Frames and sub-assemblies such as trusses, girders and other pre-formed welded assemblies need special attention by the detailer to ensure that the assembly can be immersed and withdrawn from each stage in the process in a safe, efficient and effective manner. The pre-treatment solutions from the galvanizing process and the molten zinc must be able […]
Galvanizing – Frames and Assemblies Read Article »
Galvanizing of hollow sections and pipes requires that the item be properly vented to allow for the free flow of Pre-treatment Liquids both inside and outside of the item. Also, when the item is dipped into the galvanizing bath it must allow for the ingress of the molten zinc to fully coat both the inside
Galvanizing – Hollow Sections and Pipes Read Article »
Provided the general Welding Guidelines are observed and that the necessary precautions are taken to Avoid Distortion, the galvanizing of open sections present few problems, their open nature ensures an efficient run-off of pre-treatment liquids and a smooth flow and equal coating of molten zinc. However, end-plates, stiffeners and gusset plates can hinder drainage and
Galvanizing – Open Sections Read Article »
The Importance of Adequate Venting and Draining The purpose of venting and draining is to ensure the part can be immersed and withdrawn from each stage in the process in a safe, efficient and effective manner. The pre-treatment solutions from the galvanizing process and the molten zinc must be able to flow freely into and
Galvanizing – Venting and Draining Read Article »
There are various do’s-and-don’ts that should be observed by the detailer when it comes to welding of fabricated structures or components which are to be galvanized. The first considerations relate to the residual stresses which may lead to distortion. (Refer to: Avoiding Distortion during Hot Dip Galvanizing) The second relates to proper venting and the
Galvanizing – General Welding Guidelines Read Article »
Distortion occurs due to the relief of locked-in stresses within a steel section or fabrication. At room temperature, the steel is sufficiently strong to accommodate such stresses, but at the galvanizing bath temperature (about 450°C), the steel`s yield strength may be reduced by up to 40% (Note, the steel recovers its full strength when it
Galvanizing – Avoiding Distortion Read Article »
In suitable applications, hot dip galvanizing provides ideal corrosion protection for steel – no other coating matches galvanizing’s unique combination of low initial cost, ease of inspection for coating quality, durability, predictable performance, low maintenance and resistance to abrasion and mechanical damage. Hot dip galvanizing is often perceived to be more expensive than it is.
Galvanizing – The Process / Introduction Read Article »
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
HSS – Splice Connections Read Article »
Steel hollow sections have until recently been used almost exclusively for truss girders, bridge girders and in recent examples, columns, taking advantage of their inherent properties when axially loaded in tension and compression. The use of hollow sections as beams in frame structures subject to bending moment conditions is a fairly new application and their
HSS – Bolted Connections – Introduction Read Article »
The blind bolt hole centers are a function of the outside corner radius (r2) of the hollow section profile. To determine the bolt hole centers it’s necessary to work from the outside-in, therefore, dimension (e1) is a function of the corner radius + clearance for the blind fastener (c1) – this will vary depending on
HSS – Edge Distances for Detailing Read Article »
There are basically 3 means of connecting steel hollow sections, which include: Welding Through-Bolting, and Blind-Bolting Welding is usually restricted to workshop joints and applied mainly in the fabrication of trusses, lattice girders and sub-assemblies. For more information on this go to Welded Joints Site welding should be avoided – it’s costly, often difficult and
HSS – Fastener Options Read Article »
A moment connection is designed to resist rotation at the joint – most hollow section connections, unlike open section connections, will not allow a great deal of flexibility and will rely on the rotation capacity of the connection components of the incoming beam. These connections are defined specifically as Moment Resisting which means the load
HSS – Beam to Column / Bolted Moment Connections Read Article »
Typical Examples Beam to column connections using Fin-Plates are probably the most widely used connection due to their relative ease of fabrication and erection. The main advantage lies with the fact that they are all Through-Bolted. The following examples show typical connections graduating for the simplest and most straightforward to the more complex (and costly)
HSS – Beam to Column / Bolted Fin-Plates Read Article »
These connections are not generally regarded as Moment Resisting, but due to their configuration they will offer some resistance against rotation. The determining factor lies with the Rotation Capacity of the joint components. (For more about the rotation capacity go to Moment Connections) Typical Examples The first 4 examples show typical beam to column connections
HSS – Beam to Column / Bolted End-Plates / Cleats Read Article »
Typical Examples Bolting beam to beam using hollow sections is not widely used – it can prove to be quite costly due to the welding of the various components of the joint. Also, the joint is exposed and is not particularly aesthetically pleasing (Though there is a hidden joint option, which we’ll look at later)
HSS – Beam to Beam Bolted Fin Plates Read Article »
Typical Examples Here we’ll look at some typical examples of a hollow section beam to beam connections. The first examples illustrate a hollow section beam bolted to a hollow section supporting member – as mentioned in the Introduction, this is not a widely used configuration and are used in mainly single-storey lightweight structures. Figs. 1
HSS – Beam to Beam Bolted End-Plates / Cleats Read Article »
Square, Rectangular, and Round Hollow Structural Section (HSS) The hollow section profile possesses a greater strength-to-weight ratio than conventional open sections which allows for a greater flexibility in use due to its enhanced efficiency and inherent resistance to compression and torsion. This makes them ideal for use as structural column, shafts, trusses, composite beams and
Steel Hollow Sections Read Article »
Generally, hollow section trusses and lattice girders are welded together in the workshop and delivered to site as a unit, this allows for better quality control and more efficient site erection. The trusses usually connect at each end to a support column, but they may connect to another truss forming a space frame. Trusses may
HSS – Trusses and Lattice Girders / Welded Connections Read Article »
Hollow sections are commonly used in welded steel frames where members experience loads from multiple directions – hollow sections have uniform geometry and thus uniform characteristics with excellent resistance to torsion making them a good choice for columns. They can also be used for beams, though conventional hot-rolled I-shapes are generally more efficient for this
HSS – Materials and Specifications Read Article »
Isolation Isolation pads are used to protect the structure against the effects of Vibration – how well the isolator works depends on its deflection. The greater the deflection, the less the vibration transmission. There are three classes of vibration isolators which include: Isolation Pads which are made from either Rubber or Neoprene which are fitted
Mechanical Isolation and Damping Read Article »
Loads, and what the steel detailer should know Some may argue that and understanding of loads and how they affect a steel structure is the realm of the engineer and designer, which is absolutely true – but it’s an advantage to any structural steel detailer to have at least a basic understanding of what it
Loads – Introduction Read Article »
Live loads are dynamic in nature and may be generated from within or outside of the structure. Those from within are produced by the use and occupancy of the building and may be induced by human activity, vehicles in motion, or operational machinery and equipment. Note! Occupancy loads may also be classified as Superimposed Loads
The earth’s surface is made up of numerous tectonic plates which are constantly in motion relative to one another pushing one against the other. These points of contact are known as the ‘Fault-Lines’, and when the pressure of the contact reaches a certain level, something has to give, resulting in a violent and sudden slip.
Wind loads are essentially horizontal in nature and are exerted by wind pressure acting upon the external surfaces of the structure, and like a sailboat, the greater the surface area presented to the wind, the greater the force. Wind pressure is directly related to wind velocity. At ground level, the wind velocity is virtually zero
Gravity Loads Gravity Loads or Static Loads are essentially what you would imagine, stationary loads imposed by gravity, which can be divided into 2 sub-categories which include Dead and Superimposed Loads: Dead Loads: include the self-weight of the structure including all items that are permanently connected to, and forming part of the structure, including, walls,
Index In this sub-section we look at typical vertical bracing connections for various bracing types. they include: Single Angles Double (Battened Back-To-Back) Angles Double (Battened Starred) Angles Single and Double (Battened Back-To-Back ) Channels Heavy Duty Bolted / Welded Heavy Duty All Bolted Compression Struts with End-Plates Compression Struts with Splice-Plates Girder (Bridge) Connections
Typical Vertical Bracing Connections Read Article »
This type of connection is commonly found in Girder Trusses, particularly Bridge Girders. The horizontal beam(s) may be orientated with the flanges top and bottom or rotated through 90° with the flanges to the side. The advantage with the latter is that the beams and bracing members can be of the same section making it
Typical Vertical Bracing Connections Girder (Bridge) Trusses Read Article »
These heavy-duty bracings are generally designed to work in compression, with the tensile stress being considered insignificant and largely ignored. Such bracing is often used in structures which are subject to high lateral loads, particularly in areas which are subject to seismic activity. The joint ends should be faced for full bearing, but this can
Typical Vertical Bracing Connections Compression Struts with Splice Plates Read Article »
Theses heavy-duty bracings are generally designed to work in compression only, with the tensile stress being considered insignificant and largely ignored. Such bracing is often used in structures which are subject to high lateral loads, particularly in areas which are subject to seismic activity. The joint between the flanges must be true and square in
Typical Vertical Bracing Connections Compression Struts with End-Plates Read Article »
The following typical connections apply to –I- or –H- profile bracing which may be subject to tension or compression. The flange angles are bolted to the gusset plate and site-bolted to bracing member on erection. This all-bolted option allows for some fabrication alignment (but not much) as the bolt clearance holes will allow for some
Typical Vertical Bracing Connections Heavy-Duty All Bolted Read Article »
The following typical connections apply to –I- or –H- profile bracing which may be subject to tension or compression. The flange plates are slotted to ‘wrap around’ the gusset plate and shop welded in position. The bracing members are then site-bolted to the flange and web plates. Any misalignment may be compensated for by allowing
Typical Vertical Bracing Connections Heavy-Duty Bolted / Welded Read Article »
The following typical connections are for channel section bracing which may be either single or doubled back-to-back, being the more common. This type of bracing usually requires a double row of bolts equally spaced about the centre-line of the bracing member. The general rules-of-thumb for the spacing of the battens applying to Angle bracing may
Typical Vertical Bracing Connections Single and Double (Battened) Channels Read Article »
The following typical connections are for double (starred) angles connected by means of Gusset Plates – To ensure the angles work together as a single unit they should be joined together by means of battens, which are fabricated spacers placed at intervals along the bracing member’s length. Star-Battens will be looked at later in this
Typical Vertical Bracing Connections Double (Starred) Angles Read Article »
The following typical connections are for double (back-to-back) angles connected by means of Gusset Plates – To ensure the angles work together as a single unit they should be joined together by mean of battens, which are fabricated spacers placed at intervals along the bracing member’s length. Back-to-Back Battens will be looked at later in
Typical Vertical Bracing Connections Double (Battened) Angles Read Article »
The following typical connections are for single angles connected by means of Gusset Plates: The bracing angles are set out to a common Work Point located at the intersection of the centre lines of the beams, columns and bracing members. Other options for locating the Work Points can be found at Vertical Bracing – Setting
Typical Vertical Bracing Connections Single Angles Read Article »
What are Flexible Connections? Flexible Connections will be the most common type likely to be encountered by the detailer, they will make up just about all beam-to-beam connections and for braced frames, will be found to make up the beam-to-column connections as well. So, what is a Flexible Connection? When a vertical load is applied
Flexible Connections Read Article »
Introduction A steel structure is exposed to numerous different load conditions. In simple terms, they can be categorized as Vertical or Horizontal and may be either static or dynamic. Vertical loads, also referred to a Gravity or static Loads include the self-weight of the structure including all parts that are permanently connected to, and forming
Stabilizing Systems – Introduction Read Article »
Fabricated profiles can come in many forms, but usually they are limited to Plate Girders, Box Girders and castellated or Cellular profiles. Plate Girders A plate girder (or built-up section) is typically formed into an I or H profile from separate web and flange plates. The plates may be either bolted, riveted, or welded together
Fabricated Profiles – Introduction Read Article »
In this example, we show an all-bolted pitched truss (or Fink Truss) For all-bolted trusses formed using angles, the work points may be established from the centroids or centers of the members. Technically, he correct way is to use the centroids but as the holes are commonly set out on the center-line of the lacing
Pitched Truss (Fink Truss) – All Bolted Read Article »
In this example, we show an all-welded pitched truss (or Fink Truss) For All-Welded trusses formed from angles, the work points should be established from the centroids of the members. In order to achieve maximum weld contact between the members, the diagonal lacing members are located on the far-side of the chords. The apex joint
Pitched Truss (Fink Truss) – All Welded Read Article »
In this example, we show an all-welded heavy girder truss. It may be formed from hot-rolled I or H sections For all-welded trusses formed using hot-rolled I and H sections, the work points are established from the geometric centers. Splices should ideally be located so that they are staggered equally about a vertical truss member.
Heavy Girder Truss – All Welded Read Article »
In this example, we show an all-bolted Heavy girder truss. It may be formed from hot-rolled I or H sections For all-bolted trusses formed using hot-rolled I and H sections, the work points are established from the geometric centers. Splices should ideally be located so that they are staggered equally about a vertical truss member.
Heavy Girder Truss – All Bolted Read Article »
In this example, we show an all-bolted medium girder truss. It may be formed from either single or double (battened) channels. For all-bolted trusses formed using channel chords and angle diagonal members, the work points may be established from the centroids or centers of the members. Sometimes, a splice may be necessary, in such cases
Medium Girder Truss – All Bolted Read Article »
In this example, we show an all-welded medium girder truss. It may be formed from either single or double (battened) channels. For all-welded trusses formed using angles, the work points may be established from the centroids or centers of the members. Detail -5- illustrates a typical channel splice for both a single and double (battened)
Medium Girder Truss – All Welded Read Article »
In this example, we show an all-bolted light/medium girder truss. It may be formed from either single or double (battened) angles. The members are connected using gusset-plates. For all-bolted trusses formed using angles, the work points may be established from the centroids or centers of the members. Technically, he correct way is to use the
Light / Medium Girder Truss – All Bolted Read Article »
In this example, we show an all-welded lightweight girder truss. Its formed from single angles with alternating lacing members. For All-Welded trusses formed from angles, the work points should be established from the centroids of the members. In order to achieve maximum weld contact between the members, the diagonal lacing members are located on the
Light Girder Truss – All Welded Read Article »
A Truss or Lattice Girder may be formed from almost any combination of steel sections including: Hot Rolled Sections Square, Rectangular or Circular Hollow Sections, and – Cold Formed Profiles In this article, we’ll look specifically at Hot Rolled Sections including: Angles, Channels, Tees and I / H profiles, both Bolted and Welded. The one
Truss Girders – Nodes and Work Points Read Article »
A typical Truss is comprised of the top and bottom horizontal members known as the Chords – the vertical members are either the Ties of Struts, depending on whether they are in Tension or Compression, while the diagonal members form the Lacing. The distance between the intersection points (known as the Nodes) of the Lacing
Truss Girders – Setting Out Read Article »
Introduction A Truss or Lattice-Girder is essentially a triangulated system of interconnected elements which connect at common work-points or ‘Nodes’, they are designed to primarily resist bending with the top chord being the compression element, and the bottom chord being the tension element. The diagonal lacing being axially loaded will work either in tension or
Truss Girders – Introduction Read Article »
