Presentation2_78092C_mid-term

plantcitybusinessUrban and Civil

Nov 26, 2013 (3 years and 8 months ago)

56 views

Ceiling structures

CEILBOT
-
PROJECT

MID
-
TERM REPORT,

CEILING STRUCTURES


Eelon Lappalainen

A.Aalto, Maison Carré, France

History


Ceiling is quite new ”invention” in residential
buildings, started to become general after
WW II


Ceilings were used before WW II usually in
castle’s and churches


Before 19th century ceilings were mostly
made of timber or masonry


During 19th century cast iron, steel and
concrete were also used in ceilings


Ceiling made of cast and wrought iron:
1780
-

1900


Ceilings made of concrete: 1850
-


Ceilings made of steel: 1880
-


Typical for ceilings is diversity of different
structures and support systems


Old ceilings were designed mainly to
support it’s own weight
-
> adding more load
will usually cause problems (big deflection,
cracking, even collapse)


Design methods and quality of materials
varies a lot

”A
ceiling

is an overhead interior surface that bounds ("ceils") the upper limit of a room.”
Wikipedia

Situation today


Pre
-
fab pre
-
stressed slabs (etc. hollow
core slab) are commonly used


In residential buildings ceiling is
normally in washrooms and hallways
(installations are hidden behind ceiling)


In office buildings ceiling is usually in
large areas and hide’s structures and
installations (main installation routes
are in hallways and vertical shafts)


Small family houses, day
-
cares, ware
-
houses and even some industrial
buildings timber structures and ceiling
is used


Fire regulations strongly defines
materials what is allowed to use in
certain buildings


Modern ceiling usually hangs from
load bearing structure by fasteners


Installations inside the ceiling

Walls


Wall material limits the
methods for robot route and/or
new openings


Reinforced concrete


Masonry


Timber


Steel profiles


Wall could have several
functionalities


Load bearing


Stiffening wall (wind,
earthquake, eccentricity)


Fire wall (30…240 min)


Partition wall


Acoustic wall


Door frame and openings

Sports hall environment


Open space demand
-
> Long spans
-
> larger
deformations


Structural geometry (main structure)


Trusses


Arches


Frames


Domes


Cable structures


Airdome / balloon structure


Division in main structure and secondary structure


Ceiling or/and installations can be suspended
from both


Secondary structures usually beams, trusses,
slabs, steel sheeting


Materials


Steel


Timber (Glue Laminated, Laminated Veneer
Lumber)


Reinforced concrete (with or without tendons)


Cables (high strength steel)


System movements (deflection, creep, moisture and
temperature deformations) must be noticed for
designing installations (etc. Robot railings)

Some sports halls

Sports hall in Oulu

Sports hall in Joensuu

Loading


Basic loads are given in design codes
(Eurocode, ACI, DIN, RakMK)


Dead load


Live load (1,5…10kN/m2)


Ceiling weight (~0,2…1kN/m2)


Dead load, live load and ceiling loads
for are in horizontal structures mainly
vertical loads


Installations (HVAC, motors, robot
etc.) causes three dimensional loads


Three dimensional loads are usually
handled separately in structural
dimensioning


Some cases (depends on load type
and structure) dynamic loading can be
expressed:



static load x dynamic factor


displacements are limited


Complex dynamic problems are
usually calculated by FEM

Fastening


Ceiling is fastened to load
bearing structure (slab,
beam, truss)


Fasteners and anchors
should carry mainly
vertical dead loads from
ceiling and attached
equipment (electric,
HVAC)


There are numerous
different fastener types


All fasteners and anchors
which are strained
dynamically, should be
approved for such
purpose


Actions causing fatique
will decrease allowable
stress level


TIMBER

SCREW

HOLLOW CORE SLAB

LOCKING PART

FIXING DEVICE

COLD FORMED STEEL PROFILE

FIXING DEVICE

SCREW

NUT&BOLT


ANCHOR BOLT,

CHEMICAL ANCHOR

CONCRETE SLAB

Vibration and sound insulation


Walking 1,6…2,2Hz


Natural frequences are divided in two
classes:


Low frequency floor (f
0
<8Hz)


Heavy, long span


High frequency floor (f
0
>8Hz)


Light or mid
-
weight


Resonance should be avoided by
tuning


Passive damping (fixing points)


Active damping (etc. robot equipped
with sensors, regulators and actuators)


Structure
-
borne (impacts) and airborne
sounds should be avoided


Impact sound level L
´
n,w
<
53dB
(residential buildings in Finland)


Sound reduction index (airborne)
R
´
w
>
55dB (residential buildings in
Finland)


Robot fixing points and railing systems
should be insulated from structure

Free oscillation


Free oscillation,
damping


Forced oscillation


Forced oscillation,

damping


steady
-
state

steady
-
state













Vibration sources and isolation

Risks


Overloading and wrong
material choises could be fatal
and may cause serious
damages and even loss of
life’s


Fastener type must be safe
and inspected properly


All fastenings should be
designed so that they are easy
to check and maintain


Design boundaries should be
clear; who is designing and
what
-
> responsibilities

Collapsed spa ceiling in Kuopio, Finland

Sources


RT 84
-
10916, Alakatot ja sisäkattoverhoukset


RT 83
-
10902, Välipohjarakenteita


Betoni Suomessa 1860
-
1960, Betoniyhdistys ry


Tutkintaselostus B 4/2003 Y, Kylpylän alakaton romahtaminen
Kuopiossa 4.9.2003, Onnettomuustutkintakeskus


Terasrakenneyhdistys.fi//Esdep


wikipedia.org


SFS
-
EN 1991
-
1
-
1


Fastening Technology Manual, Hilti Corporation, 2004


Lattioiden värähtelysuunnittelu, VTT Rakennus
-

ja
yhdyskuntatekniikka


KSU
-
3010 Mekaaniset värähtelyt, Luentomoniste, Machine
Dynamics Lab, Tampere University of Technology


Teräsrunkoisten välipohjien värähtelyjen hallinta, VTT
Rakennustekniikka