GIS-Based Analysis and Display of Amplified Earthquake Surface Ground Motions in Geographic Regions

 

 

I.INTRODUCTION

 

Thousands of earthquakes of varying magnitude occur each day throughout the world. Fortunately many of these release only a moderate amount of energy and do not create much damage. Unfortunately the earthquakes, which release a large amount of energy, can cause widespread destruction and loss of life over large areas. Because of the destructive potential of strong earthquakes, these phenomena must be understood and techniques developed to predict the potential levels of ground motion, which may be developed in a given region so that engineered facilities can be, constructed which will provide the maximum achievable level of safety for the persons who will use them. There are two important problem areas which must be considered: the potential frequency of earthquakes in a given region and the levels of ground shaking which may be generated if a specific earthquake occurs. This project is concerned with the second of these areas: the potential level of surface ground motions and their geographic distribution.

Computer technology has evolved considerably in the past decade and also made it possible to do tasks that seemed previously impossible. Among the computer developments has been the development of computer graphics capabilities linked with computational capabilities. In the scientific-technical areas these developments have resulted in CAD and GIS. A software environment called Geographic Information System (GIS) plays a significant role to help geographers and other professionals in improving their work. This powerful tool provides users an advance capability in database management, analytical, data storage, classifying data, and in displaying the output in a simpler and user-friendly format. 

GIS related programs have a broad range of application such as in weather, population problems, commercial and city planning to name a few. In this project, GIS is used to analyze a problem in the civil engineering field, especially in earthquake engineering. During the past decade, the investigations in earthquake engineering using a computer program have become more popular, due to the large variety of data and information, which can be analyzed.

Earthquake, a natural phenomena event, is capable of causing death, injuries and property damage. Today, millions of people in the world live with significant risk from earthquake damage. There are several types of hazard, which can arise from earthquakes such as ground motion, structural hazard, liquefaction, landslide, lifetime hazard, and tsunami and seiche hazard. Ground motions maybe the most important hazard, as it is an important element in other hazards.

In this project the objective is to develop a program, which will simplify the process of predicting a surface acceleration using GIS platform. The program uses soil data collected from a particular site. Results are displayed in a simple and understandable format using the graphical output capabilities of the program Arc View. This program can help engineers or other users to established level of earthquake ground motion, which must be used in design.

 

II.        EARTHQUAKE

 

A countless number of earthquakes happen each year, but only a few earthquakes make the world headlines. These natural hazards cause tremendous damage around the world each year. Earthquakes are a global phenomenon and a global problem.

An earthquake is defined as any abrupt disturbance within the Earth that is tectonic or volcanic in origin and that results in the generation of elastic waves. The passage of such seismic waves through the Earth often causes violent shaking at its surface.

Hazards associated with earthquakes are commonly referred to as seismic hazard and they cause surface faulting and ground shaking. Ground shaking can create structural hazards, liquefaction, and landslides, retaining structure failure, tsunami and seiche hazards. Ground shaking is probably the most important hazard among those mentioned above, because it creates the largest level of damage.

 

II.1.     Ground Shaking-Strong Ground Motion

 

Ground shaking is what occurs at the earth's surface as a result of the release of energy during an earthquake. A vibrating or seismic wave is generated from the source of the earthquake, much like the waves created when you toss a rock into a pool of water. Generally, the closer you are to the source, the greater the ground shakes. Seismic waves propagate from the source rapidly through the earth’s crust. They produce shaking that may last from second to minutes. The duration and the strength of the shaking at a particular site depend on the size, the distance from source and the characteristic of the site.

            Basically seismic waves generated by an earthquake source are commonly classified into three main types. The first two, the P and S waves, are propagated within the Earth, while the third, consisting of Love and Rayleigh waves, is propagated along its surface.

 

 

(A)
 

(B)
 

(C)
 

(D)
 

Figure 2.1  Type of seismic waves:(A) P-wave; (B) SV-wave; (C) Rayleigh wave; (D) Love wave. From earthquake by Bolt.

 

            From requirements of structure design two design environments are possible. These are near field in which both surface waves and repropogated waves may have to be considered and design environments in which surface waves have largely damped out and energy delivery to the surface is primarily from energy propogated to the surface from underlying bedrock.

As the seismic waves travel from the bedrock to the ground surface, this trip is often through soil, and the characteristic of the soil can greatly influence the nature of shaking at the ground surface. Soil tends to filter the seismic waves as they travel through it, resulting in attenuating motion at certain frequencies and amplifying it at others. Since soil conditions can vary dramatically in a short distance the level of ground shaking or ground motion can also have great variations within a small area. It is important to have data on local soil conditions in order to evaluate the ground motion in a specific area. Our major interested is strong ground motion, a motion that has a sufficient strength to affect people and their environment.

 

II.2.     Soil Amplification

 

            It is well known that the amplification of earthquake waves comes from the strong contrast between the physical properties of the bedrock and sedimentary soils. The amplification of earthquake motions by soft surface soils may cause severe damage to structures. Typical evidence for motion amplification is from the 1985 Mexico earthquake, where extensive damage due to soil amplification was observed in Mexico City [Seed et al., 1987]. There has been considerable interest in evaluating site amplification and ground response during earthquakes.

Soft soils can amplify ground shaking. If you live in an area that in past earthquakes suffered shaking stronger than that felt in other areas at comparable distance from the source, you are likely to experience relatively strong shaking in future earthquakes as well. An example of this effect was observed in San Francisco, where many of the same neighborhoods were heavily damaged in both the 1906 and 1989 earthquakes. The influence of the underlying soil on the local amplification of earthquake shaking is called the site effect.

Other factors influence the strength of earthquake shaking at a site as well, including the earthquake's magnitude and the site's proximity to the fault. These factors vary from earthquake to earthquake. In contrast, soft soil always amplifies shear waves. If an earthquake is strong enough and close enough to cause damage, the damage will usually be more severe on soft soils.

 

II.2.a   Soil Types and Shaking Amplification

 

One contributor to the site amplification is the velocity at which the rock or soil transmits shears waves (S-waves). Shaking is stronger where the shear wave velocity is lower. The National Earthquake Hazards Reduction Program (NEHRP) has defined 6 soil types based on their shear-wave velocity (Vs):

A.     Vs > 1500 m/sec. Soil type A includes unweathered intrusive igneous rock. Soil types A and B do not contribute greatly to shaking amplification.

B.     1500 m/sec > Vs > 750 m/sec. Soil type B includes volcanic, most Mesozoic bedrock, and some Franciscan bedrock. (Mesozoic rocks are between 245 and 64 million years old. The Franciscan Complex is a Mesozoic).

C.    750 m/sec > Vs > 350 m/sec. Soil type C includes some Quaternary (less than 1.8 million years old) sands, sandstones and mudstones, some Upper Tertiary (1.8 to 24 million years old) sandstones, mudstones and limestone, some Lower Tertiary (24 to 64 million years old) mudstones and sandstones, and Franciscan melange and serpentinite. In other words, it a very dense soil or soft rock.

D.    350 m/sec > Vs > 200 m/sec. Soil type D includes some Quaternary mud, sands, gravels, silts and mud or stiff soil. Significant amplification of shaking by these soils is generally expected.

E.     Vs < 200-m/sec. Soil type E includes water-saturated mud and artificial fill. The strongest amplification of shaking due is expected for this soil type.

F.     Site-specific evaluation is required, for example liquefiable soil, peats, high plasticity clays, etc.

 

II.2.b. Soil Classification

           

There are some soil classification method used in soil mechanic that can be used to describe the type of soil such as the ASTM classification and United Soil classification System. In this project United Soil Classification will be use. There are some elements that need to be understood about this code. Important feature are:

There are some advantages using United Soil Classification system.

§         Conforms with nation wide practice of USED, NAVFAC, GSA, USBR, SCS, and others

§         Conforms with ordinary terminology for concrete aggregates.

§         Gives more detail quantitative divisions than former code or other systems except AASHO method (M145-49).

§         Results are reproducible with experience.

§         Classification of fine grained soils by limits has advantages:

o       Limits related more directly to engineering properties than does grain size of fine-grained soils.

o       Degree of plasticity can be estimated more readily than can the gradation of fines.

o       Limit test is cheaper and faster than hydrometer analysis.

Although there are advantages the United Soil Classification also has disadvantages

Ø      Necessitates a more detailed technical evaluation than previously required.

Ø      Not familiar to drillers, architects, etc.

Ø      For some period of familiarization its use can results in difference between soil engineer and driller’s description.

 

 

III.       GEOGRAPHIC INFORMATION SYSTEM

 

            A Geographic Information System, or GIS, is a computer system capable of database management, storing data, manipulating data, analyze and displaying geographical information. This powerful tool helps to provide solution to many problems such as economic analysis and marketing, population issues, environmental issues, catastrophic problems, climates changes and a lot more.

            The use of GIS, particularly in earthquake engineering, has become useful due to its capability to deliver informative data along with a geographical visualization. The use of GIS in Earthquake Hazard Analysis first appeared in the early 1990’s, utilizing static display without any interactive capability.

Recently, real time sets of integrated GIS tools for seismic hazard analysis were developed at SUNY-Buffalo (Ren, 1996 and Nikolaou, 1998). The analysis was based on deterministic, historic or user-specified, earthquake ground motion estimations (Ren, 1996) and probabilistic estimations earthquake ground motion, time history and structural damage evaluation (Nikolaou, 1998).

The primary effort in this project is to produce a set of program modules in a GIS platform to help users to estimate site-specific soil amplification, which may occur over a geographic region. The external module will be used in this project is written in conventional language such as Fortran, Visual Basic or C++ and the integrated script capability built into the Arc view GIS program called Avenue. The data, which will be used are a published soil Maps and a soil data from boring test.

Finally, the results will be presented using the  GIS computer software called Arc View. Using the capability built in the Arc View to modified, analyze, manage data, and visualize information, the final output expected to be more interactive and user-friendly, therefore the user effort is simplified and optimized. For example, if a user wishes to have a contour plot of amplified surface acceleration in a specific area, the program can be supplied with the required input data and the program will analyze and calculate the value. Calculated results can be plotted to show contours of the values. 

 

III.1.     Arc View GIS

 

Recently, many GIS related computer programs have become available in the market. For the purpose of this project a GIS program from ESRI called Arc/View V.3.1 will be the primary program. Some of the tasks that need to be accomplished must be done using the Arc Info V.7.2.1 program, which is a separate GIS program.

The input needed is soil information from a particular site to be analyzed and a base map of area. The soil information was entered into a Dbase file in order to be displayed in Arc View.

There are numerous published maps that can be used for analysis. These are available from federal or state agencies. For instant, the TIGER/Lineâfiles provided by US census bureau contains a wealth of information such as, political boundaries, streets, lifelines, zip codes, etc. This map was used as a base map for the purpose of this project.  A typical Tiger/line files Map is shown below.

 


 


Figure III.1        Arc View Program

 

Many of the functions in Arc View GIS are accessed through extensions that come with the software and can be turned on or turn off as needed. Choosing extensions from the file menu opens the extensions dial box. You will see a list of extension that you can check to turn the extension on and uncheck to turn them off. Examples are Geoprocessing, spatial analysis, 3D analysis, JPEG image support and a lot more. In this section some of the functions in Arc View that have been used to complete this project will be described.

III.1.a.            Geoprocessing

 


When the Geoprocessing extension is loaded, a menu choice called Geoprocessing wizard appears on the View menu. This wizard organizes and performs six spatial data processing tasks such as dissolve, merge themes, clip themes, intersect, union and spatial join.

 


Figure III.2         Geoprocessing wizard

 

 These functions provided a capability to merge themes together. Merging themes appends the feature of one or more themes to those of another theme of the same type. A new output is created that contains all features of each input theme. Field names in the output theme table are taken from the selected input theme. Attributes from the other input themes are included in the output theme table as long as their filed names match those of the selected input theme.

This function is needed particularly to append maps that are obtained from TIGER/Line Files. The maps in TIGER/Line files are separated into counties in the US. If it is desired to work with more than one county in an integrated fashion, it is most convenient to join these maps into an integrated theme. Careful attention must be paid to the attributes for the integrated theme. With careful planning it is possible to join attribute tables and then to work with them.

 

III.1.b  Arc View Spatial Analysis

 

The basic building blocks in Arc/View and Arc/Info are points, lines and polygon features. These features provide vector data, which defines geographic objects in terms of X, Y coordinate pairs their connectivity and associated polygons, which are formed. A single X, Y coordinate pair defines a point, while lines and polygons are defined by sets of coordinate pairs. The vector data model is an effective way to represent discrete feature, but it doesn’t do full justice to spatial phenomena that change gradually, have indistinct borders, or are mixed together.

With Arc/View spatial analyst you can create continuous surfaces from representative sample data points and analyze these surfaces to derive new information. The surfaces can be overlaid consisting a multiple surfaces containing different data to solve complex spatial problems.

When the Arc view Spatial Analyst extension is loaded, two new menus are added to the arc view GIS application windows. One of them is called surface and the other one is called analysis. To create a surface from sample data, first it is necessary to interpolate a grid from the surface menu.

 


 


Figure III.3 Surface analysis

 

In this project the analysis feature, which can create contours or interpolate a grid to show the level of surface acceleration was used. The value of surface acceleration is considered as a contour line in the view. This makes it possible to estimate the unknown value around the points for which soil data is known.

III.1.c.  Arc View 3D Analyst

 

Arc view 3D analyst lifts spatial data out of the flat display of the view and

 

gives it three-dimensional perspective. It adds a new document type, called 3D scene, to Arc View GIS.

Like Arc/View spatial Analyst, Arc/View 3D Analyst can create elevation surfaces directly from sample points. Then it can display these surfaces in three dimensions to give them the appearance of terrain.


it is possible to display the depth of the base rock in a particular area using this extension if sufficient spatial data is available. In this project only a limited amount of data was available for the project. Given enough time and more data points, the resulting surface map will provide a greater amount of detail on surface ground motion.  

 


Figure III.4     3D Scene of a surface

 

III.2    SSOIL.EXE Module

 

SSOIL is a computer program written in the FORTRAN programming language in 1998 by Dr. Aspasia Nikolaou. This program is useful to calculate soil amplification. The example below was scaled to the target rock Uniform Hazard Spectrum of this site by using a factor of 0.89. The scaled motion was passed through the soil profile of figure III.6 and amplified to the free field surface using the 1-D model of SSOIL.

 

 

 

SOIL

BLOW

SHEAR WAVE

 

 

 

 

TYPE

COUNT

VELOCITY (m/s)

DESCRIPTION

 

 

 

 

 

 

 

 

 

OH

 

 

 

ESTUARINE CLAY

15

 

 

( 11- 65 )

121.92

SLIGHTLY TO

 

 

CH

 

 

 

MODERATELY

 

 

 

 

 

 

ORGANIC

 

 

 

 

 

 

 

 

 

OL

( 11 - 65 )

 

 

ESTUARINE CLAY

30

 

 

TO

152.4

AND SILT

 

 

CL-ML

( 9 - 65 )

 

 

SLIGHTLY

 

 

 

 

 

 

ORGANIC

 

 

 

 

 

 

ESTUARIBE SILTY

 

 

SM

( 8 - 65 )

365.76

FINE SAND

 

 

 

 

 

 

 

50

 

SM-GM

 

762

GLACIAL OUTWASH

 

 

 

 

1828.8

BEDROCK

 

 

 

 

 

 

 

 

 

Figure III.6    Site 1 Typical Soil Profile

 

 

 

Figure III.7             Time History of earthquake

Figure III.8             Amplification function of site 1

 

This microzonation-type analysis is isolated for earthquake hazard analysis, because detailed soil information of a local soil condition is needed to know the effect of amplification.

With the help of Arc view GIS this information can be plotted on a map. It is possible to draw contours of soil amplification and surface accelerations in the specific area if enough information on the soil condition are available; in this project ten point records of soil boring information from Eastern New York region were used.

 

III.2.1.            SSOIL Files Description

 

            Ssoil.Inp Description

Ø      Line 1 (number of layers)

    N = Number of layers

Ø      Line 2 (soil properties; repeat N times)

    H (l), ES (l), PS (l), BS (l), POISS (l)

    Where:     H (l) = thickness of (1) layer

ES (l) = elasticity modulus of layer (1)

PS (l) = mass density of layer (1)

BS (l) = damping of layer (1)

         POISS (L) = Poisson's ratio of layer (1)

Ø      Line 3 (rock properties)

    KEY10, ES, PS, BS, POISS

    Where:        KEY10 = 1 for elastic rock

2 for rigid rock and ES, PS, BS, POISS same as Line 2 but for rock

Ø      Line 4 (frequency input)

           NW = number of frequencies for printing transfer function

Ø      Line 5 (values of frequencies)

           Wl, W2,                  WN = values of the NW frequencies

Ø      Line 6 (alternative frequency input)

     KEY20, Wl, DW, NSTEPS

     Where:    KEY20 = 1 for using a range of frequencies defined by Wl, DW, NSTEPS Wl starting frequency (rad/sec)

     DW frequency step

     NSTEPS = number of steps

Ø      Line 7 (time domain input)

          KEYTIME = 1 if you want time domain analysis to be performed

Ø      Line 8 (time history; needed only if KEYTIME = 1)

    NORM, NNT, TMIN

    Where:     NORM = factor to multiply the time history with NNT = number of Fourier points TMIN = minimum period to be used (recommended: 0.01)

NOTE:   Use the option of Line 6 for frequency input.  For lines 4 & 5 just enter what I sent you in the input files (they won't be used if you activate KEY20 = 1)

 

 

 

 
 
 

 

 

 

 

 


Figure III.9  Typical SSOIL Input File

 

            Extern.Th Description

·        Line 1    (time history data)  NSRC, DTSRC

    Where:        NSRC = number of points in accelerogram DTSRC = time step

 

·        Line 2 (acceleration values)

ACCROCK = acceleration values (repeat NSRC times; put data in 1 column)

       NOTE: Use consistent units (m, m/s, Mg/M3, M/S2 , etc.)

 

Figure III.10.  SSOIL Extern.TH file

            SSOIL.Out Output Files Description

1, W, TRF (l), ATRF

Where:         I = frequency number

                   W = frequency value

                  TRF = transfer function for freq.  W (COMPLEX NUMBER) 

                  ATRF = amplification function at freq.  W

Figure III.11       SSOIL output file

 

            Time.Out Description

Gives the surface acceleration time history in a column

NOTE:   Ignore top 7 lines (check/echo writing).  The maximum of the column is the peak surface acceleration.

            P *.Out Description

(* is an index for the depth for the particular output)

FFDISP (J) FFSH (J) free field displacement at depth * in freq. domain (complex number)

 

III.3    SPEC.EXE Module

           

            Besides the SSOIL program module an additional program module, SPEC module was used. This module also written in FORTRAN, it takes the time history surface motion calculated by SSOIL and calculates specific dynamics value. Using a user specified period or range of periods, values of spectral acceleration, spectral velocity and spectral displacement are calculated. Details of SPEC input and Output are described below.

 

III.3.1   SPEC Files Description

 

            Input file: Spec.Inp

Line 1à IN$, OUT$ (histor2.th histor2.sp)

Name of time history file; name of output file (use 9 to 1 0 characters in total to name each files). You can choose your output file name and input file name.

Line 2à PERMIN, PERMAX, DPER, BB (0.01 4.0 0.01 0.05)

Minimum period to calculate spectrum; maximum period; period step; damping

Line 3à NURECMAX, RULE, NORMAL (12000 4 1.0000)

Maximum number of points of the accelerogram to be considered; rule; factor to multiply the whole accelerogram.

(Use always 12000 for NURACMAX and 4 for rule)

 Figure III.11 SPEC input file

 

            Time History

The input time history file must have a first line with NUREC, DT (number of points and time step) followed by a column of acceleration values.     

 

Figure III.12 Typical SPEC input File

            Output File

            The first 4 lines is an echo of the input Then there are 4 columns

First column: period

Second: Spectral acceleration

Third column: spectral velocity

Fourth column: spectral displacement

 

Figure III.14       Typical output file from SPEC

 

 

IV.   PROGRAMMING

            In this chapter the method, analysis and program design for the project will be described. The flow chart for the analysis will be divided into 3 major sections, Input, Analysis and Output. The analysis it self will be using modules like SSOIL, SPEC and Microsoft Excel. This analysis will be integrated with automation written in Visual Basic and Macro Excel. The flowchart for the analysis is shown below;

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure IV.  Flow Chart of the project and the Program Step to obtain output

 

IV.1     Input

 

IV.1.a.    Base Map

The map that we are using in this project was obtained from TIGER/Line Files 1997. US Department of Commerce Economic and Statistic Administration, Bureau Of The Census published the TIGER/Line files. These files are extracts of selected geographic and cartographic information from census TIGERâ (Topologically integrated Geographic Encoding and references) database. First released in 1988, TIGER/Line files have been improved through the increasing of data address and addition of ZIP codes.

            TIGER/Line files are being released by county or statistically equivalent entity based on the January1, 1995 boundaries. They include files for all counties and statistically equivalent entities in the US, US Virgin Island, Puerto Rico, Hawaii and the American Samoa.

For the purpose of this project county map with code number 36005 is used as a demonstration. The 36005 files were imported as Arcs using Arc/INFO command, called TIGERTOOL. The resulting files contain attributes that  will be used to make queries such as, TIGER/Line Identification Number (TLID), Census Feature Class Codes (CFCC), Landmark Feature, etc.

Figure IV.1             Bronx County with ACODE table

IV.1.b  Soil Data

 

            Sample soil data was supplied by Mueser Rutledge Consulting Engineers, with the help of Dr. Sissy Nikolaou. Due to Confidentiality Issues for the information the exact location of this data will not be released. To protect the confidentiality of the data, the values were used to develop an example analysis for another area. The data contain boring information of ten sites includes soil types and shear wave velocity.

From shear wave velocity it is possible to obtain ES, the soil elastic modulus, which the SSOIL program uses. It is necessary to be sure that the units are consistent.

 

Where:

Vs: Shear wave velocity (m/s)

Gs: Soil shear modulus (Kpa)

P: Mass density (Mg/M3)

Where:

Es = Soil elastic Modulus (Kpa)

V = Poisson’s Ratio

 

 

 

N

BLOW

SHEAR WAVE

 

 

 

 

VALUE

COUNT

VELOCITY (m/s)

DESCRIPTION

3

 

8

( 11- 65 )

91.44

FILL

 

 

 

 

 

 

 

 

 

 

 

 

MED. COMPACT GRAY

 

 

20

( 8 – 65 )

274.32

F SAND

 

 

 

 

 

 

19.8

 

 

 

 

 

 

 

10

( 11 - 65 )

152.4

STIFF ORGANIC

25.9

 

 

( 10 - 65 )

 

CLAYEY SILT

 

 

30

( 8 – 65 )

396.24

GRAY-BROWN

32

 

 

 

 

SAND AND GRAVEL

 

 

40

( 7 – 65 )

457.2

COMPACT

38.1

 

 

 

 

COARSE SAND

 

 

20

( 10 - 65 )

213.36

DARK GRAY

44.2

 

 

 

 

ORGANIC SILT

 

 

50

( 7 – 65 )

548.64

SANDAND COARSE SAND

 

 

 

 

 

SAND AND GRAVEL

 

 

80

( 6 – 65 )

853.44

 

56.3

 

 

 

 

 

 

 

100

( 5 – 65 )

1219.2

JAMECO SAND

 

 

 

 

 

 

62.4

 

 

 

1828.8

BEDROCK

 

 

 

 

 

 

 

 

Figure IV.2     Sample of soil boring test

 

IV.2     Modules

 

IV.2.a      Working with Arc/View GIS

 

      In the beginning phase it is necessary to have a digital map. Base map from TIGER\Line files 1997; code 36005 was used in this case.  A second step is to create a separate point theme in the view windows, and to save this as a separate file. The point theme can be generated from a .dbf file with information on X, Y. and Z values for the points.

Point id

X

Y

Z

1

199060.7

231467

125

2

213297.7

226541.2

150

3

197893.3

219821.5

160

4

209908.4

218568.3

170

5

203000

227300

200

6

205000

222000

180

7

207500

225600

200

8

210222

223100

145

9

201224

223750

160

10

202278

219223

120

 

Figure IV.3. Example of point input file

 

 

Note: The dimensional units for the X and Y coordinate must agree with the projection used in the Arc/View. for this project  a state plane 1983 projection was used.

For this process the Arc/View extension called GeoProcessing was used. This command converts a .dbf file into a shape file theme. The function is “Add event theme” in view menu toolbar. The table which contains information about X and Y coordinates must be available

Figure IV.4. Create a point theme using table
 

The Shape file will have the attributes that are included in the dbf file. At later stage, running the Conout.exe program, which is created with macro program from excel files. Tables can be added and joined in Arc/View project, will generate an output file. This process will be explained later in this report. . If it is necessary convert a shape file into a theme file “Shape arc” Command in Arc Info can be used.

     

IV.2.b    Working with Excel

 

      For this an excel file, called Prodata.xls was prepared, and has a Macro program within it. The soil data from boring test are inserted into this work sheet and the macro is run. Basically the Macro will create an input file that can be read by the SSOIL program and to run the SSOIL program. The short cut key is CTRL+SHIFT+P. The results will be written to a c:\temp\ folder. In order for the program to run properly, do not change the format of the Prodata.xls.

For the convenience of the user, Execute program is also include  that run this process called Prodata.EXE. This program can be run automatically with double clicking a Prodata.EXE.

 

Note: this program will take several second to be completed (depend on how fast is your system). It is necessary to wait the calculation to be completed before proceeding to the next step. Explore the C:\temp folder to confirm if the program is finish.

 

IV.3   Analysis

Running a program called PERIOD carries out the analysis. This program will make it possible to input the number of points that will be to analyze (10 points for this project) and the period of earthquake on that particular site (recommended period range from 0.2 until 4 sec for Eastern New York).

This program was written using visual basic. It will create an input for SPEC program and run the SPEC program.

Figure IV.5  PERIOD.EXE

IV.4     Output

 

The final procedure is to collect the output using a macro that stores data in files called CONOUT.xls. This program will generate a file called Pointout.dbf in the C:\TEMP\  folder.

            The output of this project will be displayed using the Arc/View 3.1 program. Using the capability of Arc View. To display and to manage table that we had, we hope that the output will be more preventative.

The contours of surface response can be generated using a CREATE CONTOUR command in Arc View. The Z value can be the amplification value, Spectral Acceleration, spectral velocity or spectral displacement, which in the example is generated from ten points. The extension for spatial analysis and 3D analysis should be activated from the extension menu. The user can use the graphical plot to interpolate the surface ground motion parameters for areas at the points where the borings were located.

 

Figure IV.6   Create contour, create TIN and Interpolate Grid

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure IV.7   The Contour of Acceleration at 0.7 sec

 

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure IV.8 The Grid acceleration at 0.2 sec

 

V.      APPLICATION EXAMPLE

 

The Eastern New York region was selected as a case study for this project. The computer program develop in this project performs calculations. The Soil data attached in this report were obtained from a leading Geotechnical Consulting Company. In order to keep the data confidential, then the actual ones are assigned to the different coordinates possible points..

We use the period of 0.2 sec and 0.7 sec to display the difference of the result. Using the Spatial analysis mention above we create contour for Spectra Acceleration, Spectra Velocity and Spectra Displacement for each period.

The interpolate grid function is used to improve the presentation. Shown below is the acceleration for a 0.2 sec period and 0.7 sec periods.
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure V.1 Acceleration at 0.2 sec

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure V.2 Acceleration at 0.7 sec.

 

 

 

 

VI.       CONCLUSION

 

 

This project has demonstrated that It is possible to analyze and display amplified earthquake surface ground motions and to integrate the analysis into a convenient program. This is accomplished using the Arc View GIS program and integrating it with external program modules written in compiler languages such as Fortran and Visual Basic and other programs such as Microsoft Excel. The program integrates sub programs such as SSOIL and SPEC, which are written in the FORTRAN language. Using the Arc View program final results can be displayed in the form of a contour plot for different spectral acceleration, velocity and displacement values. Information can also be output as data tables. This information will be useful for designers and engineers. The information will make an important contribution in being able to design safe structures.

The overall design of the program will make it possible to input data related to just one county or for larger geographic regions. A key need is to have enough field data that provides points within a reasonable distance of one another. With more field data the quality and accuracy of the contours that are drawn will improve and present a valuable guide to selecting earthquake design values for a project at a specific point in a region.

Several examples of the analysis capabilities of the program developed in this project are presented to demonstrate the capabilities of the program.

 

 

VII.              SUGGESTIONS FOR FUTURE RESEARCH

 

As is known soil characteristics change in both the horizontal and vertical directions and there may be great variability over even relatively modest areas. Therefore it is desirable to obtain as much field information as possible. As field information is expensive to collect, plans must be carefully made to collect the information within reasonable time and cost restraints.

Although the primary elements of the GIS-based analysis have been demonstrated in this project, further improvements can be made by more closely integrating the program elements, to develop an improved user-friendly interface and in incorporating additional features such as automatic integration of earthquake attenuation for the wave energy transmitted through the sub-soil rock layer.

 

 

 

VII.      REFERENCES

 

 

1.      Barnhard, Theodore; Frankel, Arthur; Mueller, Charles; Perkins, David; Leyendecker, E.V., Dickman, Nancy; Hanson, Stanley; Hopper, Margaret., (1996), ”National Seismic Hazard Map”, USGS Documentation.

2.      Baumbach, M., Grosser, H., Romero, G., Rojas, J., Sobiesiak, M., Welle, W., Schmitz, M. (1997), “Time and Space Distribution of Cariaco Aftershocks, Focal Mechanisms and Statistical Analysis”, WWW Publication http://www.gfz-potsdam.de/pb2/pb21/Task_Force/ Einsaetze/Cariaco/cariaco.html

3.      Chester, Thomas, Alden Richard (Contributor)(1997), Mastering Excel 97, January 1997

4.      Environmental System Research Institute Inc. (1997), “Getting to know Arc/View GIS”, The geographic information system (GIS) for everyone.

5.      Kramer, Steven L. (1996), “Geotechnical Earthquake Engineering”, Prentice-Hall Inc.

6.      Nikolaou, Aspasia S. (1998), “A GIS Platform for Earthquake Risk Analysis”, Doctor of Philosophy Dissertation State University Of New York at Buffalo, UMI, A Bell & Howell Company

7.      Petroutsos, Evangelos (2000), Mastering Visual Basic 6
Sybex, Inc.; ISBN: 0782122728

8.      YANG, J. and SATO, T. (2000),” Seismic Amplification At A Soft Soil Site With Liquefiable Layer”, Journal of Earthquake Engineering, Vol. 4, No. 1 (2000) 1-23.

9.      Walter W. Hays, Amar A. Chaker, and Craig S. Hunt, (1999), “Learning From Disaster), Civil Engineering magazine December 1999.

 

 

 

 

Hosted by www.Geocities.ws

1