CEMP-E
TI 809-02
1 September 1999
Section 5d of ASCE 19 will be modified by substituting (1.5 T4) where T4 is the net
tension in the cable due to dead load, prestress, live load, and seismic load. A load factor of
1.1 will be applied to the prestress force to be added to the load combination of Section 3.1.2
of ASCE 19.
e. Crane Runways and Supports.
(1) Stops and Bumpers. Stops refer to rigid assemblies installed at the ends of crane
runways to prevent traveling cranes from running beyond the ends of the runway. Bumpers
refer to those devices (usually fitted onto the crane) which are resilient or other energy
absorbing construction designed to limit the deceleration force resulting from the crane's hitting
the runway stops. Stops engaging the thread of the wheel will not be less than the radius of
the wheel. Stops engaging other parts of the crane are recommended. Requirements for the
design of crane stops are controlled largely by the design of the crane bumpers. Procurement
documents for cranes will mandate that crane bumpers be designed in accordance with
requirements of the Occupational Safety and Health Act (OSHA) including.
Bumpers will be capable of stopping the crane (not including lifted load) at an average
deceleration of no more than 3 feet per second per second with the crane traveling at 20
percent of rated speed.
Bumpers will, at a minimum, have sufficient energy absorbing capacity to stop the
crane when its traveling at 40 percent of rated speed. The forces to be resisted by the
stops will either be indicated by the crane manufacturer or determined as set forth in
Whiting Corporation Overhead Crane Handbook.
(2) Deflections. Vertical deflection of crane runway girders will be limited as set forth in
Crane Manufacturer's Association of America (CMAA) 70 and 74. Horizontal deflection will be
checked to assure compatibility with clearance between flanges of double-flanged wheels and
bearing area of single-flanged wheels.
(3) Additional Information. Additional information useful in the design of crane runways
and supports can be found in the Navy MIL-HDBK-1038, "Weight Handling Equipment", and
Navy guidance document No. P-307, "Management of Weight Handling Equipment". These
documents provide information on crane loadings that can occur during operation and testing.
7-4. SERVICEABILITY.
a. General. AISC Specification for Structural Steel Buildings-Allowable Stress Design
(AISC-ASD) provides design guidance with respect to the following serviceability related
issues:
Camber
Expansion and contraction
Deflection, vibration and drift
Connection slip
7-2
Previous Page
