LONG SPAN STRUCTURES: PART 1

1 LONG SPAN STRUCTURES: PART 1 Mircea GeorgescuLecture 18: 02/03/2017 European Erasmus Mundus Master CourseSustainable Constructions under Natural Hazards and Catastrophic Events520121-1-2011-1-CZ-ERA MUNDUS-EMMC L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span General about long span structures. History and Rigid space Flexible space -Rigid-flexible combined space 1 LONG SPAN STRUCTURESL10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span General about long span structures [2] Definitionof long span building [2]: Buildings that create unobstructed, column-free spaces greater than 30 m (100 feet) for a variety of functions / activitiesExamples of relevant activities.

2 Where visibilityis important: auditoriums and covered stadiums ..where flexibilityis important: exhibition halls and certain type of manufacturing facilities ..where large movable objectsare housed: aircraft hangarsL10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresSpectacular long span structures in late 20thcentury [2]:Upper limitsof span for previously mentioned categories: Largest covered stadium =210 m span Largest exhibition hall = 216 m span Largest hangar = 75-80 m span (to fit largest commercial fixed-wing aircraft with a wingspread of 69,4 m) OBSERVATION: in such buildings the structural systemis a MAJOR CONCERN!L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresStructural systems: ClassificationClassifiedinto two groups [2]: Structural systems subject to bending(have both tensileand compressiveforces) Funicular structures(work either in pure tension or in pure compression): use of cablescombined with rigid membersOBSERVATION: Bridgesare a common type of long-span structure which has continuously influencedthe development of long span buildings!

3 L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresBending structures include: The plate girder (made of welded steel plates to produce beams deeper than standard rolled shapes: span up to 60m) The two-way grid (made either of two-direction plate girders : span up to 90 m) The one-way truss (hollowed out beam, made of linear slender members joined together in stable triangular configurationswith optimum h/L = 1 ) The two-way truss (made of two-directions trusses) The space truss / grid (optimum h/L=1/40)[h/L = depth-per-span ratio]L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresFunicular structures include: The parabolic arch: in form of truss for greater rigidity, reach spans up to 98 m; Tunnel vault-and-dome(act in pure compression; have rise-to-span ratio 1 :2).

4 Steel truss domes = used for several stadiums reaching 204 m span Cable stayed roof= derived from bridge building (steel cablesradiating downwards from masts that rise above roof level: spans up to 72 m result) Bicycle wheel= two layers of radiating tension cables separated by small compression struts, connect a small inner tension ring to the outer compression ring supported by columns Warped tension surfaces(act in pure tension). Built of cable networksand synthetic fabrics to form tension surfacesL10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresMaterial used for long-span structures (1): All reinforced concrete (RC) including precast All metal ( mild-steel, structural steel, stainless steel or alloyed aluminium) All timber Laminated timber Metal + RC (combined) Plastic coated textile material (fabric) for roofing / cladding Fiber reinforced plastic for roofing / cladding8L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresMaterial used for long-span structures (2).

5 Each of previous materials is applicableup to a certain value of the (long) span Steelis the MAJOR material for long-span structures, allowing for the maximum spansto be reached The frequent use of steel is due to its advantages: light weight, high strength-to-weight ratio, ease of fabrication, ease of erection and convenient cost 9L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span History and classification Proposed periods of the history of long-span space structures (by the authors of paper [1]): Period of ancientlong-span space structures (up to 1925) Period of premodernlong-span space structures (between 1925 and 1975) Period of modernlong-span space structures (from 1975) 10L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresAncient long span structures (before 1925):The only materials available in ancient times: Timber Masonry made of stone(vulnerable in tension and bending) Masonry of bricks made of clay(also vulnerable in tension and bending)RESULT: Reaching long spans in such constructions = EXTREMELY DIFFICULT!

6 ONLY POSSIBILITY: via the arch-and-vault systems (cathedrals, palaces) working in compression only 11L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresConstruction of an arch system [3]12L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresVault system in cathedrals [3]13L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresProgress: Industrial revolution (started in century) Production of steel on industrial scale Available price of steel as material used in construction Capability of steel to resist in tension and bendingunder loadsRESULT: Possibility of ever larger span construction:World fairs organized after 1850 by the new industrialized countries (England, France, Germany) = occasion to expose technological progress in construction 14L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresExample: Crystal Palace-London [3]15L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresExample.

7 Gallery of Machine-Paris [3]16L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresLater ancient space structures [1], [4] (between 1920 and 1975) : Examples: 1922: Airship hangarUS Navy-New Jersey -79 m span 1924: the first hemispherical single-layer latticed shell, made of steel (pig iron) was built in Zeiss Planetarium, Germany 1925: the first reinforced concrete thin-shell structure with a diameter up to 40 m was built in Jena, Germany 1937: Glenn L. Martin Co. Aircraft Assembly Building-Baltimore Flat truss 91 m span 1942: Airship hangarUS Navy-New Jersey -100 m span17L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresModern space structures [1], [2] (after 1970):Examples: 1970: Shanghai Exhibition Hall-China (28 m x 36 m) air supported membrane 1975: at the Pontiac Gymnasium (span >100m), the first representative air-supported membrane structurewas built in the US 1986: Comprehensive Gymnasium of Seoul Olympic Games = first cable-dome in the world designed by the American engineer Geiger 1988.

8 Tokyo Dome = air supported membrane structure (ellipse 180 m x 150 m)18L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresComparison ancient-modern in terms of span [3]:19L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresExample: Louisiana Superdome, USA [3] 20 Longest span dome: 680 ft = 210 m clear span; 252 ft =77,1 m heightL10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresInterior of the superdome (approx.)

9 Audience)21L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresCLASSIFICATION OF LONG-SPAN SPACE STRUCTURES22L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresAge partition of space structures [1]23As visible on the figure: premodern space structures are STILL in use!L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresDefinitionof modern long-span space structures [1]:Modern long-span space structures are light and efficientstructures, developed starting in the 1970 s and 1980 s on thebasis of: new technologies and light-weight high-strength materials such as -high strength steel, -membrane steel cables24L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresExtension!

10 Renewingpremodern space structures in recent times: Premodern space structures (thin shells, space trusses, lattice shells, odinary cable structures) were also modernizedto fit nowadays requirementsNew space structures have been developed on premodern basis by: Combinationof different structural forms and materials Application of prestressing technology Innovationof structural concepts and configurations25L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong span StructuresBasic elements of space structures:(also used in FEM analysis): Rigid elements (plate / shell, beam, bar) Flexible elements (cable and membrane)Resulting categoriesof modern long-span space structures: Modern rigid space structures Modern flexiblespace structures Modern rigid-flexiblecombined space structures26L10 Mechanical properties of cast iron, mild iron and steel at historical structuresEuropean Erasmus Mundus Master Course Sustainable Constructions under Natural Hazards and Catastrophic EventsLong Span StructuresTraditional classification for long-span space structures [1]:27 Already obsolete: unable to cover new existing space structures !