steeldetailing
02.06.2009, 13:31
Steel connections detailing (beam/beam or beam/column) is an important exercise when planning definite distribution of loads transmitted from one structure member to another. This article helps you to become familiar with the more simple ways of joining steel components like beams and columns in a building frame. Basic design routines used for steel connection detailing purposes are: flexible end plates, bolted angle cleats and fin plates. All three of these are the most useful for steel beam/column or beam/beam connections.In steel connection detailing process connections are assumed not to transmit any load from the target beam to another beam or column and for this to occur the connection must allow a small amount of rotation. With web cleats this happens from slip in the connected members and buckling of the cleats. Fin plates and End plates are purposely constructed of relatively thin material that will deform rather than transmitting any considerable moment.To reduce steel fabrication expenses, the BCSA (British Constructional Steelwork Association) has proposed a number of standardized angle web cleat, fin plate and end plate connections and you should follow this for building steel frames. These fittings will usually be made of Grade 43 steel. In general the tops of all the fittings are placed 50mm below the top of the beam and the first bolt row will be 90mm below the top of the beam. A standard bolt pitch of 70mm is applied wherever possible. These recommended standards need to be customized for small components and for heavily loaded members.To form beam-beam connections it is essential to notch the top and sometimes the bottom of the supported beam to clean up the flanges of the supporting beam. The BCSA standards utilize a 50mm deep notch rather than the lowest notch depth specified in the property tables of steel section. BCSA proposes use of fully threaded bolts or screws which are appropriate for 80-90% of connections in a typical steel frame. This means that there will be threads in the shear plane of the bolt so the threaded area of the bolt is used in estimating its shear capacity.When detailing steel beam connections or column connections you need to examine the CAD program output closely to make sure that the recommended design can be physically constructed and that there is sufficient room to tighten the bolts. All steel connections are only as strong as the weakest link – hence the information provided here will enable you to avoid major slip-ups in steel framing and building design.To know more about steel connections detailing and structural designs email us at info@outsourcingsteeldetailing.com or visit us at http://www.outsourcingsteeldetailing.com