Accordingly, a means of egress is a continuous, unobstructed path for evacuees from any point in a building to a public way. Its three parts are: Exit accessthat portion that leads to an entrance to an exit Exitthe portion that is separated from all other building spaces by construction or equipment required to provide a protected path to the exit discharge Exit dischargethe portion that connects the termination of an exit to a public way Means of egress may be provided by exterior and interior doors and enclosed horizontal and vertical passageways, including stairs and escalators. (Elevators and exterior fire escapes are not generally recognized as reliable means of egress in a fire.) Exit access includes the space from which evacuation starts and passageways and doors that must be traversed to reach an exit. Types of Exits. Building codes generally recognize the following as acceptable exits when they meet the codes safety requirements: Corridorsenclosed horizontal or slightly inclined public passageways, which lead from interior spaces toward an exit discharge. Minimum floor-to-ceiling height permitted is generally 80 in. Minimum width depends on type of occupancy and passageway (Table 3.7 and Art. 3.5.11). Codes may require subdivision of corridors into lengths not exceeding 300 ft for educational buildings and 150 ft for institutional buildings. Subdivision should be accomplished with noncombustible partitions incorporating smokestop doors. In addition, codes may require the corridor enclosures to have a fire rating of 1 or 2 hr. Exit passagewayshorizontal extensions of vertical passageways. Minimum floor-to-ceiling height is the same as for corridors. Width should be at least that of the vertical passageways. Codes may require passageway enclosures to have a 2-hr fire rating. A street-floor lobby may serve as an exit passageway if it is sufficiently wide to accommodate the probable number of evacuees from all contributing spaces at the lobby level. Exit doorsdoors providing access to streets or to stairs or exit passageways. Those at stairs or passageways should have a fire rating of at least 3/4 hr. Horizontal exitpassageway to a refuge area. The exit may be a fire door through a wall with a 2-hr fire rating, a balcony providing a path around a fire barrier, or a bridge or tunnel between two buildings. Doors in fire barriers with 3- or 4-hr fire ratings should have a 11/2-hr rated door on each face of the fire division. Walls permitted to have a lower fire rating may incorporate a single door with a rating of at least 11/2 hr. Balconies, bridges, and tunnels should be at least as wide as the doors providing access to them, and enclosures or sides of these passageways should have a fire rating of 2 hr or more. Exterior-wall openings, below or within 30 ft of an open bridge or balcony, should have at least 3/4-hr fire protection. Interior stairsstairs that are inside a building and that serve as an exit. Except in one-story or two-story low-hazard buildings, such stairs should be built of noncombustible materials. Stairway enclosures generally should have a 2-hr fire rating. Building codes, however, may exempt low dwellings from this requirement. Exterior stairsstairs that are open to the outdoors and that serve as an exit to ground level. Height of such stairs is often limited to 75 ft or six stories. The stairs should be protected by a fire-resistant roof and should be built of noncombustible materials. Wall openings within 10 ft of the stairs should have 3/4-hr fire

fixed-end moment at L due to the load on LR fixed-end moment at R due to the load on LR KL  fixed-end stiffness at end L KR  fixed-end stiffness at end R CL  carry-over factor toward end L CR  carry-over factor toward end R Since ends L and R are not fixed but actually undergo angle changes L and R at L and R, respectively, the joints must now be permitted to rotate while an end moment ML is applied at L and an end moment MR at R to produce those angle changes (Fig. 5.73). With the use of the definitions of carry-over factor (Art. 5.11.2) and fixed-end stiffness (Art. 5.11.3), these moments are found to be The slope-deflection equations for LR then result from addition of M to mLL , which yields ML, and of M to mR, which yields MRR : d M  K (  C  )  MF  K (1  C ) (5.133) L L L RR L L R L d M  K (  C  )  MF  K (1  C ) (5.134) R R R LL R R L L For beams with constant moment of inertia, the slope-deflection equations become 4EI 1 6EI d M 
     MF  (5.135) L L L 2 R L L L 4EI 1 6EI d M 
     MF  (5.136) R L R 2 L R L L where E  modulus of elasticity I  moment of inertia of the cross section Note that if end L moves downward with respect to R, the sign for d in the preceding equations is changed. If the end moments ML and MR are known and the end rotations are to be determined, Eqs. (5.131) to (5.134) can be solved for L and R or derived by superposition of simple-beam components, as is done in Art. 5.11.4. For beams with moment of inertia varying along the span: d   (M  MF)   (M  MF)   (5.137) L L L L R R L d   (M  MF)   (M  MF)   (5.138) R R R R L L L where  is given by Eq. (5.105) and  by Eq. (5.106). For beams with constant

Paneled doors consist of solid wood or plywood panels held in place by verticals called stiles and horizontals known as rails (Fig. 11.60). The joints between panels and supporting members permit expansion and contraction of the wood with atmospheric changes. If the rails and stiles are made of a single piece of wood, the paneled door is called solid. When hardwood or better-quality woods are used, the doors generally are veneered; rails and stiles are made with cores of softwood sandwiched between the desired veneer. Tempered glass or plastic may be used for panels. In exterior doors, the lights should be installed to prevent penetration of water, especially in veneered doors. One way is to insert under the glass a piece of molding that extends through the door and is turned down over the outside face of the door to form a drip. Another way is to place a sheet-metal flashing under the removable outer molding that holds the glass. The flashing is turned up behind the inside face of the glass and down over the exterior of the door, with only a very narrow strip of the metal exposed. Flush doors also may be solid or veneered. The veneered type has a core of softwood, while the flat faces may be hardwood veneers. When two piles are used for a face, they are set with grain perpendicular to each other. Flush doors, in addition, may be of the hollow-core type. In that case, the surfaces are made of plywood and the core is a supporting grid. Edges of the core are