BUILTECH FEST 20016

Department of Building Engineering and Construction Management(BECM) Khulna University of Engineering and Technology Khulna-9203,Bangladesh

EARTHQUAKE SUSTAINABLE BUILDING USING FLUID VISCOUS DAMPER

Rakibul Hasan1 and Ahasanul Kabir sabbir2

Student ,BECM,KUET1 and Student, BECM,KUET2

Every Structure is subjected to some kind of dynamic loading during its life span like wind load,earthquake load etc. Earthquake is a major natural disaster which caused a lot of destruction in many areas of the world.Earthquake Engineering has emerged to analysis of structures subjected to seismic loading and ultimatly finding solution for sustainability of a structure in seismic event. With most structures, a relatively small amount of Fluid Viscous damper provides a large reduction in stress and deflection by dissipating energy from the structure. Building shaking laterally back and forth during a seismic event. Column stress is at a maximum when the building has flexed a maximum amount from its normal position. This is also the point at which the flexed column reverses direction to move back in the opposite direction. If we add a Fluid Viscous Damper to the building, damping force will drop to zero at this point of maximum deflection.

Base isolation of large structures has proven to be an effective way to attenuate seismic excitation. However it can be costly, and can also involve major building modification. It is now possible to secure a comparable degree of earthquake mitigation with fluid viscous dampers located throughout a structure, without having to isolate the building.

A Fluid Viscous Damper is one of the most implemented seismic protection systems in earthquake prone areas. FVDs are often used as an energy dissipation device on structures built in seismic hotspots. A structure that utilizes fluid viscous dampers will increase its critical damping ratio and reduce the dynamic magnification factor. This reduction will reduce the dynamic response of a structural system in the event of an earthquake or other external excitation.FVD works according to following principle- Fdamper = C*Vq.... (1) ; where C = damping constant (lb*sec/in) ; V = velocity (in/sec); q = velocity exponent.

Figure 1: Critical applications require high-performance damping devices.

As the fastest urbanizing country in South Asia,Bangladesh is in earthquake risky resion. Bangladesh, being located close to the plate margins of Indian and Eurasian plates, is susceptible to earthquakes. The collision of the Indian plate moving northward with the Eurasian plate is the cause of frequent earthquakes in the region comprising Bangladesh and neighbouring India, Nepal and Myanmar. The possibility of a major earthquake occurring soon is quite high.Dhaka, located in the central region of Bangladesh, could be affected by any of the four earthquake source zones, presented earlier.As a result, there is a concerted need to raise awareness of earthquake risk and safe building practices among migrant workers and households. So it is egerly need to find out a method that is that is cost effective to build a

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earthquake sustainable building.For this purpose Fluid Viscous damping is more cost effective and essy to use in constructoin (lick building ,bridge etc.)

The Fluid Viscous Damper are constructed of stainless steel and other extremely durable materials as required to furnish a life at least 40 years.The demping fluid is silicone oil,which is inert,non-flammable,non-toxic,and stable for extremely long period of time.The damping action is provided by the flow of fluid across at the piston head.The fluid through orifice flows at high speed as the damper strokes.It works as equation (1).When the fluid viscous damper strokes in compression, fluid flows from Chamber 2 to Chamber 1. When the fluid viscous damper strokes in tension, fluid flows from Chamber 1 to Chamber 2. The high pressure drop across the annular orifice produces a pressure differential across the piston head, which creates the damping foce. Fluid viscous dampers can be installed as diagonal members in several ways, or can tie into chevron braces.

Figure 2:Working Mechanism of Fluid Viscous Damper.

The constant force output of a friction damper increases maximum column or pier stress under any deflection of the structure while Fluid Viscous Dampers do not increase column stresses due to their inherent out of phase response output.Friction dampers put out an essentially constant force when deflected, independent of velocity. This response causes continual stress in the structure during all thermal expansion and contraction of the structure while Fluid Viscous Dampers put out virtually zero force at the low velocities associated with thermal motion. Friction dampers restrict a structure from restoring itself to its original position after seismic events while Fluid Viscous Dampers allow the structure to re-center itself perfectly at all times.

Fluid Viscous Dampers have a successful history of more than 50 years of use by the U.S. Government and U.S. heavy industry. This devices has produced over two million Fluid Viscous Dampers since 1955, designed and manufactured at a single manufacturing site in North Tonawanda, NY, U.S.A.Pressure cylinders and end caps of all dampers are machined from alloy steel billet, internally threaded, and through hardened.Its operating temperature range is -40°F to +160°F. All Fluid Viscous Dampers are built to be maintenance free. No reservoirs, external plumbing, fluid level indicators, accumulators, or periodic fluid changes are needed. Thus, all users benefit from this device to construct earthquake proof building. In bangladesh, it is suggested to use Fluid Viscous Damper in steel and concrete structure for earthquake sustainable construction safety.Fluid viscous dampers can be added to either a new or an existing structure to greatly improve structural performance during a seismic event. They offer an attractive alternative to base isolation in terms of cost and ease of installation .

In fine, we would like to express our sincere gratitude and respect to our honourable teacher Mr.Md.Hamidul Islam for guidelines and to our parents as our unfailing source of inspiration.

Reference: [1] EN 1998-1:2004 . Design of Structure for Earthquake Resistance. Part 1: General Rules, Seismic Action and Rules for Buildings (Euro code 8). CEN ,European Committee for Standardization. [2] Earthquake resistant designs: By, M. Mayur,Siddharth Institute of Engineering and Technology ,Puttur. [3] http://theconstructor.org/tag/earthquake-engineering/page/2 [4] http://articles.architectjaved.com/earthquake_resistant _structures/effect-of-earthquakes-on-structure. [5] http://articles.architectjaved.com/earthquake_resistant _structures/effect-of-earthquake structure (chapter -3) [6] AASHTO(1999).”Guide specifications for Seismic Isolation Design “,American Association of State Highway and Transportation Officials, Washington, D.C. [7] www.taylordevices.com [8] www.iosrjournals.org/

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