design of fastenings for dynamic actions teheran
DESCRIPTION
PPP seismic design of anchorsTRANSCRIPT
Seismic design for anchors 1www.hilti.com
Design of Fastenings for Dynamic Actions (Seismic Loads)
Seminar Teheran
November , 2006
Seismic design for anchors 2www.hilti.com
Jenö Varga
1976 - 1981: Civil Engineering Diploma, Technical University of Budapest, Hungary
1981 - 1982: Structural Designer, “Olajterv” – Budapest, Hungary
1882 - 1983: Engineer, Hungarian Army, Hungary
1983 - 1991: Research Officer, Technical University of Budapest, Hungary 1984 - 1987: Post-graduate Research, The University of Adelaide, Australia
1991 - 1993: Senior Lecturer, The University of Witsvatersrand, Johannesburg, South Africa 1991 – 1993 Post-Doctoral Research
1993 - 1998: Research Officer, IWB, The University of Stuttgart, Germany approval and development tests of various pre-cast and post-installed
fasteners, contribution into CEB Fastening Design 1995 – 1997: Teacher Diploma, The University of Budapest
1998 - 2000: Teacher, International School of Stuttgart, Germany
Mathematics, Physics, Computing – IB course Higher lever
2000 - : Engineer, Hilti AG, Fastening Technologies (application support for non-code cases – fastenings, training Hilti staff,
calculation control, Profis Anchor - project manager, HAT-175 developer)
Seismic design for anchors 3www.hilti.com
Basics
induced accelerations activate forces of inertia and dampingDifferences to static design, classification, characteristics:
Classification Fatigue Seismic Shock
Number of
load cycles
Rate of strain
Examples
104 < n < 108 101 < n < 104 1 < n < 20
10-6 < < 10-3 10-5 < < 10-2 10-3 < < 10-1
•Traffic loads•Machines, cranes•Ventilators•Wind, Waves
•Earthquakes•Artificial earthquakes
•Explosions•Abrupt Structure failure•Crash Barriers
Ratio FR,dyn/FR,stat 30 (!) - 100% 80 - 130% 100 - 200%
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Examples EarthquakeTypical Fastening Problems (structural and non structural)
Suspended Ceilings
San Francisco Airport
Loma Prieta earthquake
1989
Toppled and damaged
furniture,City Hall Kobe, 1995
Falling wall panels
Public Building, Kobe, 1995
Damages in a Switchyard
Managua, 1972
Destroyed column fixing
San Francisco, 1989
Seismic design for anchors 5www.hilti.com
Earthquake Relevance
Seismic design for anchors 6www.hilti.com
Video from Hyogo-Ken Nanbu EarthquakeKobe, JapanJanuary 17, 1995 5:46 am
moment magnitude: 7.2 (JMA)loss of life: 5,200injured: > 26,000homeless: > 300,000estimated total loss: $100 billion
Kobe2.mpg
Seismic design for anchors 7www.hilti.com
Examples Shock
Typical Fastening Problems (structural)
Crash barrier fixing on concrete
(e.g. on bridges, etc.)
Explosions
(e.g. installations in civil shelters)
Emergency Installations
(e.g. emergency stop
fixings in elevators)
Seismic design for anchors 8www.hilti.com
Examples Fatigue
Machine fixing
(e.g. pumps, ventilators,
punching machines, etc.)
Robot fixing
(e.g. in automobile
industry, etc.) Fixing of cranes,
hydro-jacks, etc.)
Seismic design for anchors 9www.hilti.com
Suitability of Different Anchor Types
++ very suitable + suitable – not suitable
Anchor Type
Base Material
Displacem
ent controlled
Bonded
Bonded E
xpansion
Concrete screw
Torque controlled bolt
Torque controlled
sleeve
Undercut
Un-cracked concrete + ++ ++ ++ ++ ++ ++Cracked concrete Small cracks w<0,5mm
- + ++ ++ ++ ++ ++
Cracked concrete Medium cracks 0.5mm<w<1.0mm
- - + + + ++ ++
Cracked concrete Large cracks w>1,0mm
- - - - - + ++
Seismic design for anchors 10www.hilti.com
General Rules for Seismic Safe Design
• EQ-proof position and fastening
• EQ-proof design of the fixing
• Limitation or allowance of displacements
• Additional Fixings as constructive measure
Design Constructive
measures
Examples • design of anchors
• design of cross-
sections, etc.
• screws, clamping etc. to limit displacements
• struts to take horizontal loads
• free space to allow differential displacements
Seismic design for anchors 11www.hilti.com
Design for Earthquakes
Main difficulties for a proper earthquake design
1. Predictability of Seismic activities and loads Ground acceleration
time
time
Floor acceleration
Equipment acceleration
time
2. Cracks 3. Ductility
Seismic design for anchors 12www.hilti.com
Design for Earthquakes
FP static horizontal loadZ factor for seismic zone (from code)I factor for accelerationCP factor for stiffness of structureWP mass of element / equipment
ppp WCIZF
Example: Uniform Building Code (USA)
•estimation of horizontal load (static)
•resistance: safety factor 4
“fasteners shall be designed for four times the forces determined“
Seismic design for anchors 13www.hilti.com
3 main design possibilities
Stiff fixture: ”equivalent force process” Based on the building floor acceleration and the mass of the fixture.
Elastic fixture: “response spectra process” low natural frequency, the load on the fas-tening is governed by the fixture's response to dynamic incitation. Acceleration of the fixture is relevant when using this process.
Ductile fixture: “plastic design” fastening design is based on the maximum load that can be applied to the anchor when plastic deformation takes place.
stiff fixing
elastic fixing
ductile fixing
Seismic design for anchors 14www.hilti.com
Example: Equivalent Force Processafloor = 0.75 g ≈ 7.5 m/s2 (e.g. from codes)F=m . afloor
F=500 . 7.5 = 3,750 N = 3.75 kN Vd=F / 4Vd=3.75 / 4 = 0.94 kNNd= F . hCG / (2 . b)Nd= 3.75 . 100 / (2 . 60) = 3.13 kN
Sd Vd2
Nd2
kN3.273.130.94S 22d
Case Study Seismic Design
Seismic design for anchors 15www.hilti.com
Example: Response Spectra Process
Ventilation unit mounted on springs (forinsulation reasons): f0<15Hzafloor = 0.75 g ≈ 7.5 m/s2
Increasing factor due to low natural frequency: factor Aequip = 2.0 (out of literatureor manufact. informations)-> aequip = Aequip*afloor ≈ 15 m/s2 F = m*aequip
F = 600*15 = 9,000N = 9.0kNVd = F/4Vd = 9.0/4 = 2.25 kNNd = F*hCG / (2*b)Nd = 9 . 80 / (2*175) = 2.06 kNFadm,eq = Rd,crack > Sd
Case Study Seismic Design
Seismic design for anchors 16www.hilti.com
Example: Design with Plastic Moment
Installation channels used as columns for ventilation fixing:W=3’000mm3,fy=235N/mm2
Mplast = fy . WMplast = 235*3’000 = 705’000 NmmMplast is generated Fplast, acting at a height, hp:Fplast = Mplast/hp
Fplast = 705’000 / 500 = 1,410 N = 1.41 kN
Case Study Seismic Design
Seismic design for anchors 17www.hilti.com
Seismic Design with Hilti PROFIS Anchor program
Seismic design for anchors 18www.hilti.com
DIBt Guideline for the use of anchors in Nuclear Power Plants (NPP)
Impact categories:
A) probability of 1 occurrence during service life (design earthquake, plane crash, explosions...)
B) probability of 10 occurrences during service life
C) service loads (static) and incidents with a probability of 10 occurrences during service life
For safety relevant fixings in NPP, DIBt asks for additional tests beside thestatical DIBt or ETA-approval.
DIBt: Deutsches Institut für Bautechnik (German Institute for construction technology)
Special Applications: Nuclear Power Plants - Impact
Seismic design for anchors 19www.hilti.com
Design according to concrete-capacity-method, with special load and
material safety factors
Load safety factors:
G=Q= 1.0 for category A
1.2 for category B
1.4 for category C
Material safety factors:
concreteMc=Mp= 1.7 for category A
1.9 for category B
2.1 for category C
steel: according to ETAG, Annex C
(Ms=1.4 for tensile loads and Ms=1.25 for shear loads)
Special Applications: Nuclear Power Plants - Design
DIBt Guideline for the use of anchors in Nuclear Power Plants (NPP)
Seismic design for anchors 20www.hilti.com
• all anchors are set in closed hairline cracks
crack width at test load criteria - displacement at 0.5 Fu,m
1 1.5 mm - variation of Fu,m
- value of Fu,mt
N
- no failure
2 1.5 mm - develop. of displacement in time
N
t
- no failure
3 - develop. of displacement in time
w
t
1.5mm
1.0mmt
N
t
N
tV
- variation of displ. at Fu,m
4 1.0 mm - variation of Fu,m
- no failure
5 1.0 mm - final ultimate shear load
Special Applications: Nuclear Power Plants - TestsDIBt Guideline for the use of anchors in Nuclear Power Plants (NPP)
Seismic design for anchors 21www.hilti.com
Many different test procedures according to national regulations
Excerpt from ICC ES Acceptance Criteria (seismic method 6.2.7.2):
• Tension: pulsating sinusoidal seismic cycle• shear: alternating sinusoidal seismic cycle• frequency 0.1 to 0.2 Hertz• at least 5 anchors• shallowest and deepest embedment depth
Earthquakes: Testing of Anchors
Seismic design for anchors 22www.hilti.com
• Maximum load Ns: 1.5tension value for which recognition is desired
• The minimum load value shall not be smaller than 5% of Fu
• Uncracked concrete
Ns Ns: maximum tension test load
Ni Ni: a load midway between Ns and Nm
Nm
Nm: 1/4 of the average ultimate tension load Tref
Earthquakes: Testing of Anchors - Tension
10 30 100
load
cycles
Seismic design for anchors 23www.hilti.com
• Maximum load Vs: 1.5shear value for which recognition is desired
• The value for which recognition is desired shall not be larger than 133.33 percent of the allowable static loads under the same conditions
• Uncracked concreteVs
Vs: maximum shear test load
Vi
Vi: a load midway between Vs and Vm
Vm
Vm: 1/4 of the average ultimate tension load Tref
-Vs
-Vi
-Vm
Earthquakes: Testing of Anchors - Shear
10 30 100
load
cycles
Seismic design for anchors 24www.hilti.com
not suitable for EQ limited suitable for EQ
General Improvement of Fixings to Steel Beams
Standard Fixings
Seismic design for anchors 25www.hilti.com
General Improvement of Fixings to Steel Beams
Improvement with
Hilti MF-CS
Seismic design for anchors 26www.hilti.com
General Improvement of Fixings to Steel Beams
Securing of
channels with
End- Stoppers
Seismic design for anchors 27www.hilti.com
General Improvement of Fixings to Steel Beams
Securing of
channels with
End- Stoppers
Securing of
channels with
DX
Seismic design for anchors 28www.hilti.com
Installations: Pipes
The distance between the supports, the size and mass of the pipe and the horizontal acceleration are decisive whether or not struts are necessary.
Seismic design for anchors 29www.hilti.com
Installations: EQ Proof Channels
multiple fixing Load Direction
lateral longitudinalType
direct
hanger
console
no additional measures for EQ necessary
stiff U-Joch constructions or struts necessary
no additional struts
additional struts
necessary
ceili
ngw
all