Freyssinet UK - Specialist provider of Civil Engineering Projects » Seismic safety http://freyssinet.co.uk Bearing Tester, Concrete Repairs, Bearing Replacement, Concrete Corrosion Prevention Post Tensioning Bearing Manufacturer, Bearing Testing, Bridge Bearing Repair, Bridge Bearing Replacement, Bridge Bearings, Bridge Expansion Joints, Flat Jacks, PSC Post Tensioning, Stay Cable, Cable Stay Bridge, Concrete Corrosion Prevention, Structural Concrete Refurbishment, Concrete Repairs, Concrete Bridge Repairs, Concrete Building Repairs, Concrete Structure Repairs, Bearing Tester, Post Tensioning, High Tensile Bars, High Strength Bars, Prestressing Bars, Post Tensioning Bars, Freyssibar Fri, 14 Jun 2013 10:37:21 +0000 en-US hourly 1 http://wordpress.org/?v=3.4 Controlling Seismic Risks: Looking at buildings as an example http://freyssinet.co.uk/controlling-seismic-risks-looking-at-buildings-as-an-example/ http://freyssinet.co.uk/controlling-seismic-risks-looking-at-buildings-as-an-example/#comments Mon, 23 Jan 2012 10:19:56 +0000 admin http://freyssinet.co.uk/?p=1168 Although we cannot change seismic hazard, in other words the magnitude and occurrence of earthquakes, we can however increase a structure’s resistance/resilience and so reduce seismic risk through preventive measures. How structures respond Buildings do not all respond to earthquakes in the same way and their structural and architectural design influences how they are affected. [...]

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]]> Although we cannot change seismic hazard, in other words the magnitude and occurrence of earthquakes, we can however increase a structure’s resistance/resilience and so reduce seismic risk through preventive measures.

How structures respond
Buildings do not all respond to earthquakes in the same way and their structural and architectural design influences how they are affected. The structures act as oscillators which amplify or reduce ground movements to varying degrees.

Structure types
In terms of building structures, two main types emerge: portal frame construction with brick infill, and concrete or brick shell construction. In an earthquake, these two types respond differently: portal frame types are flexible and behave with a flexural tendency, whereas concrete or masonry structures are more subject to shear stress, especially in the case of low buildings.

Fragility – evenness
Good architectural design aims for: non-resonance of the structure with the oscillations of the ground, elimination of torsional phenomena, minimising stress concentrations (uneven loads), continuous mass distribution, bracing elements distributed in a way appropriate to mass distribution, etc.

Seismic repair and reinforcement strategies
There are three main operational methods, once the fragility and evenness factors of the building have been dealt with:
- Increasing ductility (for example, carbon fibre jacketing of columns)
- Increasing strength (for example, use of shotcrete)
- Reducing seismic action (for example, Transpec® damper or use of bearing systems to isolate from the ground)

Freyssinet operates in all the following fields:

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]]> http://freyssinet.co.uk/controlling-seismic-risks-looking-at-buildings-as-an-example/feed/ 0 Seismic safety: a major concern http://freyssinet.co.uk/seismic-safety-a-major-concern/ http://freyssinet.co.uk/seismic-safety-a-major-concern/#comments Mon, 23 Jan 2012 10:04:16 +0000 admin http://freyssinet.co.uk/?p=1160 Robert G., South-East Regional Director in France* presents seismic safety regulations and related issues. The context: In the world each year there are over one hundred and fifty earthquakes with magnitudes of 6 or higher (in other words earthquakes that release enough energy to be potentially destructive). The area of seismic safety is the subject [...]

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]]> Robert G., South-East Regional Director in France* presents seismic safety regulations and related issues.

The context:
In the world each year there are over one hundred and fifty earthquakes with magnitudes of 6 or higher (in other words earthquakes that release enough energy to be potentially destructive).
The area of seismic safety is the subject of numerous regulations and obligations the world over. Every natural disaster brings better knowledge of the energies that can be released and sometimes gives rise to changes in “seismic zones”, as was the case with France and the new “zoning” brought in in 2009.
Freyssinet provides an extensive range of solutions to meet seismic safety requirements for both new builds and repair.

What does Freyssinet offer in this area?
We operate in two major fields: new builds and repair of existing buildings.
- In the case of new builds, Freyssinet has developed appropriate seismic safety systems and offers a full range of dedicated products.
• Dampers that absorb seismic energy (TRANSPEC® range)
• Connectors that keep a structure firmly fixed to its foundations during an earthquake (TRANSPEC® Connector)
• Bearing systems (elastic, visco-elastic, pendulum, etc.)
• Shock absorbing cross bracing systems created with hydraulic or seismic safety dampers
• Tuned mass dampers
These various devices can be used alone or in combination to achieve the most effective and most appropriate protection for a particular construction project. Seismic protection is based on three fundamental operational modes which are: isolation, connection and dissipation. Every year numerous structures are built throughout the world incorporating these three protective methods.
In addition, Freyssinet is launching its new ISOSLAB® foundation solution used to isolate a series of buildings or a district and minimise seismic acceleration in traditional construction works. ISOSLAB® is certainly the safest slab foundation solution around, useable in all risk areas (buildings, basements, streets, play areas, etc.) and serving to isolate the general public from the effects of earthquakes.

- In the case of existing buildings, Freyssinet operates at all phases of a project, both pre- and post-quake: diagnosis, studies and works.
Freyssinet’s engineering & design and technical teams help clients make an initial diagnosis before deciding on how to strengthen structures and selecting the desired level of protection. The company can also intervene at the execution stage of the works our clients decide on.

In addition to the techniques described above, Freyssinet carries out seismic protection works based on two major intervention methods:
• Strengthening, consisting in making the structure more resistant, or more ductile (examples of works carried out: buildings, bridges, nuclear plants, etc.)
• Isolation, consisting in cutting into the structure at foundation level and then supporting it in order to insert a series of bearings that may or may not be connected to a damper
Foreva® techniques and solutions, for example underpinning, additional prestressing and carbon fibre reinforcement, are frequently used, effective solutions for achieving compliance with seismic safety regulations and are a major competitive advantage in this market.

*The South-East Region is one of the French regions with the highest earthquake risk levels in the country, 4 out of a possible 5, and is very experienced in handling projects in this field.

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