The architect or engineer converts these requirements into a set of drawings and written specifications that usually are sent to interested general contractors for bids. The successful bidder or bidders in turn subcontract plumbing, painting, electrical wiring, structural frame construction and erection, and other jobs to firms specializing in these crafts. Dead loads include the weight of the building itself and all major items of fixed equipment. Dead loads always act directly downward, act constantly, and are additive from the top of the building down. Live loads include wind pressure, seismic forces, vibrations caused by machinery, movable furniture, stored goods and equipment, occupants, and forces caused by temperature changes.
Live loads are temporary and can produce pulsing, vibratory, or impact stresses.
In general, the design of Building must accommodate all possible dead and live loads to prevent the building from settling or collapsing and to prevent any permanent distortion, excessive motion, discomfort to occupants, or rupture at any point. A third trend is the production or redevelopment of such large structural complexes as shopping centers, entire campuses, and whole towns or sections of cities. State and local inspectors review the work for general compliance with the local Building code. The immediate responsibility of the contractor, architect, and engineer ends when the local authorities approve the Building for occupancy and the owner accepts the building. However, the contractor, architect, and engineer are legally responsible for any deficiencies in the construction or design for a period of several years after acceptance, the time depending on the terms of the contract and local laws.