Ultra High Performance Concrete (UHPC) is a high-strength, ductile material formulated by
combining portland cement, microsilica, fine
sand, water, and steel or ceramic fibers and
mesh.
The UHPC concrete provides compressive
strengths up to 250 MPa and flexural strengths
up to 30 MPa.
strengths up to 250 MPa and flexural strengths
up to 30 MPa.
The ductile behavior of UHPC is, with the
capacity to deform and support flexural and
tensile loads, even after initial cracking.
capacity to deform and support flexural and
tensile loads, even after initial cracking.
Façade elements made by UHPC, protect people and vehicles in an earthquake against
fragments litter in building structures made
of concrete and brickwork.
Concrete ceilings are rigid and brittle structures
that at the an earthquake stress the concrete
structure can break partially. The fracture is not
a slow phenomenon under load - the fracture
occurs when overloading on suddenly.
that at the an earthquake stress the concrete
structure can break partially. The fracture is not
a slow phenomenon under load - the fracture
occurs when overloading on suddenly.
The result is that to loosen individual fragments
of the ceiling could (fragments litter) fall on
machines or people. Are the fragments large
enough, it can lead to complete component
failure.
of the ceiling could (fragments litter) fall on
machines or people. Are the fragments large
enough, it can lead to complete component
failure.
UHPC prefabricated ceiling structures preventlike a prestressed network the fragments
become loose during the quake from the ceiling.
People and machines are protected by such
a suspended ceiling construction.
a suspended ceiling construction.
Emergency exits can win with such additional
structure several times of safety.
structure several times of safety.
Just as concrete ceilings and concrete
columns are complex constructions an
essential safety feature of a quake. The
concrete columns must take tremendous
flexural and compressive forces. A chipping
of the concrete structure of the inner steel
reinforcement would have a very rapid
component failure result.
columns are complex constructions an
essential safety feature of a quake. The
concrete columns must take tremendous
flexural and compressive forces. A chipping of the concrete structure of the inner steel
reinforcement would have a very rapid
component failure result.
Concrete columns can by a jacket (by
shedding) of UHPC gain much stability
and carrying capacity. A chipping of the
concrete structure at a load by an
earthquake of small and medium thickness
is almost impossible with the appropriate
cover.
In any case, should structural modifications such as
those described here, be agreed in consultation with
an architect, stress analysts and the competent local
planning authority.
www.hhbc-consulting.de
info@hhbc-consulting.de
shedding) of UHPC gain much stability
and carrying capacity. A chipping of the
concrete structure at a load by an
earthquake of small and medium thickness
is almost impossible with the appropriate
cover.
Advantages of UHPC
- Extreme high compressive strength
- High flexural strength
- Extreme low porosity
- Extreme good flowability
- Fast increase of compressive strength (min. 70% after 48 hours)
- High wear and impact resistance
- Absolute frost and thaw resistance
- Impermeable to fluids but still vapour permeable
- Anticorrosive features
- Good bonding to sub-bases, aggregates and reinforcement
- High temperature resistant
- Jointless lining
- Usable as mortar, grout and spray
- High ductility in combination with fibres or nano fibres
- Usable with standard concrete tools
Identification of damage in reinforced concrete building
- Soft storey failure
- Floating columns
- Plan and Mass irregularity
- Poor quality of construction materials and corrosion of reinforcement
UHPC®- His entry before and after a quake
UHPCmaterials can be used as additional safety in new concrete structures such as buildings, bridges, etc. For existing buildings and very old buildings, targeted activities involving the use of UHPC materials can significantly increase the safety of people and buildings. With UHPC materials, damaged buildings can be repaired to restore their old stability or improve their stability against earthquake loads by improving their building structure.
Possible applications for high quality UHPC materials
Repairing
To make existing structures safer for future earthquake
Retrofitting
To upgrade the earthquake resistance up to a level of
the present day codes by appropriate techniques
the present day codes by appropriate techniques
Strengthening
To upgrade the seismic resistance of the a damage
building
building
Rehabilitation
Reconstruction or renewal of a damaged building
to provide the same level of function, which the
building had prior to the damage
to provide the same level of function, which the
building had prior to the damage
Restauration
Rehabilitation of buildings in a certain area
Remoulding
Reconstruction or renewal of any part of an existing
building owning to change of usage or occupancy
building owning to change of usage or occupancy
Example of retrofitting techniques
- Minor cracksRepair by injecting UHPC
- Buckled longitudinal reinforcement, broken ties and crushed concreteReplacement of new reinforcement welded with existing bars and new additionally closed ties were placed, UHPC concrete with low shrinkage properties installed.
- Severely damaged columns adjacent to added wallsRetrofitting with encasing in UHPC concrete with appropriate longitudinal and transfers reinforcement.
- Other columnsRetrofitted with wire mesh and cover with 50 mm UHPC concrete by spraying or casting
- Existing masonry wallsAre retrofitting by using wire mesh and 30 mm of UHPC® mortar or spray
Like concrete cover constructions, concrete columns are
also essential safety aspect in a quake. The supports
have enormous bending and compression forces to take.
A spalling of the concrete structure from the internal steel reinforcement would have a very fast component failure
result.
also essential safety aspect in a quake. The supports
have enormous bending and compression forces to take.
A spalling of the concrete structure from the internal steel reinforcement would have a very fast component failure
result.
As with the concrete floors, columns can be replaced by a
grouting UHPC gain significantly in stability and carrying
capacity. A flaking of the concrete construction is under
load from a quake of small and medium strength with
appropriate sheath almost impossible.
grouting UHPC gain significantly in stability and carrying
capacity. A flaking of the concrete construction is under
load from a quake of small and medium strength with
appropriate sheath almost impossible.
In a quake will be in the brickwork of a building very quickly
showing cracks in the in the worst case, individual stones
break loose (Rubble throw) or a whole bandage, which
too can lead to a component failure.
showing cracks in the in the worst case, individual stones
break loose (Rubble throw) or a whole bandage, which
too can lead to a component failure.
The cracks in the masonry after a quake are permanent
and can become one uninhabitability and demolition of
the building to lead.
and can become one uninhabitability and demolition of
the building to lead.
Damaged masonry will be repaired differently depending
on the degree of damage.
on the degree of damage.
Fine cracks can be filled with UHPC injection methods.
Loose masonry, bad mortar can be increased by new
masonry and UHPC mortar substantially in the strength
and bending tensile strength.
masonry and UHPC mortar substantially in the strength
and bending tensile strength.
Masonry can also be improved in its entire surface with
a fibre reinforced UHPC layer in combination with steel
or fibreglass reinforcement substantially in its static
structure. Especially glass fibre or carbon fibre reinforced
UHPC show a high ductility.
a fibre reinforced UHPC layer in combination with steel
or fibreglass reinforcement substantially in its static
structure. Especially glass fibre or carbon fibre reinforced
UHPC show a high ductility.
those described here, be agreed in consultation with
an architect, stress analysts and the competent local
planning authority.
www.hhbc-consulting.de
info@hhbc-consulting.de
Comments
Post a Comment