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Ceiling structures CEILBOT-PROJECT INTRODUCTION TO CEILING STRUCTURES History Situation today Loading Fastening Vibrations and sound Risks Eelon Lappalainen.

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Presentation on theme: "Ceiling structures CEILBOT-PROJECT INTRODUCTION TO CEILING STRUCTURES History Situation today Loading Fastening Vibrations and sound Risks Eelon Lappalainen."— Presentation transcript:

1 Ceiling structures CEILBOT-PROJECT INTRODUCTION TO CEILING STRUCTURES History Situation today Loading Fastening Vibrations and sound Risks Eelon Lappalainen A.Aalto, Maison Carré, France A ceiling is an overhead interior surface that bounds ("ceils") the upper limit of a room. Wikipedia

2 History Ceiling is quite new invention in residential buildings, started to become general after WW II Ceilings were used before WW II usually in castles 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: –Ceilings made of concrete: –Ceilings made of steel: Typical for ceilings is diversity of different structures and support systems Old ceilings were designed mainly to support its own weight -> adding more load will usually cause problems (big deflection, cracking, even collapse) Design methods and quality of materials varies a lot

3 Benedectine Abbey of Einsiedeln, Switzerland

4 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 hides 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

5 Installations inside the ceiling

6 Loading Basic loads are given in design codes (Eurocode, ACI, DIN, RakMK) Dead load Live load (1,5…10kN/m2) Ceiling load (~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 For simple calculations dynamic loading can be expressed: – static load x dynamic factor –displacements are limited Complex dynamic problems are usually calculated by FEM

7 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 strength TIMBER SCREW HOLLOW CORE SLAB LOCKING PART FIXING DEVICE COLD FORMED STEEL PROFILE FIXING DEVICE SCREW NUT&BOLT ANCHOR BOLT OR CHEMICAL ANCHOR CONCRETE SLAB

8 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 oscillationFree oscillation, damping Forced oscillation Forced oscillation, damping steady-state

9 Vibration sources and isolation

10 Risks Overloading and wrong material choises could be fatal and may cause serious damages and even loss of lifes Fixing type must be safe and inspected properly All fixings 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

11 Sources RT , Alakatot ja sisäkattoverhoukset RT , Välipohjarakenteita Betoni Suomessa , Betoniyhdistys ry Tutkintaselostus B 4/2003 Y, Kylpylän alakaton romahtaminen Kuopiossa , Onnettomuustutkintakeskus Terasrakenneyhdistys.fi//Esdep wikipedia.org SFS-EN 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


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