Frame Relay. A high-speed protocol used in WANs. A frame alignment signal is sent as well as the frames. Frames are actually consecutive time slots. FM. Factory Mutual, a building and industrial insurance underwriter who provides guidance and approval of building products. FM also has a nonprofit research center and writes standards. Gateway. Electronic equipment or computer that converts protocol from one network or system to another. Gigabit Ethernet. Ethernet network transmitting over 1 Gbps or 1000 Mbps. Hub. A piece of electronic LAN equipment located in a communications closet that connects to the desk PCs. Like a wheel, the hub is at the center, the spokes are the cabling to desk PCs. Hubs may be intelligent or dumb. If a hub is not labeled as intelligent, it is dumb. An intelligent hub has processing electronics to manage the network, sometimes to bridge, route, and switch. If the hub is too smart, it is not a hub, it is a switch. The industry is increasing the use of switches and decreasing the use of hubs. Interface. A device, or group of devices, that allow two incompatible systems to communicate. A protocol that allows two incompatible systems to communicate. ISDN. Integrated Services Digital Network is a digital transmission standard and service. Basic-rate ISDN provides two switched B channels (64 kbps for voice and data) and one D channel (16 kbps for control). Primary-rate ISDN provides 23 B channels and one D channel for a capacity of 1.544 Mbps. ISDN may be provided over a T1 line (two twisted-pair cables). ISDN was never embraced by the public or the industry; it was too confusing. The most common use in commercial buildings is for videoteleconferencing where a two-pair ISDN cable is terminated in a conference room. An ISDN terminal adapter is used to connect to a computer and phone. The owner will hire a vendor to provide and set up a videoteleconferencing package. Some training and user assistance is usually

Bracing may be temporary or permanent. Permanent bracing, required as an integral part of the completed structure, is shown on the architectural or engineering plans and usually is also referred to in the job specifications. Temporary construction bracing is required to stabilize or hold in place permanent structural elements during erection until other permanent members that will serve the purpose are fastened in place. This bracing is the responsibility of the erector, who normally furnishes and erects it. Protective corners and other protective devices should be installed to prevent members from damaged by the bracing. In wood truss construction, temporary bracing can be used to plumb trusses during erection and hold them in place until other secondary framing and roof sheathing are installed. The major portion of temporary bracing for trusses is left in place, because it is designed to brace the complete structure against lateral forces. Failures during erection occur occasionally and regardless of construction material used. The blame can usually be placed on insufficient or improperly located temporary erection guys or braces, overloading with construction materials, or an externally applied force sufficient to render temporary erection bracing ineffective. (See Handling, Installing and Bracing Metal Plate Connected Wood Trusses, Truss Plate Institute, Madison, Wis., for guidance in erection of lightweight metal plate connected, wood trusses.) Structural members of wood must be stiff, as well as strong. They must also be properly guyed or laterally braced, both during erection and permanently in the completed structure. Large rectangular cross sections of glued-laminated timber have relatively high lateral strength and resistance to torsional stresses during erection. However, the erector must never assume that a wood arch, beam, or column cannot buckle during handling or erection. Specifications often require that: 1. Temporary bracing shall be provided to hold members in position until the structure

where d is the deflection of the beam. For axial compression, the moment Pd should be given the same sign as M, and for tension, the opposite sign, but the minimum value of M  Pd is zero. The deflection d for axial compression and bending can be obtained by applying Eq. (5.62). (S. Timoshenko and J. M. Gere, Theory of Elastic Stability, McGraw-Hill Publishing company, New York; Friedrich Bleich, Buckling Strength of Metal Structures, McGraw-Hill Publishing Company, New York.) However, it may be closely approximated by d d  o (5.69) 1  (P/P ) c where do  deflection for the transverse loading alone Pc  the critical buckling load 2EI/L2 (see Art. 5.7.2) 5.5.17 Eccentric Loading An eccentric longitudinal load in the plane of symmetry produces a bending moment Pe where e is the distance of the load from the centroidal axis. The total unit FIGURE 5.32 Concentrated load at any point of a simple beam. FIGURE 5.33 Concentrated load at midspan of a simple beam. stress is the sum of the stress due to this moment and the stress due to P applied