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





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





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

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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



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

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