1 1

where ID is the moment of inertia of girder AD. Similarly, the deflection of girder 9-9 at node 1 (Fig. 4.25d) equals

m3 k3

where I9 = moment of inertia of girder 9-9 S9 = deflection of girder AB at node 9

Girder AB carries the reactions of the interior girders spanning in the y direction (Fig. 4.25e):

where IAB is the moment of inertia of girder AB. The equation for vertical displacement at node 1 is obtained by equating the right-hand side of Eqs. (4.147) and (4.149) and substituting S7 and S9 given by Eqs. (4.148) and (4.150).

After similar equations have been developed for the other five interior nodes, the six equations are solved simultaneously for the unknown forces Xr. When these have been determined, moments, shears, and deflections for the girders can be computed by conventional methods.

(A. W. Hendry and L. G. Jaeger, Analysis of Grid Frameworks and Related Structures, Prentice-Hall, Inc., Englewood Cliffs, N.J.; Z. S. Makowski, Steel Space Structures, Michael Joseph, London.)

Planar structural members inclined to each other and connected along their longitudinal edges comprise a folded-plate structure (Fig. 4.26). If the distance between supports in the longitudinal direction is considerably larger than that in the transverse direction, the structure acts much like a beam in the longitudinal direction. In general, however, conventional beam theory does not accurately predict the stresses and deflections of folded plates.

A folded-plate structure may be considered as a series of girders or trusses leaning against each other. At the outer sides, however, the plates have no other members to lean against. Hence the edges at boundaries and at other discontinuities should be reinforced with strong members to absorb the bending stresses there. At the supports also, strong members are needed to transmit stresses from the plates into the supports. The structure may be simply supported, or continuous, or may cantilever beyond the supports.

Another characteristic of folded plates that must be taken into account is the tendency of the inclined plates to spread. As with arches, provision must be made to resist this displacement. For the purpose, diaphragms or ties may be placed at supports and intermediate points.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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