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Transcript of Prezentace aplikace PowerPoint - cvut.czkps.fsv.cvut.cz/upload/files/masonry.pdf · ·...
Settlement of pier – clay soil, tensile and shear craks
Masonry Structure Vertical load – bearing structure
Declination of pier in
footing bottom - incorect
drainage and effects of
traffic – damages in
masonry of bay
raised humidity and
damage of surface layer of
pier
Damage of piers of structure – after ultimate limit state
Exterior part of pier – formwork from stone
block, interior part – filler from stone + mortar
Failures of head and
socle (base) of pier
Static securing of
overloading
(overstressing) piers
Local load of masonry under
binding beam
Deterioration (failure) of
thin masonry pier -
ultimate limit state
Cracks in facade – deformation
of steel beam overhead outlay
Part result of experimental works Brick P15 and P30
The influence of moisture on modul of elasticity and strength
abso
rpti
on
Str
ength
,
modul
of
elas
tici
ty
Brick
Brick
Brick
Brick
Brick
Brick
Sand stone – hard and soft spongilite stone
The influence of moisture on modul of elasticity and strength Part result of experimental works
Sand stone – hard Sand stone – soft
E
R
Abso
rpti
on
(%) A
bso
rpti
on
(%)
hard
soft
Mutual cooperation of brick and mortar in bed joint
Mortar with high strength
cohesion between brick and mortar – high
rigidity (small strain of mortar) - cracks in bed
joints
Mortar with small strength
Cohesion between brick and mortar – cracks
in bricks
tension
pressure tension
pressure
Mortar with high strength
cohesion between brick and mortar –
high rigidity (small strain of mortar)
- cracks in bed joints
Mortar with small strength
Cohesion between brick and mortar –
cracks in bricks
Isoline of principal stress σ1
Failure of masonry pier by cracks
Separate cracks Grave failure Emergency conditions
idealized work diagram
Deformation on
proportional limit
Formation
of
continuous
cracks –
plasticity of
mortar,
masonry
failure
ultimate deformation of masonry
Critical load Nt and ultimate load Nobs of
masonry depend on:
Compressive and tensile strength of mortar nad
brick (stone)
Dimensions, at first on depth of structurarl
matrials
Depth a quality of bed joints
Quality of mortar
Cohesion and workability of mortar
Brick bond
First cracks Expansion of
cracks Failures brick
pier - ultimate
limit state
deformation
pre
ssure
load
N
Failure of masonry pier load by normal force
first cracks load elastic zone Zone of cracking
creating continuous tension cracks
development and dissemination of tensile cracks
course of pressure trajectories Damage of pier in weaking zone
Zone of rise
of normal
strain – zone
of rise oblique
tensile cracks
Tensile cracks
Parting of pier into pole –
decrease of stability
trajectories of principal stresses Isoline of normal stress σx Isoline of normal stress σy
Failure of brick pillars
after reaching the ultimate load
Hmotnostní vlhkost (%) 1,5% 3,5% 14 % 16%
Mezní únosnost (kN) 630,9975 626,8 481,2 380,2
Mezní svislé poměrné přetvoření 0,00059 0,00080 0,00185 0,002065
Mezní příčné poměrné přetvoření -0,00589 -0,00719 -0,00377 -0,01962
Influence of moisture on load bearing capacity and vertical and horizintal
deformations of compression masonry piers – experimetal work
(bed joint 15mm, brick P15, lime mortar MV1)
CIX
12,312,88
13,76
11,56
13,0214,16 14,06
12,37
12,4
16,1614,97
14,78
150
150
11,56
12,37
14,7812,4
13,02
12,3
Mass moisture
Destruction of building – cause flood
Limit of rate vertical deformation
Limit of load capacity
Limit of rate horizontall deformation
Moisture – horizontal and
vertival section
631,0kN
101%626,8kN
100%
481,2kN
76%
380,2kN
60%
0,0kN
100,0kN
200,0kN
300,0kN
400,0kN
500,0kN
600,0kN
700,0kN
1,36% 3,56% 14,26% 15,81%
Vlhkost (%)
Za
tíže
ní
(kN
)
Comparation of limit load bearing capacity –
depending on the moisture
relativní únosnost podle ČSN 731101 a ČSN 730038, (e=0) relativní únosnost stanovená z pevností cihel v tlaku /2/ experimentálně stanovená relativní únosnost zděných pilířů
vlhkost (%)
rela
tivní ún
osnost (%
)1)
1) vztaženo k únosnoti při w < 5% (100%)
Lo
ad
Moisture
Rat
e of
Lo
ad
Moisture
Load capacity – Czech standard
Load capacity – exprimental work – brick and mortar
Load capacity – experimental work – masonry pier
Damage of masonries with different
moduls of deformation
cement
mortar lime mortar lime mortar
Maintenance of masonry structure with cracks
a) surface failures structure – removal of plaster and failure parts of masonry – removal of mortar from joint (to depth 30 –
50 mm) depth of cemented joint loading and liaison activated fine-grained cement mortar made new lime or cement plaster
b) Considerable failures pieces of building materials – greatly disturbed unit building material should be replaced by new,
contact gap between the original block and stone seals can be covered with steel or brass buckles anchored with epoxy resin
d) Masonry piers with vertical tensile cracks – bracing and switch clamping (securing before transverse tensile strain and
transverse prestress strain raising load press capacity of pier)
c) Local failures of masonry structure – at first securing of bearing structure, removal of failure part of masonry, filling
from pieces building materials (similar properties as original materials), anchor by bond or steel elemets, joint between new
and old part overlay by reinforce
Bracing failures mortar piers
Prestress by steel plate
Spiral wrap by wire
or rod
Prestress wire or rod
steel profile
Prestress of masonry pier
by wire or rod – without
continouse crackcs
Bracing of pier by
angel iron and pin Bracing of pier by steel plate and
pin
pin Angel iron
Weld steel plate
e) Local craks (active, passive) tensile and sheare – „stitching“ by steel rod 14 mm - 25 mm with fixing in load
bearing part of masonry (masonry without failures), steel element should be protected with a layer of cement mortar backing
and then covered with plaster and networks against corrosion
Schema of using steel buckle
distance
Cement
mortar
Groove in
masonry
Steel
buckl
e
Schema of using buckle by failure corner
anch
or
pla
te
fill a crack by cement mortar
fill a hole
Schema of using steel
buckle
Crossection a-a´
view
ground plan
fixing
buckle
Scheme of using steel rod
(buckle)
distance
Cement
mortar
Groove in
masonry
Steel
rod
Scheme of using rod (buckle) by failure
corner
anch
or
pla
te
fill a crack by cement mortar
fill a hole
Scheme of using steel
rod (buckle)
Crossection a-a´
view
ground plan
fixing
buckle
large distance
between the
clamps
„stitching“
e) Group of active cracks – switch clamping with sealing and injecting of cracks (cement, epoxide resin, polyester resin,
cement mortar and resin)
steel net
anchor
cement plaster
cracks
cracks
High sterngth steel bars (HELI bars) in grove
Spínání narušených zdí – Bracing of failure walls
Bracin of masonry structure by steel tie or prestress cabels (for prestress use steel wedge, screw or special elements), for
statics is better symetric design of tie by both side of wall
Groove in masonry
Front wall view
cross-section
cross-section cross-section cross-section
steel tie
pin
cross-section
cross-section cross-section
steel tie
pin
closing the outer ring
of reinforced concrete Temporary bracing
Strengthening and maintenance of mortar piers and walls
a) Sterngthening by brick wall – good qaulity bricks, connection between origin and new structure by wall pocket or
steel anchor, fine grain mortar, inserting reinforcement bars into every 3rd and 6th horizontal mortal joints and bonding with
high strenthmortar
b) Strengthening by concrete – at least concrete C12/15, thickness 60 – 120 mm, reduce shrinkage – reiforced net +
concrete grouting, grunite concrete
Strengthening by
concrete
stirrup
stirrup
concrete
maso
nry
concrete
Bore hole
Wall (thickness 440 mm) + concrete monierka (layer)
Dependance of load bearing capacity of pier
with strengthening by concrete – diferent
thickness of concrete layers (a), rate of
transvers reinforcement (b)
brick pillar dimensions 450 mm x 450 mm,
height of 3.3 m of brick mortar P10 MVC 2.5
Cement plaster
Comparation of load bearing capacity
strengthening by concrete strengthening by brick wall
brick pillar dimensions 450 mm x 450 mm, height of 3.3
m of brick mortar P10 MVC 2.5
60 mm thick of concrete, strengthening by brick wall –
brick CP20, mortar MVC 5
c) strengthening by reinforced plaster – transversal reinforcement prevets development of tension cracks
reinforce net
Plaster
masonry
stirrup
strengthening by reinforced
plaster
strengthening by
additing steel stirrup
d) strengthening by additing steel stirrup on every or every 2nd bed joint + cement mortar
Pier 450 mm x 450 mm (brick P10, mortar MVC 2,5)
Change of transversal reinforcement
Comparasion of load bearing capacity of masonry pier - strengthening by reinforced plaster (25
mm thick)
design as
concreting
e) strengthening by steel jacketing – contact between original masonry and steel angle – cement mortar
Strap before welding preheating from 500 till 700 °C,
After cooling on normal temperature – steel structure prestress masonry
masonry
strap
Masonry pier 450 mm x 450 mm (brick P10, mortar
MVC 2,5) depending on the size (dimension) of
vertical steel angles (a) and horizontal steel bands (b)
Comparasion of load bearing capacity of
masonry pier - strengthening by steel
jacketing
Bands 35/5 Bands 40/5 Bands 45/5
Strengthening with carbon (CFR) or glass
(GFR) materials and wire
wire strap
Attention –
Use epoxi resin - low melting temperature
(80°C)
(concreting tl. 80mm, B20, reinforcement
Ø 6mm á 100mm) experimetal work
Parts results of experimetal works
Comparison of experimentally determined ulitimate loads of pressure
reinforced
plaster steel
stirrup
Sterngtheni
ng by
concrete
Steel
jacketing
Steel
jacketing
without
strengthe
ning
ult
imat
e lo
ad
f) strengthening by steel structure (thin – walled profile) – no reological changes, continualy load transfer, no
requirements of foundation strengthening
thin-walled steel profiles
Load bearing capacity of
thin-walled steel profiles
distributing angle
mas
onry
wal
l
Cement bed Steel plate
tensioning screw
Cement mortar
Replacement of
column
New
foundation
Lifting by
hydraulic
press
temporary
security
column
pulled
down the
pillars
temporary
masonry piers
Setting
new
steel
column Concrete middle
part of fundation
Masonry Structure Sterngthening by brick wall
good qaulity bricks,
connection between origin and new structure by wall pocket or steel anchor,
fine grain mortar,
inserting reinforcement bars into every 3rd and 6th horizontal mortal joints and bonding with high
strengthmortar
Sterngthening by concrete
at least concrete B15,
thickness 60 – 120 mm,
reduce shrinkage – reiforced net + concrete grouting, gunite concrete
strengthening by reinforced plaster
transversal reinrorcement prevets development of tension cracks
strengthening by additing steel stirrup
on every or every 2nd bed joint + cement mortar
strengthening by steel jacketing
contact between original masonry and steel angle – cement mortar, preheating strip
strengthening by steel structure (thin – walled profile)
no reological changes, continualy load transfer, no requirements of foundation strengthening
strengthening by bracing
without continouse crackcs in pirer
Masonry Structure Cracks: passive, active
a) sewing (perpendicular)
b) grouting (from bottom up)
c) switch clamp (tie, activation! – tension can caused buckling
d) bonding
Cause of failure of stress mortar piers and wall are lateral tension
Principal stress 1 in masory compression pier (thickness 450 mm) – influence of rate of moduls of elasticity
Ec : Em and thickness of bed joint
bed joint bed joint bed joint
Principal stress 2 in masory compression pier (thickness 450 mm) – influence of rate of moduls of elasticity
Ec : Em and thickness of bed joint
bed joint bed joint bed joint
Typical failures of wall bay
windows and masonry in areas of
concentrated stress
Tensile cracks
shear cracks
exfoliation
of surface
layer
shear stress compressive normal stress
Schema of deformation and failure of bay masonry course of shear force in
reinforced concrete load bearing structure
cantilever
beam Backing masonry
reinforced concrete
beam
Deformation of
Cantilever beam
wall,
pier
compressive normal stress
wall,
pier
beam, girder
shear forces
areas of concentrated stress