2nd EQ Quiz Flashcards
Multi-storey buildings are the most suitable example. These may be divided into two groups:
-Shear Buildings
-Moment Shear Buildings
The floors move only in the horizontal direction and there is no rotation of a horizontal section at the level of the floors.
Shear Buildings
The floors move in both the rotational and horizontal directions.
Moment-Shear Buildings
is the force required to produce a unit displacement
of the two adjacent floor levels.
stiffness coefficient or spring constant, kj
involve the estimation of dynamic soil properties and the study of the behaviour of various types of soils under dynamic loads.
SOIL DYNAMICS
The ________ of earthquakes is the most critical.
wave action
The extent of damage caused by earthquakes depends essentially on the dynamic response of soil deposits, which is governed by the cyclic nonlinear and strength characteristics of soil. Ground response analysis is used for the following:
- To predict ground surface motion for the development of design response spectra.
- To evaluate dynamic stresses and strains for the evaluation of liquefaction hazards.
- To determine the earthquake-induced forces.
Soil dynamics problems are generally divided into either:
-small strain amplitude responses
-large strain amplitude responses
to solve many important problems, particularly those dominated by wave propagation effects, only strains of small amplitude are induced in the soil.
small strain amplitude responses
for other problems such as those involving the stability of masses of soil, large-
amplitude strains are induced.
large strain amplitude responses
Under the influence of earthquake loading, the soil element may be one of the following
conditions:
- The initial static stress is large and the additional stresses induced by the
earthquake are small (Figure a). Here, a symmetrical pulsating stress system is
superimposed on an initial sustained stress. - The sustained stress is small and the pulsating strain is larger. The combined
effect is shown in Figure b.
Soil behavior under dynamic loading depends on the strain magnitude, the strain rate,
and the number of loading cycles. The strength of certain soils increases under rapid cyclic
loading, while saturated sand or sensitive clay may lose strength with vibration.
Dynamic Behavior of Soil
Loose sands can get compacted under _________.
vibration
A simple method to predict settlement consists of determining the ____________
critical void ratio,
maximum amount of possible settlement can be determined by
∆H = ((ecr − e)/(1 − e))*H