16.9.10 Additional Elevator Safety Devices Automatic elevators require several safety devices in addition to those usually installed in elevators with operators. These devices include: An automatic load weigher to prevent doors from closing and the car from starting when it is overloaded Car and hall buttons that passengers can push to stop the doors from closing and to hold them open Means for preventing doors from closing when the entrance is obstructed Emergency power system that is activated as soon as the primary system fails Lights to indicate landings for which calls have been registered Two-way communication with a supervisor outside the hoistway (G. R. Strakosch, Vertical Transportation: Elevators and Escalators, John Wiley & Sons, Inc., New York.) For low-rise elevators, hydraulic equipment may be used to supply the lift. Two basic designs are available: one where the car sits atop a plunger or piston which operates in a pressure cylinder (Fig. 16.15), and the other where two plungers are located inside the elevator shaft to lift the elevator either by direct connection to the carframe or indirectly using hoist ropes. Oil serves as the pressure fluid and is supplied through a motor-driven positive-displacement pump, actuated by an electric-hydraulic control system. To raise the car, the pump is started, discharging oil into the pressure cylinder and forcing the plunger up. When the car reaches the desired level, the pump is stopped. To lower the car, oil is released from the pressure cylinder and is returned

The maximum height of internal walls is 2.7m. See National Construction Code. The lengths of external walls up to 2.7m high must not be greater than the following shown in Table 8: Table 3 Maximum external wall lengths up to 2.7m high. Wind Category Walls with four sides supported Walls with four sides supported Walls with a free end and no opening N1 9.8m N2 7.3m N3 5.4m Joints All corners must have filled perpends; Gable walls and party walls must have filled perpends. Top and bottom courses must have filled perpends; Walls over windows and doors must have filled perpends. All perpend joints should be filled when sound and fire ratings are a consideration. The widths of any unfilled perpends must not be greater than 12mm but may be zero. Wall Ties All wall ties shall meet the requirements of AS2699.1: 2000, Built-in Components for Masonry Construction - Wall ties and conform in anchorage and embedment to the requirements of AS3700: 2001. Wall ties for cavity walls should be spaced as follows: For N1 wind category, light-duty ties at 450mm horizontally and 600mm vertically. For N2 wind category, light duty ties at 300mm horizontally and 600mm vertically or medium duty ties at 600mm horizontally and 600mm vertically. For N3 wind category, medium duty ties at 450mm horizontally and 600mm vertically. and an opening or control joint

where p(x)  load distribution on the span [p(x)(x) is the varying force] n(x)  characteristic shape of the nth mode (see Art. 5.18.2) L  span length w  uniformly distributed weight on the span The response of the beam then is given by Eq. (5.278), and the dynamic deflection is the sum of the modal components, An n(x). Nonlinear Responses. When the structure does not react linearly to loads, the equations of motion can be solved by numerical analysis if resistance is a unique function of displacement. Sometimes, the behavior of the structure can be represented by an idealized resistance-displacement diagram that makes possible a solution in closed form. Figure 5.112a shows such a diagram. Elastic-Plastic Responses. Resistance is assumed linear (R  ky) in Fig. 5.112a until a maximum Rm is reached. After that, R remains equal to Rm for increases in y substantially larger than the displacement ye at the elastic limit. Thus, some portions of the structure deform into the plastic range. Figure 5.112a, therefore, may be used for ductile structures only rarely subjected to severe dynamic loads. When FIGURE 5.112 Response in the plastic range of a one-degree system with resistance characteristics indicated in (a) and subjected to a constant force (b) is shown in (c). this diagram can be used for designing such structures, more economical designs can be produced than for structures limited to the elastic range, because of the high energy-absorption capacity of structures in the plastic range. For a one-degree system, Eq. (5.273) can be used as the equation of motion for the initial sloping part of the diagram (elastic range). For the second stage, ye  y  ym, where ym is the maximum displacement, the equation is