Logo

The need for guidance on detailing

Steelwork offers the opportunity for architectural expression, as well as being a structurally versatile and adaptable material. Good quality detailing is vital because it affects structural performance, cost, build ability and, perhaps most importantly, appearance.

Whilst the choice of the structural form is often the province of the structural engineer, architects should have a broad appreciation of the factors leading to the selection of the structure and its details. Traditionally, most detailing of connections is the responsibility of
the steelwork fabricator but, for exposed steelwork, detailing is of much more interest to the architect, as it impacts on the aesthetics of the structure.

In this respect it is important that designers appreciate the common fabrication and erection techniques which may exert a strong influence on the method and approach to the detailing of modern steelwork in buildings.

Connections to other materials

The attachments of other elements, such as cladding and stairs to the steel structure, are described in another series of publications. These ‘interfaces’ are crucial to the efficiency and build ability of steel framed buildings. Reference is made to good practice details in the Steel Construction Institute’s (SCI’s) publications on curtain walling,1
connections to concrete,2 and lift-shaft details.3

 

1.  Advantages of steel construction

The distinct advantages of the use of steel in modern building construction may be summarised as follows :

• The modular nature of its fabrication (a ‘kit of parts’), which can be delivered ‘just in time’ to site when required.
• The potential for rapid erection of the framework on site, which also reduces local disruption, noise and site storage.
• It is prefabricated to a high degree of accuracy.
• Long spans can be achieved economically by a variety of structural systems in steel and composite construction, permitting greater usable space.
• Steel or composite frames are lighter than concrete frames of the same span, thus reducing foundation costs.
• Steelwork permits adaptation in the future, and components can be re-used by unbolting.
• Composite steel-concrete floors can contribute to a thermally efficient building.
• A high proportion of steel production is recycled from scrap, and all steel is recyclable.

 

2. Opportunity for architectural expression

Steelwork possesses various advantages for architectural expression, as follows :

• External structures clearly express their function.
• Slender members can be designed efficiently, particularly using tubular sections.
• ‘Lightness’ can be accentuated by openings in beams and by latticework in the form of trusses.
• Curved members, such as arches, can be formed easily.
• Tension structures are efficient and lightweight, particularly for long-span enclosures.
• Connections can be designed expressively.
• The fire resistance of exposed steelwork can be enhanced by the use of intumescent coatings, or by concrete or water filling (of tubular sections).
• Colours and finishes of painted steelwork can be used to great effect.

 

In architecture, the decision to express or conceal the structural frame, either externally or internally, is usually decided by aesthetic preference coupled with technical and functional issues. The desire to express the structure of the building is an association extending from the use of iron and early steel in the last century.

 

Having decided to express the structure, the architect then considers a number of design factors against which he may test his proposals. Such considerations may include architecture and functional, planning or organisational requirements, as follows.

 

Architectural requirements (Colour Plates 8, 13, 15, 16, 22 and 24) :

 

• The required overall visual effect of solidity or transparency; multiplicity of elements or minimalism; individuality or repetition of elements.
• Use of bespoke or standardised components.
• The nature of the architectural language; i.e. elegance and slenderness; strength and robustness.
• The relationship in visual and functional terms between the inside and outside spaces.

 

 

Functional requirements (Colour Plates 3, 4, 5, 9 and 27) :

• Building form and function.
• Dimensional parameters, i.e. height of building, scale, use of column-free space.
• Stability requirements (particularly for tall buildings).
• Initial cost and life-cycle cost.
• Climate; both internally and externally.
• Services provision and maintenance, and opportunities for
services integration.
• Interface details, particularly of the cladding to the frame.
• Durability, including maintenance implications and time to first maintenance.
• Fire-safety considerations.
• Health and safety requirements are now extended to Construction (Design and Maintenance) Regulations 1994 (CDM Regulations) requirements.4
• Protection from impact damage and vandalism.

 

Planning or organisational requirements (Colour Plates 2, 10, 11 and 23) :

• Local planning and statutory requirements, including building height, and impact of the building on the locality.
• Programme / timescale requirements, not only of the construction project, but also of the resources/demands placed on consultants.
• Agreement on the responsibilities of the architect, structural engineer and constructor.
• Client input and acceptability of the design concept.
• Availability of suitable resources for construction, and opportunities for prefabrication (e.g. on a remote site).

 

Excellent examples from the 1980s showed what could be achieved in the expressive use of steel. In the Sainsbury Centre, a simple portal-frame structure was proposed initially, but rejected in favour of the deeper and more highly articulated structural frame that
was finally adopted (see Figure 1.1).

 

The highly perforated structural members of the Renault Parts Distribution Centre (Figure 1.2) are an ‘architectural’ expression of engineering and technological efficiency, yet they do not necessarily represent the most efficient structural solution. These are conceptual

issues in which both the structural engineer and the architect should share a close interest, and which must be resolved jointly at the early stages of design. However, many examples of exposed steel follow a much more straightforward approach (see Colour Plate 26).

 

1.1 Portal-frame structure used in the Sainsbury Centre, Norwich (architect: Foster and Partners)

3. Holistic approach

To achieve economic and practical architectural details, there has to be a basic appreciation of the performance of the overall structure itself and the loading conditions imposed on the member or component in question. The form of the structure will strongly
influence the details employed.

 

For the architect, details often evolve through the logical stages of conceptual design, followed by further rationalisation into the detailed design, i.e. from the macro to the micro. The architect may approach the concept design with the key component details already in mind. However, the final solution will be influenced by structural issues, an understanding of the fabrication and construction process, and other functional constraints (see Colour Plate 14).

As one of the first examples of external support using masts and cables, the steelwork for the Renault Parts Distribution Centre (see Figure 1.2) was subject to considerable refinement at the design stage by computer analysis, and the components were finally rigorously tested to assess their load capacity. The ‘mast and arm’ details reached a high level of sophistication, creating a strong aesthetic and functional appeal for what could have been a bland enclosure.

 

1.2 The Renault Parts Distribution Centre, Swindon, showing mast and tension structure (architect: Foster and Partners)

 

 

4. Scale and ornament

4.1 Scale

Buildings should be designed well at a range of scales. An understanding and an appreciation of all the scales will help in the art of assembly and detailing. Therefore, an elegant and well proportioned building will have been successfully considered at the large scale as well as in its details. Good details alone do not necessarily lead to architectural success. This achievement relies on the consideration of all elements of the composition of varying scale(see Colour Plates 14 and 20).

 

For example, the canopy of the pavilion building contrasts and compliments the monumental scale of the Millennium Dome, as illustrated in Figure 1.3.

 

Examples of the order of scale are as follows :

 

1. Volumetric scale: The big picture for the whole project and its locality.
2. Structural scale: The structural system, e.g. a 40 m span roof structure.
3. Module scale: A column grid, say, of 9 m.
4. Elemental scale: Repetitive elements, such as beams.
5. Assembly scale: The form of the connections.
6. Detail scale: The detail of the base of a column, or part of a truss.
7. Textural scale: Surface appearance.
8. Point scale: For example, the head of an individual bolt on a plate.

All of these elements of scale represent opportunities for architectural expression.

 

1.3 Pavilion at the Millennium Dome, Greenwich, UK (architect: Richard Rogers Partnership)

 

 

4.2 Ornament

In architectural composition, ornament has traditionally been sought in those places where portions of the building change significantly from one part to another, whether it be from wall to roof, wall to ceiling, one structural element to another, i.e. beam to column, or column to ground, and so on (see Colour Plates 9 and 27).

 

Much of the ornament and articulation of parts established in twentieth-century architecture has been found in the attention to the junctions between prefabricated components, whether they be parts of the structure or of the cladding systems. Consequently, in steel framed buildings where the structure is exposed, ornament is usually sought in the connections between structural members and between the elements which comprise them (see Colour Plate 19). The careful shaping of the connection plates, stiffening elements, bolting and welding patterns, hubs for diagonal bracing and tie-rod assemblies, have taken on an important role, which is not only structural but also gives expression to the functionality of construction.

Examples where attention to detail can be used to provide ornamentation to an otherwise plain structure are :

• articulated attachment of horizontal and vertical members (Figure 1.2 and Colour Plates 12, 25 and 26)
• supports to arched members (i.e. at foundations) (Figures 1.3 and 1.4)
• suspension and bracing members, including tie rods (Figure 1.5 and Colour Plate 11)
• tie members that counterbalance a long-span portal frame (Figure 1.6)
• connections within trusses (Figure 1.7 and Colour Plate 20)
• fabricated beams or stiffened members (Figure 1.8 and Colour Plate 19)

 

1.4 Thames Valley University, pinjointed connections supporting curve darched steel members (architect: Richard Rogers Partnership)

 

1.5  Dynamic Earth Centre, Edinburgh (architect : Michael Hopkins & Partners)

 

 

           

1.6 St Paul’s Girls School (architect: Faulkner Browns)

 

 

1.7 Inland Revenue Headquarters, Nottingham, showing truss details which provide interest and articulation (architect : Michael Hopkins and Partners)

 

 

1.8 Operations Centre at Waterloo, London, showing a fabricated cantilever beam supporting a walkway (architect : Nicholas Grimshaw & Partners)

 

1.9 Orange Operational Facility, Darlington (architect : Nicholas Grimshaw & Partners)

 

 

 

1.10 Support to fabric roof at the Imagination Building, London (architect : Ron Herron and Partners)

 

 

• mullions with multiple perforations (Figure 1.9)

• support to a fabric roof (Figure 1.10 and Colour Plate 19).

 

 

Relationships can be established between the individual parts and the overall building form, which have a basis in elementary structuralaction.

 

 

5. Steel ‘kit of parts’

A wide range of steel components is available to the architect and designer from:
• hot-rolled sections, such as I, H and L shapes
• tubular sections of circular, square and rectangular shape
• fabricated sections made by welding
• light steel components made from strip steel
• stainless steel components
• modular units made from light steel components.

This book concentrates on the application of hot-rolled and tubular-steel structures, but the principles are applicable to a ‘kit of parts’ of steel components. Indeed, in many buildings, I-sections are used for beams, H-sections for columns, tubular sections for bracing, fabricated sections for primary beams or transfer beams supporting columns, light steel for infill walls, and modular elements for plant rooms and toilets. Site connections are usually made by bolting, although welded connections may be preferred for factory-made connections.

 

More information on the technical characteristics of steel is presented in Chapter 11.

 

 

5.1 Hot-rolled steel sections

A wide range of standard steel sections is produced by hot rolling, from which designers can select the profile, size and weight appropriate to the particular application. Table 1.1 illustrates the range of ‘open’ sections used in the UK, which are universal beam (UB), universal column (UC), parallel flange channel (PFC) and angle sections.

 

In continental Europe, IPE and HE sections are generally used rather than UB and UC sections. In the USA, W and WF sections are used (which are similar to UB and UC sections).

Modern steel sections have parallel flanges. Also, parallel flange channels largely replace channels with tapered flanges. The ‘serial size’ refers to the designated section depth and width in which there are a range of weights of section. However, it should be noted that the UB or UC section designation, such as 406 × 140 × 39 kg/m refers to the approximate depth, width and weight, and exact dimensions should be obtained from standard tables.

 

 

Table 1.1 Standard hot-rolled sections (UB, UC, and L)

 

Universal beam (UB)	Universal Beams
	Nominal dimensions (mm)
	D           B 203      102 and 133 254      102 and 146 305      102 and 165 356      127 and 171 406      140 and 178 457      152 and 191 533      210 610      229 and 305
Universal beam (UC)	Universal Columns D          B 152     152 203      203 254      254 305      305 356      368 and 406
Channel (PFC)	Parallel Flange Channel D          B 100      50 125      65 150      75 and 90 180      75 and 90 200      75 and 90 230      75 and 90 260      75 and 90 300      90 and 100 380      100 430      100
Equal angle	Rolled Steel Angles External dimension of equal angle: 25, 30, 40, 45, 50 60, 70, 80, 90, 100 120, 150, 200, 250
Unequal angle	Rolled Steel Angles External dimension of unequal angle Various sizes from : 40 × 25 to 200 × 150 Including common sizes of : 75 × 50, 100 × 75, 150 × 75, 200 × 100

 

 

Table 1.2 Typical proportion of cost and man-hours per tonne in steel fabrication in buildings

 

Item	Man-hours per tonne	Total % of cost
Materials production Fabrication Erection Protective treatment	3–4 8–12 2–4 1–2	30 45 15 10
Total	14–22	100

 

 

The serial size of UBs and UCs varies in increments of approximately 50 mm depth for the shallower sections, and 75 mm for the deeper sections. Within each serial size, the designer maychoose from a number of different sections of similar height. The standardisation of steel sections has also led to the adoption of standard connections, which have become familiar within the industry.5,6

 

Table 1.2 shows the breakdown of costs in a typical framework of a building. It is apparent that only 30% of the cost associated with a steel frame relates to the material itself. Costs can increase significantly if fabrication and detailing create a demand for increased labour time. For example, using a heavier steel section is generally cheaper than using a lighter section that has to be stiffened at its connections.

 

 

1.6 Tubular steelwork

 

The use of tubular steelwork creates a wide range of architectural opportunities in internal or external applications. The word ‘tubular’ has come to mean applications using all forms of structural hollow sections, rather than just circular sections. Tubular sections are available as circular hollow sections (CHS), and square or rectangular hollow sections (SHS and RHS, respectively). Oval tubes are also available. SHS can also be used as the generic title ‘structural hollow sections’. More detail on the methods of manufacture is presented in Section 11.3.

 

Table 1.3 defines the common section sizes. All tubular sections have exact external dimensions for detailing purposes.

 

The factors that influence the use of tubular construction are their :

•    aesthetic appeal, which is often due to their apparent lightness of the members

•    reduced weight of steel due to their structural efficiency,depending on their application

•   torsional resistance (hollow sections are particularly good at resisting torsional effects due to eccentric loading)

•   compression resistance for use as columns or bracing members(tubular sections are very efficient in compression due to their reduced slenderness in buckling conditions)

 

 

Table 1.3 Structural hollow sections (note, external dimensions are constant for a given serial size in all hollow sections)

 

	Square Hollow Section (SHS)External dimension of square section (mm) : 40, 50, 60, 70, 80, 90 100, 120, 140, 150, 160 200, 250, 300, 350, 400
	Rectangular Hollow Section (RHS)External dimension of rectangular section : Depth (mm) × width (mm). Various sizes from : 50 × 25 to 500 × 300 Including common sizes of : 100 × 50, 150 × 100, 200 × 100, 250 × 100250 × 150, 300 × 200, 400 × 200, 450 × 250
	Circular Hollow Section (CHS) Size of CHSs Various sizes from : 21.3 mm diameter to 508 mm diameter Including common sizes of : 114.3, 168.3, 193.7, 219.1, 244.5, 273, 323.9, 355.6, 406.4, 457

 

 

• bending resistance of slender sections (if a beam is unrestrained throughout its length, the tubular section can be more efficient than a conventional I-section)

• efficiency under combined bending and torsion, such as instructures curved on plan

• fire and corrosion protection costs (which are reduced because of the low surface area of the tubular section)

• ease of site assembly, as also influenced by requirements forwelding

• availability in higher grade S355 steel.

 

Fabricators cost all the steel-related items accurately, but the cost of fire and corrosion protection would normally be estimated separately. Some fabricators are specialists in tubular construction and can advise on costs and details at the planning stage. Additional aspects, such as the grinding of welds and special connection details,should be identified at this stage.

 

When using larger CHS, for example in long-span trusses, it is important to identify fabricators with specialist profiling equipment who can make the connections between the chords and web-members efficiently. This is particularly important for more complex assemblies, such as triangular lattice girders, which require a greater amount of fabrication effort and skill (see Section 6.8). The alternative may be to use SHS, which only require cutting the ends of the chord members at the correct angle, rather than profiling the cut ends.

 

The Waterloo International Terminal by Nicholas Grimshaw and Partners gains most of its visual impact by its striking light weight roof. The roof consists of a series of tubular trusses supporting stainless steel cladding and glazing. Every truss is different, but considerable economy and simplification was achieved by repetition of the same external dimensions of the tubular sections(see Figure 1.11).

 

The excellent torsional resistance and stiffness of tubular sections(often ten times greater than that of I-sections of equivalent area),makes them suitable for curved bridges and canopies where members curve on plan and possibly also on elevation (see Colour Plate 14). Architects such as Santiago Calatrava have utilised this property by creating tubular spine-beams and inclined arches that resist eccentric loading in bending and torsion. An excellent example of the use of tubular-inclined arches is in the Millennium Bridge,Gates head (Colour Plate 16).

 

Transportation buildings have also exploited the qualities of tubular construction. Examples include Stansted and Stuttgart Airports (see Figure 1.12 and Colour Plate 9, and also see Colour Plate 7). One ofthe largest buildings in the world employing tubular steel is the International Airport at Kansai, Japan, designed by Renzo Piano (seeFigure 1.13).

 

Tubular structures are not only reserved for large projects. The lightness of tubular members is emphasised at the ‘Gateway’ in Peckham, London (see Colour Plate 10). Similarly, the inclined tubular members created a curved appearance in Hodder Associates’ enclosed pedestrian footbridge in Manchester (see Colour Plate 17).

 

1.11 Waterloo International Terminal,striking long-span roof comprised of tapering tubular trusses (architect: Nicholas Grimshaw & Partners)

 

1.12  Stuttgart Airport Roof using tubular column ‘trees’—see also Colour Plate 9 (architect: Von Gerkan Marg &Partners)

 

1.13  Tubular trusses at Kansai Airport, Japan (architect: Renzo Piano Workshop)

 

 

6. Fabricated sections

 

Fabricated steel sections are produced by welding steel plates in a factory process. These sections are fabricated to the required geometry and are not standard sections. They are usually economic where :

 

• the section size can be ‘tailor-made’ to the particular application and member depth

• long-span primary beams would not be achievable using hot-rolled sections

• heavy ‘transfer’ or podium structures are required to support columns or other heavy loads

• asymmetric sections are more efficient than standard sections

• tapered sections are specified, e.g. in grandstand canopies

• curved members are created by cutting the web and bending the flange into a curve of the required radius.

 

The use of fabricated sections in a floor grillage is presented in Section 4.2. The primary practical consideration is the availability of standard plate sizes and the relative thicknesses of the plates used in the flanges and web of the section. Examples of the use of fabricated members are also illustrated in Section 2.4.

 

 

6.2 Cold-formed sections

 

A variety of cold-formed sections (CFSs) are produced and these sections are widely used as secondary members, such as purlins, or in light steel framing for primary structural applications. Typical C sections are illustrated in Table 1.4. CFSs are produced by cold rolling from galvanized strip steel in thicknesses of 1.2 to 3.2 mm for structural applications. Various SCI publications, including an Architect’s Guide,6describe the use of cold-formed steel sections and light steel framing in building.

 

 

Table 1.4 Cold-formed sections (produced by various manufacturers)

 

Standard C and Z sections	Depth of C or Z sections (typical) (mm) : 75, 100, 125, 140, 170 200, 240, 300
Modified C and Z sections	Steel thickness (typical) (mm) : 1.2, 1.6, 1.8, 2.0, 2.4, 3.2

 

 

 

 

Cold-formed steel sections can be used as :

• infill or separating walls in steel framed buildings

• floor joists and secondary members in frames

• light steel framing, erected as storey high wall-panels, in housing and residential buildings

• purlins in roofs and in over-roofing in building renovation

• modular units in cellular building forms, such as hotels and student residences

• cladding support members and over-cladding in building renovation.

 

Steel decking is produced in steel thicknesses from 0.9 to 1.25 mm,and is available in two generic forms :

• deck profiles of 45 to 80 mm depth for use in composite construction

• deep deck profiles of 210 or 225 mm depth for use in Slim dek construction.

 

These applications in composite construction are covered in more detail in Section 4.1.

 

 

6.3 Modular construction

 

Modular construction uses prefabricated ‘volumetric’ components which are generally made from light steel-frames, although they often incorporate SHS columns for the corner ‘posts’. It is most economic where the modules can be manufactured repetitively to achieve ‘economy of scale’, and where the dimensions of the modules are suitable for transportation and installation (3.0 to 4.2 mare typical module widths).

 

The Peabody Trust’s Murray Grove project in London achieved architectural acclaim by being the first major use of modular construction in the social-housing sector (see Figure 1.4). The modular nature of the building was softened by using prefabricated balconies, access walkways, and a ‘core’ lift and stairs structure at the axis of the two wings of the building.

 

More guidance on the use of modular construction can be found in recent SCI publications.7,8. Modular units can be used in more regular framed structures in the form of prefabricated plant rooms,‘clean rooms’, bathrooms and toilets, which are often lifted or slid into place on the floor.

 

1.14 Modular construction of social housing in London for the Peabody Trust
(architect: Cartwright Pickard Architects)

The Office of Architecture in Barcelona (OAB) blends youth and experience. Born  of the Carlos Ferrater Partnership’s 40-year legacy, OAB is described  by founder Carlos Ferrater as both  ‘a certified “laboratory of ideas” and  a professional company of the highest standard’. Since its inception in 2006 the firm, co-founded with Xavier Martí, Lucía Ferrater and Borja Ferrater, has expanded with great success. Its latest building, the Azahar Group’s headquarters, is designed to give identity to a group  of companies committed to promoting sustainable practice in  the fields of landscape design, recycling and waste treatment, environmental consultancy and construction. Situated on a 5.6ha. coastal site between Castellón de la Plana and Benicàssim in Spain, its striking white form (finished with  a self-cleaning, flexible stucco)  was devised to reflect the dramatic topography of its mountainous surroundings. These forms also combine to create a new topography in which the individual companies find their own unique place.

 

Looking south and east towards the coast, the Azahar Group headquarters has a striking white topography    

 

 

Orientated on an east-west axis, the plan is formed by two near-linear wings that buckle to create three distinct interstitial territories, which are resonant with, but purposefully isolated from, the landscape beyond. In contrast to the building’s blank exterior, its inner faces are fully glazed and open to the new internalised landscape, revealing interiors that faithfully trace the roof’s cranked cross-section. Approached from the west, visitors cross a patio – a ‘parade ground’ that functions as an external reception area. To the east, a more enclosed, concave area provides external space with a greater sense of privacy  and intimacy. In between is a large internal foyer; a central patio that unifies the two wings of cellular accommodation with a soaring toplit roof at the heart of the plan. Open  to the north, this space is filled with light borrowed by adjacent rooms.The building’s form is more than a picturesque response to its setting; it serves to create a sheltered and controlled environment. Even the roof makes a contribution, collecting all run-off water in a reservoir to irrigate the adjacent landscape.

 

 

Unlike the patios, the building’s exterior is characterised by blank white walls

 

 

Patios are dominated by full-height glass walls, seen here in the eastern private    garden   

 

 

 

The internal patio forms the heart of the building, with north -  facing rooflights

 

 

1.    office    suites

2.   entrance    patio

3.   central    patio

4.   private    patio

 

Visions... have always been  my pastures... there is no wisdom comparable to that  of exchanging what is called  the realities of life for dreams.  Old castles, old pictures,  old histories, the babble of old people make one live back  into centuries that cannot disappoint one.’ So said Horace Walpole (1717-97), youngest  son of Great Britain’s first prime minister, Robert Walpole.

 

Walpole realised his dream after acquiring a summer villa  in Twickenham, south-west London, in 1747. He altered  and extended it to create  ‘the castle... of my ancestors’, and later renamed it Strawberry Hill. Strawberry Hill changed the course of architectural history.  It was one of the earliest and most influential examples of Gothic Revival architecture, based on antiquarian printed design sources (the arched bookcases in the library were inspired by a choir screen seen in an engraving of London’s Old St Paul’s Cathedral). It was the first purpose-built, antiquarian ‘museum’ interior; a sequence  of theatrical spaces that played with scale, atmosphere and colour as a background to Walpole’s collection of objects, all ‘singular’, ‘unique’, or ‘rare’.

 

To coincide with Inskip + Jenkins Architects’ £8 million renovation of Strawberry Hill, due to reopen later this year,  a lively and colourful exhibition at the V&A brings together part of Walpole’s collection of pictures, silver, ceramics, glass, miniatures, enamels and  curious objects of virtu. Backgrounds of grey or faintly inscribed Gothic tracery on white paper evoke the atmosphere of ‘gloomth’ that Walpole created, and recall his remark that ‘my castle is built of paper’.

 

 

 

The exhibition, designed  by Block Architecture, first introduces us to the ‘Strawberry Committee’ of amateur designers: Walpole, John Chute, whose pivotal role was the ‘oracle in taste’, artist Richard Bentley and poet Thomas Gray. Walpole did not employ an architect until the later stages of development. He eventually commissioned Robert Adam for the round drawing room – even then dictating the design – and James Essex for the offices, executed by James Wyatt.

 

Next, we are taken through  a series of dynamic, irregular spaces on a journey through the house. We encounter ‘gloomth’ in the hall and armoury – spaces that inspired Walpole’s 1764 Gothic novel, The Castle of Otranto – and in the refectory, which was part country-house dining room and part monastic eating room. The library, designed by Chute, is Strawberry Hill’s most serious essay in medieval Gothic. The Holbein chamber, focusing on the early 16th century, is followed by the state apartments, including  the gallery, the round drawing room, the great north bedchamber, and finally the Tribune. Designed to contain Walpole’s finest things, this room has ‘the air of a Catholic chapel’ and was named after the Tribuna, the room of treasures  at the Uffizi in Florence, Italy.

 

The exhibition’s display faithfully follows Walpole’s picture-hanging principles, mixing portraits with landscapes and hanging canvases of different sizes side by side to give the impression of accretion over time. His ‘principal curiosities’ are identified with labels featuring a star. This exhibition is an unmissable opportunity to see part of Walpole’s collection – one of  the most unusual and interesting of the 18th-century, and surely an inspiration for that other great collector, John Soane.

 

 

+ A chance to see Walpole’s fascinating collection of ‘singular’ objects    

 

- The exhibition design has  too much ‘gloomth’ and not enough colour

Flicking through the opening pages of this book, three key images present contrasting  traits of Japanese architecture. There is of course much more to come, with over 600 photographs,  two essays and over 100 case studies. Nevertheless, these introductory images seem particularly well chosen. Shot  by photographer Edmund  Sumner – with text by wife Yuki and co-authors Pollock and Littlefield – Atelier Bow-Wow’s Gae House, Sou Fujimoto’s Final Wooden House and Terunobu Fujimori’s Takasugi-an illustrate the curious nature of contemporary Japanese architecture by setting an ingeniously planned domestic building alongside the nation’s love of traditional craft and fascination with the absurd.

 

In one of the project’s  most celebrated images, Sumner’s enthusiastic manner persuaded the client of Gae House to pose in his sunken study, where he prepares literary critiques with bikes hanging overhead and shoes neatly aligned next to the front door. With equal fluency, the photographer’s interpretation  of Fujimoto’s rustic bunk barn shows how the interior regularises but preserves the wilderness of the surrounding forest, while his ungrounded image of Fujimori’s tree/tea house amplifies the manner in which this maverick architect takes history with a pinch of salt, as he takes tea within his own curious bird box. Whatever the context – be it city, suburb or woodland clearing – Sumner’s shots surprise and delight, giving this book equal appeal  to anyone with an interest in  the culture or nature of this fascinating country. And,  for those who want to delve deeper, essays bring first-hand accounts of the current architectural scene.

 

Sou Fujimoto’s Final Wooden House

 

 

Perhaps a victim of the  tried and tested (and popular) intro-essay-case-study publishing format, there is  little connection between Edmund and Yuki’s observations in the book. The fact that the Sumners work so closely together, reading architecture  in different media, could have produced far more critical tension had a more bespoke format been used to record  their combined efforts. That said, however, the project  texts are clear and concise  and two essays cover the common ground of Japan’s haphazard and chaotic  condition while successfully making their own mark. Yuki leads the narrative with a piece entitled The Residue of Japan-ness, in which she wrestles with describing the ambiguity  of Japan-ness, saying that  as ‘a comfort zone from the nation’s traumatic past …  subtle subversions of the norm  offer temporary escape from stifling rules and regulations, rituals and protocols that plague its society’, before focusing  on two current dualities. First,  the recent trend to embrace visual chaos, which goes against the tactic epitomised  by Tadao Ando, who traditionally built solid walls to contain interiors. Second, the duality between ‘the jagged, earthy work of Fujimoto and Fujimori  on one side; and the smooth, transparent, more refined output of Ito, Kengo Kuma and SANAA  on the other’. Pollock also discusses variations of Japanese normality in her  essay Architecture in Japan: In Context. Here she quotes architect Hitoshi Abe to describe the current post-bubble condition, saying that ‘until about 20 years ago, you often heard Japanese culture being dismissed as “all copies no originals” … [but] it’s now an indisputable fact that Japan  has become a nation that exports culture.’

 

  Terunobou Fujimori’s Takasugi-an, a tea house on stilts

 

 

In accordance with Abe’s claim, this book clearly shows that the best from Japan is  now all original, producing some of the world’s most creatively charged work in response  to its remarkably energetic environment. With one or two niggles, such as the omission  of a contents map, this is by  far the best book on Japan’s recent architectural exports.

 

 

+ Captures Japan’s creative, chaotic condition     

 

-  A more bespoke format might have better suited the collaborative approach

 

Buku ini memberikan penjelasan persyaratan jembatan terhadap gempa. Persyaratan ini melengkapi bagian-bagian lain dari Tata Cara danharus dibacasecara berkaitan satu dengan lainnya.

 

Persyaratan dalam Bagian ini mewakili standar pelaksanaan yang baik dan berlaku. Syarat-syarat tersebut tidak mutlak, tetapi sedapat mungkin harus diikuti untuk menjamin bahwa suatu jembatan mempunyal kemungkinan terbaikuntuk selamat dalam kejadian gempa besar.

 

Buku ini digunakan untuk Jembatan Jalan Raya diseluruh wilayah Indonesia, kecuali untuk struktur khusus.

 

Perencanaan struktur khusus menuntut penggunaan tehnik analisa yang diluar lingkup bagian ini, walaupun telah diberikan beberapa pedoman umum untuk analisa dinamik. Tehnik demikian hanya boleh digunakan dibawah pengawasan Ahli Tehnik Perencana yang cukup berpengalaman dalam perencanaan seismik jembatan.

 

 

http://www.ziddu.com/download/11062775/4.Bridge-Design-Code-Vol-2.rar.html

1. Introduction 

   
Gypsum is a non-hydraulic binder occurring naturally as a soft crystalline rock or sand. Puregypsum is a white translucent crystalline mineral and is so soft that it can be scratched by afinger nail. When heated to 205°C, pure gypsum loses its luster and its specific gravity isincreased from 2.3 to 2.95 due to the loss of water of crystallization. Gypsum has a uniqueproperty of moulding. When heated it gives up combined water and easily turns into powder.On adding water to the powder it can easily be shaped and moulded, and in a short time ithardens again and becomes similar to what it was in its natural state. When water is added thegypsum forms interlocking crystals. As the gypsum hardens it is this crystallisation that makesit such an effective fire resisting material.

 

There are two commercial varieties of crude gypsum, rock gypsum and gypsum or gypsiteused for the manufacture of gypsum binding material. These substances consist principally ofa hydrous sulphate of lime (CaSO4 + 2H2O) with varying percentages of silica, carbonate oflime, carbonate of magnesia, and iron oxide. Building gypsum is an air-setting binder composedmainly of semihydrate gypsum and obtained by processing gypsum at temperatures 150°C–160°C.

 

Gypsum items have a number of valuable properties like relatively small bulk density,incombustibility, good sound absorbing capacity, good fire resistance, rapid drying andhardening with negligible shrinkage, superior surface finish, resistance to insects and rodentsand low energy input during burning to produce gypsum plaster. The major shortcomings areits poor strength in wet state and high creep under load. Gypsum plaster, e.g., Plaster of Paris, wall plaster stucco, and hard finish plaster are extensively used in wall construction. Flooringplaster, made by calcining gypsum at a high temperature has been considerably used. In all ofthese powders, gypsum in a more or less dehydrated state is the essential element. Gypsum-based items should be used only in dry state and in premises of not more than 60 per centrelative air humidity

2. Effect of Heat and Moisture

 

The water of crystallization in the gypsum (CaSO42H2O) is not held firmly by the mineral.Therefore, when it is heated to about 160°C it loses a part of water of crystallization and isknown as half-hydrate gypsum.

 

At still higher temperatures (About 200°C), gypsum loses all its water of crystallization and turns out into an hydrate gypsum.

 

The lost water of crystallization can be regained under favourable damp or moist conditions.

 

 

3. Setting and Hardening

 

The setting and strengthening of gypsum are due to intergrowth of very fine and poorlysoluble crystals of dehydrated gypsum as they precipitate from a solution which remainsoversaturated as long as the hydration of gypsum proceeds. Following are the two theories ofsetting of gypsum.

 

According to the crystallization theory proposed by Le-chatelier when water is added togypsum, the latter dissolves forming a saturated solution of dehydrate gypsum. Since thesolubility of semihydrate gypsum is about 3.5 times more than of dehydrated gypsum, thesoloution that is saturated with respect to the semihydrate gypsum causes dehydrated gypsumto crystallize. In this process the concentration of semihydrate gypsum is reduced causingmore of it to dissolve until again the solution is oversaturated and consequently again yieldingcrystals of dehydrate gypsum. The process continues until all the semihydrate gypsum ishydrated and crystallized.

 

According to colloidal theory when water is added to gypsum, the semihydrate gypsumgoes into solution until the latter is saturated. In an oversaturated solution, the interaction ofwater with the solid semihydrate continues on their surface due to high mutual chemicalaffinity. The resultant dehydrated gypsum fails to dissolve further and precipitates as anunstable disperse colloid mass in the form of gel, the process being accompanied by the settingof the mass. The resultant crystals grow both in number and size, while orienting randomlyand interwining, convert the jelly like mass into a crystalline growth. The resultant CaSO42H2O crystals grow into a single crystalline concretion which on drying becomes very strong.

 

Gypsum sets within 20 minutes and it is difficult to use it for some purpose. Suitable settingretarders like lime-kerat in glue and sulphite -alcohol vinasse may be used.

 

 

4. Classification

 

Gypsum binders are classified as low and high burning varieties. The low burning variety ismanufactured by heating dehydrated gypsum to a temperature of about 160°C. The examplesof low burning variety are building and extra strong gypsums. The high burning (anhydrite)variety is obtained by burning dehydrated gypsum at 700°C–1000°C, when the chemicallybound water is lost totally. Gypsum may also be classified as low strength gypsum—obtainedby heating natural gypsum rock at normal pressure, the resultant gypsum ( modification) isvery hygroscopic (60–65%) and porous (40%), and extra strong gypsum—obtained by heatinggypsum at pressure of 2–3 atm followed by drying at 160°C–180°C (    modification). The extrastrong gypsum is used in metallurgical industries for manufacture of moulds.

 

 

5. Manufacture

Law Burning Variety

   
A 75 per cent dehydrated gypsum is referred to as Plaster of Paris. The pulverized Plaster ofParis is the basic material used to make many of the gypsum building materials. For refinedgrade of Plaster of Paris the oven, kettle and rotary processes are used. Hard finish plaster ismade in kilns similar to that used in calcining lime.

 

The excavated raw materials are crushed, and if the kettle process is used, ground untilabout 60 per cent pass No. 100 sieve. In the rotary process the final pulverization is omitteduntil calcination is completed.

 

The kettles employed for calcinations are 2.5 or 3 m in diameter and about 2 m high. Thepulverized material is chuted into the kettle and temperature raised gradually so as to drive offthe mechanically held water. At about 100°C the whole mass bubbles up violently and thensinks. At 150°C the combined water begins to boil out and between 170° and 200°C the processis stopped. The kettle process requires about 2 to 3 hours to calcine a charge yielding 5 to 6tonnes. The calcined product is then cooled partially in a vat and is sent to the screens. Residuesfrom the screen are ground; the fines are stored in bins.

 

In the rotary process the raw material is crushed to pass through 25 mm mesh and is then fedinto a rotating cylinder inclined to the horizontal. Calcination is accomplished with theintroduction of hot furnace gases. The roasted material is conveyed to calcining vats in whichfurther changes are bought by the heat within the material. The product is then groundscreened and stored.

 

In case of Plaster of Paris or stucco the time of setting is delayed by adding fraction of oneper cent of retardant like glue, saw dust or blood after the plaster has cooled to increase thehandling time. Cattle hair or wood fibre is introduced for cohesiveness of plastics. Wall plastersmade from pure raw materials are adulterated with 15–20% of hydrated lime, the addition isnot required for the raw materials containing considerable amount of clay. If instead of usingmoderate heating the gypsum is heated sufficiently to drive off all the water, the product nolonger combines readily with water to form a useful plastering material. If small quantity ofaccelerating salts is added to it, a useful range of materials is again formed.These are known asanhydrous gypsum plasters or hard burnt plasters.

 

 

High Burning Variety

 

Anyhydrite cement is obtained by burning natural dihydrate gypsum at a temperature ofabout 700°C and then grinding the product together with hardening catalyzers (lime, mixtureof sodium sulphate with green or blue vitriol, burned dolomite, granulated basic blast-furnaceslag, etc).

 

A typical anhydrite binder may be of the following composition: lime, 2–5%; a mixture ofsodium bisulphate or sulphate with green or blue vitriol in amounts of 0.5 to 1% each; dolomiteburned at 800–900°C, 3–8%; granulated basic blast-furnace slag, 10–15%. Green and bluevitriols consolidate the surface of hardened anhydrite cement, so that the catalyzers do notseep out and discolour the item’s surface. The action of the catalyzers is due to the ability ofanhydrite to form complex compounds with various salts in the form of an unstable multiplehydrate, which then decomposes yielding CaSO42H2O.

 

Anhydrite cement can also be obtainedby grinding natural anhydrite with the above additives.Anhydrite cement is a slowly setting binder; its setting starts not earlier than in 30 min andends not later than in 24 hours. It is used for preparing brick-laying and plastering mortars,concretes, heat insulating materials, artificial marble and other ornamental items.

 

A variety of anhydrite cements is the high-burned gypsum (estrich gypsum). It ismanufactured by burning natural gypsum or anhydrite at a temperature between 800 to1000°C followed by fine grinding. This results not only in complete dehydration but also inpartial decomposition of anhydrite with the formation of CaO(3–5%) according to the reactionCaSO4 = CaO + SO3. When estrich-gypsum is mixed with water, CaO acts as a catalyzer whichpromotes the hardening of the anhydrite cement in a manner discussed above.High-burned gypsum is used to prepare brick-laying and plastering mortars, to build mosaicfloors, to manufacture artificial marble, etc. Items from high-burned gypsum have low heatand sound conductivity, higher frost and water resistance and a smaller tendency to plasticdeformation than products from building gypsum.

 

 

6. Plaster of Paris or Stucco

 

It is produced by incompletely dehydrating pure finely ground gypsum at a temperature somewhat lower than 185°C. Most plasters theoretically approach — 421CaSO +  HO2— whichcontains about 6.2 per cent of water.

 

The setting of plaster of paris is attributed to the formation of gypsum crystals from asupersaturated aqueous solution. When substances of colloidal nature (for example glue) aremixed with the plaster the formation of crystals is hindered and the time of set retarded. Inhardening, Plaster of Paris first shrinks then expands. The latter property makes the materialsuitable for making casts, since a sharp impression of the mould can be secured. For the samereason it forms an excellent material for filling cracks, holes in the plastered surfaces and alsoon the wooden surfaces before painting/polishing.

 

Owing to the rapidity of set and difficulty in working, its use in structures is limited toornamental works. Being unstable in water it should be used for indoor works only.

 

Properties

 

1.White in colour

2.Setting time is 5 to 10 minutes

3.Specific gravity is 2.57.

 

7. Gypsum Wall Plasters

 

Gypsum wall plasters gain one-half of their one-month strength in a day. Plaster and sandmortars of 1:1 proportions may be expected to develop 80 per cent of the neat strength atcorresponding ages, while those of 1:2 proportion generally possess one-half to two-third ofthe neat strength.The gypsum to sand neat plaster in proportion of 1:3 should set in 2 to 32 hours and in 1.5to 8 hours when mixed with wood fibres. The dry set density of gypsum wall plaster is850–1040 kg/m3, and compressive strength of 1:2 gypsum wall plaster is 6 to 15 N/mm2. Gypsum wall plasters are divided into following four categories.  

Gypsum Neat Plaster is 60.5 per cent or more of calcined gypsum (plaster of paris) withmaterial added to control workability, time of set and cohesiveness.

 
Gypsum Wood Fibre  Plaster is 60.5 per cent or more of calcined gypsum and, wood fibre 1.0per cent or more to increase cohesiveness, and the remaining material to control workabilityand time of set.

 

Calcined Gypsum is used for finishing coat. It may or may not carry a retardent. Calcinedgypsum may be white or grey.

Gypsum Ready Sanded Plaster consists of cementing material, predominantly calcinedgypsum, which has been mixed at the mill with the proper proportions of sand and otherdesirable constituents. It is prepared for use simply by adding water. There are two grades of Gypsum Ready Sanded Plaster, the scratch or first coat, and the browning or second coat.The scratch coat contains 2 sand to 1 cementing material by weight. The browning coatcontains 3 sand to 1 cementing material by weight. The cementing material carries at least 60.5per cent by weight of calcined gypsum and other ingredients to control set and workability.Some of the properties of gypsum plasters are given in Table 19.1

 

 

8. Hard Finish Plaster

When gypsum is burnt at considerably high temperature than that for calcining of cementplaster, and treated with certain solutions like alum and Glauber’s salt (Na2SO4), the plastersso produced show slow setting but ultimately become very hard. Such plasters may be polishedto form a smooth surface and make a very satisfactory finish for interior walls. Often walls ofthese plasters are marked to imitate tiling with pleasing effects.Two commercial hard finishplaster cements are available. 

Keene’s Cement is made by burning a very pure rock gypsum at a red heat (700°C), cooling,and then adding 1.0 per cent of potassium and aluminium sulphates to accelerate the set.Subsequently the material is ground so that 90 per cent or more passes No. 100 sieve. It is pureCaSO4 of pure white colour. Keene’s cement is not injured by storage and mortars of it may beretempered. Set occurs between 20 minutes to 6 hours. At 7 days the tensile strength is 3.16N/mm2. It is used as a finish plaster only where a greater resistance to moisture and surfaceabrasion is required.

Mack’s Cement is made by burning gypsum at a very high temperature and adding about0.4 per cent of burnt Glauber’s salt or potassium sulphate. It is said to form unusually hard,dense and durable surface which will take paint very well.

 

 

9. Gypsum Plaster Boards

 

It is a gypsum product of recent origin made of thin layers of card board or wood cementedtogether with wall plaster, used for lining walls and ceiling of buildings. The boards may bestrengthened by incorporating fibres as fibrous gypsum plaster boards. Sissal or coconut fibresare generally used. The weight of plaster in the later variety is 10 kg/m2 of board and that offibre is 250 g/m2 of board. They are very light weight and have high fire resisting properties.Gypsum plaster boards can be sawn to desired size and shape. They are available in widths400, 600, 800, 900, 1200 mm; in length 1200, 1500, 1800, to 3600 mm in steps of 100 mm and; inthickness 9.5 to 15 mm. They are classified as

 

The breaking load of the boards are given in Table 19.2.

 

 

10. Non-Load Bearing Gypsum Partition Blocks

These can be solid or hollow, rectangular with straight and square edges and true surfaces. Thecompressive strength of these partition blocks should not be less than 50 N/m2 on gross area.These boards are available in sizes as given in Table 19.3.

 

11. Pyrocell

 

It is finely ground powder containing an admixture, forms a gas on being mixed with waterand expands the mixture to 3 or 4 times its volume. This inflated paste hardens into a light,cellular, fire resistant mass possessing good acoustical and insulating properties.