:

S = 12Mmax

Fb

where:

S = section modulus (in3)

Fb = allowable stress in bending of steel (psi)

The allowable stress, Fb, for ASTM A 36 structural steel is

22,000 psi (150 MPa) for members laterally supported.Solid brick masonry walls under most conditions providesufficient lateral stiffness to permit the use of the full22,000 psi (150 MPa). This is especially true when floorsor roofs frame into the wall immediately above the lintel.The design for non-laterally supported lintels should be inaccordance with the AISC Specification for the Design,Fabrication and Erection of Structural Steel for Buildings.

Using the design property tables in the AISC Manual,a section having an elastic section modulus equal to, orslightly greater than, the required section modulus isselected. Whenever possible, within the limitations ofminimum thickness of steel and the length of outstandingleg required the lightest section having the required sec-tion modulus should be chosen.

Combined Flexure and Torsion. In some cases, thedesign for flexure will need to be modified to include theeffects of torsion. This is the case in cavity and veneerwalls where the load on the angle is not through the shearcenter.

In some situations, such as veneers, panel or curtainwalls, the lintel may be supporting only the triangular por-tion of masonry directly over the opening. If this is thecase, then the torsional stresses will usually be negligiblecompared to the flexural stresses, and can be safelyignored.

If, on the other hand, there are imposed uniform loadswithin the triangle or imposed concentrated loads abovethe lintel, then a detailed, combined stress analysis will benecessary. The design of a lintel subjected to combinedflexure and torsion should be in accordance with the AISCSpecification for the Design, Fabrication and Erection ofStructural Steel for Buildings.

Shear. Shear is a maximum at the end supports, andfor steel lintels it is seldom critical. However, the computa-tion of the unit shear is a simple calculation and shouldnot be neglected. The allowable unit shear value forASTM A 36 structural steel is 14,500 psi (100 MPa). Tocalculate the shear:

vmax = Rmax

AS

where:Vmax = the actual maximum unit shear (psi)

Rmax = maximum reaction (lb)

As = area of steel section resisting shear (sq. in.)

4

Bearing. In order to determine the overall length of asteel lintel, the required bearing area must be determined.The stress in the masonry supporting each end of the lin-tel should not exceed the allowable unit stress for the typeof masonry used. For allowable bearing stresses, see"Building Code Requirements for Engineered BrickMasonry," BIA; "American Standard Building CodeRequirements for Masonry," ANSI A41.1-1953 (R 1970);or the local building code. The reaction at each end ofthe lintel will be one-half the total uniform load on the lin-tel, plus a proportion of any concentrated load or partiallydistributed uniform load. The required area may be foundby:

Ab = Rmax

fm

where:Ab = required bearing area (sq in.)

fm = allowable compressive stress in masonry (psi)

In addition, any stresses due to rotation from bendingor torsion of the angle at its bearing must be taken intoaccount.

Since in selecting the steel section, the width of thesection was determined, that width divided into therequired bearing area, Ab, will determine the length of

bearing required, F and F1, in Fig. 2b. This length should

not be less than 3 in. (75 mm).If the openings are close together, the piers between

these openings must be investigated to determinewhether the reactions from the lintels plus the dead andlive loads acting on the pier exceed the allowable unitcompressive stress of the masonry. This condition will notnormally occur where the loads are light, such as in mostone and two-story structures.

ServiceabilityIn addition to the stress analysis for the lintel, a ser-

viceability analysis is also important. Different types oflintels have different problems of deflection and rotation,and each must be analyzed separately to assure its prop-er performance.

Deflection Limitations. After the lintel has beendesigned for stresses, it should be checked for deflection.Lintels supporting masonry should be designed so thattheir deflection does not exceed 1/600 of the clear spannor more than 0.3 in (8 mm) under the combined superim-posed live and dead loads.

For uniform loading, the deflection can be found by:

∆t = 5wL4

(1728)

384 EI

where:∆t = total maximum deflection (in.)

E = modulus of elasticity of steel (psi)

I = moment of inertia of section (in.4)

For loadings other than uniform, such as concentratedloads and partially distributed loads, deflection formulaemay be found in the AISC Manual.

Torsional Limitations. In cases where torsion is pre-sent, the rotation of the lintel can be as important as itsdeflection. The rotation of the lintel should be limited to1/16 in. (1.5 mm) maximum under the combined superim-posed live and dead loads. As mentioned before, all addi-tional bearing stresses due to angle rotation must betaken into account in the design for bearing.

Design AidsIn order to facilitate the design of steel angle lintels,

several design aids are included. These design aids arenot all-inclusive, but should give the designer some helpin designing lintels for typical applications. Conditionsbeyond the scope of these tables should be thoroughlyinvestigated.

Table 1 contains tabulated load values to assist thedesigner in the selection of the proper size angle lintel,governed either by moment or deflection under uniformload. Shear does not govern in any of the listed cases.The deflection limitation in Table 1 is 1/600 of the span, or0.3 in. (8 mm), whichever is less. Lateral support isassumed in all cases.

Table 2 lists the allowable bearing stresses taken fromANSI A41.1-1953 (R 1970). In all cases, allowable bear-ing stresses set by local jurisdictions in their buildingcodes will govern.

Table 3 lists end reactions and required length inbearing, which may control for steel angle lintels.

SUMMARYThis Technical Notes is concerned primarily with the

design of structural steel lintels for use in brick masonrywalls. It presents the considerations which must beaddressed for the proper application of this type ofmasonry support system. Other Technical Notes addressthe subjects of reinforced brick masonry lintels and brickmasonry arches.

The information and suggestions contained in thisTechnical Notes are based on the available data and theexperience of the technical staff of the Brick Institute ofAmerica. The information and recommendations con-tained herein, if followed with the use of good technicaljudgment, will avoid many of the problems discussed.Final decisions on the use of details and materials as dis-cussed are not within the purview of the Brick Institute ofAmerica, and must rest with the project designer, owner,or both.

5

TABLE 1

Allowable Uniform Superimposed Load (lb per ft) for ASTM A 36 Structural Steel Angle Lintels 1,2,3,4,5,6

HorizontalLeg (in)

2 1/2

3 1/2

Angle Size (in x in x in)

2 x 2 1/2 x 1/42 1/2 x 2 1/2 x 1/4

5/163/8

3 x 2 1/2 x 1/43 1/2 x 2 1/2 x 1/4

5/163/8

2 1/2 x 3 1/2 x 1/43 x 3 1/2 x 1/4

3 1/2 x 3 1/2 x 1/45/163/8

4 x 3 1/2 x 1/45/16

5 x 3 1/2 x 5/163/8

6 x 3 1/2 x 3/8

Weight perft (lb)

3.64.15.05.94.54.96.17.2

4.95.45.87.28.56.27.78.7

10.411.7

Span in Feet (Center to Center ofRequired Bearing

ResistingMoment

(ft-lb)

45871588010451027139317051998

752108214481797210818882310355741985940

ElasticSectionModulus

(in3)

0.250.390.480.570.560.760.931.09

0.410.590.790.981.151.031.261.942.293.24

Moment ofInertia

(in4)

0.3720.7030.8490.9841.171.802.192.56

0.7771.302.012.452.872.913.566.607.7812.90

3 4 5 6 7 8

352 146 73631 279 141 80777 336 170 96923 390 197 112908 467 237 135 83

1233 692 366 210 130 861509 846 446 255 158 1041769 992 521 298 185 122

664 308 155 88956 518 263 150 92

1281 718 409 234 145 951590 891 498 285 177 1161865 1046 583 334 207 1361672 938 594 341 212 1402046 1147 726 417 260 1723153 1770 1130 779 487 3243721 2089 1333 918 574 3815268 2958 1889 1308 958 638

1Allowable loads to the left of the heavy line are governed by moment, and to the right by deflection.

2Fb = 22,000 psi (150 MPa)

3Maximum deflection limited to L/600

4Lateral support is assumed in all cases.

5For angles laterally unsupported, allowable load must be reduced.

6For angles subjected to torsion, make special investigation.

TABLE 2

Allowable Compressive Stresses (psi) in Masonry 1

Type of Wall

Solid walls of brick or solid unitsof clay when average compressivestrength of unit is as follows:

8000 plus psi4500 to 8000 psi2500 to 4500 psi1500 to 2500 psi

Grouted solid masonry of brick and other solid units of clay

4500 plus psi2500 to 4500 psi1500 to 2500 psi

Masonry of hollow units

Type of Mortar

M

400250175125

350275225

85

S

350225160115

275215175

75

N

300200140100

200155125

70

O

20015011075

---

-

1 Adapted from “American Standard Building Code Requirements for Masonry,” National Bureau of Standards, ANSI A41. 1-1953 (R 1970).

6

REFERENCES

1. AISC, Manual of Steel Construction, AmericanInstitute of Steel Construction, Inc., New York, New

York, Eighth Edition, 1980.2. AISC, Specification for the Design, Fabrication

and Erection of Structural Steel for Buildings,American Institute of Steel Construction, Inc., NewYork, New York, 1978.

3. ANSI, American Standard Building Code Requirements for Masonry, ANSI A41.1-1953 (R1970), American National Standards Institute, NewYork, New York.

4. BIA, Building Code Requirements for Engineered Brick Masonry, Brick Institute of America, McLean,Virginia, 1969.

TABLE 3

End Reaction1

and Required Length of Bearing2

for Structural Angle Lintels

2 1/2” Leg Horizontal 31/2” Leg Horizontal

fm

psi

400350300275250225215200175160155150140125115110100857570

fm

psi

400350300275250225215200175160155150140125115110100857570

Length of Bearing Length of Bearing

3 4 5 6

3000 4000 5000 60002625 3500 4375 52502250 3000 3750 45002063 2750 3438 41251875 2500 3125 37501688 2250 2813 33751613 2150 2688 32251500 2000 2500 30001313 1750 2188 26251200 1600 2000 24001163 1550 1938 23251125 1500 1875 22501050 1400 1750 2100938 1250 1563 1875863 1150 1438 1725825 1100 1375 1650750 1000 1250 1500638 850 1063 1275563 750 938 1125525 700 875 1050

3 4 5 6

4200 5600 7000 84003675 4900 6125 73503150 4200 5250 63002888 3850 4813 57752625 3500 4375 52502363 3150 3938 47252258 3010 3763 45152100 2800 3500 42001838 2450 3063 36751680 2240 2800 33601628 2170 2713 32551575 2100 2625 31501470 1960 2450 29401313 1750 2188 26251208 1610 2013 24151155 1540 1925 23101050 1400 1750 2100893 1190 1488 1785788 1050 1313 1575735 980 1225 1470

1End Reaction in lbs.

2Length of Bearing in inches.

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