AD 285: Floor systems for simple construction using discontinuous columns and continuous beams

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Advisory Desk AD 285 Floor Systems for Simple Construction using Discontinuous Columns and Continuous Beams This AD provides advice on the floor-plate systems to be used with discontinuous (storey- high) columns and continuous beams in simple construction. AD 281 provides general advice on this form of construction and AD 283 covers the design of the column. As previously noted, this form of construction need not be restricted to the residential sector alone. Floor-plate Figure 1 Continuous beam model The column design procedure outlined in AD 283 be to use precast concrete units in the depth construction but offers no rotational restraint implicitly relies on rotational restraint both out- of the floor beam with topping, and with any out-of-plane to the column ends. of-plane and in-plane to the column ends for voids between the precast units and the beams the permanent condition, although the column’s filled with grout. Both solutions are suitable for Floor beams effective length factor is taken as unity. This residential and commercial developments. The floor beam in this form of construction allows the use of a simple design model with The above systems, with the floor-plate may be designed as simply supported or nominal moments even though the actual within the depth of the beam, have the continuous but it is assumed that no moment behaviour is complex. In BS 5950-1, the term advantage that the column ends are rotationally is redistributed from the beam to the column. ‘rotational restraint’ is described as directional restrained out-of-plane by the slab. The use of Therefore, pins (no stiffness) or knife edge restraint. AD 281 and AD 283 assume that the box ties and structural tees, as shown in AD 281 supports must be used in the frame or floor-plate is Slimdek but an alternative would and AD 283, offers positional restraint during beam analysis. The column is designed in 395 FICEP 6 models2XHpgs 10.3.5 3/22/05 10:40 AM Page 1 6 members of our squad that’s designed to make you far ECONOMICAL CUTTING DRILLING & SAWING MARKING & NOTCHING FLEXIBLESHEARING, PUNCHING, UP TO 700mm WIDE BARS & SECTIONS STEEL SECTIONS FROM 100mm-2500mm WIDE PROCESS UP TO 250mmWIDE FLATS & ANGLES CAMBERS BEAMS FICEP’s comprehensive range of machines for the processing of FICEP now has a range of almost 100 versatile machines which structural steel beams, angles and plates can match the precise incorporate precise measuring systems that enhance accuracy to production requirements of the smallest or largest fabricator - so improve quality and fit which in turn reduces errors, lead times and now every company can reap the benefits of FICEP’s high minimise wastage. technology CNC machines. All these benefits are supplemented by the highest levels of These machines can dramatically increase productivity and profitability, maintenance and service support which can include remote reduce labour costs and improve processing by up to 40%. diagnostic software and comprehensive bespoke service contracts. Call 0113 265 3921 for more detailed information. If your goals are to reduce production costs and increase productivity LTD FICEP UK Ltd., 10 The Courtyards,Victoria Park,Victoria Road, Leeds LS14 2LB. 30 NSC April 2005


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