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Steel designers manual pdf free download - Steel Designers' Manual
Free PDF Books. Instrumentation for Process Measurement and Control. Valve selection handbook. Basic electricity and electronics for control. In he moved to edf. He also has a Masters degree from the University of Sheffield. In , he joined the United Steel Companies at Swinden Laboratories in Rotherham to work on the corrosion of stainless steels. The laboratories later became part of British Steel where he was responsible for the Corrosion Laboratory and several research projects.
He became principal technologist for Corus. He is a member of several technical and international standards committees, has written technical publications, and has lectured widely on the corrosion and protection of steel in structures.
He has had a longstanding professional relationship with the Institute of Corrosion. In , he joined the newly formed SCI as Research Manager for steel in buildings, with particular reference to composite construction, fire engineering and cold-formed steel. He has been responsible for a wide range of projects with special innovatory structural engineering including Sydney Opera House, the Millennium Dome, Mannheim Gridshell Roof, and the concept and scheme for Phoenix Stadium Retractable Roof.
Since then he has over 40 years of experience in steel structures of all kinds over the commercial, industrial and nuclear sectors. He also has extensive experience in roller coasters and large observation wheels. Allan has authored a number of papers, won a number of prizes and been closely associated with the Institution of Structural Engineers throughout his career.
Dr Moore has over 20 years experience of research and specialist advisory work in the area of structural engineering and has published over 70 technical papers on a wide range of subjects. He has also made a significant contribution to a number of specialised design guides and best practice guides for the IJK and European steel industry.
Many of these publications are used daily by practising structural engineers and steelwork contractors. As principal author, he worked on the manuscript almost continuously for a period of two years. Mitchell, to review progress and resolve outstanding technical problems. A remarkable book emerged. Within approximately pages it was possible for the steel designer to find everything necessary to carry out the detailed design of most conventional steelwork.
Although not intended as an analytical treatise, the book contained the best summary of methods of analysis then available. The standard solutions, influence lines and formulae for frames could be used by the ingenious designer to disentangle the analysis of the most complex structure. Information on element design was intermingled with guidance on the design of both overall structures and connections.
It was a book to dip into rather than read from cover to cover. However well one thought one knew its contents, it was amazing how often a further reading would give some useful insight into current problems.
Readers forgave its idiosyncrasies, especially in the order of presentation. How could anyone justify slipping a detailed treatment of angle struts between a very general discussion of space frames and an overall presentation on engineering workshop design? However, provision of thermal mass will only ever be beneficial as part of an overall strategy, as the energy absorbed must then be purged during the cooler night time, using ventilation which is appropriate for example secure and controlled not by infiltration through a leaky envelope.
The amount of thermal mass will ideally reflect not only the external climate how many consecutive hot days are typical but also the building occupancy pattern. For example too much mass may not provide the responsiveness needed in a home that is unoccupied during the day and on cold days needs to heat up rapidly just before the occupants arrive home from work. For a dwelling that is unoccupied during the day, absorbing heat which is subsequently radiated back into the living space during 14 Integrated design f o r successful steel construction the night may also be less than desirable for temperatures in bedrooms.
Clearly some careful planning is needed. A further problem with the provision of thermal mass is exposing it. Completely divorced from the building construction, but very important when controlling internal temperatures, is the performance of appliances.
In time one would imagine that this will happen by default as other sorts of appliances will no longer be available. Normally the main concern is ensuring that noise from public areas does not impact on the comfort of those occupying residential spaces, but rules also exist for ensuring a minimum level of noise in public areas e. Sound insulation for both routes is controlled by the following three characteristics: mass isolation sealing. Direct transmission depends upon the properties of the separating wall or floor and can be estimated from laboratory measurements.
Flanking transmission is more difficult to predict because it is influenced by the details of the junctions between the building elements and the quality of construction on site. In certain circumstances flanking transmission can account for the passage of more sound than direct transmission.
It is therefore important that the junctions between separating elements are detailed and built correctly to minimise flanking sound transmission.
Figure 2. Transmission of airborne sound across a solid wall or a single skin partition will obey what is known as the mass law. However, lightweight framed construction achieves far better standards of airborne sound insulation than the mass law would suggest because of the presence of a cavity which provides a degree of isolation between the various layers of the construction. It has been demonstrated that the sound insulations of individual elements within a double skin partition tend to combine together in a simple cumulative linear relationship.
The overall performance of a double skin partition can therefore generally be determined by simply adding together the sound insulation ratings of its constituent elements. In this way, two comparatively lightweight partitions can be combined to give much better insulation than the mass law alone would suggest. This is the basis of many lightweight partition systems. The width of the cavity between separate layers is important, and should be at least 40mm.
It will of course be recognised that the need to isolate elements to avoid acoustic transmission may be in conflict with the need to tie elements together to achieve adequate structural performance. It is important to provide adequate sealing around floors and partitions because even a small gap can lead to a marked deterioration in acoustic performance. Joints between walls and between walls and ceilings should be sealed with tape or caulked with sealant. Where walls abut profiled metal decks, or similar elements, mineral wool packing and acoustic sealants may be required to fill any gaps.
Where there are movement joints at the edges of walls, special details are likely to be necessary. Ideally, wall linings should not be penetrated by services.
This is particularly important for separating walls between dwellings. Where service penetrations do occur in sensitive locations, particular attention should be given to the way in which these are detailed.
SCI has published guidance on the detailing of both hot-rolled and cold-formed steel structures, including indicative acoustic performance values. Their use avoids the need for site testing, as in order to become a Robust Detail a number of examples must be built and tested, and show a level of performance over and above the Building Regulation requirements in order to cover variations of workmanship on site.
This applies to buildings as much as it applies to anything else, indeed it is very important in terms of the built environment given the materials and energy that are used to build and then operate. It has already been noted that the right choice for the designer is not always obvious.
Designing a new residential building for the prescribed level of imposed loads for that application will mean that the building would not readily lend itself to future conversion for office use, where certain rooms would be subject to much higher loading.
Some of the other choices are less obvious. Design for deconstruction is frequently mentioned as a methodology for reducing the materials used in construction. It clearly makes sense to be able to dismantle a building when it has reached the end of its useful life, and reuse or recycle the components.
Steel framed buildings are well placed for this given their similarity to Meccano. To ease deconstruction it must be relatively easy to separate the building components. However, if we think about one of the most structurally efficient forms of construction currently used in buildings, with composite steel and concrete beams and floor slabs, the efficiency comes from the fact that the materials act together.
By tying together steel beams with concrete slabs, via shear studs welded to the beam and embedded in the concrete, the tensile strength of the steel and compressive strength of the concrete are used to best effect.
The profile shape and formed embossments of steel decking enable it to transfer shear with the concrete to which it is attached, so that it acts as external reinforcement. So by intimately tying together the steel and concrete it is possible to use less of the materials. Composite solutions are also an extremely effective way of forming long spans, which allow greater internal flexibility because there are fewer columns or load bearing walls.
So is it better to adopt a solution that can be easily dismantled, e. Client requirements f o r whole building performance, value and impact 17 2.
More costly items are the building services and cladding, either of which might typically cost three times as much as the frame. Other parts of this Manual explain how to design and detail cost-effective frames, but it makes no sense to save a proportion of the frame cost if it compromises the services or the cladding. The cost of cladding can be reduced by reducing the overall height of a building.
This can be achieved by making the effective depth of structural floor zones less. This could either mean the depth of the structural zone is literally less, or effectively less because it allows services to occupy the same zone. Steel solutions such as socalled slim floors address the first solution by making the steel beams occupy the same space as the concrete slab , whereas solutions such as cellular beams enable services to pass through the beam webs so avoiding them taking up more space below the structural zone.
Some slim floor solutions allow services to run within the depth of the slab, at least in one direction. So the choice of floor solution will affect the cost of the cladding, and the ease of installation and therefore cost of the services, as well as the cost of the structure.
Interface detailing, and its impact on building economy, is considered in more detail in Section 2. Reducing the envelope area of a building also reduces fabric heat loss. Another aspect of economy for the designer to consider is the cost of time spent on site. For some applications this is vitally important. Off-site volumetric solutions have also served the needs of the education sector very well, allowing student accommodation to be completed on site within the summer vacation.
Whilst both these examples are rather niche, steel solutions in general allow time to be saved on site. As well as yielding whole life savings, e.
Not surprisingly therefore, it is in these areas where measures, both voluntary and mandatory, have been introduced to effect change. It is important to distinguish between embodied and operational environmental impacts. Embodied impacts refer to the impacts associated with the winning, processing, transporting, and erecting of construction products and materials.
Operational impacts relate to the impacts arising from heating, lighting, cooling and maintaining the building. Regulatory requirements have, to date, focussed on the operational environmental impacts of buildings, mainly via Part L of the Building Regulations. Historically this has made good sense since the relative importance of building operational impacts has been much greater than the embodied impacts. Based on the Building Regulations for example, the ratio of embodied to operational impacts of a commercial building over a year design life is estimated to be of the order of This ratio is changing, however, and as building operational impacts are reduced through regulation, by a combination of building fabric and services improvements and the introduction of zero- and low-carbon technologies, the relative importance of the embodied impacts becomes greater.
It is therefore highly likely that in the future, the Building Regulations will address embodied as well as operational impacts of buildings. Unfortunately, quantification of embodied impacts is far more complex and controversial than operational impacts and this may hinder their inclusion within the Building Regulations for some time. For the case of operational impacts such as heating, cooling and lighting, carbon is a sensible proxy for environmental impact and is relatively easy to quantify.
Embodied impacts are often far more diverse and although carbon remains an important metric, there are many other impacts that should be considered. These include water extraction, mineral resource extraction, toxicity, waste, eutrophication and ozone creation.
This raises the important question about how these different impacts can be objectively compared. The most widely used and highly regarded tool for quantifying the environmental impacts of construction is life cycle assessment LCA. Despite being conceptually quite straightforward, LCA can be very complex with many important, often material-specific, assumptions than can significantly influence the outcome.
Although designers should be aware of the environmental impacts of the structural materials they specify, their choice should not be at the cost of the wider sustainability aspects of the building that the structure supports. This, and a broad range of sustainability issues, is addressed in more detail in Section 2. The purpose of this section is to consider sustainability in a more detailed and focused way, with specific references to regulations, guidance, tools and themes.
Before the engineer can begin to consider how to design a sustainable building he or she has to understand what a sustainable building actually is. This is arguably a greater challenge than any structural design problem they will encounter in their career!
Engineers, in general, work with algorithms and absolute values that yield black or white answers, albeit with factors of safety to provide a degree of conservatism that covers, for example, variations in material properties and necessary simplifications in design models.
Sustainable development is not like this; it is a concept, not an absolute that can be defined by algorithms. Work is underway to develop more robust metrics for sustainability but its complexity will preclude the establishment of an agreed set of metrics within the short to medium term.
The concept of sustainable development is simple but the detail is complex. Central to this definition is the consumption of non-renewal resources and the environmental impacts to air, ground and water arising from human activities. This definition raises an important point of relevance to sustainable construction; namely that it is not physically possible to construct a building, no matter how small, without depleting some resources and without generating some impact on the environment.
The challenge to the engineer is to fulfil their traditional role of providing robust, safe, fit for purpose and economic buildings, but with the minimum impact in terms of non-renewable resource use and environmental impact. The first and arguably most significant decision therefore is whether or not a proposed building is really needed.
It is noted that such decisions are generally not within the remit of the structural engineer. Now let us assume that the need for a building has been established, the challenge for the design team is to ensure that the building is fit for purpose, is affordable however defined and that these objectives are met in the most sustainable way possible. There is no single solution to this challenge and it is more likely that the client will set a specific target, or set of targets, that are reasonably measurable.
This has been unfortunate since it has distracted designers from delivering more sustainable buildings. Although the environmental impact of construction materials is clearly an important part of sustainability, the product of primary consideration is the building itself.
Be it a school, a hospital, an office building or a home, how successfully the building fulfils its intended function is paramount. Buildings that achieve this are likely to be cherished by users and hence last a long time; a key feature of a sustainable building. Therefore it is how different materials, usually in conjunction with one another, can enable the construction of sustainable buildings that is key.
Sustainable development is generally recognised as having three interdependent dimensions; that is economic, social and environmental. Although the challenge is to consider and balance these dimensions holistically, the focus or priority is to reduce the environmental impact while simultaneously addressing the economic and social dimensions.
In recognition of this, by far the majority of effort to date has focussed on understanding, quantifying and setting targets for the environmental impacts of construction and buildings. Planners are particularly concerned with social impacts of the built environment and achieve this by addressing spatial development issues associated with new construction and infrastructure. All national and local planning polices including Local Development Frameworks and Regional Spatial Strategies have sustainability at the core.
Architects generally address social issues at a more local scale including master planning and at the individual site or building level. The quality of buildings and the built environment is a key social sustainability consideration.
Good design and construction yields buildings that can enhance the quality of life of their users. Social attributes of a sustainable building include issues such as security, indoor air quality, thermal comfort, safety and access. The social considerations of sustainable construction are however much more than just the physical building itself. Other issues that should be considered include: the welfare of construction workers particularly their health and safety, skills and training local impacts of construction work including congestion, noise, and disruption the social impact of the construction materials supply chains corporate social responsibility CSR of contractors and material suppliers.
The social dimension of sustainable construction is probably the least well understood, particularly when it comes to its assessment and metrics. Work is underway Design for sustainability 21 within the European standardisation body CEN to develop a framework for the assessment of social performance of buildings but it is likely to be some time before robust assessment methodologies are available.
The contribution of these activities to the sustainability of the UK economy should not be underestimated. At the project level, economic considerations are generally dictated by the prevailing market conditions.
The construction industry has notoriously been fixated with initial capital cost rather than whole life cost and whole life value. This bias towards initial cost is frequently counter to holistic sustainable construction decision-making.
Building energy efficiency is a good example of where decisions based on whole life costing can yield both environmental and direct economic benefits particularly for building owner occupiers. For many other environmental impacts however there are economic costs for their mitigation.
Material, construction and energy costs are relatively easy to manage, albeit they are subject to significant fluctuations. There are other elements of sustainability for which an economic value could be attributed. An obvious example is carbon but others could include building quality, flexibility,adaptability and reusability of buildings and components.
Although such attributes are recognised qualitatively, their economic quantification is more difficult to define. A further complication of such assessments is that traditional whole life costing using treasury discount rates yields only marginal net present value benefit over typical building design lives. As for social impacts, work is underway at CEN to develop a framework for the assessment of the economic performance of buildings. It is beyond the scope of this chapter to address environmental sustainability in detail.
Instead, the fundamental aspects of sustainable building design will be summarised and some key areas where the structural steel designer can play a part will be highlighted. Assessment methods for measuring the environmental sustainability of buildings are also addressed. Originally launched in , the methodology has been adapted and updated to reflect the improved understanding of the subject. Although the core BREEAM methodology is consistent, different versions are available for different generic building types, including offices, industrial, schools, hospitals, etc.
Since , it is mandatory for new homes to have a Code rating although it is not required that buildings be assessed against the Code if not assessed they are given a zero rating. The number of credits available in each category does not necessarily reflect the relative importance of the issues being assessed. Credits achieved are then added together using a set of environmental weightings to produce a single overall score for the building.
Table 2. Below are listed the fundamentals of sustainable building design that are currently most commonly considered in UK construction projects. This is by no means a comprehensive list and no priority or importance should be inferred from the listings.
Where possible, redevelop a brownfield site. Consider opportunities to reuse any existing buildings on the site. Site the building to enhance the ecological value and biodiversity of the site. Incorporate the right amount of thermal mass within the building. Use glazing, rooflights, etc. Provide shading to prevent overheating and glare. Insulate the building well to reduce fabric heat losses.
Incorporate a suitable degree of air-tightness. The HVAC systems should be selected to match the building response and the pattern of occupancy. Use natural ventilation wherever possible. Design buildings and services that have the capacity to meet predicted future climate change scenarios. Provide good controls, sub-metering and operating instructions for the building users. Undertake seasonal commissioning of the building.
Provide appropriate and controllable ventilation to ensure good indoor air quality. Consider the whole life environmental impacts of construction materials using tools such as the Green Guide to Specification. Specify reused, recycled or recyclable materials and products. Minimise the use of primary aggregates. Consider whether Modern Methods or off-site construction offer advantages in terms of speed, waste, etc. Specify inert and low emissions finishes.
Where possible use prefabricated and standardised components to minimise waste and enable subsequent reuse. Use the Considerate Constructors scheme. Minimise local impacts from construction activities such as traffic congestion, noise and dust. Design for sustainability 25 Design robust buildings. Design buildings to minimise ongoing maintenance requirements. Consider site and building security, for example using the Secured by Design14 Principles.
Design buildings using components and materials that can be easily reclaimed, segregated and either reused again or recycled - this should include the substructure and particularly any piled foundations. It is important that the sustainability requirements of the project are clearly set out and agreed with the client early in the design process and that all parties are fully aware of the impacts of their design choices and decisions.
However there are many aspects of the structural design that have a bearing on the sustainability of the building. Issues that need to be considered and balanced by the structural engineer include the following. It is important that the structural efficiency of different materials is considered and that whole building assessments are undertaken. For example a lighter superstructure may require smaller foundations. In terms of environmental impact, it is important that recycling and the recyclability of structural materials are properly taken into account in any assessments undertaken.
Issues for the structural engineer to consider include: 26 Integrated design f o r successful steel construction changing weather patterns including increased wind loading and storm events ground movements resulting from extended wet and dry periods, impacting on the building substructure prolonged hot periods causing overheating designing new buildings such that low- and zero-carbon technologies can be easily retrofitted, if necessary, in the future.
The structural engineer has a role to consider how the structural form of the building can be optimised so that the performance of such technologies, e. There are also loading and vibration issues that the structural engineer should consider, for example green roofs and roof-mounted wind turbines.
Faqade retention, internal reconfiguration of floors and walls, and horizontal and vertical extensions all require specialist structural design expertise. For example by providing a degree of redundancy in the structure or providing long clear spans that allow internal walls to be reconfigured.
Both of these examples may require heavier potentially over-designed structures and therefore the engineer has to weigh up the relative benefits. Building services are likely to have a much shorter life than the structure and therefore providing a structure that is flexible to alternative servicing strategies is a further important consideration for the structural engineer.
Examples include the provision of holes through floor slabs and the use of cellular steel beams which provide flexible servicing options through the web openings. This integration of services within the structural zone can reduce floor-to-floor heights with knock-on benefits in terms of faqade costs and reduced heat loss through the envelope.
Design for overall economy 27 2. This is far too complex a subject to deal with here. However, key issues include: Natural ventilation - the structural form can contribute to the effectiveness of cross or stack natural ventilation where this is appropriate. Thermal mass - key issues relating to the provision of optimum levels of thermal mass in naturally ventilated buildings relate to its position and degree of exposure.
Where floor soffits are exposed their appearance is often a key consideration. Thermal bridging - attention should be paid to fabric heat losses caused by thermal bridging. Particular issues include thermal bridging at structural interfaces, e.
Solar shading - provision of appropriate external solar shading such as brise soleil to limit unwanted solar gains. Where possible buildings should be designed so that they can easily be deconstructed to facilitate reuse of the building or its components or, as a last resort, so that the building materials can be easily segregated for recycling. In the case of steel structures, sections should be standardised where possible, clearly labelled, in terms of their material properties, and straightforward bolted connections used in preference to welds.
Greatest overall economy will be achieved if the interfaces are given due consideration, and this can only happen if the designer recognises and understands two fundamental ideas: Geometric deviations occur on site.
The most efficient use of space for example the depth of the floors is often achieved by combining functions. This is illustrated with some of the examples given below. More detail on many of the issues covered in this section may be found in the SCI publication Design for Construction. A potential downside with long span solutions is however their depth; typical composite beams will have a span-to-depth ratio of around 18 to Increased depth may mean a greater area and therefore cost of cladding, or fewer floors if the total height of the building is limited.
A range of steel and composite solutions is available. One of the most common modern products is cellular beams, see Figure 2. The cutting and rejoining process includes forming holes in the web, which are normally circular but can be elongated. This asymmetry is useful when, as is often the case, the beams are composite and so exploit the presence of a concrete upper flange. A similar end product can be achieved using welded sections with holes simply cut into the web plate.
Other solutions adopted during the past twenty years or more include things like tapered beams, where the beam depth varies as a function of the structural need at a particular point in the span, so that services can pass under the shallower sections. A downside of the more complex solutions such as trusses is that the cost of fire protection may increase.
The depth of the beams may also be reduced by making them continuous, or perhaps semi-continuous, by adopting moment-resisting end connections. Deflections, which often govern long span beams, can be greatly reduced with relatively little end continuity. Downsides to this approach are that column sizes will probably increase due to moment transfer from the beams, frame design may be more complicated, and connection details may be more complicated.
Design for overall economy 29 Figure 2. The steel beams are integrated within the depth of the concrete slab, rather than sitting underneath it. The slab may be formed from precast concrete planks, or may adopt profiled steel decking and in-situ concrete to form a composite slab.
Unpropped spans of around 6 m can be achieved. The shape of the decking means that very useful voids are formed within the slab, which are big enough to allow services to pass within the slab depth and through holes in the beam webs, see Figure 2. This solution therefore saves on floor depth firstly by integrating steel beams and concrete within the same zone and secondly by locating some of the services in this zone.
One of the great things about design is that various issues must be weighed up in order to identify the best solution for a given situation. The same is true when considering how best to combine the structural floor and services. Whilst long span solutions with services passing through the beams are attractive, for a building that is highly serviced and where the services are likely to be replaced frequently it may be better to simply hang them underneath the structural floor for ease of fitting and removal.
As discussed above, there has been much debate in recent times, some of it rather misguided, about the need to provide thermal mass in order to limit internal temperatures during hot periods.
When choosing the optimum building solution the designer must consider potentially conflicting requirements for aesthetics exposing the thermal mass of the floor slabs may mean exposing the soffits , structural performance and internal temperature control. More exotic solutions such as watercooled slabs may also be considered.
One of the biggest issues for designers to consider is that the tolerances within which the steel frame can be fabricated and erected will normally be considerably perhaps ten times greater than those associ- Design for overall economy 31 Figure 2. These are not artificial limitations; it is not possible to control the position of steel frame members to within say Smm because within the span of an element there is no provision to adjust things on site the ends of a beam can be adjusted to bring them within tolerance but the mid-span position relative to the ends is a function of the fabrication deviations and load present , and indeed the steel frame members will move as weight is added e.
The National Structural Steelwork Specification recognises these limitations. On the other hand larger deviations in the position of cladding panels may affect the integrity of seals between panels, the aesthetics of a plane of cladding etc. To avoid increased cost, delays and general frustration on site the designer should adopt details such as adjustable brackets that will allow deviations to be accommodated and maintain the various building components within tolerance. The designer should also give due consideration to how a building will deform under load.
Some types of cladding are brittle - glazing being the most obvious example. Problems will arise if brittle cladding is fixed to flexible parts of the supporting structure via rigid connections. When heavyweight cladding such as brickwork is used, consideration should also be given to how this will affect the frame. Significant load applied eccentrically to the central part of a beam will cause torsional moments.
Another key consideration when designing and detailing the structure-to-cladding interface is the minimisation of cold bridging. This occurs when metal or other conductive material penetrates an insulation layer. There is potential conflict between the need to positively fix the external skin and the desire to avoid any thermal bridging from the skin back to the insides of the building. Common examples of this are at the foundations see below and when balconies are present.
A number of specific materials and products have been developed for balcony connections that combine the necessary qualities of structural resistance and resistance to the transmission of heat.
As shown in Figure 2. This is normally done using shims to allow for differing distances between the positions required for the undersides of the column baseplates and the upper surface of the concrete slab or footings. Deviations in the line of the foundations are best allowed for by using holding-down bolts in sleeves which are filled with grout only once the columns have been finally positioned.
Alternatives such as cast-in column bases or post-drilled bolts may also be considered. When detailing column base connections the designer should also give consideration both to buildability, including minimising risks during erection, and cost. In terms of buildability four-bolt connections should always be used so that the column can be landed on shims to ensure the right level and then held by the four bolts as its position line and verticality is adjusted.
Whilst two bolts might suffice for the final condition they would not be advisable during the temporary state. Base connections should be kept simple to keep costs down - whilst moment-resisting bases may appear to save money on the steelwork by allowing member sizes to be reduced simply at the expense of thicker baseplates, this misses the fact that the concrete base may need considerably more reinforcement, and in addition to the material costs this will inevitably make erection more difficult.
It should also be recognised during the design process that a particular construction sequence may be dictated by site access, so the designer may not be free to choose which columns can be erected first to form the basic permanently braced unit to which other steelwork is subsequently attached.
A different kind of issue also affects the foundations interface, namely that of thermal bridging. Clearly column bases must be placed on something that is stiff Conclusions 33 I Figure 2. However, it may also be necessary to isolate the column bases from the cold external environment, so that the columns do not represent significant thermal bridges penetrating the insulation layer at the base of the building.
They would also like the building to meet future performance requirements, which may include a desire for it to be adaptable to suit different needs. They will want these things to be achieved with the greatest economy and lowest environmental impact. In order to achieve the most cost-effective solution it is important that the structural engineer puts the frame in the context of the whole building.
Cladding and services are considerably more costly items than the frame itself, and the frame should be designed recognising this, for example by facilitating services routing. Getting the interfaces right is key to achieving an economic solution.
In the past the operational impact of a building swamped other considerations, but as building efficiencies improve driven primarily by regulations embodied considerations are becoming much more important. Some compromises will clearly need to be made. Designing the floors to carry relatively high levels of loading will offer the greatest flexibility in terms of future use.
However, such an option will also maximise initial material use, and cost. Designing a structure that can be dismantled will facilitate reuse or recycling, but combining materials in composite solutions will often reduce material use because of the structural efficiencies implicit in such forms of construction. Despite the fact that the steel frame is a relatively small part of the overall building cost, and structural engineering is only one of a broad range of design skills that are needed, this chapter identifies a number of areas where decisions made by the structural engineer are key to developing a good, integrated solution.
References to Chapter 2 1. Building Regulations - see www. London, BSI. Department for Education and Skills Building Bulletin 9. London, The Stationery Office. Department of Health. Health Technical Memorandum Ascot, SCI. Code for Sustainable Homes, www. Oxford, Oxford IJniversity Press. Watford, BRE. Institution of Civil Engineers Demolition Protocol. London, ICE. Design Quality Indicators, www. Considerate Constructors scheme, www. Secured by Design, www.
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