Earthquake

• viscous damper- Mechanical device that added to the systems for the purpose of limiting or retarding vibration.
• Seismic isolation


  A sophisticated strategy employed in seismic design to mitigate the impact of ground motion on structures
• Seismic isolation


  Decoupling the building from the ground motion by introducing isolation devices or base isolators between the structure and its foundation
• Passive damping


  A key component of seismic design aimed at dissipating energy and reducing the structural response to seismic forces
• Passive damping


  Integration of damping devices or systems into a structure to absorb and dissipate vibrational energy generated during seismic events
• Passive damping systems


  • Operate without external power input and are designed to provide effective energy dissipation over a wide range of seismic excitations
• Semi-active and active systems


  Advanced seismic mitigation techniques that involve the use of controlled damping or energy-absorbing devices to actively modify the structural response to seismic forces
• Unlike passive damping systems, which operate autonomously, semi-active and active systems require external control systems to adjust damping levels based on real-time seismic input
• Smart material


  Advanced seismic mitigation techniques that involve the use of controlled damping or energy-absorbing devices to actively modify the structural response to seismic forces
• Displacement-activated dampers


  • Metallic dampers
  • Friction dampers
  • Self-Centering Systems
• Velocity-activated dampers


  • Viscous dampers
  • Viscoelastic dampers
• Displacement-activated dampers: Cyclic response


  How these damping systems behave over repeated cycles of displacement during dynamic loading events, such as earthquakes
• Displacement-activated dampers: Cyclic response


  Structure undergoes displacement, the damper activates, dissipating energy by forcing the viscous fluid through orifices, reducing the amplitude of vibrations and controlling the movement of the structure
• Metallic dampers


  Damping devices that utilize metal components to dissipate energy and reduce oscillations or vibrations within a system
• Metallic dampers


  • Rely on the inherent properties of metals, such as their ability to deform, absorb energy, or generate friction, to provide damping
• Triangular Added Damping Added Stiffness (TADAS)


  A variation of ADAS system using triangular metallic plate dampers
• TADAS systems


  • Not affected by gravity loads because of the slotted holes in the base plate, and no rotational restraint are required at the top of the brace connection assemblage
• Lead Extrusion Devices (LED)


  Devices that take advantage of extrusion of lead through orifices within a cylindrical chamber
• LED devices


  • Have a stable hysteretic behavior, and the fatigue failure is avoided for elevated number of cyclic deformations, low sensitivity to thermal gradient, but the toxicity of lead represents the main disadvantage
• Buckling Restrain Braces (BRB)


  Composed of a steel core plate encased in a steel tube filled with concrete, where the steel core carries the axial load while the outer tube, via the concrete, provides lateral support to the core and prevents global buckling
• Friction dampers


  Devices that use friction to dissipate energy and stabilize structures during seismic events such as earthquakes
• Friction dampers


  • Provide resistance to dynamic forces by utilizing the friction generated when two surfaces slide against each other, helping to absorb and dissipate energy from ground motion, reducing the impact on a building or structure and enhancing its overall resilience
• Shape Memory Alloy Damper


  Devices made of shape memory alloy wires, where the hysteretic behavior is caused by a phase transformation (from martensite to austenite)
• Self-Centering Systems


  Devices used to reduce or eliminate the cumulative damage to the main structural elements, allowing the structural system to return to its original position after an earthquake
• Viscous and Viscoelastic Dampers


  Dissipate energy by transforming the mechanical energy into heat, consisting of a container with a liquid that passes through holes due to the movement of a piston
• Viscous and Viscoelastic Dampers


  • Disadvantages are the sensibility to temperature variations, the large dimensions, and the cost
• Viscoelastic Dampers


  Have hysteretic behavior and their simplest representation is the model kelvin solid, where the displacement is expressed in terms of strains and the force in terms of stress
• Viscous Wall Dampers


  A structural implementation of viscous dampers, made of a steel box filled with viscous fluid with a vane dipped in it, where the relative movement causes the plate to move through the viscous fluid
• Displacement-activated dampers


  A type of damping mechanism that respond to displacement or movement within a system, activating and providing damping force when a certain threshold of displacement is exceeded
• Velocity-activated dampers


  A type of damping mechanism that respond to the velocity of movement within a system, adjusting their damping characteristics based on the velocity of motion
• Characteristics of dampers


  • Reduce the displacement
  • Increase the energy dissipation
  • Increase the structural resistance
  • Increase the stiffness of the structure
• Damped Brace System


  Bracing system that increases the stiffness of a structure, accompanied by a reduction of the structure's fundamental period, while damping systems increase the lateral stiffness of the structure due to their inelastic effect
• Configurations of concentric devices

  • Diagonal form
  • V form
  • K form
• Diagonal form


  Diagonal members strategically placed to intercept and absorb horizontal forces generated during seismic events, acting as energy dissipators
• V form


  Tension and compression elements arranged in a V-shaped pattern, allowing the device to resist lateral forces by distributing them between the tension and compression elements, helping to dissipate energy and mitigate the effects of seismic activity
• The K form resembles the V configuration but is not classified as a damping system, as it does not serve the same purpose of dissipating seismic energy
• Viscous dampers (VD)


  When used in high-rise buildings in seismic areas, should reduce the vibrations induced by both strong winds and earthquakes
• Viscoelastic Coupling Damper (VCD)


  Made up of a viscoelastic polymer that provides instantaneous viscous and elastic restoring forces when in shear, providing additional damping for wind and earthquake, reducing the force imposed to the tower and allowing the structure to achieve a ductile performance
• Base isolation


  A seismic protection technique designed to minimize the impact of earthquakes on structures by physically separating the building's superstructure (upper portion) from its substructure (lower portion) resting on the ground
• After the Messina earthquake, the Commission for the reconstruction of the town of Messina in the South of Italy proposed two different solutions to isolate the buildings from the ground, which were not approved


  1909