LONGSPAN AND DEEP LONGSPAN STEEL JOISTS, LH-AND …

1 43 LONGSPAN and deep LONGSPAN STEEL joists are rela-tively lightweight shop-fabricated STEEL STEEL joists are used for the direct supportof floor or roof slabs or decks between walls, beams,and main structural members. deep LONGSPAN SteelJoists are used for the direct support of roof slabsor decks between walls, beams and main LH-AND DLH-Series have been designed for thepurpose of extending the use of joists to spans inexcess of those covered by Open Web Series joists have been standardized indepths from 18 (457 mm) through 48 (1219 mm), forclear spans through 96 feet (29260 mm).

2 deep LONGSPAN Series joists have been standardizedin depths from 52 (1320 mm) through 72 (1829 mm),for clear spans up through 144 feet (43891 mm). LONGSPAN and deep LONGSPAN STEEL joists can be fur-nished with either underslung or square ends, with par-allel chords or with single or double pitched top chordsto provide sufficient slope for roof drainage. Squareend joists are primarily intended for bottom pitch is 1 8 per foot (1:96). If pitch exceedsthis standard, the load table does not apply. The joistdesignation is determined by its nominal depth at thecenter of the span and by the chord size meet the demand for pitched top chord members(when necessary for roof drainage) a standard pitch of1 8 per foot (1.)

3 96) has been depth of the bearing portion at the ends of under-slung joists has been established at 5 (127 mm) forLH-Longspans, and 5 (127 mm) for chord sizes thru17 and 71 2 (191 mm) for chord sizes 18 and 19 for LONGSPAN and deep LONGSPAN STEEL joists are fab-ricated with standardized camber as listed in para-graph TYPESACCESSORIESLONGSPAN AND deep LONGSPAN STEEL JOISTS, LH-AND DLH-SERIES44 These specifications cover the design, manufactureand use of LONGSPAN STEEL joists LH-Series, and DeepLongspan STEEL joists , term LONGSPAN STEEL joists LH-Series and DeepLongspan STEEL joists DLH-Series , as used herein,refers to open web, load-carrying members utilizinghot-rolled or cold-formed STEEL .

4 Including cold-formedsteel whose yield strength * has been attained by coldworking. LH-Series are suitable for the direct support offloors and roof decks in buildings, and DLH-Series aresuitable for direct support of roof decks in design of LH-AND DLH-Series joist chord or websections shall be based on a yield strength of at least36 ksi (250 MPa), but not greater than 50 ksi (345 MPa). STEEL used for LH-AND DLH-Series joist chordor web sections shall have a minimum yield strengthdetermined in accordance with one of the proceduresspecified in Section , which is equal to the yieldstrength assumed in the design.

5 LH-AND DLH-Seriesjoists shall be designed in accordance with these spec-ifications to support the loads given in the attachedStandard Load Tables for LH-AND DLH-Series joists .* The term yield strength as used herein shall designate theyield level of a material as determined by the applicablemethod outlined in paragraph 13 - Yield strength , or para-graph 12 - Yield Point , of ASTM A370, MechanicalTesting of STEEL Products , or as specified in Section this STEELThe STEEL used in the manufacture of chord and websections shall conform to one of the following ASTMS pecifications of latest adoption: Structural STEEL , ASTM A36/A36M.

6 High- strength Low-Alloy Structural STEEL , ASTMA242/A242M. High- strength Carbon-Manganese STEEL ofStructural Quality ASTM A529/A529M, Grade 50. Hot-Rolled Carbon STEEL Sheet and Strip,Structural Quality ASTM A570/A570M. High- strength Low-Alloy Columbium-VanadiumSteels of Structural Quality ASTM A572/A572M,Grades 42, 45, and 50. High- strength Low-Alloy Structural STEEL with 50ksi (345 MPa) Minimum Yield Point to 4 inches(102 mm) thick, ASTM A588/A588M. STEEL Sheet and Strip, Hot-Rolled and Cold-Rolled,High- strength , Low-Alloy, with Improved CorrosionResistance, ASTM A606. STEEL Sheet and Strip, Hot-Rolled and Cold-Rolled, High- strength , Low-Alloy, Columbiumand/or Vanadium, ASTM A607, Grades 45 and 50.

7 STEEL , Cold-Rolled Sheet, Carbon Structural ASTMA611, Grade shall be of suitable quality ordered or produced toother than the listed specifications, provided that suchmaterial in the state used for final assembly and man-ufacture is weldable and is proved by tests performedby the producer or manufacturer to have the propertiesspecified in Section SPECIFICATIONS FOR LONGSPAN STEEL joists , LH-SERIES ANDDEEP LONGSPAN STEEL joists , DLH-SERIESA dopted by the STEEL Joist Institute February 15, 1978 Revised to May 2, 1994 - Effective September 1, 1994 SECTION Specifications and Load Tables, LongspanSteel joists LH- Series and deep LongspanSteel joists DLH- Series, Copyright Joist InstituteSECTION MECHANICAL PROPERTIESThe yield strength used as a basis for the designstresses prescribed in Section 103 shall be at least 36ksi (250 MPa), but shall not be greater than 50 ksi (345 MPa).

8 Evidence that the STEEL furnished meets orexceeds the design yield strength shall, if requested,be provided in the form of an affidavit or by witnessedor certified test material used without consideration of increase inyield strength resulting from cold forming, the speci-mens shall be taken from as-rolled material. In the caseof material the mechanical properties of which conformto the requirements of one of the listed specifications,test specimens and procedure shall conform to thoseof such specifications and to ASTM the case of material the mechanical properties ofwhich do not conform to the requirements of one of thelisted specifications, the test specimens and procedureshall conform to the applicable requirements of ASTMA370 and the specimens shall exhibit a yield strengthequal to or exceeding the design yield strength and anelongation of not less than (a) 20 percent in 2 inches(51 mm)

9 For sheet and strip or (b) 18 percent in 8 inch-es (203 mm) for plates, shapes and bars with adjust-ments for thickness for plates, shapes and bars as pre-scribed in ASTM A36/A36M, A242/A242M, A529/A529M, A572/A572M, and A588/A588M, which everspecification is applicable on the basis of design number of tests shall be as prescribed in ASTM A6for plates, shapes, and bars ; and ASTM A570/A570M,A606, A607, and A611 for sheet and as-formed strength is utilized, the test reports shallshow the results of tests performed on full sectionspecimens in accordance with the provisions ofSections and of the AISI Specification for theDesign of Cold-Formed STEEL Structural Members, andshall indicate compliance with these provisions andwith the following additional requirements:1.

10 The yield strength measured in the tests shallequal or exceed the design yield Where tension tests are made for acceptance andcontrol purposes the tensile strength shall be atleast 6 percent greater than the yield strength ofthe Where compression tests are used for acceptanceand control purposes the specimen shall withstanda gross shortening of 2 percent of its original lengthwithout cracking. The length of specimen shall notbe greater than 20 times its least radius of If any test specimen fails to pass the requirementsof subparagraphs 1, 2 and 3 above, as applicable,two retests shall be made of specimens from thesame lot.