0The Column Base-Plate is welded tp the base of the column and in turn, fastened to the foundation by means of specially designed Anchor Bolts. They have to deal with a variety of load conditions including, Compression, Shear and Rotational Moments. All column bases will have to deal with a combination of these loads to a greater or […]
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Castellated Beams Castellated beams are created by cutting two standard beams or girders along their webs at a predetermined position, the high points of the webs are then welded together to form the castellated section, they are useful for their high strength to weight ratio resulting in a lighter section capable of greater spans. Castellated
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Fabricated box-girders are used for extra-long span, high load applications such as bridges, stadiums, and other such high density public access areas. Their aesthetically pleasing appearance makes the popular for such applications due to the fact that there is no external visible stiffening or joints. Box-girders may be formed to almost any shape, but most
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Fabricated plate-girders are used in long-span applications where commercially available sections are either unavailable or unsuitable. They comprise of two flange plates and a web plate configured into an ‘I’ or ‘H’ profile. They may be either bolted of welded and can be fabricated to almost any size. Bolted Plate Girders Bolted Plate Girders are
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In North America there is the Unified Screw Thread, which come in both fine and coarse – the thread is measured in TPI (Threads per Inch) For metric bolts there is the ISO Metric Screw Thread, which also comes in both fine and coarse – the thread is measured according to its Pitch which is the spacing
Bolt lengths come in preferred sizes which generally are in regular production – these are indicated in the table below as X – while those denoted (X) refer to bolts which are available, but not considered to be in regular production. Availability of these bolts should be confirmed by the supplier. Bolt diameters have been
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Just about every steel structure today will use bolts as the primary means of connecting the various parts together. For the uninitiated, the appropriate selection of suitable bolts can be somewhat intimidating – There are literally hundreds of possible bolt and nut combinations – not to mention, standards, material types, grades, classes etc. – add
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A structural bolt typically has a partial thread, the unthreaded portion is the shank, which when added to the thread length gives the overall bolt length. The thread length is a function of the bolt diameter and length, which for the most part is standardized across the range of bolts – but it’s always wise
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Bolt Standards In North America bolts are classified according to ASTM standards (American Society for the Testing of Materials) while in Europe, they are classified according to national standards of the individual states. Each state has its own national standards institute BSI, DIN, AFNOR, etc. with each operating independently. To establish common standards within the
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Bolt Diameters In practice, the vast majority of bolts used for load bearing connections will be between M16 (5/8”) and M24 (1”). Anything less than M16 is unlikely to be certified and should be avoided. Greater than M24 would be used only in the most exceptional circumstances. The table below will provide some idea of
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Floor Types Here, we’ll be looking at 3 floor types which represent most types likely to be encountered, they include: Down-hand Construction Integrated Constructions Slim-Floor Construction Down-Hand Construction This is where the concrete floor sits on top of the supporting steelwork. The metal decking would typically span across multiple beams making it stiffer and stronger
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Composite construction has contributed significantly to the dominance of steel frames in the commercial building sector worldwide. Composite floors are usually incorporated into multi-storey commercial structures and typically consist of profiled steel decking with a reinforced concrete floor cast in-situ. The decking not only acts as a permanent shutter, but it also provides sufficient shear-bond
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This article was updated on the 24/06/2021 Open grid flooring is generally to be found in industrial applications where its open nature allows for the passage of light and air circulation. Also being open prevents the build-up of debris and standing water making it ideal for platforms and walkways when safety is a prime consideration.
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Here we’ll look at typical horizontal bracing connections connecting to beams and columns. They include both welded and bolted gusset plates. For information on bolt hole edge-distances and spacing refer to Bolt-Hole Spacing and Edge-Distances Welded Gusset Plates to a Beam Fig’s 1 and 2 illustrate typical welded Gusset-Plates. Fig. 1 – shows the Gusset
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Horizontal bracing is employed to resist horizontal / lateral loads on the structure and distribute them to the outer columns and thereby into the vertical stabilizing system. Horizontal bracing will also maintain the planar integrity of the structure and prevent it from deforming out of shape. The bracing configuration works with the horizontal beams to
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Gusset Plate Geometry Gusset-plates are the most common means of connecting bracing, they may act either in tension or compression depending on how the bracing is configured. They should be as compact as possible to minimize the risk of out-of-plane buckling when in compression. When setting out the bracing, it should be borne in mind
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Here, we’ll be looking at the setting-out procedure for Concentric vertical bracing using gusset-plates, the general principles will apply to all bracing configurations irrespective of member sizes. Concentric bracing implies that the Work-Points are derived from the center-line intersections of the beam, column, and bracing member. The center-lines represent the neutral axes of the members,
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The Vertical Braced-Frame is the most straightforward and efficient vertical stabilizing system. It’s fairly straightforward to resolve, and equally straightforward to fabricate and erect. Braced frames are flexible in the sense that they can be adapted to suit almost any conditions and a wide variety of load combinations. Bracing is also the most economical stabilizing
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Shear walls may be constructed from steel plate, reinforced concrete, or masonry, and are usually to be found in structures built is seismically active zones. A shear-wall could loosely be described as a solid infill brace, often placed within the confines of the structure to assist the primary stabilizing system located at the periphery. Shear-walls
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A leaned frame is fairly self-descriptive; it is employed mostly in single-storey or low-rise / multi-bay structures where one of the bays is designed as a rigid frame, while the others, as Pin-Jointed frames lean against it. The Rigid Bay, though illustrated over as a moment resisting rigid frame, may be any of the other
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Rigid or Moment Frames seem uncomplicated and straightforward in appearance and resemble simple post and beam construction, but in fact, they are radically different in structural behavior. The best way to describe rigid frames is to compare them with pin-ended braced structures. The horizontal beams in a braced frame are subject to ‘bending’ when a
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Vertical braced-frames are the simplest and most effective of the stabilizing options, they are relatively straightforward to analyze, economic to fabricate, and can be erected in a relatively short space of time. Hence, Braced-Frames are without doubt the most popular and efficient stabilizing option and will account for a great majority light commercial and industrial
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Diaphragms are usually incorporated into Multi-Storey commercial structures and typically consist of Profiled Steel Decking with a reinforced concrete floor cast in-situ. The decking not only acts as a permanent shutter, but it also provides sufficient shear-bond with the concrete by means of the shear-studs, so that when the concrete has gained sufficient strength the
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Horizontal braced frames are usually found in industrial type structures, where due to their open nature Composite Floors are not an option. Lateral force distribution is achieved by, what is effectively a Horizontal Triangulated Girder or Truss. The bracing system may be configured in any number of ways, depending on the limitations and/or the requirements
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Vibration, Resonance and Fatigue Steel, being flexible, is an excellent conductor of vibration. Dynamic activity in one part of a structure can be transmitted through the structure itself by means of the horizontal and vertical components to any other adjacent part. Even dynamic activity outside of the structure such as road or rail traffic can
Introduction to Lateral Restraints In lightly loaded short-span Crane-Girders the top-flange of the girder may be stiffened by fixing an inverted channel horizontally to give additional support and to resist lateral loading from the crane wheels. However, the channel itself only offers limited resistance against anything but the lightest lateral load conditions, consequently, in most
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Crane-Rails Standard flat-bottom rails are usually used for light to medium duty applications, but because of their height-to-width ratio they may be prone to overturning when subjected to large lateral loads. Their relatively thin webs are also subject to a combination of high vertical stress and bending stress from the lateral loads causing what could
Crane Classifications Two cranes with the same rated capacity and span may differ in their average load intensity and/or expected loading cycles. There are different standards which classifies cranes based on the service class. The Crane Manufacturer Association of America (CMAA) classifies bridge cranes according to average load intensities and number of cycles. On the
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Introduction to Crane-Beams and Girders Crane-Beams of Girders, are a stand-alone structural component, in that unlike conventional beams and Plate-Girders they have to withstand high lateral forces generated by the movement of the crane gantry along the track, and the cross-movement of the trolley across the crane gantry. Additionally, they have to resist the longitudinal
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Crane-Columns are a subject unto themselves, they differ from the more conventional column in that they must resist substantial dynamic forces generated by the movement of the crane. These loads include the mass of the crane-gantry itself together with its maximum load carrying capacity, additionally these loads must be factored for the impact of the
Multi-Storey structures generally require that the columns be ‘spliced’ in order to extend their length for the full height of the structure. Splices may be either bolted or welded and its always assumed that welded splices are ‘shop-welded’ while bolted splices are ‘site-bolted’. It is possible to call for a site-welded splice, but making such
What is a Hot-Rolled Steel Section? Hot rolled sections are produced by steelmakers where the molten steel is cast into a steel ‘blank’ approximating the shape of the finished product, the blank is then re-heated in a re-heating furnace and drawn through a series of carefully calibrated rollers to the final shape. The beams are
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Under normal circumstances it’s generally unnecessary to strengthen a beam – it’s an expensive and time-consuming exercise and generally avoided, however, there will always be occasions where it’s necessary. Strengthening the Beam Flange The beam flange may be stiffened to improve the bending capacity of the beam, and to provide resistance to lateral forces. Fig
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The definition of a beam is; a horizontal member which spans between supports and supports loads at right-angles to the member. Almost any steel section can be classified as a beam provided it can be supported adequately and meets the duty requirements. A beam is usually designated according to the manner in which it’s supported,
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REVISIONS TO PAGE References to Fig’s 1 – 4 corrected Moment connections may be either shop-welded / site-bolted, or shop-welded / site-welded. By far the most common is the shop-welded / site-bolted, examples of which are illustrated below and include: Site-Bolted End-Cleats Site-Bolted End-Plates Site-Bolted Flange-Plates Site-Bolted Moment-Trees Typical Site-Welded connections Bolted End Cleat Moment
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What are Moment Connections? REVISIONS TO PAGE Duplicated text removed At first glance, a moment-frame appears to be a simple post-and-beam construction With a braced-frame these lateral forces are absorbed by the bracing system, which transmits those forces through the diagonal members, into the vertical columns, and into solid ground via the foundations. The best
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To assist the detailer in selecting the appropriate connection type, the following guide has been prepared to provide an insight into the practical advantages and disadvantages of each, which includes: Welded End-Plates Bolted End Cleats Welded Fin-Plates Welded Tees Seating Connections Though all these connection types work and generally fulfill the criteria of being ‘Flexible’
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At the turn of the 20th century national standards institutes were formed to standardize and regulate the dimensions and properties of ‘standard’ steel sections. Though they operated independently within their own jurisdictions, there was cooperation among the bodies to ensure that the characteristics and properties of the various steel sections were consistent, enabling the various
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