Engineering for Earthquakes

1. Engineering for Earthquakes By Mrs. Shaw

2. What is an Engineer? • Engineering is the application of scientific and technical knowledge to solve human problems. • There are many types of engineers, some are listed below: • Civil – includes Structural / Architectural • Aerospace • Chemical • Biomedical

3. What do Structural Engineers do? • Structural Engineers must identify, understand, and integrate the constraints on a design in order to produce a successful result. • For example: • Designs for Buildings planned for close to the beach must take into account the wind load, water effects and erosion issues.

4. Earthquake Resistant Buildings • The focus of our project is to use some of the same design elements that structural engineers use to create buildings in areas where earthquakes happen frequently. • Where would they happen more frequently than anywhere else?

5. What is a fault line? • A fault line is where two tectonic plate boundaries meet.

6. Review of Earthquakes • An earthquake is what happens when two blocks of the earth suddenly slip past one another. • The surface where they slip is called the fault or fault plane. • The area where the earthquake energy is generated is called the focus. • The location directly above the focus it on the surface of the earth is called the epicenter.

8. How do Earthquakes happen? • Most earthquakes result from plate boundaries gliding past each other creating frictional stress. • When the frictional stress exceeds a critical value that results in a violent displacement of the Earth’s crust and the elastic strain energy is released and radiated out.

9. How is the energy measured? • Seismometers are instruments that measure motions of the ground, including those of seismic waves generated by earthquakes, volcanic eruptions, and other seismic sources. Seismometer seismograph

10. Building movements in EQ’s • In an earthquake, the building base experiences high-frequency movements, which results in inertial forces. • **Review: Inertia is the ability of an object to resist a change in motion.

11. Example of inertial strain • During an earthquake, if a rigid block is free-standing it will move freely in the direction opposite the ground movement. • If the block is solidly founded in the ground, it must absorb the inertial force internally and the result will be a crack near the base.

12. EQ Resistant Building Designs • Engineers choose from various structural components when designing buildings to withstand earthquakes. • Examples include: • Diaphragms • Shear walls • Braced frames • Base isolation • Energy dissipation devices

13. Diaphragms • Diaphragms are horizontal resistance elements, generally floors and roofs that transfer the lateral forces between the vertical resistance elements (shear walls or frames).

14. Shear Walls • Shear walls are vertical walls that are designed to receive lateral forces, from diaphragms and transmit them to the ground.

15. Braced Frames • A Braced Frame is a structural system which is designed primarily to resist wind and earthquake forces. • Members in a braced frame are designed to work in tension and compression, similar to a truss. • Braced frames are almost always composed of steel members.

16. Base Isolation • A base isolated structure is supported by a series of bearing pads, which are placed between the buildings and building foundation.

17. Energy dissipation devices • Dampers are mechanical devices designed to absorb kinetic energy. • Dampers are mechanical devices designed to absorb kinetic energy. • They are used in base isolation designs.