Rehabilitation and maintenance of buildings - 03 Karel Mikeš.
-
Upload
kristin-fox -
Category
Documents
-
view
215 -
download
2
Transcript of Rehabilitation and maintenance of buildings - 03 Karel Mikeš.
Rehabilitation and maintenance of buildings - 03
Karel Mikeš
2
Contents Properties of material Failures of steel structures Types of refurbishment Methods of reliability verification Basis of members design of steel structures Basis of joint design Assessment of steel structures Strengthening of members Strengthening and refurbishment of structures Refurbishment of masonry structures using
steelwork Seismic upgrading using steel structure
3
Connections Bolted Welded Riveted (history)
Realised: In shop On site
Calculation: on resistance on calculated internal forces
4
ConnectionsBolted connections
Types: According to static behaviour:
Normal (no preloading) Slip‑resistant (controlled tightening)
According to loading: Shear Tension
5
Bolted connections Shear loading
Common bolts: shear bearing
Slip‑resistant bolts: slip bearing
6
Bolted connections Shear resistance
for bolt grades 4.8, 5.8, 10.9
for other bolt grades
As Core area of cross section of bolt
fub Ultimate strength of bolt
i Number of shear planes
gM2 =1,25
2
60
M
ubsRd.v
fA,iF
2
50
M
ubsRd.v
fA,iF
7
Bolted connections Bearing resistance
p 1e1
d
d
0
Fb.Sd
521 ,k
1
4
1
33 0
1
0
1 ;f
f;
d
p;
d
emin
u
ubb
Effect of bolt pitches
t Minimum thickness in one directiond Diameter of boltd0 Diameter of holefub Strength of boltfu Strength of material
2
1
M
ubRd.b
ftdkF
8
Bolted connections Resistance of slip-resistant bolts
Slip resistance
prestressing force
As Core area of cross section of bolt
fub Ultimate strength of boltn Number of friction planesm friction coefficient ... 0,2 to 0,5
C.pM
sRd.s F
nkF
3
ubsC.p fA,F 70
2513 ,M
9
Bolted connections Bolts loaded in tension
Resistance in tension
The same resistance for common and preloaded bolts
2 90 MsubRd.t Af,F
10
Welded connections
Fillet welds
Butt welds fully supply basic material
Welds = rigid connections (no slip)
11
Welded connections Fillet welds
a effective throat thickness of the fillet weld┴ direct stresses perpendicular to the throat┴ shear stresses perpendicular to the axis of weld║ shear stresses parallel to the axis of weld║ direct stresses parallel to the axis of weld (neglected)
12
Welded connections Check of fillet weld
2
222 3Mw
uII
f
2
90M
uf,
2512 ,M
bw correlation factor
depends of steel grade
13
Welded connections Two fillet welds in parallel shear
0
Mww
ufll
aF
ll 2
14
Welded connections Connection of cantilever
V – transferred by web:
M – transferred by whole weld cross-section:
Point 1: tII, t┴, s┴
Point 2: t┴, s┴
aF
ll 2
zI
W wewe
weR W
MweW
M2
15
Welded connections Flange-to-web weld
Longitudinal shear flow Vℓ:
VSd
V
]m/kN[ISV
V
222 Mw
uf
aI
SV
a
Vll
16
Riveting Assembly
Heated to white heat Pneumatic hammer
(clamping rivet’s length max. s = 4,5 d)
Function (after cooling) Fully filled hole
Before riveting diameter is by 1 mm less then hole diameter Prestressing connected sheets
Material Rivet from steel with lower strength than basic material (when
they are exchanged can be cut off) Head
Half spherical (Countersink)
17
Riveting Supply at the refurbishment:
Additional rivets or bigger diameter Bolts – slip resistant connection, „retro“ heads of
bolts Bolts injected by epoxy
Riveting is history Exhibition on 3rd floor of Eiffel's tower
18
Riveted connections - Resistance Shear
Shear
Bearing ... as for bolts
Tension2
060
M
urt,Rd
Af,F
2
060
M
urv,Rd
Af,F