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Below is an introduction to the topic of Estimating and Tendering. You can also search for your specific topic using the Search box at the top of the page or click on any of the following keywords and phrases: Procurement process – Quotations – Commercial submission.
The translation of the client brief into tender documentation commences in tandem with the design specification. The full tender is normally submitted through a competitive tender process and involves input from those involved in the commercial side of the project, as well as from the design and manufacturing side. These include the project management team, architects and quantity surveyors.
Steelwork tenders are vetted commercially, technically and contractually by the client, main contractor and their advisers, who decide upon the most attractive offer and award a contract.
Steelwork tenders are vetted commercially, technically and contractually by the client, main contractor and their advisers, who decide upon the most attractive offer and award a contract. Sustainability and whole life costing considerations will become more important in the tender adjudication process.
The BCSA endeavours to share best practice, as far as member companies’ confidentiality allows, in the art of estimating and tendering. The structural steelwork sector has many bespoke and standard aids such as 3 and 4D modelling, as well as unrivalled experience, to promote early involvement in the procurement process, which will add value and reduce cost.
The BCSA members all go through very thorough periodic assessments, which should improve client confidence and provide a common basis for tenders.
An increasingly popular alternative to the traditional procurement route described earlier is Design & Build. Here, the steelwork contractor is responsible for the structural design. In-house design engineers optimise the solutions using their detailed knowledge of steel availability and the economics of fabrication and erection in their own companies. The tender is submitted as an inclusive price for design, fabrication and erection of steelwork, and it is the steelwork contractor’s unique solution for the project.
Normally Design & Build procurement is controlled by main contractors, who compare the various bids, selecting the best in terms of price, programme, quality and suitability of the proposed solution.
Working closely with the Design Engineer who has prepared the original structural design, draughtsmen and technicians at the steelwork contractor prepare detailed fabrication drawings showing how each steel component is to be made up and positioned in the structure. This work is normally subject to formal approval by the Design Engineer before fabrication commences.
The process of detail design embodies two functions: the development of connection design and the geometrical detailing of components at a joint. Current advances in 3D modelling software have allowed the development of complex detailing and draughting systems.
A steel structure is the product of a highly professional team. Like any successful sporting team, every team member makes a vital contribution in achieving the right final result.
The steel construction team includes architects, design engineers, quantity surveyors, contractors, steelwork contractors, erectors, steel producers and specialist suppliers.
BCSA provides guidance on steel construction issues, including publications covering specification, design, assessment, contracting, finance, health and safety.
Fabrication is the process used to manufacture steelwork components that will, when assembled and joined, form a complete structure. The structure generally uses readily available standard sections that are purchased from the steelmaker or steel stockholder, together with such items as protective coatings and bolts from other specialist suppliers.
Although a wide range of section shapes and sizes are produced, the designer may find that the required section size is not available. In this case, built-up girders may be fabricated from plate. Sections and plate girders may also be strengthened by stiffening the web or flanges depending upon the load to be carried.
Most modern steelwork fabrication plants have computer aided design and detailing which is linked directly to shop floor CNC machinery creating a genuine CAD/CAM environment. The accuracy of the computer generated details being transmitted to the manufacturing machinery increases the quality standards of production far beyond the expectations of several years ago.
The fact that machinery has taken over from the tape measure means that the structure is produced to high quality standards which are reflected in the speed and accuracy of steel erection on site. This results in significant benefits both to the client and main contractor alike.
The following are commercial factors that should be considered when estimating the cost of steel construction projects:
History of Parties Involved: As with any specialist work, the degree of risk is significantly dependent upon the trust that each of the parties has in the others. When the parties (client, engineer, main/management contractor and steelwork contractor) have successfully worked together in the past, a lower price for the work, with fewer post-contract claims, can be expected.
Expertise of the Engineer: Some consulting engineers are more used to designing steel construction projects than others, with resulting simplicity and economy in their designs that will reduce total costs.
Early Selection: Best practice is the early selection and appointment of the steelwork contractor. This is often left far too late for the good of the project. In order to fully obtain the experience and expertise of the steelwork contractor and the benefits of value engineering, the steelwork contractor should be engaged at the earliest possible opportunity. While delivery periods of 12-14 weeks or less are commonly achieved, it frequently leaves less time than is desirable for the consultants, the contractor and the steelwork specialist to jointly review the design and construction methods and agree the very best solutions to be used. Earlier involvement will also increase the levels of understanding and project knowledge of all concerned and reduce the likelihood of variations and/or delay.
Contract Conditions: Comparatively aggressive terms and conditions will result in higher prices from specialist contractors such as steelwork, which requires significant investment in materials and fabrication processes before any completed work arrives on site. Making interim payments for work and materials in the process of being fabricated, but not yet delivered or erected, will often lower the overall steelwork costs and improve contingency planning. Similarly, the system of deduction of cash retentions is inefficient and outdated and has no place in the modern construction industry.
Market Conditions: Current order levels and mix of work/fabrication shop loading characteristics will affect price levels. When negotiating with or inviting potential steelwork contractors for a particular project, ascertain how busy they are in terms of their total design, detailing, fabrication and erection capacity when the work is to be placed.
Complete “Frame Package”: Many steelwork contractors are able to undertake additional work packages, for example concrete work, fire protection, decking and cladding. Also the larger the project the greater the scope is for economies of scale, for example a special production line can be set up for repetitive components.
Site Organisation: Good site co-ordination will facilitate a smooth running project. “Closed” sites in central city locations, as well as remote sites, necessitate premiums due to transport and logistics. Ensure that there is adequate access for steel transportation, unloading and erection, both on the site as well as on surrounding or adjacent access roads. Ensure that there is sufficient well prepared level ground that is adequate to take the requisite wheel loads. Ensure that everyone is aware of the need to comply with the BCSA Safe Site Handover Certificate and maintain its provisions. Ensure that pre-site co-ordination is defined and that where the crane is to be supplied by others, it will always be available in accordance with the agreed erection schedule. Ensure that all foundation work will be completed within the agreed schedule and that all anchor bolts will be set in place within the specified tolerances, free from damage and contamination. All work to be connected to or dependent upon the steelwork needs to be properly identified as to whether the steelwork contractor is responsible for supplying and/or installing it, or it is the responsibility of others.
There are a number of general "technical" factors that apply to most projects. Some relate to the complexity of the particular project, whilst others are specific to the type of project, eg multi-storey, portals, trusses.
Specification: Conformance with the National Structural Steelwork Specification for Building Construction (NSSS) will reduce uncertainty; more demanding tolerances or testing than that specified in the NSSS will increase costs.
Bay Size: Structural steelwork prices are influenced by the size of each individual piece (ie number of pieces per tonne), which is largely dependent on bay size. Consider larger bay sizes, where the extra weight due to longer spans may be totally offset by the reduced price per tonne and the saving in number of columns and related workmanship. Also the resultant column–free space generally adds value to a project. Structural steel frames must have the required degree of lateral resistance to wind loads. This can be provided by a stiff core or by the frame itself - diagonal steel bracing is usually a less expensive solution than moment frames.
Complexity: Modern CNC fabrication equipment can cope with complex individualistic designs but, in general, the more complex the fabrication required the greater the cost. Fabrication is more economic with:
Wherever possible, leave the choice of the connection detail to the steelwork contractor as the type and design of connections directly influences the total frame cost. Rationalise the range and tonnages of section sizes used. Complex individualistic designs are going to cost more per tonne, even with modern CNC equipment. If you wish to keep costs down – keep it simple!
Materials: Avoid mixing steel grades where possible and rationalise the range of section sizes/tonnages used in order to minimise cost, lead times and shop handling. In general steel grade S275 will be adequate, unless the strength requirements of grade S355 are essential. Ensure that the most appropriate sections are specified for the particular application. “I” sections are usually most economical in conventional framing, while tubular sections are a possible alternative for columns as well as for long span trusses. While tubular sections are higher in first cost than “I” sections, their lower overall gross weight required to perform the same function can largely offset this, often with an “aesthetic bonus”. Asymmetric beams are often used as part of a reduced construction depth floor system. Plate is usually used to fabricate economic “I” sections for longer spans and in connections, stiffeners and base plates.
Architectural Influence: Ensure that unnecessary finishing is not specified and that any applied corrosion resistant coating is appropriate for the environmental conditions to be encountered. Grinding of welds is usually only required for exposed steel in close proximity to a building’s occupants.
Quality of Engineering and Documentation: Completeness and accuracy of information are vital for a steelwork contractor to be able to properly assess the work involved. Where the steelwork is pre-designed, ensure that all member sizes are shown and that the connection forces are shown or are available.
Lead Times: Steel construction "lead time" figures of, say, 10 to 12 weeks are often quoted in journals. The figures usually quoted are in fact "length of order book".The information that specifiers really need to know is the elapse time from placing an order to the time of start of delivery of steelwork to site and commencement of erection. Obviously this varies depending upon the size and complexity of the project, but for relatively straightforward projects the period from receipt of order with full information to start of delivery can be typically around 6 to 8 weeks.Similarly erection times can vary depending upon location and complexity of the project, but for, say, an 8-storey office building, are typically around 1,500 m² of floor area per week, using two cranes.
On-Site Erection: Transportation of the fabricated pieces to the site and the logistics programming of on-site activities can be major operations, particularly if the contract is a large and/or an overseas one that involves shipping. The most suitable type of craneage, eg tower and crawler, will need to be selected. The speed of erection involves the resourcing and contracting of erection teams. Use of the Safe Site Handover Certificate reduces the risk of accidents and delays due to poor and unsafe site conditions. Once the materials start arriving on site the erection teams work in close co-operation with the builders to ensure rapid completion of the contract. Erection is immediately started on prepared foundation with the structure being built-up with floor, wall and roof supports to form the finished frame ready for the next stage of construction. Technicians and engineers regularly check that the steel is plumb and level during erection and that the work is being carried out safely to the approved method statement. When the construction has been satisfactorily completed, the structure is handed over and completion contracts signed off. The following trades then finish their work.
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