Military Handbook- Structural Engineering Steel Structures

Section 2: STANDARD DESIGN CRITERIA - CLASS A STRUCTURES

Class A structures are those to which standard specifications for bridge type structures are applicable. Included are bridges, trestles, viaducts, and their components. The basis for classification as a Class A structure is the type of loading applied. This type of loading consists of groups or trains of wheels moving on the structure with impact effect. In addition the wheels and tires are presumed to be within a size range and range of inflation pressure (generally less than 100 psig) corresponding to those of wheels and tires for passenger car and truck usage. Class A includes structures carrying automobile and truck traffic, railroad traffic, certain typed or materials-handling equipment such as forklift truck (other than those having solid tires), and straddle carries. Class A does not include supports for overhead traveling cranes (Class B), mobile cranes or types of heavy lift cranes generally used for waterfront work (Class c), equipment Or . other equipment operating on tracks or oversize tires or forklift trucks having solid tire (Class C). In general, consider supports for machinery under Class B, with due consideration for impact and resonant response.