Long Quiz Flashcards
is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth’s lithosphere that creates seismic waves. (cannot be prevented nor accurately predicted)
Earthquake
What are the 3 CAUSES of (NATURAL) EARTHQUAKE
Volcanic origin, Tectonic origin, Collapse of underground spaces
The most harms and losses on human assets are caused by what type of earthquake
Tectonic earthquake
The main cause of earthquake is volcanic eruptions. These earthquakes occurs in areas with frequent volcanic activities.
Volcanic origin
Earthquake produced by sudden movement along faults and plate boundaries.
TECTONIC ORIGIN
are pieces of earth’s lithosphere
Tectonic Plates
3 types of tectonic plates
Major Plates, Minor Plates, Microplates
comprise the bulk of the continents
and the Pacific Ocean
Major Plates
These smaller plates are often not shown on major plate maps, as the majority do not comprise significant land area.
Minor Plates
These plates are often grouped with an adjacent major plate on a major plate map.
Microplates
What are examples of major plates?
African Plate
Antarctic Plate
Eurasian Plate
Indo-Australian Plate
Pacific Plate
North American Plate
South American Plate
What are examples of minor plates?
Somali Plate
Nazca Plate
Indian Plate
Amurian Plate
Sunda Plate
Philippine Sea Plate
Okhotsk Plate
Arabian Plate
Yangtze Plate
Carribean Plate
Cocos Plate
Caroline Plate
Scotia Plate
Burma Plate
New Hebrides Plate
What are examples of microplates?
Adriatic
Aegean Sea
Anatolian
Balmoral Reef
Banda Sea
Bird’s Head
Burma
Capricorn
Coiba
Conway Reef
Easter
Explorer
Futuna
Galapagos
Gonâve
Gorda
Greenland
Halmahera
Iberian
Iranian
Juan de Fuca
Juan
Fernández
Kerguelen
Kermadec
Madagascar
Malpelo
Manus
Maoke
Mariana
Molucca Sea
New Hebrides
Niuafo’ou
North Andes
North Bismarck
North Galapagos
Nubian
Okinawa
Panama
Pelso
Philippine Mobile Belt
Rivera
Sangihe
Seychelles
Shetland
Solomon Sea
South Bismarck
South Sandwich
Timor
Tisza
Tonga
Woodlark
The movement of tectonic plates is most evident at the boundaries between the plates. There are three main types of boundaries:
Convergent Boundary, Divergent Boundary, Transform Boundary
is where two tectonic plates push
together. Although the movement is slow,
these type of boundary can be areas of geological activity such as the forming of mountains and volcanoes. They can
also be areas of high earthquake activity.
Convergent Boundary
A _______ boundary is one where two plates are getting pushed apart. New land is formed by magma pushing up from the mantle and cooling as it reaches the surface.
Divergent Boundary
A_________ boundary is one where two plates slide past each other. These places are often called faults and can be
Transform Boundary
In convergent boundary, sometimes one plate will move under the other. This is called _________
Subduction
The area on land where divergent boundary occurs is called a ________
Rift
Places where transform boundary occurs and can be areas where earthquakes often occur.
Faults
Quote to remember
Plate boundaries are always faults; but not all faults are plate boundaries
What are the 4 types of faults?
NORMAL FAULT
REVERSE FAULT
STRIKE SLIP FAULT
OBLIQUE FAULT
the hanging wall moves downward, relative to the footwall.
Normal Fault
is the opposite of a normal fault wherein the hanging wall moves up relative to the footwall.
Reverse Fault
When rocks on either side of a nearly vertical fault plane move horizontally
Strike-slip Fault
is special type fault that forms when movement is not exactly parallel with the fault plane.
Oblique Fault
The application of civil engineering to reduce life and economic losses due to earthquakes, (i.e to mitigate seismic risk)
Earthquake Engineering
is a major inter-related system of geological faults throughout the whole of the Philippine Archipelago, primarily caused by tectonic forces compressing the Philippines into what
geophysicists call the Philippine Mobile Belt.
Philippine Fault System
is composed of a large number of accretionary blocks and terranes.
PHILIPPINE MOBILE BELT
Some notable Philippine faults include
the Guinayangan , Masbate and Leyte Faults
MOST ACTIVE FAULTS IN THE PHILIPPINES
Marikina Valley Fault System
Western Philippine Fault
Eastern Philippine Fault
Southern of Mindanao Fault
Central Philippine Fault
2 major segments of the Marikina Valley Fault System
West Valley Fault and East Valley Fault
also known as the Valley Fault System ( is a dominantly right lateral strike slip fault system in Luzon, Philippines It extends from Doña Remedios Trinidad, Bulacan in the north and runs through the provinces of Rizal, and the Metro Manila cities of Quezon, Marikina, Pasig, Makati, Taguig and Muntinlupa, and the provinces of Cavite and Laguna that ends in Canlubang
Marikina Valley Fault System
is used to describe an area where earthquakes tend to focus.
SEISMIC ZONES IN THE PHILIPPINES
Types of SEISMIC ZONES
Zone II (least seismic region)
Zone IV (Most seismic region)
Where should we avoid constructing our buildings?
Phivolcs recommends avoiding construction within 5 meters on each side of a fault trace, or a total width of 10 meters. This is called the ideal “10 meter wide no build zone “ in the vicinity of a fault.
Ideally, we should not build in the 10 meter wide no build zone to avoid the hazard of ground fissure.
is the primary earthquake measuring instrument. It produces a digital graphic recording of the ground motion caused by the seismic waves.
Seismograph
The digital recording produces by a seismograph is called a ______
Seismogram
is the amount of energy released by an earthquake. It is quantitative (measurable) and can be recorded by a seismograph. (Richter’s Scale). It does not vary with the distance from the epicenter and are written in hindu arabic numbers and decimals.
Magnitude
it is the strength of the earthquake as experienced by the observer. It is qualitative (describable) and can be determined from the shaking and damage produced. (mercalli scale). It varies on how close or far the location from the epicenter is. Written in roman numerals
Intensity
is a measure of the strength of shaking during the EQ
intensity
is a number, which is a measure of energy released in an earthquake
magnitude
Computation on how big an earthquake magnitude is
Divide langz
is actually the measure of the PHYSICAL SIZE of the Earthquake, not the Strength (ENERGY) of the Earthquake.
It is the energy or strength that knocks down buildings, this is really the more important comparison.
The MAGNITUDE SCALE
Computation on how strong an earthquake magnitude is
logE = 1.5 M
then divide
an oscillation of the parts of a fluid or an elastic solid whose equilibrium has been disturbed, or of an electromagnetic wave.
Vibration
is defined as the oscillating, reciprocating, or other periodic motion of a rigid or elastic body or medium forced from a position or state of equilibrium.
Vibration
TYPES OF VIBRATION
FREE VIBRATION
FORCED VIBRATION
DAMPED VIBRATION
Occurs when a mechanical system is set in motion with an initial input and allowed to vibrate freely. The mechanical system vibrates at one or more of its natural frequencies and damps down to motionlessness.
Free Vibration
Classifications of Free Vibration
Longitudinal
Transverse
Torsional
is when a time varying disturbance is applied to a mechanical system The disturbance can be a periodic and steady state input, a transit input or a random input
Forced Vibration
is when an energy of a vibrating system is gradually dissipated by friction and other resistances
Damped Vibration
is also known as a long period seismograph If the natural period of the pendulum is long relative to the period of the ground motion and if an appropriate damping coefficient for the pendulum is chosen, the displacement, x, of the pendulum is proportional to the ground motion, x g i e 𝑥∝𝑥𝑔 Thus the recorded displacement can be expressed in terms of ground motion times constant
DISPLACEMENT SEISMOGRAPH
If the natural period of the pendulum is set close to that of ground motion and if the damping coefficient of the pendulum is large enough, then x is proportional to ሶ 𝑥𝑔 and the ground velocity, ሶ 𝑥𝑔 can be determined
VELOCITY SEISMOGRAPH
is also known as a short period seismograph These are also called accelerometers If the period of the pendulum is set short enough relative to that of ground motion, by means of an appropriate value of the pendulum’s damping coefficient, 𝑥=ሷ 𝑥𝑔is obtained Thus, the ground acceleration ሷ 𝑥𝑔can also be recorded
ACCELERATION SEISMOGRAPH
Earthquakes can be classified into the following four groups:
- Practically a single shock
- A moderately long, extremely irregular motion
- A long period ground motion exhibiting pronounced prevailing periods of vibration
- A ground motion involving large scale, permanent deformations of the ground
At the site of interest, there may be slides or soil liquefaction
A ground motion involving large scale, permanent deformations of the ground
Such motion results from the filtering of earthquakes of the preceding types through layers of soft soil that exhibit linear or almost linear soil behavior, and from the successive wave reflections at the interfaces of these mantles
A long period ground motion exhibiting pronounced prevailing periods of vibration
Motion of this type occurs only at short distances from the epicenter, only on firm ground, and only for shallow earthquakes
Practically a single shock
This is associated with a moderate distance from the focus and occurs only on firm
ground
A moderately long, extremely irregular motion
The motion of the ground can be described in terms of _____, ______, ______
displacement, velocity, or
acceleration
the variation of ground acceleration with time, recorded at a point on the ground during earthquake
Accelerogram
For structural engineering purposes,
________ gives the best measure of an
earthquake’s intensity
acceleration
The __________ is directly related to the energy transmitted to the structures and the intensity of damage caused
ground velocity
The ____________ may be of interest for the design of underground structures
ground displacement
interaction between the elastic ground acceleration and a structural response.
it represents the earthquake motion for the calculation of design seismic actions, at a given point on the surface of the earth
ELASTIC RESPONSE SPECTRUM
resists the effects of ground shaking although it may get severely damaged, it does not collapse during a strong earthquake
This implies that the damage should be controlled to acceptable levels, preserving the lives of the occupants of the building at a reasonable cost Engineers thus tend to make the structures earthquake resistant
Earthquake-resistant structure
one of the methods of analysis in earthquake design where a static force equivalent to the dynamic force is applied to the structure.
EQUIVALENT LATERAL FORCE METHOD
load where the magnitude, direction, or a point of application varies with time.
Dynamic Load
Classifications of Dynamic Load
-Deterministic (prescribed)
-Stochastic (random)
if the loading is a known function of time, and the analysis of a structural system to a prescribed loading is called ________
Deterministic analysis
The variations of a random force in time may be affected by a number of factors, so its determination always implies a certain probabilistic element.
Stochastic Analysis
are examples of repetitive loads exhibiting
time variation successively for a large number of cycles.
Periodic Loading
Classifications of Dynamic Loading
-Periodic Loading
-Non-periodic Loading
The simplest periodic loading is the sinusoidal variation termed as _____
simple harmonic
may either be short duration impulsive
loadings or long duration.
Examples: Earthquakes, wind, blasts and explosions
Non-periodic loading
the process by which free vibration steadily diminishes in amplitude
Damping
Mechanisms by which energy is dissipated from a deforming structure
Damping Mechanisms
Three Approaches of Discretization of a Structure that may be used depending upon the suitability
- LUMPED MASS APPROACH
- GENERALIZED DISPLACEMENT PROCEDURE
- FINITE ELEMENT PROCEDURE
The inertia forces resulting from structural displacements are influenced by the magnitude of masses This makes the analysis complicated and necessitates that the problem is formulated in terms of differential equations
LUMPED MASS APPROACH
represent an infinite degrees of freedom (DOF) system
Continuous models
To simplify the analysis, it may be assumed that the mass of the beam is concentrated in a series of discrete points and that the inertia forces will develop only at these mass points Such discrete points are called 1. ______ and the concentrated mass in these points is called 2. _______. In this case, the displacements and accelerations need to be defined only at these mass points The lumped mass models depict finite DOF systems
- lumps
- lumped mass
the number of displacement components to be considered in order to represent the effects of all significant inertia forces of a structure
Dynamic Degree of freedom
is most effective for a system where the mass is quite uniformly distributed throughout The underlying assumption is that the deflected shape of the structure can be expressed as the sum of a series of specified displacement patterns these patterns then become the displacement coordinates of the structure
GENERALIZED DISPLACEMENT PROCEDURE
is the most efficient one, especially for expressing the displacements of arbitrary structural configurations It combines certain features of both, the lumped mass approach and the generalized coordinate approach It provides a convenient and reliable idealization of the system and is particularly effective in digital computer analyses
FINITE ELEMENT PROCEDURE
the mathematical expressions defining the dynamic displacements of the structure.
EQUATIONS OF MOTION
METHODS TO FORMULATE AND SOLVE EQUATIONS OF MOTION to provide the required displacement histories
- DIRECT EQUILIBRATION USING D’ ALEMBERT’S PRINCIPLE
- PRINCIPLE OF VIRTUAL DISPLACEMENTS
- HAMILTON’S PRINCIPLE
The essential physical properties of any linearly elastic structural system subjected to dynamic loads include its:
-mass
-elastic properties (flexibility or stiffness)
-energy-loss mechanism (Damping)
-external source of excitation (Loading)
A single storey structure can be modelled as an ________
SDOF system
is the most commonly used measure of the intensity of shaking at a site.
PEAK GROUND ACCELERATION (PGA)
