FLOOR STRUCTURES
Basic functions and requirements architectural function and requirements - variability of interior layout - aesthetic function structural function and requirements - load-bearing capacity of floor structure - deflection of floor structure - horizontal stiffness fire safety function and requirements - inflammability of materials - fire resistance acoustics function and requirements - airborne sound transmission - impact sound transmission thermal function and requirements
Architectural function and requirements aesthetic function variability of interior layout span thickness of floor structure
Structural function and requirements load-bearing capacity of floor structure uniform load (self weight + impose load kn/m 2 2,0 residential - 3,0 offices - 4,0 cinemas - 5,0 concentration - 6,0 concentration + movement requirement of minimal self weight x acoustics deflection of floor structure aesthetics, function of components span: 200-500 horizontal stiffness interaction with horizontal load bearing structures Fire safety function and requirements inflammability of materials fire resistance 15 180 min
Acoustics function and requirements airborne sound transmission loss impact sound transmission loss 42 67 db 48 68 db Thermal function and requirements heat transfer coefficient U decrease of touch floor temperature thermal stability of room limitation of heat bridges Values of heat transfer coefficient U N Floor structures floor structures under/above unheated space lightweight structure heavy structure Req. W/(m 2 K) 0,24 0,30 Recom. W/(m 2 K) 0,16 0,20
PRINCIPLES OF STRUCTURAL SOLUTION
Principle of vaults - external load is carried by the only internal compression in the vault e t/6 - vault produce large horizontal forces at the support ratio of rise to span f / l f l
Beam structure - load effects are carried mainly by flexure interaction of compressed and tensioned parts of cross section I = W/e[m 4 ] inertia moment Shear stress section modulus - influence of cross-sectional shape on the affectivity of structure k = f (E,I) stiffness
- influence of beam support on its stress
Slab structure - importance of slab support - one-way slabs flexure, shear - two-way slabs flexure, shear, torsion - importance of self weight reduction
Principle of reinforcement - combination of two materials: one with high strength in compression (e.g. concrete) and one with high strength in tension (e.g. steel) thermal expansion coefficient - reinforced concrete (RC) elements - timber glue-laminated beams with steel reinforcement
Principle of prestressing - in prestressed elements, compressive stresses are introduced into a member to reduce or nullify the tensile stresses which result from bending due to the applied load - prestressing of concrete structures - prestressing of timber glue laminated structure - prestressing of timber or steel beams using free tension tendons
Interaction of structural elements - basic structural principle - type of joint selection level of interaction of elements (not only static!) - static interaction: importance of joints rigidity normal and shear stress - coupled structures: RC floor structures, composite steel and concrete structures, timber glued beams and nailed beams etc.
STRUCTURAL VARIANTS OF FLOOR STRUCTURES Structural classification vaults - stone vaults, brick vault, concrete vault slab structures - one-way slabs - two-way slabs beam structures - one-way joist and ribbed floor structures - two-way grid bearer floor structures Material classification timber floors - slab structures - beam (joist, plank) structures stone floors - vaults, floors from stone plates floors from ceramic materials - brick vaults concrete floors - concrete vaults and shell roofs - slab structures (RC slabs, composite RC structures) - beam structures (joist, girder, ribbed) steel floors - slab structures (from formed steel sheets) - beam structures combined load-bearing floor structures - composite steel and concrete structures etc.
Technological classification masonry floors - vaults monolithic floors - monolithic RC floor structures precasted floors - precasted RC floors, steel floors, timber floors prefa-monolithic floors - composite RC joists and slabs ( filigran ), prefa-monolithic slabs with mushroom ceiling Real solution of floor structures results from combination of these structural, material and technological variants. According to dominant characters floor structures are commonly classify into: vaults timber floors RC floor structures steel and composite RC-steel floor structures
VAULTS
Structure of vault shape of main arch of a vault structural elements of vaults vaults supports
f l buttress external support
construction of vaults resistance to horizontal thrust
Barrel vaults straight arch inclined barrel arch, skewed vault trumpet arch (conic) raking arch (domed)
Lunette (stripping) vaults
Structure of barrel vault
Cloister vaults classic classical vaults trouhg valult
mirror vault fake mirror vault
dome vault Bohemian vault Prussian vault
Prussian vault
Cross vaults classic cross vault lierne vault
Cell vault (diamond vault)
Modern vaults vaults from mass concrete RC vaults and shells
FUNCTIONS AND REQUIREMENTS