Overview of Multi Storey Construction

1. Overview of Multi Storey Construction

2. Basic Principles – Domestic Construction • Masswall – Masonry house • Masswall -Timber Framed House These rely on a loadbearing wall that forms the enclosing element also. They are very suitable for low rise buildings. There is no independent structural frame with these buildings.

3. The Multi-Storey Structural Frame • A skeletal frame, normally steel or concrete supports all the loads of the building. • All internal walls and the cladding are non-loadbearing. • They are extremely strong in both tension and compression and can go to great heights.

4. Discussion • In small groups list some of the reasons of how multi-storey structures achieve stability.

5. Principles of Multi-Storey Construction • Most multi-storey buildings are designed on the basis that wind forces acting on the external cladding are transmitted to the floors which form horizontal diaphragms, transferring the lateral load to rigid elements and then to the ground. These rigid elements are usually either lattice or rigid jointed frames or reinforced concrete shear walls. • Composite construction is widely used because of the economic advantages it offers. • Floors may either act compositely with the supporting beam, or independently of it. Composite action enables the floor slab to work with the beam, enhancing its strength and reducing deflection. It has therefore become very popular in steel framed construction for multi-storey buildings.

6. Principles of Multi-Storey Construction • The design of the floor structure is concerned mainly with vertical loads. The criteria determining member sizes depend on floor span. • The criteria determining the choice of a member size in a floor system varies with the span. • The minimum size is fixed by practical considerations such as fitting practical connections. As the span increases, the size will be determined by the bending strength of the member and, for longer spans, by the rigidity necessary to prevent excessive deflection under superimposed load or excessive sensitivity to induced vibrations. • Floor framing systems may be either simply supported or rigid at the supports. Continuous construction is more efficient structurally, giving shallower floors, but heavier columns, increased complexity at junctions and connections with higher fabrication costs. In practice, the great majority of steel framed multi-storey buildings use simple construction.

7. Multi-Storey Construction –the lectures focus on these two materials • Reinforced Concrete Frame (either in-situ or precast) • Structural Steel Frame

8. Cladding To Framed Buildings • Glazing – Curtain Walling • Sheet Metal Cladding

9. Upper Floor and Flat Roof Construction • In-situ Concrete Floors on Formwork • Precast Concrete Floors

10. Multi Storey Construction –other less common forms • Cross Laminated Timber Panels • Traditional Timber Frame Panels – up to 8 stories

11. Question? • Many of the old industrial mills and warehouses were built using masonry. Why is loadbearing masonry not used for multi-storey buildings (those over 3 storeys) now? • See the Monadnock building later on also.

12. Home Insurance Building • It was constructed in 1884 in Chicago, Illinois, USA and was the first tall building to use structural steel in its frame, but the majority of its structure was composed of cast and wrought iron. • Whilst the Ditherington Flax Mill was an earlier fireproof cast and wrought iron framed building, it was only five stories tall. • Due to the Chicago building's unique architecture and unique weight-bearing frame, it is considered the first skyscraper in the world. • However, it was never the tallest building in the world or even in Chicago. It had 10 stories and rose to a height of 138 ft (42 m) In 1890, two additional floors were added to the original structure

13. Flatiron Building – Steel Frame • Building the Flatiron was made feasible by a change to New York City's building codes in 1892, which eliminated the requirement that masonry be used for fireproofing considerations. This opened the way for steel-skeleton construction. • Since it employed a steel skeleton – with the steel coming from the American Bridge Company in Pennsylvania, it could be built to 22 stories (285 feet) relatively easily, which would have been difficult using other construction methods of that time.[ • The building opened in 1902.

14. Rand McNally Building – First all steel framed building in the world. • The Rand McNally Building (1889-1911), in Chicago, was designed by Burnham and Root and was the world's first all-steel framed skyscraper. • It had 10 stories, 16 stores, and 300 offices, but the main tenant was Rand, McNally & Co., printers and publishers, with 900 employees. • It was torn down in 1911 and a taller building of that era still stands on the site.

15. Monadnock Building – Tallest loadbearing wall building • The Monadnock's final height was calculated to be the highest economically viable for a load-bearing wall design, requiring walls 6 feet (1.8 m) thick at the bottom and 18 inches (46 cm) thick at the top. • Greater height would have required walls of such thickness that they would have reduced the rentable space too greatly. • With its 17 stories (16 rentable plus an attic), its 215 feet (66 m) high load-bearing walls were the tallest of any commercial structure in the world. To support the towering structure and reinforce against wind, the masonry walls were braced with an interior frame of cast and wrought iron

16. Royal Insurance Building - Liverpool • The building was constructed between 1896 and 1903 as the head office of the Royal Insurance Company. The design was the result of a competition won by James F. Doyle in 1895. The assessor for the competition was Norman Shaw, who was retained as an advisory architect for the project, but it is uncertain what part he played in it. • The building is constructed around a steel frame and is the earliest example of this type of construction in the United Kingdom

17. Ingalls Building • The Ingalls Building, built in 1903 in Cincinnati, Ohio, was the world's first reinforced concrete skyscraper. • Prior to 1902, the tallest reinforced concrete structure in the world was only six stories high. Since concrete possesses very low tensile strength, many people from both the public and the engineering community believed that a concrete tower as tall as the plan for the Ingalls Building would collapse under wind loads or even its own weight

18. Royal Liver Building • Opened in 1911, the building is the purpose-built home of the Royal Liver Assurance group, which had been set up in the city in 1850 to provide locals with assistance related to losing a wage-earning relative. • It was one of the first office buildings in the world to be built using reinforced concrete. The Royal Liver Building stands at 98.2 m (322 ft) tall to the top of the spires, and 50.9 m (167 ft) to the main roof.

19. Weavers Mill - Swansea • The rather imposing building of Weaver's was built in 1897 by the French engineer FrançaisHennebique was Europe's first multi-storey reinforced concrete building.

20. The Tallest Concrete Framed Building In the World • BurjKhalifaknown as Burj Dubai before its inauguration, is a skyscraper in Dubai, United Arab Emirates. It is the tallest man-made structure in the world, standing at 829.8 m (2,722 ft).

21. The Tallest Steel Framed Building in the World • The top floor of One World Trade Center is 1,368 feet (417 m) above ground level, along with a 33 ft 4 in (10.16 m) parapet; • This is identical to the roof height of the original One World Trade Center. • The tower's antenna/spire brings it to a pinnacle height of 1,776 feet (541 m),a figure intended to symbolize the year 1776, is the world's tallest all-office building, and the fourth-tallest skyscraper in the world.

22. Exercise • In small groups make a list of reasons why steel may be more suitable than concrete for multi-storey buildings?

23. Why use Steel over Concrete • Time gain – Perhaps the most important aspect of using steel frame construction as compared to reinforced concrete is the element of time for the on-site erection of the steel frame. • Reduced time presence for the Contractor on site translates to a shorter construction time for project delivery and this leads to reduced overheads during project construction. On multi storey buildings the time gain can be substantial • Ref. www.steelconstruction.info

24. Why use Steel over Concrete • Quality Control – Off-site prefabrication of steel members in isolated factory conditions means better quality control of manufacturing compared to pouring concrete frames in situ. Due to being exposed to the weather elements and with reinforcement and formwork works subject to labour intensive construction processes that may affect quality. • Furthermore, offsite prefabrication increases the overall speed of construction and facilitates enhanced safety. • Ref. www.steelconstruction.info

25. Why use Steel over Concrete • Design flexibility – Longer spanning structural steel frames create column free areas that offer greater flexibility and functionality of floor layouts thereby facilitating sales or lettings of the completed buildings. • Pipes and ducts can run easily through steel members and can also be inspected in the future whereas no such flexibility exists with concrete members. Ref. www.steelconstruction.info

26. Why use Steel over Concrete • Sustainability – Steel is 100% recyclable without any loss of quality, whereas concrete is not recyclable. In the UK, when buildings using metal frames come to an end of their useful lives, approximately 86% of the steel sections are recycled to create more steel products and 13% are reused in their existing form. Recycling rates for reinforcement bars used in reinforced concrete frames are negligible. • What references are needed here? How do we know this is true? • Note the source is www.steelconstruction.info

27. Why use Steel over Concrete • Construction Costs – Construction costs for steel frame high rise buildings that are above 10 levels compare favourably with reinforced concrete frame high rise buildings. • Although a cost premium in the order of 10-15% may be evident initially for high rise steel frame buildings, this is usually offset by the substantial reduction in the erection time of steel frame high rise buildings on site and the associated substantial overheads charges by main contractors for prolonged stay on site when slower concrete methods are used. • Ref. www.steelconstruction.info

28. What are the advantages of Concrete over Steel? – Google some answers • Advantages • Source of Information for each

29. Sources of Information • www.steelconstruction.info • www.concretecentre.com