Structural systems : Structural systems Submitted by:
uma Suspended roofs : Suspended roofs Suspension shell (membrane) roofs from prestressed concrete structures allow designing attractive architecture with minimum material use.
Large span structures can be erected without complicated and expensive scaffoldings when simple precast members are used. Types of suspension : Types of suspension Arch suspension
Catenary cable suspension Arch suspension : Arch suspension Arch suspension involves suspending the roof beneath an arch. Slide 5: Cables are used distribute the stabilising effect of the arch over a wider area of the roof.
strength of an arch depends upon how curved it is - an external arch will often tend to have a smaller radius of curvature Wembley national stadium ARCHITECT:foster : Wembley national stadium ARCHITECT:foster partly retractable roof
The roof is supported structurally by a spectacular 135-metre-high arch
The arch leans asymmetrically to the north, clear from the path of the moving roof panels on the south east and west sides. The arch structure supports approximately 60% of the total weight of the main roof. The arch has a span of 315m, is 135m high : The arch structure supports approximately 60% of the total weight of the main roof. The arch has a span of 315m, is 135m high For this span, the arch form uses approximately two thirds of the amount of steel compared to using a conventional truss girders. Catenary suspension : Catenary suspension catenary is the curve that an idealised hanging chain or cable assumes when supported at its end
Only a few roof structures have been constructed which utilise the principle of the suspension bridge.
This type of structures represent about the best way to construct very long spans. Paper Mill at Mantua : Paper Mill at Mantua Location: Italy
architect— Pier Luigi Nervi.
The main reason for choosing this type of roof was the need for a clear span of 525 ft
The roof consists of a steel deck suspended by four steel cables. and two side cantilevers each of 140 ft.
The whole roof structure is carried on four large reinforced concrete supports 164 ft. high Simply curved systems : Simply curved systems curved roofs have their top surface curved which are provided to give architectural effects. such roofs include cylindrical,parabolic shells and shell domes,doubly curved shells such as hyperbolic paraboloids, and folded slabs.
Curving can be done in one of two ways. With spring curving: the steel is brought on site in flat sheets
free-form curve :created by attaching it to the roof rafters. This method is most suitable for roofs that have a gentle curve
such roofs are more suitable for public buildings like libraries,theatres,recreation centres,etc. shells : shells Shells can be defined as curved structures capable of transmitting loads in more than two directions to supports. Curved styles : Curved styles Cranked: A continuous roof line with a curve on top instead of a ridge where the two sections of a pitched roof would otherwise meet . Kresge Auditorium (shell structure) : Kresge Auditorium (shell structure) ARCHITECT: ERO SARINEN one-eighth of a sphere rising to a height of 50 feet, and sliced away by sheer glass walls so that it comes to earth on only three points. Sitting on a circular brick platform, the dome contains a concert hall(with seating for 1226 people The Church of St. Aloysius : The Church of St. Aloysius Hyperbolic Paraboloid roof structure. Architect : Erdy McHenry Peak height :53feet no interior supports Saarinen employed free-hanging acoustic "clouds" that absorb and direct sound, instead of a traditional plaster ceiling.