FLOOR
STRUCTURES
Floor structures
Building Construction I.
●
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
Floor structures
Building Construction I.
●
Architectural function and
requirements
● aesthetic function
● variability of interior layout – span
● thickness of floor structure
Floor structures
Building Construction I.
●
Structural function and requirements
● load-bearing capacity of floor structure
uniform load (self weight + impose load kN/m2 – 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
Floor structures
15 – 180 min
Building Construction I.
●
●
Acoustics function and requirements
● airborne sound transmission loss
42 – 67 dB
● impact sound transmission loss
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 UN
Req.
Recom.
W/(m2K)
W/(m2K)
lightweight structure
0,24
0,16
heavy structure
0,30
0,20
Floor structures
floor structures
under/above unheated
space
Floor structures
Building Construction I.
PRINCIPLES OF
STRUCTURAL
SOLUTION
Floor structures
Building Construction I.
●
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
Floor structures
Building Construction I.
● Beam structure
- load effects are carried mainly by flexure → interaction of compressed and
tensioned parts of cross section
I = W/e[m4]
inertia moment
section modulus
Shear stress
- influence of cross-sectional shape on the affectivity of structure
k = f (E,I)
stiffness
Floor structures
Building Construction I.
- influence of beam support on its stress
Floor structures
Building Construction I.
● Slab
structure
- importance of slab support
- one-way slabs → flexure, shear
- two-way slabs → flexure, shear, torsion
- importance of self weight
reduction
Floor structures
Building Construction I.
● 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
Floor structures
Building Construction I.
● 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
Floor structures
Building Construction I.
● 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.
Floor structures
Building Construction I.
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.
Floor structures
Building Construction I.
● 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
Floor structures
Building Construction I.
VAULTS
Floor structures
Building Construction I.
● Structure of vault
● shape of main arch of a vault
● structural elements of vaults
● vaults supports
Floor structures
Building Construction I.
f
l
Floor structures
buttress – external support
Building Construction I.
● construction of vaults
● resistance to horizontal thrust
Floor structures
Building Construction I.
●
Barrel vaults
● straight arch
● inclined barrel arch,
skewed vault
● trumpet arch (conic)
● raking arch (domed)
Floor structures
Building Construction I.
●
Lunette (stripping) vaults
Floor structures
Building Construction I.
●
Structure of
barrel vault
Floor structures
Building Construction I.
●
Cloister vaults
● classic classical vaults
● trouhg valult
Floor structures
Building Construction I.
● „mirror“ vault
● fake „mirror“ vault
Floor structures
Building Construction I.
● dome vault
● Bohemian vault
● Prussian vault
Floor structures
Building Construction I.
Prussian vault
Floor structures
Building Construction I.
●
Cross vaults
● classic cross vault
● lierne vault
Floor structures
Building Construction I.
Floor structures
Building Construction I.
Floor structures
Building Construction I.
Cell vault (diamond vault)
Floor structures
Building Construction I.
●
Modern vaults
● vaults from mass
concrete
● RC vaults and shells
Floor structures
Building Construction I.
Floor structures
Building Construction I.
FUNCTIONS AND
REQUIREMENTS
Floor structures
Building Construction I.