ASME BTH-1-2005 pdf free download.Design of Below-the-Hook Lifting Devices.
Commentary A bof ted connection is defined for the purpose of this Standard as a nonpermanent connection in which two or more parts are joined together with threaded fasteners in such a manner as to prevent relative motion. A connection in which a single fastener is used is considered a pinned connection and shall be designed as such.
Allowable stresses or allowable loads in bolts are established as the ultimate tensile strength, the ultimate shear strength, or slip resistance divided by the eppro’ priate design factor, The ultimate shear strength Is taken as 82% of the ultimate tensile strength (Kulak. at al. 19871. This value is reasonable for relatively compact bolted connections. If the length of a bolted connection exceeds about 15 in. 1380 mm), the allowable shear per bolt should be reduced to account for the Increasing inefficiency of the connection (Kulak. at al. 1987). EquatiOn (3-43) is derived from Kulak. et al (19871. Eq. 4.1. Actual stresses due to applied loads are to be computed based on the bolt’s gross area, root area, or tensile stress area, as applicable.
The configuration of bolted connections in lifting devices will likely vary greatly from the standard types of connections used in steel construction. This Standard does not attempt to address the many variances with respect to evaluating the strength of the connected pieces other than to require that the strength of the connected pieces within the connection provide a design factor of at least 1.2ON,
Figure C3-2 illustrates the special case of block shear failure of a connected part. The strength of the part is the sum of the allowable tensile stress acting on the indicated tensile area plus the allowable shear stress acting on the indicated shear area. Although the figure shows a bolted connection, this type of failure can also occur in a welded connection.
The slip resistance of connections In which the bolt ho4es are more than 1 in. 12 mml greater than the bolts exhibit a reduced slip resistance. If larger holes are necessary. the test results reported in Kulalç et al 11987) can be used to determine the reduced capacity of the connection.
The slip resistance defined in this Standard is based on taying surfaces that are tree of loose mill scale, paint. and other coatings. The slip resistance of painted or coated surfaces varies greatly, depending on the type and thickness of coating. It Is not practical to deline a general acceptable slip resistance for such connections, Testing to determine the slip resistance is required for slip-resistant connections in which the faying surfaces are painted or otherwise coated lYure and Frank, 1985).
The design provisions for slip.crltical connections are based on experimental research IKulak. at al, 1987) on connections made with ASTM A 325 and A 490 bolts. In the absence of similar research results using other types and grades of bolts, pars. 3-3.2 limits the types of bolts that may be used in sIlp.critlc& connections to ASTM A 325 and A 490.
3.3.3 PInned Connections
Comm.ntary A p,nned corrnoctiorl is defined for the purpose of this Standard as a nonpermanent connection in which two or more parts are joined together in such a manner as to allow relative rotation. Even if a threaded fastener is used as the pin, the connection is still considered a pinned connection and shall be designed as such.
3-3.3.1 Static Strength of the Plates. [he strength of a pin-connected plate in tlie region of the pin hole shall be taken as the least value of the tensile strength of the effective area on a plane through the center of 11w pin hole perpendicular to the line of action of the applied load, the fracture strength beyond the pin hole on a single plane parallel to the line of action of the applied load, and the double plane shear strength beyond the pin hole parallel to the line of action of the applied load.
The allowable tensile strength through the pin hole Pt shall be calculated as follows.