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Humming earthquakes incident - حادثة الطنين من الزلازل والاهتزاز وتصدع الأبنية -- effect of seismic on soil type
effect of seismic on soil type
ﺗﺄﺛاﻟﺗﺄﺳﯾس ﺗرﺑﺔ ﻧوع ﻋﻠﻰ اﻟزﻻزل ﯾر
اﻷﺑﻨﯿﺔ ﻋﻠﻰ اﻟﺰﻻزل ﺗﺄﺛﯿﺮ
Effects of Earthquakes on Buildings
Ground shaking (pushing back and forth, sideways, up and down)
generates internal forces within buildings called the Inertial Force
(FInertial), which in turn causes most seismic damage.
FInertial = Mass (M) X Acceleration (A).
اﻟﻜﺘﻠﺔ = اﻟﻌﻄﺎﻟﺔ ﻗﻮى×اﻟﺘﺴﺎرع
The greater the mass (weight of the building), the greater
the internal inertial forces generated.
Lightweight construction with less mass is typically an
advantage in seismic design
Greater mass generates greater lateral forces, thereby
increasing the possibility of columns being displaced, out of
plumb, and/or buckling under vertical load (P delta Effect).
Earthquakes generate waves that may be slow and long, or
short and abrupt.
The length of a full cycle in seconds is the Period of the
wave and is the inverse of the Frequency.
All objects, including buildings, have a natural or
fundamental period at which they vibrate if jolted by a shock
The natural period is a primary consideration for seismic
design, although other aspects of the building design may
also contribute to a lesser degree to the mitigation
If the period of the shock wave and the natural period of the
building coincide, then the building will “resonate” and its
vibration will increase or “amplify” several times.
Fig. 4. Height is the main determinant of fundamental period—each
object has its own fundamental period at which it will vibrate.
The period is proportionate to the height of the building.
اﻟﺒﻨﺎء دوراﻟﺒﻨﺎء ارﺗﻔﺎع ﻣﻊ ﯾﺰداد T
The soil also has a period varying between 0.4 and 1.5 sec.,
very soft soil being 2.0 sec. Soft soils generally have a
tendency to increase shaking as much as 2 to 6 times as
compared to rock.
Also, the period of the soil coinciding -with the natural
period of the building can greatly amplify acceleration of the
building and is therefore a design consideration.
Fig. 5. Tall –
buildings will undergo several modes of vibration, but for
seismic purposes (except for very tall buildings) the
fundamental period, or first mode is usually the most significant
ﺗرﺑﺔ واﺳﺗﺑدال إﺣﻼل ﺑﻌﻣل ﯾوﺻﻲ
ﻋﻣﯾﻘﺔ اﺳﺎﺳﺎت اﺳﺗﻌﻣﺎل اواﻟﺧوازﯾﻖ ﻣن
-ﻟﺑﺷﺔ اﺳﺗﻌﻣﺎل وﯾﻣﻛناﻟﻧزول ﻣﻊ (ﺣﺻﯾرة )اﻷﻋﻣﺎق اﻟﻰ
اﻷﻗﺑﯾﺔ طواﺑﻖ ﻣن ﻋدد ﻣﻊ
ﻣﺣﯾط ﻋﻠﻰ ﺳﺎﻧدة ﺟدران ﺑﻧﺎء اوﻗﺎﻋدة ﺗﺻﺑﺢ ﺣﯾث اﻟﺑﻧﺎء
ھروب ﯾﻣﻧﻊ ﻣﻐﻠﻖ ﻛﺻﻧدوق اﻷﺳﺎسﺧﺎرج اﻟﺗرﺑﺔ ذرات
اﻟﺗﻣﯾﻊ ﺣﺎدﺛﺔ وﯾﻣﻧﻊ اﻟﻠﺑﺷﺔ ﻗﺎﻋدة ﺣدود
whirring incident in the vibrational animations
of wind and earthquakes
Incident whirring is when the period T1 of building
equal With the period of soil T2
Instead of the soil absorbs and dispersion part of
the earthquake forces But increases and doubles
inertia forces becuse of equal The two periods
T1=T2 and building collapses to a strong stress internal
inertia is greater than that designed the building on
• For an incident to avoid whirring and equal periods
Between rocky soil Low period T1 and building period T2
in case wind, earthquakes and seismic animations
This occurs only in buildings with little height as
in apartments One floor to two and buildings with rigid
shear sentences Where T as small as the period at the stone
buildings and blocks
So in the rocky soil prefer to choice of construction
structural type and sentence shear flex type, such as frames
not only the shea walls, but frames or joint sentences
Mixed shear walls and frames to make the building more
Flexibility and increase the period T from a period of rocky soils
In the case of construction stone or brick blocks ,the prefer
to use concrete frames surround walls to increase flexibility
In case sandy soils and clay with a period of higher T1
Resort to the opposite in buildings tower to relieve
high period T 2 By increasing the stiffness and adding
Shear walls or Maximize section Earthquake dampers or
add to whirring process does not occurTo become less than
the period of soil
And when presence poor clay soil or presence water
with sandy soils it is undesirable in terms of earthquakes
shake the soil beneath the foundations of the building,
especially in sandy soil with the presence of water
In the case of foundation mat will lead to a filtering the soil
and the soil particles escape Outside the mat and increasing
ratio of water and dilute the soil to escape the atoms
And it increases the slope of building even rotation and cracking
Therefore, in the event of poor clay soil and high water levels
Especially in the case of (the mat) prefer to presence soil report
recommends doing substitution and replacement of soil
Or use of deep foundations Piles
- can be used (mat) with go down to the depths with a number
of floors basements
Or the design of walls building supported on the perimeter of the base
where they become The foundation a closed box prevents the escape
of soil particles outside the boundaries of the base mat and prevents