SEISMIC ACTIVITIES OF JAZAN AREA Case Study: …colleges.jazanu.edu.sa/eng/civil/Documents/SEISMIC...
Transcript of SEISMIC ACTIVITIES OF JAZAN AREA Case Study: …colleges.jazanu.edu.sa/eng/civil/Documents/SEISMIC...
Jazan University College of Engineering
Civil Engineering Department
SEISMIC ACTIVITIES OF JAZAN AREA Case Study: Seismic Analysis of a Multi-Story
R.C. Building in Fifa City
By Team Members:
1. Abdulrahman Ahmed Jabir Otaif201110901 2. Ahmed Muslih Ali Safi201110674 3. AlbraaArarQassimHedisy201110543 4. Ali Hassan AliHarby201111046 5. Hisham Nasser Abdullah Yassin200910354
Supervisor:Assistant Prof. Dr. Ali Eltom Hassaballa
A Senior Project Final Report submitted in partial fulfillment
of the requirements for the degree of BACHELOR OF Science (B.Sc.),
in Civil Engineering
(Completion Date: Dec. 2015)
Examination committee
Jazan University College of Engineering
Civil Engineering Department
SEISMIC ACTIVITIES OF JAZAN AREA Case Study: Seismic Analysis of a Multi-Story
R.C. Building in Fifa City
By Team Members:
Abdulrahman Ahmed Jabir Otaif 201110901 Ahmed Muslih Ali Safi 201110674
AlbraaArarQassimHedisy 201110543 Ali Hassan AliHarby 201111046
Hisham Nasser Abdullah Yassin 200910354
Supervisor:Assistant Prof. Dr. Ali EltomHassaballa
A Senior Project Final Report submitted in partial fulfillment
of the requirements for the degree of BACHELOR OF Science (B.Sc.),
in Civil Engineering
(Completion Date: Dec. 2015)
Examination committee
Jazan University College of Engineering
Civil Engineering Department
SEISMIC ACTIVITIES OF JAZAN AREA Case Study: Seismic Analysis of a Multi-Story
R.C. Building in Fifa City
APPROVAL RECOMMENDED:
Examination Committee:
1. Professor Dr. Hossam Eldin Mohamed Sallam
2. Professor Dr. Ahmed Ahmed El-Abbasy
3. Professor Dr. Fathelrahman Mohamed Adam
PROJECT SUPERVISOR Dr. Ali Eltoum Hassaballa
Date
DEPARTMENT HEAD
Dr. Mohamed Mubarki
Date
COURSE INSTRUCTOR
Date
APPROVED DEAN OF COLLEGE OF ENGINEERING
Dr. Jabril Ahmed Khamaj
Date
ABSTRACT
Jazan area is located in the most active seismic zone region of the
Kingdom of Saudi Arabia where there is a complicated geological
structures and tectonics. This project reviews the seismic activities
occurred in Jazan area together with reviewing the Saudi Building
(Seismic) Code (SBC-301-2007). A multi-story reinforced concrete
building in Fifa city was seismically analyzed using the Equivalent
Lateral Force Procedure with the aid of STAAD PRO software. The
building, which was Ordinary Reinforced Concrete Moment Resisting
Frame (ORCMRF), analyzed in compliance with the provisions of (SBC-
301-2007). The most important parameters governing the analysis of this
frame were dead load, live load and seismic loads. Seismic loads were
computed as pairs of accelerations versus times. The damping ratio was
taken as 0.05 (5% of the critical damping).
The ground accelerations versus time periods were calculated using SBC-
301-2007 together with parameters necessary to be used as input data for
the program to calculate the seismic parameters, i.e., reactions,
displacements, base shear, bending moments, shearing forces, drifts. The
obtained results show effects of earthquake ground motions on building
studied herein is so greater for the higher increases of the values of
outputs resulting from seismic load comparing to that due to static load
only.
Finally, the results obtained, clearly, show the importance of taking the
Saudi seismic code provisions into account when analyzing and designing
multi-story buildings in Jazan area.
v
DEDICATION
To my Family, my friends,
vi
ACKNOWLEDGEMENT
This project was written under the direction and supervision of the
Assistant Prof. Dr. Ali EltomHassaballa, who was abundantly helpful
and offered invaluable assistance, support and guidance throughout the
stages of this project. Sincere thanks are due to the
Assistant Prof. Dr. Fathalrahman M. Adam for his continuous assistance.
vii
TABLE OF CONTENTS
PAGE ABSTRACT…….………………….…………………………….………………........v DEDICATION…….……………………………………………………….…………vi ACKNOWLEDGEMENT……..…….…….………………….………….……..…...vii TABLE OF CONTENTS…………………………………….................................viii LIST OF FIGURES ……………………………………………..…………..……….x LIST OF TABLES…………………………………….…….………..……..………..xi
CHAPTER (1) INTRODUCTION ………………..………………………………1 1.1 General Introduction ……………………….……...…………………...1 1.2Statement of Research problem …………………..…….…………...…2 1.3 Objectives of Research …………………………….…………………..3 1.4Methodology of Research……………….………...…………………….3 1.5 Research Outlines……………………………………………...……..…………….3
CHAPTER (2) DYNAMICS OF STRUCTURES AND EARTHQUAKE ENGINEERING…………………………….………………………………….……4
2.1Introduction…………….…………………………………………….…...4 2.1.1 Deterministic Analysis…………………...………………………….….4 2.1.2 Nondeterministic Analysis………………………...…………………....4
2.2 Types of Prescribed Loadings …………….………..……….…...............4 2.3 Definitions………………………………………….………………….….6 2.4 Lateral Stiffness of Simple Structures ………………………………........7 2.5 Analysis of Vibration Frequencies for Undamped Systems……….….…..9 2.6 Earthquake Engineering Definitions ………………………………....…11 2.7 Faulting…………………………………………………………….……..11 2.8 Causes of Earthquakes……………………………………………….…...12 2.9 Seismic Waves……………………………………………………………12 2.10Elastic Rebound Theory …………………………………………….…..15 2.11Measures of Earthquake Size……………………………………….…...16 2.11.1 Magnitude…………………………………………………………......16 2.11.2 Earthquake Intensity……………………………………………….….17 2.11.3 Earthquake Energy…………………………………………………....17 2.12 Structural Damage………………………………………………………18 2.13 Damage as a Result of Soil Problems…………………………………...19 2.13.1 Liquefaction…………………………………………………...………19 2.13.2 Landslides……………………………………………………………..20 2.13.3 Weak Clay…………………………………………………………….20 2-14 Damage as a Result of Structural Problems…………….……….……...21 2.14.1 Foundation Failure…………………………………….…….………...21 2.14.2 Foundation Connections……………………………………….……...21 2.14.3 The Lack of Secure Connection to Foundation……..………….……..21 2.14.4 Soft Story…………………………...…………………………..……..22 2.14.5 Torsional Moment……………..………………………………..…….22 2.14.6 Shear…………………………………………………………...……...23
2.14.7 Flexural Failur………….……………………………………...……...23
CHAPTER (3) SEISMIC ACTIVITIES IN JAZAN AREA ……………...…….24 3.1 Location of Jazan………………………. ……………………...…..……24 3.2 Jazan Region And Its Importance…… …………………...………….…..24 3.3 Earthquakes Data Base of The Arabian Peninsula…………….…………26 3.4 Samples of Earthquakes in Jazan Area…………………………………..27 3.5 Seismic Ground Motion Values:…………………………………………30
3.5.1 Mapped Acceleration Parameters………………………………………30 3.5.2 Site Coefficinents and Adjusted Maximum Considered EarthquakeSpectral
Response Acceleration Parameters..................................30 3.5.3 Design Response Acceleration Parameters…………………………....31 3.5.4 Design Response Spectrum ………………………..……………….....31
3.6 Equivalent Lateral Force Procedure……………………………………...32 3.6.1 Calculation of Base Shear……………………...………………………32 3.6.2 Lateral Distribution of Seismic Forces…………………………………34 3.6.3 Horizontal Shear Distribution …………………………………………35 3.6.4 Overturning Moment……………………………………………….…..35 3.6.5 Story Drift Determination …………………………..............................35 CHAPTER 4 (SEISMIC ANALYSIS OF A MULTI-STOREY R.C. FRAME IN FIFA CITY ………………………………………………………..…..……..…..37 4.1Introduction..…………..………………………………........….......…37 4.2 Frame Details And Study Case…………..…………………......……..37 4.3 Results of The Analysis ……………………………………….....……40 4.3.1 Calculations of Mapped And Design Spectral Response Accelerations For Fifa City............................................................40 4.4Discussion of The Analysi………...........…………...….....................49 CHAPTER (5)CONCLUSION AND RECOMMENDATIONS …………........50
5.1 Conclusion …………………………………………………………......50 5.2Recommendations………………..…………………………….…........51
REFERENCES…………………………………………………………......52
1.5”
LIST OF FIGURES
FIGURE No DESCRIPTION PAGE
(2-1) Characteristics and sources of typical dynamic loadings. 5
(2-2) Free vibration of an idealized one-story undamped structures . 7
(2-3) a; idealized pergola b; idealized water tankc; free vibration due to initial
displacement8
(2-4)Lateral displacements and rotations of beam-column joints. 9
(2-5) Earthquake terminology 11 (2-6) Fundamental fault mechanisms, San Andreas fault in California 12 (2-7) Diagrams illustrating the forms of ground motion near the ground surface 13 (2-8)Massive tsunamis. 14
(2-9)Tsunami occurrence mechanism (left) , tsunami causes (right) 15 (2-10) Elastic rebound theory of earthquake generation 15 (2-11)Accelerogram from El Centro earthquake, May 18, 1940 16 (2-12)Common types of damage during large earthquakes19 (2-13)Liquifaction caused building failure in Niigata, Japan19 (2-14) About 75% homes were damaged as a result of Turnagain heights slide20 (2-15)Broken piles under bridge (left), Piles penetrating bridge deck (right)21 (2-16)House that fell from its foundation earthquake, Failure of column to pile shaft connection21 (2-17)Soft story collapse in San Francisco 22 (2-18)Plan view of nine-story SRC building in Kobe,Nine-story SRC buildingimmediately 22 (2-19)Damage to north side of Mt. McKinley apartments,California,Shear failure of Pier 150 on Kobe Route3 23 (2-20)Flexural damage to columns at lower level of Dakki subway during the 1995 Kobe earthquake,Pier 585on Kobe Route 3 during the 1995 Kobe earthquake23
(3-1) Seismograph stations of the Saudi National Seismic Network 27 (3-2) Seismicity up to 2013 including historical and instrumental earthquakes above Ml 3 (Saudi geological survey database) 28 (3-3) Distributed of instrumental earthquakes in Jazan area and vicinity 29 (3-4)Sabkha corrosion action on structures 29 (3-5) Design Response Spectrum 31 (3-6) Deflection of frame structure 36 (4-1) Plan and elevation joint numbers of the studied frame 38 (4-2) Dimensions and member numbering of the frame 39 (4-3)Design Response Spectrum for Fifa City42 (4-4) Relation between horizontal reactions (Fx) due to L/C1 and L/C2 43 (4-5) Relation between vertical reactions (Fy) due to L/C1 and L/C2 44 (4-6) B.M. at supports of the frame due to L/C1 and L/C2 44 (4-7) Relation between nodal resultant displacements due to L/C1 and L/C2 46 (4-8) Axial forces of columns due to combinations L/C1 and L/C2 47
(4-9) Axial forces of columns in the first ground of theframe
due to L/C1 and L/C248
(4-10) B.M. in beams due to combinations L/C1 and L/C2. 49
LIST OF TABLES TABLE No DESCRIPTION PAGE (2.1) Modified Mercalli Intensity scale (MMI) of earthquakes.18
(3-1) Governorates and number of population of Jazan region. 26
(4.1) Samples of calculated accelerations versus times for Fifa City. 42
(4-2) Reactions at supports of the studied frame.43 (4.3) Nodal displacements of the
studied frame. 45(4.4) Columns end forces of the studied frame.
46 (4.5) Beam end forces of the studied frame. 48
���� ��زان��� ���� ا�
� ا�������� ��� ا�
��� ا����ا��� �� ���� ��زان�� ا���� ���$ ز��ا�$#"��! : درا%& ��'�� (��
.��د ا��-ا,+ �$ �*�� ��(�
:ط0ب �%*+ ا���!
���5��4201110901 ��,% 4'�ا�%��3 أ
$��6 $�4 (�7 ���201110674أ
��201110543� ھ�*�$ ا�'%اء 4%ار
3��201111046ا�"%,$ $�4 $�4
200910354 ��6% 4'�هللا *��3ھ��م
�%ف ا���%وع:
��4 ا�.-م ��? هللا. د
� ا�������� �%وع ا�.D%ج ��م ��"7-ل �4$ در�� ا�'��A-ر*-س �$ ا� %*%�#
2015د*��'%
1
Chapter One
INTRODUCTION
1.1 General Introduction Earthquakes are broad-banded vibratory ground motions, resulting from a
number of causes including tectonic ground motions, volcanism, landslides,
rock burst, and man-made explosions. Of these, naturally occurring tectonic-
related earthquakes are the largest and most important. These are caused by
a fracture and sliding of rock along faults within the earth's crust. The study
of strong earthquake ground motions and associated seismic hazard and risk
plays an important role for the sustainable development of societies in
earthquake prone areas. There are a great number of historical and recent
earthquake have occurred in the southern red sea and southwestern Saudi
Arabia. Jazan area is located in most active region in the KSA where there is
a complicated geological structures and tectonics. This project reviews the
seismic activities occurred in Jazan area and conducts seismic analysis for a
R.C. building located in Fifa City. Many researchers conducted researches
and studies relating to Saudi Arabia in general and southwestern Saudi in
particular such as: S.A. Ashour and H.H. Abdel-Rahman, in 1994, who
presented a paper on "Application of Seismic Risk Analysis and Earthquake
Simulation Methods to the Western Region in Saudi Arabia" [1].
A comparative study on seismic provisions made in UBC-1997 and Saudi
buiding code (SBC-301-2007) for RC buildings was prepared by Nazar and
M. A. Ismaeil (2014) [2]. A technical report on "Earthquakes Data Base of
the Arabian peninsula" was written by Abdullah M. Alamri in 1998 [3]. The
2
report describes the seismological problems associating with rifting in the
Red Sea and the geometry of the plate margins in the west and southwest.
Abdullah M. Al-Amri, Arthur J. Rodgers, Tariq A. Al-Khalifa, presented a
paper on "Improving the level of seismic hazard parameters in Saudi
Arabia using earthquake location", (2008)[4].
Awad Ali Al-Karni (2009) [5], studied the evaluation of the liquefaction
potential of the soil at the location of Jazan university in Jazan city which
lies on the east side of Red Sea. M.N. Fatani and A.M. Khan (1993)[6],
presented a conference paper on "Foundation on salt bearing soils of
Jizan",in order to present the geotechnical aspects of the area concentrating
on the foundation design and construction practice. Furthermore, the
geotechnical aspects of Jazan soil were studied by many authors as
(Dhowian et al., 1987 [7]; Erol, 1989 [8]; Dhowian, 1990 [9]; Al-Shamrani
and Dhowian, 1997) [10].
1.2 Statement of Research Problem
Jazan area is located in the most active seismic region in the KSA where
there is a complicated geological structures and tectonics. The area has a
new urban communities and big cities with heavy populations implementing
and promising with many strategic and developmental projects.
Furthermore, most of the buildings in this area do not follow the Saudi
seismic design considerations although it is affected by many earthquake
events. For all these reasons, it is necessary to perform studies and
researches related to southwestern part of KSA in general and Jazan area in
particular.
3
1.3 Objectives of Research
1. To study the seismic activities in Jazan area.
2. To analyze, in accordance with the Saudi Seismic Code, a
reinforced concrete building in Fifa city subjected to earthquake
loading.
3. Compare and discuss the results obtained and extract valuable
conclusion and recommendations concerning buildings constructed
in Fifa city.
1.4 Methodology of Research
The following steps will be followed to fulfill the objectives of the project
1. Collection of data necessary for the project from different sources.
2. Analysis of a R.C. building under moderate earthquake loading in Fifa
City by the method of Equivalent Lateral Force using STAAD-Pro
program.
3. Computer programs were used to achieve the objectives of this research
such as STAAD PRO, ORIGIN and EXCEL.
1.5 Research Outlines
This research consists of six chapters that can be briefly resumed as follows
Chapter one: contains a general introduction, problem statement, objectives,
methodology and outlines of the research.
Chapter two: Chapter two: contains the dynamics of structures and
earthquake engineering.
Chapter three: reviews the seismic activities occurred in Jazan area and short
notes about the Saudi Seismic Code.
Chapter four: presents and discusses the seismic analysis of a R.C. building
in Fifa city.
Chapter five: covers the conclusions and proposes future recommendations.
4
Chapter Two
DYNAMICS OF STRUCTURES AND EARTHQUAKE ENGINEERING
Dynamics of Structures
2.1 Introduction
The term dynamic may be defined simply as time-varying; thus a dynamic
load may be any load of which its magnitude, direction, and/ or position
varies with time. Similarly, the structural response to a dynamic load, i.e.,
the resulting stresses and deflections, is also time-varying, or dynamic.
Two basically different approaches are available for evaluating structural
response to dynamic loads: deterministic and nondeterministic.
2.1.1 Deterministic analysis
If the time variation of loading is fully known, even though it may be highly
oscillatory or irregular in character, it will be referred to herein as a
prescribed dynamic loading; and the analysis of the response of any
specified structural system to a prescribed dynamic loading is defined as
deterministic analysis.
2.1.2 Nondeterministic analysis
If the time variation is not completely known but can be defined in a
statistical sense, the loading is termed a random dynamic loading; and its
corresponding analysis of response is defined as a nondeterministic analysis.
2.2 Types of Prescribed Loadings
There are two basic categories:
i. Periodic loading: exhibits the same time variation successively for a
large number of cycles as shown in Fig. 1(a and b).
5
ii. Non-periodic loading: loadings may be either short-duration impulsive
loadings or long duration general forms of loads. A blast or explosion is a
typical source of impulsive load; for such short duration loads, special
simplified forms of analysis may be employed. On the other hand, a general,
long-duration loading such as might result from an earthquake can be treated
only by completely general dynamic analysis procedures as shown in Fig. 1
(c and d).
Fig. (2.1): Characteristics and sources of typical dynamic loadings: (a)
simple harmonic; (b) complex; (c) impulsive; (d) long-duration.
6
A structural dynamic problem differs from its static loading in two important
respects:
1. The time varying nature of the dynamic problem because both loading
and response vary with time.
2. The effect of inertial forces which resist accelerations of the structure in
this way are the most important distinguishing characteristic of a structural
dynamics problem.
2.3 Definitions
- Periodic Motion: The motion which repeats after a regular interval of time
is called periodic motion.
- Frequency ( f) or (fn): The number of cycles completed in a unit time is
called frequency. Its unit is cycles per second (cps) or Hertz (Hz).
- Time Period: T or (Tn ) is time period of vibration
Time taken to complete one cycle is called periodic time. It is represented in
seconds/cycle.
- Amplitude (uo): The maximum displacement of a vibrating system or
body from the mean equilibrium position is called amplitude.
- Free Vibrations: When a system is disturbed, it starts vibrating and keeps
on vibrating thereafter without the action of external force.
- Natural Frequency (w) or (wn): When a system executes free vibrations
which are undamped, the frequency of such a system is called natural
frequency.
Fig. (2.2) explains graphically these definitions.
7
Fig. (2.2): Free vibration of an idealized one-story undamped structure.
- Forced Vibrations:
The vibrations of the system under the influence of an external force are
called forced vibrations. The frequency of forced vibrations is equal to the
forcing frequency.
- Resonance:
When frequency of the exciting force is equal to the natural frequency of the
system it is called resonance.
- Degrees of Freedom:
The degree of freedom of a vibrating body or system implies the number of
independent coordinates which are required to define the motion of the body
or system at given instant.
2.4 Lateral Stiffness of Simple Structures
Simple structures such as pergola and elevated water tank shown in Fig. 2.3
can be idealized as a concentrated or a lumped mass (m) supported by a
massless structure with stiffness (k) in the lateral direction.
8
Fig. (2.3): a. Idealized pergola; b. idealized water tank; c. free
vibration due to initial displacement [v(0)].
Where:
m = the mass of roof
k = the sum of stiffnesses of individual pipe columns
v = lateral displacement
9
a. b. c.
Fig. (2.4) Lateral displacements and rotations of beam-column joints
Consider the frame of Fig. 2.4a with length (L), height (h), elastic modulus
(E), and moment of inertia for beam (Ib)and for columns (Ic). The lateral
stiffness (k) of the frame can be determined for the two extreme cases:
i. If the beam is rigid [i.e., flexural rigidity EIb = ∞ (Fig. 2.4b)]
(2.1) ii. For the beam with no stiffness [i.e., flexural rigidity EIb = 0 (Fig.
2.4c)]
(2.2)
To a frame with L = 2h and EIb = EIc, and for rotational DOFs, the lateral
stiffness is
K = (2.3)
2.5 Analysis of Vibration Frequencies for Undamped Systems
The equation of motion for a freely vibrating undamped system:
(2.4)
10
In which 0 is a zero vector. Since it is simple harmonic equation (2.4) may
be expressed for a MDOF system as
(2.5)
= shape of the system, = phase angle.
Taking the second time derivative for equation (2.5), the accelerations in
free vibrations are
(2.6)
Substituting equation (2.5) and (2.6) into equation (2.4) gives
Which (Since the sine term is arbitrary and may be omitted) may be written
(2.7)
By Cramer's rule the solution of this set of simultaneous equation is
(2.8)
Hence a nontrivial solution is possible only when the denominator
determinant vanishes. In other words, finite-amplitude free vibrations are
possible only when
(2.9)
Equation (2.9) is called the frequency equation of the system.
The vector made up of the entire set of modal frequencies, arranged in
sequence, is called frequency vector (w).
11
Earthquake Engineering
2.6 Definition
An earthquake is manifested as ground shaking caused by the sudden release
of energy in earth's crust.
The actual point at which the release occurs is known as the focus. The
epicenter is the point on the surface immediately above the focus as shown
in Fig. (2.5). The focus may be close to the surface (Kobe, 1995) or many
10s of Kilometres down.
Fig. (2.5): Earthquake Terminology
2.7 Faulting
A fault is termed as the resulting fracture in the earth's crust when two
groundmasses move with respect to one another, Fig. (2.6).
Earthquakes are generated by sudden fault slips of brittle rocky blocks,
starting at the focus depth and observed at a site located at the epicentral
distance.
There are three types of earthquakes depending on focal depths:
i. Shallow earthquakes: have focal depths in the range of 5-15 km.
12
ii. Intermediate earthquakes: focal depths of 20-50 km.
iii. Deep earthquakes: occur at 300-700 km.
Fig. (2.6): Fundamental fault mechanisms (left), San Andreas fault in
California (right).
2.8 Causes of earthquakes
i. Tectonic plate movements
ii. Dislocation of the crust
iii. Volcanic eruption
iv. Man-made explosions
v. Collapse of under-ground cavities, such as mines or karsts
vi. Large reservoir-induced
2.9 Seismic Waves
Earthquake waves can be classified in three types shown in (Fig. 2.7):
13
i. Primary or compressional waves (P-waves)
P-waves are compression waves (like sound) traveling with the highest speeds (25,000 km per hour, or 7 km per second) and will reach a distant observer first. They push rocks and vibrate backwards and forwards and can travel through liquids.
ii. Shear or secondary waves (S-waves)
S-waves travel at about 13000 km per hour or 3.6 km per second reaching after P-waves.S waves are characterized by a sideways movement. The rock materials are moved from side to side as the wave passes, moving at right angles to the direction of wave motion.
iii. Love waves (L-waves)
It is the surface waves that are most damaging as they cause the earth's crust to undulate. The L-waves travel along the surface of the earth from the point directly above the quake or epicenter. These waves are the ones that cause most of the damage.
Fig. (2.7): Diagrams illustrating the forms of ground motion near the ground
surface in four types of earthquake waves.
14
iv. Tsunami (Tsunamis) or Seismic sea wave
A tsunami "harbor wave" known as a seismic sea wave or as a tidal wave, is
a series of waves in a water body caused by the displacement of a large
volume of water, generally in an ocean or a large lake. Earthquakes, volcanic
eruptions and other underwater explosions (including detonations of
underwater nuclear devices), landslides, and other disturbances above or
below water all have the potential to generate a tsunami. Wave heights of
tens of meters can be generated by large events, Fig. (2.8). A tsunami can
travel at well over 970 kph (600 mph) in the open ocean - as fast as a jet
flies.
Fig. (2.9) shows tsunami occurrence mechanism and tsunami causes (right)
Fig. (2.8): Massive tsunamis.
15
Fig. (2.9): Tsunami occurrence mechanism (left), tsunami causes (right)
2.10 Elastic Rebound Theory
It was from study, by H. F. Reid, of the rupture which occurred along the
San Andreas fault during the San Francisco earthquake in 1906. Reid
concluded that the specific source of the earthquake vibration energy is the
release of accumulated strain in the earth's crust, the release itself resulting
from the sudden shear-type rupture as shown in Fig. (2.10).
Fig. (2.10): Elastic rebound theory of earthquake generation: (a) before
straining; (b) strained (before earthquake); (c) after earthquake.
16
2.11 Measures of Earthquake Size
2.11.1 Magnitude
Magnitude is the amount of strain energy released at the source. Richter
magnitude is the (base 10) logarithm of the maximum amplitude measured
in micrometers (10-6 m) of the earthquake record obtained by a Wood-
Anderson seismograph corrected to a distance of 100 km:
ML = log A – log A0 (2.10)
Where:
ML = local magnitude
A = maximum amplitude in micrometers
A0 = a standard value[ calibration amplitude (0.001 mm)]
Fig. (2.11): Accelerogram from El Centro earthquake, May 18, 1940 (N-S
component)
Earthquakes of magnitudes less than 5 are not expect to cause structural
damage, whereas for magnitudes greater than 5 potentially damaging ground
motion will be produced.
We can measure the size of earthquakes using moment magnitude as in
equation (2.11):
M = ()[log(M0) – 16.05] (2.11)
17
Where M0 is the seismic moment defined as
M0 = GAD
Where:
G = shear modulus of rock (dyne/cm2)
A = area of the fault (cm2)
D = the amount of slip or movement of the fault (cm)
2.11.2 Earthquake intensity
Seismic intensity is a measure of effect, or the strength of an earthquake
hazard at a specific location measured by many scales such as the modified
Mercalli scale (MMI). MMI defines the level of shaking at specific sites on a
scale of I to XII as shown in Table (2.1).
2.11.3Earthquake energy (E)
Earthquake energy can be obtained by
Log E = 11.8 + 1.5 M (2.12)
Where :
E = amount of earthquake energy released
M = magnitude of earthquake
By the above formula, the energy increases by a factor of 32 for each unit
increase of magnitude.
18
Table (2.1) Modified Mercalli Intensity scale (MMI) of earthquakes
2.12 Structural Damage
During large earthquakes the ground is jerked back and forth, causing
damage to the element whose capacity is below the earthquake demand as
shown in Fig. (2.12).
19
Fig. (2.12): Common types of damage during large earthquakes
2.13 Damage as a Result of Soil Problems
2.13.1 Liquifaction
Liquifaction occurs when loose saturated sand, silts, or gravel are shaken,
the material consolidates, reducing the porosity and increasing pore water
pressure. The ground settles, oven unenenly, tilting and toppling structures
that were formerly supported by the soil as shown inFig. (2.13)
Fig. (2.13):Liquifaction caused building failure in Niigata, Japan
20
2.13.2 Landslides
When a steeply inclined mass of soil is suddenly shaken, a slip-plane can
formed and the material slides downhill, during a landslide, structures sitting
on the slide move downward and structures below the slide are hit by fallen
debris.
Fig. (2.14): about 75% homes were damaged as a result of Turnagain heights
slide.
2.13.3 Weak clay
The problems encountered at soft clay sites include the amplification of the
ground motion as well as vigorous soil movement that can damage
foundations. Several bridges suffered collapse during the 1989 Loma Prieta
earthquake due to the poor performance of weak clay, shown in Fig. (2.15).
21
Fig. (2.15): Broken piles under bridge (left), Piles penetrating bridge deck
(right)
2.14 Damage as a Result of Structural Problems
2.14.1 Foundation failure
Usually, it is the connection to the foundation or an adjacent member rather
than the foundation itself that is damaged during a large earthquake.
2.14.2 Foundation connections
2.14.3 The lack of a secure connection to foundation
It can cause damages to electrical transformers, storage bins, lifelines
facilities and a variety of other structures as in Fig. (2.16).
Fig. (2.16): House that fell from its foundation during the 1971 San
Fernardino earthquake (left), Failure of column to pile shaft connection.
22
2.14.4 Soft story
Buildings are classified as having a "soft story" if that level is less than 70%
as stiff as the floor immediately above it, or less than 80% as stiff as the
average stiffness of the three floors above it as shown in Fig. (2.17).
Fig. (2.17): Soft story collapse in San Francisco during the 1989 Loma
Prieta earthquake
2.14.5 Torsional moment
Curved, skewed and eccentrically supprted structures often experience
atorsional moment durng earthquakes as shown in Fig. (2.18).
Fig. (2.18): Plan view of nine-story SRC building in Kobe (left),Nine-story
SRC buildingimmediately after the 1995 Kobeearthqake (right).
23
2.14.6 Shear
Most building structures use shear walls or moment-resisting frames to resist
lateral forces durng earthquakes. Damage to these system varies from minor
cracks to complete collapse, see Fig. (2.19).
Fig. (2.19): Damage to north side of Mt. McKinley apartments,California
(left),Shear failure of Pier 150 on Kobe Route3 (right)
2.14.7 Flexural failure
Flexural members are often designed to form plastic hinges during large
earthquakes as shownin Fig. (2.20). A plastic hinge allows a member to
yield and deform while continuing to support its load. However, when there
is insufficient confinment for RC members, a fleural failure will occur
instead accompanied by compression or shear damage as the capacity of the
damage area has been lowered.
Fig. (2.20): Flexural damage to columns at lower level of Dakki subway
during the 1995 Kobe earthquake (left),Pier 585on Kobe Route 3 during the
1995 Kobe earthquake (right).
24
Chapter Three
Part One
SEISMIC ACTIVITIES IN JAZAN AREA
3.1 Location of Jazan
Jizan, or more properly Jazan, was known in ancient times as Almikhlaf
Alsulimani. Jazan is located on the southwest corner of Saudi Arabia on the
coast of the Red Sea and directly north of the border with Yemen. Jazan City
lies in an active zone of earthquakes classified as zone 2B with maximum
applied horizontal acceleration of 0.2g.Saudi Arabia is divided into 25
zones, each zone having its specific building code covering not only seismic
activity but other criteria as well.”
3.2 Jazan Region and its Importance
The Province of Jazan lies in the south west section of the Kingdom of Saudi
Arabia. It has a population of approximately 1,365,110 at the 2010 census
and covers an area of 40,000 km2 including some 5,000 villages and cities.
Jizan, is home to the Port of Jizan, Saudi Arabia’s third most important port
on the Red Sea. It stretches some 300 km along the southern Red Sea coast,
just north of Yemen. The region includes over 100 islands in the Red Sea.
The Farasan Islands, Saudi Arabia’s first protected wildlife area, is home to
the endangered Arabian gazelle and, in winter, receives migratory birds from
Europe.
The region is subdivided into 14 governorates as shown in Table (3.1).
25
Table (3.1) Governorates and number of population of Jazan region:
Name
Census
15 September 2004
Census (Preliminary)
28 April 2010
Abu Arish 123,943 197,112
Alddair 49,239 59,494
Alddarb 52,062 69,134
Ahad Almasarihah 70,038 110,710
Alaridah 62,841 76,705
Alaydabi 52,515 60,799
Alharth 47,073 18,586
Alraith 13,406 18,961
Baish 58,269 77,442
Damad 62,366 71,601
Farasan 13,962 17,999
Jazan 255,340 157,536
Sabya 198,086 228,375
Samtah 128,447 201,656
Total Province 1,187,587 1,365,110
Jazan is one of the Kingdom's richest agricultural regions, remarkable for
both the coffee beans, grain crops (barley, millet and wheat) and fruit
(apples, bananas, grapes, lemons, mangoes, oranges, papayas, plums and
tamarinds).
26
Jazan Economic City: is an economic city in the Jizan Province of the
Kingdom of Saudi Arabia, with a focus on the energy and manufacturing
industries. Arab News reported in January 2011 that when the city is
completed, an estimated 500,000 new jobs will be created. Jazan Economic
City focuses on four areas: heavy industries, secondary industries, human
capital and lifestyle. The proposed city will provide an environment for key
industries, technology exchanges, commerce and trade, employment
opportunities, education and training, housing and a broad spectrum of
socio-economic activities for a projected population of 300,000 people.
Jazan University is located at Jazan city with its campuses at Jazan, Sabya,
Abu Arish, Samtah, Addarb, Addair, Al Ardhah and Farasan Island. Arrayth
is one of the most beautiful mountains in the south of Saudi Arabia.
3.3 Earthquakes Data Base of the Arabian Peninsula
Recently, there are two independent analog seismic telemetry networks in
Saudi Arabia. The King Saud University (KSU) network was established in
1985 and consists of 30 stations with denser sub-networks in the Gulf of
Aqabah region (12 stations) and the southwestern part of Saudi Arabia (8
stations). A network run by King Abdulaziz City for Science and technology
(KACST) was established in 1993 with 11 short-period stations in the Gulf
of Aqabah and the southwestern part of Saudi Arabia adjacent to the Yemen
border. Saudi Arabia will set up an additional 50 advanced earthquake
monitoring stations. The Kingdom already has 150 earthquake monitoring
stations called the Saudi National Seismic Network (SNSN), and the new
ones will boost the capability by providing precise data collection [14]. Fig.
(3.2) shows the distribution of seismograph stations of Saudi Arabia.
27
Fig. (3.1) Seismograph stations of the Saudi National Seismic Network
3.4 Samples of Earthquakes in Jazan Area
In 2014, a magnitude-5.1 earthquake struck in the southwestern part of the
Kingdom, 50 km northeast of Jazan, at a depth of 10 km followed by 37
aftershocks of magnitudes ranging 0.94 - 5.1 in Richter scale [14].
Its impact was felt by inhabitants in the Asir and Najran regions. Generally,
there were many earthquakes struck Jazan area and north of Yemen in the
years 859, 1121, 1191, 1269, 1481, 1630,1710, 1941, 1947 (of magnitude 6,
killed 1200 of people), 1955, 1982, 1993 (of magnitude 4.8) as shown in
Fig. (1). Earthquakes of magnitude 6 are common along the spreading axis
of the Red Sea but generally they are not felt onshore and appear to pose
little risk to infrastructure.
28
Fig. (3.2) shows earthquake epicenters greater than magnitude 3 in the Saudi
Geological Survey (SGS) catalogue for all years up to 2013. Fig.(3.3) shows
the distribution of instrumental earthquakes in Jazan area and its vicinity.
Fig. (3.2) Seismicity up to 2013 including historical and instrumental
earthquakes above Ml 3 (Saudi geological survey database)
29
Fig. (3.3): Distributed of instrumental earthquakes in Jazan area and vicinty
Because Jazan is located on the sea-shore, water immigrates to the surface
leaving a salt crust on the top surface, which is known as 'Sabkha' soil. This
salt bearing (saline) soil and the salt dome affected the foundation
performance in the area, see Fig (3.4).
Fig. (3.4):Sabkha corrosion action on structures
30
Part Two
SAUDI SEISMIC CODE
3.5 Seismic Ground Motion Values
3.5.1 Mapped acceleration parameters
The Kingdom of Saudi Arabia has been divided into seven regions for
determining the maximum considered earthquake ground motion. The
parameter Ss shall be determined from the 0.2 second spectral response
accelerations shown on Figures 9.4.1(b) through 9.4.1(i) (SBC-301-
2007).The parameter S1 shall be determined from the 1.0 second spectral
response accelerations shown on Figures 9.4.1(j) through 9.4.1(q) (SBC-
301-2007).
3.5.2 Site coefficients and adjusted maximum considered earthquake
spectral response acceleration parameters
The Maximum considered earthquake spectral response acceleration for
short periods (SMS) and at 1-sec (SM1), adjusted for site class effects, shall be
determined by the Equations:
SMS = Fa SS (3.1)
SM1 = FV S1 (3.2)
S1 = the mapped maximum considered earthquake spectral response
acceleration at a period of 1-sec as determined in accordance with section
9.4.1 (SBC-301-2007).
SS = the mapped maximum considered earthquake spectral response
acceleration at short periods as determined in accordance with section 9.4.1
31
where site coefficients Fa and Fv are defined in Table 9.4.3a and Table
9.4.3b, respectively(SBC-301-2007).
3.5.3 Design Response Acceleration Parameters
Design earthquake spectral response acceleration at short periods, SDS, and at
1-sec period, SD1, shall be determined from the following Equations:
SDS = SMS (3.3)
SD1 = SM1 (3.4)
3.5.4 Design Response Spectrum
1. For periods less than or equal to T0, the design spectral response
acceleration, Sa, shall be given by (as shown in Fig. 3.5):
Sa = SDS (0.4 + 0.6 ) (3.5)
Fig. (3.5) Design Response Spectrum.
2. For period greater than or equal to T0 and less than or equal to TS, the
design spectral response acceleration, Sa, shall be taken as equal to SDS.
3. For period greater than TS, the design spectral response acceleration, Sa,
shall be given by:
32
(3.6)
SDS = the design spectral response acceleration at short periods, at 1-sec
SD1 = the design spectral response acceleration at 1-sec periods, in units of g-
sec.
T = the fundamental period of the structure (sec):
T0 = 0.2SD1/SDS
TS =SD1/SDS
3.6 Equivalent Lateral Force Procedure
3.6.1 Calculation of Base Shear (V)
According to "SBC-301-2007" the total base shear (V) can be calculated in
accordance with the following equation:
V = Cs W (3.7)
Where:
Cs = the seismic response coefficient determined in accordance with Section
10.9.2.1.
(3.8)
SDS = the design spectral response acceleration in the short
period range as determined from Section 9.4.4 (SBC-301-2007)
R = the response modification factor in Table II.
I = the occupancy importance factor determined in accordance with section
9.5
The value of the seismic response coefficient, (Cs), need not be greater than
the following equation:
33
(3.9)
But shall not be taken less than
(3.10)
SD1= the design spectral response acceleration at a period of 1.0 sec, in unit
of g-sec, as determined from section 9.4.4.
T = the fundamental period of the structure as determined in section 10.9.3.
The approximate fundamental period (Ta), in seconds, shall be determined
from the following equation
(3.11)
Where hnis the height in (m) of the base to the highest level of the structure,
and Ctand xare determined from Table 10.9.3.2.
Or Ta, for structures no exceeding 12 stories in height, can be determined
from the following equation Ta = 0.1 N (3.12)
Where N = number of stories
Ta for masonry or concrete shear wall structures shall be permitted to be
determined from
(3.13)
Cw is calculated from the following equation
(3.14)
34
Where:
AB = the base area of the structure m2.
Ai = the area of shear wall "i" in m2.
Di = the length of shear wall "i" in m.
n = number of shear walls in the building.
3.6.2 Lateral distribution of seismic forces
The lateral seismic force (Fx) (kN) induced at any level shall be determined
by the following equations:
Fx = CvxV (3.15)
and
(3.16)
Where:
Cvx=vertical distribution factor
V = total design lateral force or shear at the base of structure, (kN).
wi and wx= the portion of the total gravity load of structure (W) located or
assigned to level i or x.
hi and hx= the height "m" from the base to level i or x.
k = an exponent related to the structure period as follows:
for structures having a period of 0.5 sec or less, k = 1
for structures having a period of 2.5 sec or less, k = 2
for structures having a period between 0.5 and 2.5 sec, k shall be 2 or
shall be determined by linear interpolation between 1 and 2.
35
3.6.3 Horizontal shear distribution
The seismic design story shear in any story (Vx) (kN) shall be determined
from the following equation:
(3.17)
Where Fi = the portion of the seismic base shear (Vx) (kN) induced at level i.
3.6.4 Overturning moment
The overturning moments at level x (Mx) (kN.m) shall be determined from
the following equation
(3.18)
Where:
Fi= the portion of the seismic base shear (V) induced at level i.
hi and hx= the height "m" from the base to level i or x.
3.6.5 Story drift determination
The design story drift (∆) shall be computed as the difference of the
deflections at the top and bottom of the story under consideration.
The deflections of level x at the center of the mass (δx) "mm" shall be
determined in accordance with the following equation:
(3.19)
Where:
Cd = the deflection amplification factor in Table( 10.2).
δxe= the deflections determined by an elastic analysis.
36
I = the importance factor determined in accordance with section
9.5.
Story drift (∆x) =δx - δx-1, as shown in Fig. (3.6):
Fig. (3.6) Deflection of frame structure.
37
Chapter Four
SEISMIC ANALYSIS OF A MULTI-STORY
R. C. FRAME IN FIFA CITY
4.1 Introduction
In this project, an office 10-story R.C. frame, located in Jazan city, has been
seismically analyzed aiming to investigate the seismic performance of a
reinforced concrete moment resisting frame building under an earthquake
ground motion. The building was analyzed in accordance with the Saudi
Building Code (SBC-301-2007) using STAAD PRO software. Jazan city lies
in an active zone of earthquakes classified as zone 2B with maximum
applied horizontal acceleration of 0.2g.
4.2 Frame Details and Study Case
An office ten-story regular reinforced concrete frame building located in
Fifa City, with 16 m X 20 m plan as shown in Fig. (4.1), was analyzed to
investigate its seismic performance. The most important parameters
governing the analysis of this frame were dead load, live load and seismic
loads. Seismic loads were computed as pairs of accelerations versus times.
As per SBC-301-2007 the following selected load combinations were
selected for the analysis of the studied frame:
Load Case 1 (L/C1) is static load (dead and live):
1.4 DL +1.6 LL (4.1)
38
Load Case 2 (L/C2) is static load + Earthquake loads:
1.2 DL + + 1.0 E + f1 LL (4.2)
Load Case 3 (L/C3) is dead + Earthquake) loads:
0.9 DL + 1.0 E (4.3)
Where:
f1 = 1.0 for areas occupied as places of public assembly, for live loads in
excess of 0.5 kN/m2 and for parking garage live load.
f1 = 0.5 for other live loads.
In this analysis, the live load is taken as 3.5 kN/m2.
From the frame shown in Fig. (4.1), Joints' numbers 6, 11, 16, 21, 26, 31,
36, 41, 46, 51 were selected to calculate their nodal displacements for the
different loading cases.
Joint Numbering Plan
Fig. (4.1) Plan and elevation joint numbers of the studied frame.
39
Member numbering Dimensions
Fig. (4.2) Dimensions and member numbering of the frame.
One frame was analyzed using STAAD PRO program. The ground
accelerations versus time periods were calculated using SBC-301-2007
together with parameters necessary to be used as input data for the program
to calculate the seismic parameters, i.e., reactions, displacements, base
shears, bending moments, shearing forces, drifts. The damping ratio was
taken as 0.05 (5% of the critical damping).
40
• Typical columns' sections = 30 mm x 30 mm,
• Typical beams' sections = 30 mm x 45 mm, and
• Typical slab thickness = 150 mm.
Some members of the frame building were selected for the purposes of the
analysis. The selected members, which are shown in Fig. (4.2) were:
Columns Number 2, 11, 20, 29, 38, 47, 56, 65, 74, and 83.
Beams Number 6, 7, 8, and 9.
4.3 Results of the Analysis
4.3.1 Calculations of mapped and design spectral response accelerations
for Fifa City
Using the Saudi Building Code (SBC-301-2007) equations shown in
chapter three the following parameters have been calculated to be used as
input data for seismic analysis of the R.C. Building located in Fifa City (Fifa
City lies in region 6). The calculated results of these parameters are as
follows:
• SS = the mapped maximum considered earthquake spectral response
acceleration at short periods.
SS= 0.62 g = 0.62 x 9.81 = 6.08
• S1 = the mapped maximum considered earthquake spectral response
acceleration at a period of 1-sec
S1= 0.176 g = 0.176 x 9.81 = 1.73
• Fa and Fv = site coefficients
Fa = 1.00 (Table 9.4.3a) of (SBC-301-2007).
FV = 1.00 (Table 9.4.3 b) of (SBC-301-2007).
41
• SMS = The Maximum considered earthquake spectral response
acceleration for short periods , adjusted for site class effects
SMS = Fa SS = 1.00 x 6.08 = 6.08
• SM1 = The Maximum earthquake spectral response acceleration for at
1-sec periods , adjusted for site class effects
SM1 = FV S1= 1.00 x1.73 = 1.73
• SDS = the design spectral response acceleration at short periods.
SDS = SMS = x 6.08 = 4.05
• SD1 = the design spectral response acceleration at 1-sec periods.
SD1 = SM1 = x 1.73 = 1.15
• T = the fundamental period of the structure (sec):
T = 0.1 N = 0.1 x 10 = 10 sec
T0 = 0.2SD1/SDS = 0.2x1.15/ 4.05 = 0.057 sec
TS =SD1/SDS = 1.15/4.05 = 0.284 sec
• R = the response modification factor in Table II:
R = 2.5 (for ordinary R.C. resisting moment frame)
• I = the occupancy importance factor determined in accordance with
section 9.5 (SBC-301-2007):
I = 1 (for occupancy category I and II)
• The design spectral response acceleration, Sa, is calculated by: Sa = SDS (0.4 + 0.6 ).
42
Table (4.1) Samples of calculated accelerations versus times for Fifa City:
Fig.(4.3) Design Response Spectrum for Fifa City.
No Time (Sec) Accelerations (m/s2) 1 1.000 0.120
2 2.000 0.060 3 3.000 0.040 4 4.000 0.030 5 5.000 0.024 6 6.000 0.020 7 7.000 0.017 8 8.000 0.015 9 9.000 0.013 10 10.000 0.012
43
Table (4.2): Reactions at supports of the studied frame: Node L/C horizontal Vertical horizontal Moments
Fx (kN)
Fy (kN)
Fz (kN)
Mx (kN.m)
My (kN.m)
Mz (kN.m)
1 DL + LL 8.558 1043 00 0 0 -8.524
DL + LL+E 22.527 796.933 00 00 00 23.591
2 DL + LL 0.254 1833 00 00 00 -0.287
DL + LL +E 20.895 1213 00 00 00 32.777
3 DL + LL -0.000 1933 00 00 00 0.00
DL + LL+ E 20.250 1273 00 00 00 32.490
4 DL + LL -0.245 1833 00 000 000 0.278
DL +LL + E 20.574 1213 00 00 00 33.153
5 DL + LL -8.558 1043 00 00 00 8.524
DL + LL+ E 11.295 796.933 00 00 00 34.779
Fig. (4.4) Relation between horizontal reactions (Fx) due to L/C1 and L/C2
44
Fig. (4.5) Relation between vertical reactions (Fy) due to L/C1 and L/C2
Fig. (4.6) B.M. at supports of the frame due to L/C1 and L/C2
45
Table (4.3): Nodal displacements of the studied frame: Resultant
(mm)
Z
(mm)
Y
(mm)
X
(mm)
L/C NodeNo.
1.598 0.000 -1.598 -0.026 DL + LL 6
3.921 0.00 -0.875 3.822 DL + LL + E
3.491 0.00 3.057 0.009 DL + LL 11
8.645 00 -1.687 8.479 DL + LL + E
4.368 00 4.368- -0.009 DL + LL 16
13.239 00 -2.432 13.013 DL + LL + E
5.525 00 -5.525 -0.007 DL + LL 21
17.572 00 -3.102 17.269 DL + LL + E
6.254 00 -6.524 -0.006 DL + LL 26
17.572 00 -3.692 21.216 DL + LL + E
7.359 00 -7.359 -0.005 DL + LL 31
25.028 00 -4.196 24.674 DL + LL + E
8.028 00 -8.028 -0.004 DL + LL 36
27.963 00 -4.609 27.581 DL + LL + E
8.528 00 -8.528 -0.002 DL + LL 41
30.269 00 -4.924 29.866 DL + LL + E
8.857 00 -8.857 -0.016 DL + LL 46
31.877 00 -5.135 31.460 DL + LL + E
9.012 00 -9.012 0.108 DL + LL 51
32.873 00 -5.236 32.453 DL + LL + E
46
Fig. (4.7) Relation between nodal resultant
displacements due to L/C1 and L/C2
Table (4.4) Columns end forces of the studied frame: Beam No
de L/C Axial Shear Bending
Fx (kN)
Fy (kN)
Fz (kN)
My (kNm)
Mz (kNm)
2 2 DL+LL 1833 -0.245 0 0 -0.287 DL+LL+E 1213 20.574 0 0 32.777 7 DL+LL -1827 0.245 0 0 -0.448 DL+LL+E -1197 20.895 0 0 28.945
11 7 DL+LL 1633 -1.615 0 0 -1.728 DL+LL+E 1073 20.762 0 0 31.788 12 DL+LL -1627 1.615 0 0 -3.116 DL+LL+E -1067 22.882 0 0 30.499
20 12 DL+LL 1443 -3.974 0 0 -5.466 DL+LL+E 948.100 18.212 0 0 27.022 17 DL+LL -1437 3.974 0 0 -6.454 DL+LL+E -945.837 23.472 0 0 27.022
29 17 DL+LL 1263 -5.803 0 0 -8.257 DL+LL+E 827.506 15.628 0 0 23.653 22 DL+LL -1257 5.803 0 0 -9.152 DL+LL+E -820.373 23.245 0 0 23.232
38 22 DL+LL 1073 -7.414 0 0 -10.741 DL+LL+E 708.421 12.702 0 0 19.163
47
27 DL+LL -1067 7.414 0 0 -11.501 DL+LL+E -698.046 22.432 0 0 18.942
47 27 DL+LL 890.525 -8.769 0 0 -12.837 DL+LL+E 590.450 9.515 0 0 14.292 32 DL+LL -890.525 8.769 0 0 -13.469 DL+LL+E -578.363 21.024 0 0 14.253
56 32 DL+LL 711.760 -9.811 0 0 -14.566 DL+LL+E 473.254 6.109 0 0 9.102 37 DL+LL -711.760 9.881 0 0 -15.076 DL+LL+E -460.930 19.077 0 0 9.225
65 37 DL+LL 534.826 -10.718 0 0 -15.900 DL+LL+E 356.532 2.567 0 0 3.703 42 DL+LL -534.826 10.718 0 0 -16.253 DL+LL+E -345.428 16.634 0 0 3.996
74 42 DL+LL 359.162 -11.524 0 0 -17.075 DL+LL+E 239.913 -1.217 0 0 -1.965 47 DL+LL -359.162 11.524 0 0 -17.498 DL+LL+E -231.487 13.909 0 0 -1.686
83 47 DL+LL 185.781 -11.670 0 0 -17.391 DL+LL+E 123.960 4.632 0 0 -7.152 52 DL+LL -185.781 11.670 0 0 -17.619 DL+LL+E -119.878 10.685 0 0 -6.743
Fig. (4.8) Axial forces of columns due to combinations L/C1 and L/C2.
48
Fig. (4.9) Axial forces of columns in the first ground of the
frame due to L/C1 and L/C2 Table (4.5): Beam end forces of the studied frame:
Beam Node L/C Fx
(kN) Fy
(kN) Mz
(kNm) 6 6 DL+LL -8.799 90.774 42.836 DL+LL+E -3.613 78.758 71.434 7 DL+LL 8.799 101.226 -63.742 DL+LL+E 7.936 58.618 -8.402 7 7 DL+LL -10.169 97.061 8.918 DL+LL+E -6.015 78.382 71.992 8 DL+LL 10.169 94.939 -61.674 DL+LL+E 7.332 76.989 -10.466 8 8 DL+LL -10.169 94.939 61.674 DL+LL+E -6.015 76.989 70.481 9 DL+LL 10.169 97.061 -65.918 DL+LL+E 7.332 78.382 -14.525 9 9 DL+LL -8.799 101.226 63.742 DL+LL+E -3.613 85.618 75.258 10 DL+LL 8.799 90.774 -42.836 DL+LL+E 7.936 78.758 15.212
49
Fig. (4.10) B.M. in beams due to combinations L/C1 and L/C2.
50
4.4 Discussion of the Analysis
The results of the analysis indicated that the horizontal reactions (Fx) of the
frame due to L/C2 show larger values, reaching up to 8 times that due to
L/C1 in the outer supports, and this difference increased so many times in
the inner supports as shown in Table (4.1) and Fig. (4.3). The vertical
reactions (Fy) due L/C1 is slightly greater than that due to L/C2 revealing
the effect of static load on reducing lateral movements (see Table 4.1 and
Fig. 4.4). This concept is also true for bending moments (Mz) at supports
that reflects the severe effects of horizontal excitation ground motion on this
building as shown in Fig. (4.5). Table (4.2) and Fig. (4.6) show the results of
the nodal displacements due to different load cases, from which it is clearly
observed that the calculated resultant of nodal displacements due to L/C 2
were about 6 to 8 times the nodal displacements due to L/C1. These values
indicated that the horizontal motions have great effects on the lateral
displacements of the studied frame.
For columns, axial forces due to L/C1is slightly greater than that due to
L/C2. However, the forces in upper floor columns showed lesser values.
There are large increases in the values of shearing forces and bending
moments at columns when earthquake effects were considered in the
analysis as shown in Table (4.3) and Fig. (4.7). The values of bending
moments due to L/C2 in beams 6, 7, 8, and 9 were found to be about 1.5 -2.0
times the values due to L/C1 as shown Table (4.4) and Fig. (4.8).
51
Chapter Five
CONCLUSION AND RECOMMENDATIONS
5.1 Conclusions
Based on the obtained results from the analysis of the reinforced concrete
frame building in Fifa city, it can be concluded that:
1. It is found that the values of horizontal support reactions generating
from L/C2 were about 3 times that due to L/C1 in the outer supports
and this rate increases much more (up to 40 times) in the inner
supports.
2. It is clearly observed that the calculated resultant of nodal
displacements due to L/C2 were about 3 to 4 times the nodal
displacements due to L/C1.
3. Axial forces of columns due to L/C1is slightly greater than that due to
L/C2 and these forces decrease gradually in the upper floor columns
which showed lesser values.
4. Bending moments in beams and columns due to seismic excitation
(L/C2) showed much larger values compared to that due to static loads
(L/C1).
52
5.2 Recommendations
From this research and the results obtained, it can be recommended that:
1. Saudi seismic code should be taken into consideration when analyzing
and designing buildings and structures in the country.
2. Seismic risk analysis has to be conducted for major cities of Jazan
area.
3. Further studies and researches, in this field, are needed such as
analysis and design of various structures subjected to earthquake
loading in Fifa, soil dynamic investigation in Jazan area, earthquake
simulation using shake table for Jazan area, methods of rehabilitation
of ancient and historical buildings. Analysis and design of structures
subjected to wind and earthquake loading.
53
References
1. S.A. Ashour and H.H. Abdel-Rahman, "Application of Seismic Risk
Analysis and Earthquake Simulation Methods to the Western Region in
Saudi Arabia", JKAU: Eng. Sci., vol. 6, pp. 3-23 (1414 A. H/ 1994 A. D)
2. Nazar and M. A. Ismaeil, " A comparative study on seismic provisions
made in UBC-1997 and Saudi buiding code for RC buildings", World
Academy of Science, Engineering and Technology. International Journal of
Civil, Architectural, Structural and Construction Engineering, Vol. 8, No. 4,
2014.
3. Abdullah M. Alamri, "Earthquakes Data Base of the Arabian peninsula, "
Technical Report (1), Seismic Studies Center, King Saud University, 1998.
4. Abdullah M. Al-Amri, Arthur J. Rodgers, Tariq A. Al-Khalifa, "
Improving the level of seismic hazard parameters in Saudi Arabia using
earthquake location", Arabian Journal of Geosciences, Volume 1, Issue 1,
pp 1-15, july 2008.
5. Awad Ali Al-Karni,"A procedure in Engineering Analysis to Evaluate the
Liquefaction Potential of the soil at the University of Jazan City in the
Southwest of Saudi Arabia, University of Putra Malyasia, Alam Cipta 4(1),
ISSN 1823-7231, Dec. 2009.
6. M.N. Fatani, A.M. Khan, "Foundation on Salt Bearing Soils of Jizan",
Third International Conference on Case Histories in Geotechnical
Engineering, Missouri University of and Technology, 1993.
54
7. Dhowian, A. W., Erol, A. O., and Sultan, S., "Settlement prediction in
complex sabkha soil profiles", Bulletin of the the International Association
Engineering Geology, 36: 11-27, 1987.
8. Erol, A. O. "Engineering geological consideration in salt dome region
surrounded by sabkha sediments, Saudi Arabia. Engineering Geology, 26:
215-232, 1989.
9. Dhowian, A. W. "Compressibilty characteristics of sabkha complex", the
Arabian Journal for Science and Engineering", 15(1): 47-63, 1990.
10. Al-Shamrani, M. A., and Dhowian, A. W., "Preloading for reduction of
compressibility characteristics of sabkha soil profiles", Engineering
Geology, 48: 19-41, 1997.
11. Anil K. Chopra; “Dynamics of Structures”, Fourth Edition. Prentice
Hall, 2013.
12. Mario Paz and William Leigh, "Structural Dynamics",5th Edition., Mc
Graw Hill, 2006.
13. J. L. Humar, "Dynamics of Structures, Balkema, 2002.
13. Clough and Penzien, “Dynamics of Structures”, 2nd edition, McGraw-
Hill, 1993.
14. Saudi Geological Survey, www.sgs.org.sa