Since 2010, the structure built of the bridge began to be viewed primarily on design and architecture. The safety of the bridge started is highly regarded because of the many problems and failures occurred in recent years. Design engineers are challenged more to provide economic solutions that could be implemented within minimum time schedules, making an efficient use of the available resources. Bridges are key components of Malaysia infrastructure that when disrupted cause not only discomfort to users but also a big negative impact to the economy. This is because we need a bridge to cross an area is on high or below the river, lake or sea. Bridge is also used for the universal. New construction techniques, connection details and better design procedures and tools are required to reduce this ratio and help in raising the quality of our bridge system.
In Malaysia especially, there are many types of bridge such as concrete bridge, cantilever bridge, arch bridge, suspension bridge, cable-stayed bridge and truss bridge. Concrete bridges are horizontal beams supported at each end by piers. In modern times, concrete bridges are large box steel girder bridges. Weight on top of the beam pushes straight down on the piers at either end of the bridge. They are made up mostly of wood or metal. Beam bridges typically do not exceed 250 feet long. While the length of a bridge increased, the strength of the bridge is already decreased. Hence, each bridge needs strong support, such as decks and piers.
Figure 1.1: Concrete Bridge
Earthquake is release of energy waves called seismic waves in the crust of earth, leads to the creation of a natural disaster called earthquake. Earthquakes can be recorded using an instrument called as seismometer. Richter scale is used to represent magnitude and intensity of earthquakes. In recent years, an earthquake often occurs in the Asia area especially Indonesia. If more than 7 Richter scale, the earthquake was classified as a hazard to humans. This is because it can cause damage to the environment, buildings, roads and so forth.
The origin point of seismic waves is called epicenter of earthquake. If epicenter is located near the sea then it can cause the creation of Tsunami waves. This tsunami tragedy was caused by ground movement occurred under the impact of the terrible earthquake. In 2004, tsunamis have occurred in the area of Acheh, Indonesia caused a lot of debris occurred. Many buildings, bridges are collapse and also reported high mortality. Earthquakes lead to severe shaking of earth's surface, and landslides. Earthquakes are generally results of natural phenomena like geological stress, volcanic eruptions, landslides etc but earthquakes can also be induced by some human activities like mine blasts and nuclear experimentation.
Figure 1.2: Seismicity of Malaysia (United States Geological Survey's)
Nowadays, there are some cases of earthquake event that was reported in Malaysia but the earthquake event was in a small scale. Earthquake already happen in Malaysia especially in Sabah. Normally the design for the structures in Malaysia does not cover the earthquake condition. When earthquake happens, the structure will collapse. So, the analysis for the structure especially bridge should be made to make sure the performance of the bridge during the earthquake.
1.2 PROBLEM STATEMENTS
The main purpose that this research is needed to be carried out is to analyze the performance of the bridge pier which is Jejambat Kepong due to earthquake loading. The performance of the bridge pier is determined from the time history analysis which is to compute the response of the structure at each of the time steps that have been specified. The analysis can be made using software which is LUSAS software. This analysis is to evaluate the performance of the bridge and also will lead to the further understanding of characteristics that need to be focused in designing bridges in future. Due to the analysis, we can increase the safety of the bridge in Malaysia.
1.3 OBJECTIVES
In the context of the above described project, current state of the knowledge, the objectives of the study presented in this thesis are as follows;
To investigate the behavior of earthquake effect to the bridge pier by using eigenvalue mode.
To perform 3D modeling analysis by investigate the seismic response of the actual Jejambat Kepong bridge pier in the longitudinal direction.
To determine the displacement and stresses by using Time History Analysis.
1.4 SCOPE OF WORKS
The overall scope of the research presented in this thesis is to perform a comprehensive evaluation of Concrete Bridge and lateral loads to study the effects of earthquake loading details on the bridge. This study can be divided into two types which is getting all the information from WCE Consulting Engineers about the materials, dimension, structural drawing plan, and key plan and also, analyzing all the data using LUSAS software.
Preliminary Analysis.
Getting all the information detail about Jejambat Kepong, Kuala Lumpur from Public Work Department.
Analyzing data using Lusas Software
By using lusas software, the data properties will be extracted to analyze the bridge pier including earthquake loading. The data of earthquake event in Acheh, Indonesia in 2004.
1.5 SIGNIFICANT OF STUDY
In Malaysia, many structures especially bridges was built without considering the earthquake loading. This is because, Malaysia are located in the area that having low intensity. But, lately the earthquake that happens in Indonesia has slightly affected some part of Malaysia. Table 1.1 below show the list of some recent earthquake happen in Malaysia.
Table 1.1: List of Recent Earthquake in Malaysia (Malaysian meteorological department)
Date
Time
(Local Time)
Location
Latitude
Longitude
Magnitude
(Richter Scale)
Category
Distance
18/09/10
3:34am
Talaud Islands
3.7°N
126.9°E
5.4
Moderate
338km Northeast of Manado, Indonesia. 961km Southeast of Kunak, Sabah.
18/09/10
3:21am
Hindu Kush Region
36.3°N
70.4°E
6.1
Strong
228km Northeast of Kabul, Afghanistan. 4491km Northwest of Langkawi.
16/09/10
2:42am
Mindanao, Philippines
6.0°N
126.1°E
5.1
Moderate
114km Southeast of Davao,Philippine. 872km Northeast of Lahad Datu
14/09/10
3:33pm
Mindanao, Philippines
5.6°N
124.6°E
5.2
Moderate
205km Southwest of Davao,Philippine. 701km Northeast of Lahad Datu, Sabah.
This research paper focuses on the performance of a bridge when affected by an earthquake. The concrete bridge (pier) of Jejambat Kepong, KL will be used as a case study for this research.
CHAPTER 2
LITERATURE REVIEW
2.1 INTRODUCTION
This chapter presented some of the previously performed research founded in the literature dealing of earthquakes, RC structures may undergo from small elastic deformation, cracking to propagation, local fracture and even collapse. Concrete is a mixture of paste and aggregates. The paste is usually composed of Portland cement and water while the surface of concrete is determined by fine and coarse aggregates. Hydration is a chemical reaction make paste hardens and gains strength to form hard solid concrete. In this process the newly mixed concrete has plastic and malleable characteristic but after harden it very strong and durable. These are the characteristic concrete has become a key material to create a bridge and other building
2.2 BRIDGE
The main types of bridges are arches, beam bridges, cable-stayed bridges, cantilever bridges and suspension bridges. These are usually arches, beams or girders, or cantilevers, or they may be parts of bridges, for example the suspended span of a cantilever bridge, or the deck of a cable-stayed bridge or a suspension bridge. Truss bridge is sometimes reserved for those which act primarily as beams, while the others are discussed under the heading of the bridges of which they form a part. Like a box-girder or a pre-stressed span, is more a type of construction than a type of structure.
The reason that the types of most bridges are obvious is that these types have become popular because they are successful, and success is greatest in the broad central regions of the available variable-space. For example, if you make an extremely flat suspension bridge, you could put the wires in a concrete matrix, and you would have a pre-stressed beam requiring no anchorages. The same is true of arches - an extremely flat arch would generate enormous thrust, and a beam would be a better solution.
The same difficulty applies to many other human activities, and indeed of many natural groups of species: although there are many genera and species which tax the powers of biologists to classify them, the vast majority fall more easily into groups. On the other hand, where there are very many closely related species, there may be sporadic disputes between "lumpers" and "splitters".
Figure 2.1: This diagram shows the length of a bridge and two definitions of span
(Brantacan, 2010)
2.2.1 Concrete Bridge Pier
A concrete bridge is a structure made from concrete and built for the purpose of covering a certain distance. Typically, concrete bridges allow vehicles or people to cross over physical obstructions, such as lakes, rivers, valleys, or roads. Concrete is one of the most common types of materials used in modern-day bridge construction.
(Brantacan, 2010)
2.3 MATERIALS
Building a bridge out of concrete can have many advantages. Generally, concrete is a highly versatile substance because it can withstand a wide variety of climates. It can be mixed in a way that gives it the ability to resist extreme temperature fluctuations as well as corrosive chemicals. As a result, a concrete bridge functions well in most regions of the world. Concrete is also a flexible material, allowing an engineer to be creative when planning the aesthetic attributes of a concrete bridge design project.
Concrete is typically more durable than other types of materials, such as steel or timber. In fact, some types of concrete can last for up to 100 years. Because of this, concrete bridges are often lower maintenance than other kinds of bridges with fewer overall upkeep costs. The cost of initial construction is also frequently lower with concrete than with other types of materials.
Concrete is one of the most widely-used materials in current arch bridge design. A concrete arch bridge consists of a structure with a curved arch, which serves as the main support mechanism. In addition, an arch bridge usually contains two abutments, which are placed at each end of the curved arch. Contemporary concrete arch bridges are usually constructed from reinforced concrete, which contains steel reinforcement bars.
2.4 METHOD FOR DAMAGE AND COLLAPSE ANALYSIS OF RC STRUCTURE
Finite element method (FEM) and distinct element method (DEM) are the most common methods for damage and collapse analysis of RC structures. The advantages and disadvantages of these methods are compared (Table 1). FEM is valid only before structures collapse, while DEM is able to treat the whole response process from elastic phase to post-collapse; however, it is less accurate for elasto-plastic analysis and time-consuming for collapse analysis. Therefore the authors suggest two collapse analysis strategies according to study purposes. The first strategy is to adopt EDEM with a simple and approximate material
(Cen Zhou & Limin Sun, 2008)
Table 2.1 - FEM and DEM for Damage and Collapse Analysis of RC Structures
Analysis Method
Modeling for RC structure
Applicable range
Elastic
Plastic
(post-crack)
Local failure
& Re-contact
FEM
Beam-hinge
conventional
plastic hinge
Ã-
before collapse
Smeared crack
conventional
smear crack
Ã-
before collapse
Discrete crack
conventional
joint element or re-mesh
Ã-
before collapse
DEM
Ordinary
Ã-
Ã-
Assemble of discrete bodies
after collapse
EDEM & AEM
small rigid bodies connected by springs
yield or partially failure of springs
+
Re-contact spring
whole process
"Ã-" means invalid
(Cen Zhou & Limin Sun, 2008)
2.5 PRECAST CONCRETE SYSTEMS IN HIGH SEISMIC REGIONS
The use of precast concrete systems in high seismic regions has been limited due to a lack of understanding of system performance during strong ground motions. The main focuses of uncertainty in precast systems are the connections between individual members. A review of previous applications in seismic regions indicates that the use of precast superstructure systems traditionally rely on a fair amount of in situ casting of concrete to provide reliable seismic connection response. During the preliminary stages of development of the proposed connection concept, a continual desire to minimize on-site casting was reverberated. To meet the needs of industry, a precast connection concept was developed that draws on the experience of precast segmental construction.
The detail investigated consists of a precast girder-to-precast bent cap connection in which lateral strength is provided by post-tensioning which runs through the girders and bent cap to provide a reliable connection. This connection is similar to a span-by-span precast segmental bridge system commonly used throughout the world. The main issues related to this system were:
The ability to predict the positive and negative flexural capacity,
Ability to quantify the moment-rotation response,
Potential shear slip between segments
Ultimate rotation capacity.
© Matthew Joseph Tobolski, 2010
2.6 EARTHQUAKE
2.6.1 Introduction
Earthquakes are the Earth's natural means of releasing stress. When the Earth's plates move against each other, stress is put on the lithosphere. When this stress is great enough, the lithosphere breaks or shifts. Imagine holding a pencil horizontally. If you were to apply a force to both ends of the pencil by pushing down on them, you would see the pencil bend. After enough force was applied, the pencil would break in the middle, releasing the stress you have put on it. The Earth's crust acts in the same way. As the plates move they put forces on themselves and each other. When the force is large enough, the crust is forced to break. When the break occurs, the stress is released as energy which moves through the Earth in the form of waves, which we feel and call an earthquake.
(Maggi Glasscoe, 1998)
2.6.2 Types of Earthquake
There are many different types of earthquakes: tectonic, volcanic, and explosion. The type of earthquake depends on the region where it occurs and the geological make-up of that region. The most common are tectonic earthquakes (earthquake that occurs when the earth's crust breaks due to geological forces on rocks and adjoining plates that cause physical and chemical changes.). These occur when rocks in the earth's crust break due to geological forces created by movement of tectonic plates. Another type, volcanic occurs in conjunction with volcanic activity. Collapse earthquakes (small earthquakes in underground caverns and mines that are caused by seismic waves produced from the explosion of rock on the surface) are small earthquakes in underground caverns and mines, and explosion earthquakes result from the explosion of nuclear and chemical devices. We can measure motion from large tectonic earthquakes using GPS because rocks on either side of a fault are offset during this type of earthquake.
(Maggi Glasscoe, 1998)
2.7 CODES OF CONDUCT
EUROCODE 8 Part 4 1999 Design Provision for Earthquake Resistance,
BS 8110-1997 Part 1, Structural use of Concrete
BS 5400-2-1978_Steel, Concrete and Composite Bridges,
BS 5400-3-2000_Steel, Concrete and Composite Bridges (noPW)
2.8 LUSAS SOFTWARE
LUSAS is a UK-based developer and supplier of Finite Element Analysis (FEA) application software products that bear the same name.
LUSAS is an associative feature-based modeler. The model geometry is entered in terms of features which are sub-divided (discretised) into finite elements in order to perform the analysis. Increasing the discretisation of the features will usually result in an increase in accuracy of the solution, but with a corresponding increase in solution time and disk space required. The features in LUSAS form a hierarchy that is volumes are comprised of surfaces, which in turn are made up of lines or combined lines, which are defined by points.
Figure 2.2: The Bridge menu
Figure 2.3: The LUSAS Modeller Interface
This example uses the Autoloader program to aid in the linear static analysis of a
3-span curved concrete bridge deck subject to typical highway loading. Points of interest for influence surface generation The structure is modelled using thick plate elements, representing a deck of inner radius 75m, outer radius 86m and thickness 0.7m. The deck has a width of 11m consisting of a 10m wide carriageway region and two 0.5m wide verges. The live loading is to be calculated for three defined influence surfaces using the Autoloader facility.
(Application_Examples_Manual_Bridge,_Civil_and_Structural,2009)
Figure 2.4: Points of interest for influence surface generation
2.8.1 Procedure Analysis LUSAS Software
There are 3 steps in the finite element analysis using the LUSAS software, which are as follows:
a) Pre-processing phase
Pre-processing is process creating a geometric dimension that will representation of the structure being analysis by assigning it properties, then output the result of information as a formatted data file for be analysis by LUSAS.
b) Finite Element Solver
Sets of linear or nonlinear algebra equations that have different value nodes are solved simultaneously to get nodal results such as displacement values or temperature values.
c) Result-Processing
The results of analysis can be processed to show the contour of displacements, stresses, strains, reactions and other important information. From this information graphs, deformed shapes and other characteristic of a model can be plotted.
2.8.2 Earthquake Input
For two-dimensional structures, earthquake acceleration time history records can be applied in the global X- and Y-directions of the structure. For three-dimensional structures, an additional earthquake acceleration component in the global Z-direction of the structure can be applied. The input format for these acceleration records is space delimited, TAB delimited or Comma Separated Variable (CSV).
For all formats, the time step of the acceleration records must be identical in all files. IMDPlus supports the solution of up to seven earthquakes at a time with enveloping / averaging of the Secondary Response Spectra (SRS). For space or TAB delimited files the number of time steps in each directional record for multiple record files must be identical across each of the earthquakes. For Comma Separated Variable files, the number of time steps in each directional record can vary but the number of time steps in individual earthquakes must be identical. If more than one earthquake is present in the record files, the IMDPlus analysis will process all valid combinations.
(Theory Manual Volume 1[2], LUSAS, 2009)
Table 2.2: Sample Acceleration Time History Records
Space Delimited Single Combination
Space Delimited Two Combinations
0.000 0.0000E+000
0.005 -2.7459E-002
0.010 -3.4127E-002
0.015 -4.0796E-002
0.020 -4.7464E-002
0.025 -5.4133E-002
0.000 0.0000E+000
0.005 -2.7459E-002 -4.0070E-005
0.010 -3.4127E-002 8.2210E-004
0.015 -4.0796E-002 1.2618E-002
0.020 -4.7464E-002 1.4741E-002
0.025 -5.4133E-002 1.8604E-002
2.9 GAP OF RESEARCH
Gap of research differences between my research with others. There are several research that done almost same with my research, but different based on result, type of analysis and software that been used.
Table 2.3: Gap of Research
Author
Title of Research
Dimension
Name of Structure
Software
Analysis
Mohd Ritzman Abdul Karim
Analysis Concrete Bridge (Pier) Structure Due To Earthquake Acheh Intensity Condition
3D
Concrete Bridge
LUSAS
Nonlinear Dynamic
Nathan Johnson, M. Saiid Saiidi and David Sanders
Nonlinear Earthquake Response Modeling of a Large-Scale Two-Span Concrete Bridge
3D
Concrete Bridge
SAP2000
Drain 3DX
Nonlinear Dynamic
Azlan Adnan, Ismail Mohd Taib and Meldi Suhatril
Seismic Performance Of Sungai Merang Bridge In Terengganu Under Low Earthquake Ground Motion
2D & 3D
Concrete Bridge
SAP2000
IBC2000
IDARC
Linear & Nonlinear Dynamic
2.10 THEORETICAL BACKGROUND
2.10.1 Introduction
2.10.1.1 Seismic Response of a 2D Frame
This example examines the Spectral Response analysis of a 2D braced tower frame. The geometry is simplified to a wire-frame or stick representation, with each of the structural members being represented by Point and Line features only.
The model is comprised of thick beam elements for the concrete column, beam members, and steel diagonal bracing members which have pinned end connections. The structure is fully restrained against displacement and rotation at ground level.
Since the global response of the structure is required, the model of the tower is further simplified by meshing each Line with a single element. This will effectively avoid the extraction of local panel modes for individual beams and columns. These local modes could be investigated independently in a more detailed analysis.
(Application_Examples_Manual_Bridge,_Civil_and_Structural,2009)
2.10.1.2 Seismic Analysis of a 2D Frame
The Seismic Response of a Plane Frame is revisited in this example. The frame is founded in a plane strain elastic medium and the response of the structure is evaluated in the time domain using IMDPlus. The model is comprised of thick beam elements for the concrete columns, beam members, and steel diagonal bracing members, which have pinned end connections. The number of beam elements representing the components of the structure has been increased from 1 per line to 4 per line to provide greater definition of the deformed shapes. In addition to this modification, all support restraints have been removed from the frame and an additional 4.5 m length has been added to the base of each column to allow embedment of the column bases into the elastic medium. The elastic medium is modelled as a 108m by 20m block which is fully restrained along its base and with cyclic translation constraints assigned to the sides. These constraints provide support to the sides of the elastic medium without the need to apply physical restraints, thus allowing direct and shear behaviours in the elastic medium. The seismic response analysis is performed in two distinct stages. A natural frequency analysis is performed first. This is used to calculate the first 50 natural modes of vibration of the combined structure and elastic medium. The eigenvalues, frequencies and eigenvectors (mode shapes) are stored and used in the subsequent IMDPlus analysis. Although the natural frequencies are obtained from an eigenvalue analysis any information regarding the magnitudes of deformations or stresses / moments is non-quantitative. The second phase of the analysis utilises the IMDPlus option which performs enhanced time domain solutions using Interactive Modal Dynamics (IMD). This is an alternative to performing a spectral response analysis and allows the excitation of the structure using acceleration time histories instead of spectral excitation curves.
In the IMDPlus solution, the structure is subjected to a support condition excitation governed by time histories of acceleration in the model global axes. In this example this is assumed to act along the base of the elastic medium in the form of horizontal and vertical accelerations. It should, however, be noted that no deconvolution of the records has been carried out to convert the surface responses recorded for these earthquakes to at-depth acceleration time histories to be input into the analysis. As a consequence, the ground level accelerations in the analysis will not correspond to the measured values. Two earthquake records are used in the analysis, the first being the 1940 El Centro earthquake and the second being the 1994 Northridge earthquake. The two earthquake responses are computed during a single analysis.
(Application_Examples_Manual_Bridge,_Civil_and_Structural,2009)
2.10.2 Dynamic Equations
Using d'Alembert's principle, the inertia and damping forces may be included as part of the body load vector. Assuming the accelerations and velocities are approximated using the same interpolation functions as displacement:
(Application_Examples_Manual_Bridge,_Civil_and_Structural,2009)
CHAPTER 3
METHODOLOGY
3.1 INTRODUCTION
The methodology for the whole study case is important as it help to underline the activities and important issues that need to be solved earlier. It helps the study flow smoothly and managing the time efficiently. This research focused on the (title fyp). Information was gained from previous research done by other researcher. The findings from those research analyses are identified to reach the objectives and conclusion of this study. Figure below the flow chart of methodology.
Figure 3.1 - Flow chart of methodology
Conclusions and Report Preparation
Result and Analysis
Data Compilation
Investigate the Behaviour of Earthquake Effect to the Bridge using Eigenvalue mode
Structural Analysis By
Using LUSAS
Background of Study
Extract All the Data the I Get From
WCE Consulting Engineers
Determine the Displacement and Stresses by Using Time History Analysis
Analysis Bridge Superstructure Due To Earthquake Condition Using Time History Analysis
To Perform 3D Modelling Analysis to Investigate the Seismic Response of the Actual Jejambat kepong Bridge in the Longitudinal Direction
Figure 3.2: Framework of the overall procedure
3.2 BRIDGE DETAILS
In this research, I went to Public Work Department (Structural and Bridge Unit) known as JKR and also WCE Consulting Engineers to get full details of structure drawings, data investigation and cost project. The bridge is located at kepong, Kuala Lumpur.
3.2.1 Project Details
Cadangan membina jejambat konkrit di persimpangan jalan kepong / mainstreet, jalan kepong, kuala lumpur.
3.2.1.1 Location Plan
Figure3.3 below shows the location of the Jejambat Kepong project, Kuala Lumpur.
Figure 3.3: Location plan
3.2.1.2 Existing Site Condition
Figure below shows the existing of site condition at the location of the project. It can be divided into 3 phase. Figure 3.4 until 3.6 showed based on phase 1 to phase 3.
Figure 3.4: Existing Site Condition Phase 1
Figure 3.5: Existing Site Condition Phase 2
Figure 3.6: Existing Site Condition Phase 3
3.2.1.3 Typical Cross Section and Elevation
Figure below shows the typical cross section, typical road section and typical pier section design by Perunding sutera and Peremba.
Figure 3.7: Typical cross section
Figure 3.8: Typical road section
Figure 3.9: Typical pier section
3.2.1.4 Design Codes and Standards
Table 3.1: Design Parameters
DESIGN PARAMETERS
1.
DESIGN CONTROL AND CRITERIA
a) Design Standard
U5
b) Access Control
Partial
c) Terrain
Flat
d) Design Speed
80 km/h
2.
CROSS SECTION ELEMENTS
a) Lane Width
3.5 m
b) Shoulders Width (Minimum)
0 m
c) Median Width (Minimum)
1.6 m
d) Median Width (Desirable)
3.0 m.
e) Marginal Strip Width
0.5 m
f) Minimum Reserve Width
40 m
3.
ELEMENTS OF DESIGN
a) Minimum Radius
280m
b) Minimum Length of Spiral
63m
c) Normal Superelevation
2.5%
d) Maximum Superelevation
6%
e) Maximum Grade (Desirable)
4%
f) Maximum Grade
5%
g)Crest Vertical Curve (K) (minimum)
30
h) Sag Vertical Curve (K) (minimum)
28
Table 3.2: Standard Parameters
STANDARD PARAMETERS
1.
LOADINGS
a) Lane Width
BD 37/88
b) Dead load
BS 6399
c) Services
5 kN/m
d) Thermal Range
19°C
e) Seismic
none
f) Wind Speed
70 km/h
3.3 MATERIAL PROPERTIES
The table 3.3 shows the material properties that will be used in analysis.
Table 3.3: Grade of Concrete
Grade Of Concrete
Structural Members
50/20
Prestressed concrete beam
40/20
Bored Pile
Abutment
Pier
Parapet
Slab
Other reinforced concrete
Table 3.4: Concrete Cover
Structural Members
Concrete Cover (mm)
Abutment and Walls
50
Footing
70
600 Diameter Bored Pile
100
Deck Slab
35
Table 3.5: Bar Strength
Type of Bar
Fy (N/mm)
Mild Steel
250
High Yield
460
3.4 LUSAS PROCEDURE
3.4.1 Creating a New Model
Enter the file name as tower
Use the Default working folder.
Enter the title as Tower
Set the units to N,m,kg,s,C
Ensure the Structural user interface is selected.
Select the Standard startup template.
Select the Vertical Y Axis option.
Click the OK button.
3.4.2 Defining Performing IMDPlus Calculations
The IMDPlus command is initiated from the Utilities menu. The basic steps for the two analysis types are as follows:
Seismic Analysis
Select the acceleration time histories
Select the eigenmodes to include in the solution
Specify the damping for the eigenmodes
Specify the frequency interpolation technique
Specify the node / element to process and output requirements
Moving Load Analysis
Specify the movement of the load across the structure at discrete locations and the equivalent modal forces
Specify the load configuration if this has not been carried out explicitly in the previous step
Select the eigenmodes to include in the solution
Specify the damping for the eigenmodes
Specify the speed ranges to analyse along with time stepping parameters
Specify the node / element to process and output requirements
Figure 3.10: Seismic Analysis Control
3.4.3 Defining the Dynamic Excitation
Select Support Motion from the Excitation drop down list and Spectral from the Results drop down list. Ensure the Use all modes option is selected.
Figure 3.11: IMD Loadcase
Click the Excitation Set button.
On the Support Motion dialog select Acceleration support motion option in the X direction which is Relative
Click the OK button to return to the IMD loadcase dialog.
Figure 3.12: Support Motion
On the IMD loadcase dialog click the Results Set button.
On the Spectral Response dialog set the type of spectral response to CQC Combination with the damping variation correction set as none. The response spectrum TOWER read in from the command file will already be selected in
3.4.4 Eigenvalue Analysis Control
Since the first stage of a spectral response analysis involves a computation of the natural modes of vibration an initial eigenvalue extraction analysis must be carried out. The solution parameters for eigenvalue analysis are specified using an eigenvalue control dataset. In this example the first 10 natural modes of vibration of the tower are computed. Eigenvalue analysis control properties are defined as properties of the loadcase. In the Treeview, right-click on Loadcase 1 and select Eigenvalue from the Controls menu.
Figure 3.13: Eigenvalue Analysis Control
The Eigenvalue dialog will appear.
The following parameters need to be specified:
Set the Number of eigenvalues as 10
Ensure the Shift to be applied is set as 0
Ensure the Type of eigensolver is set as Default
3.5 EARTHQUAKE DATA FROM ACHEH EARTHQUAKE EVENT
Figure 3.14: Peak Ground Acceleration at Acheh Earthquake
During earthquake events at acheh on 24th December 2004, the time history at surface were 0.012g. This data record at Ipoh station.
CHAPTER 4
EXPECTED OUTCOMES
4.1 INTRODUCTION
Upon completion of analytical history modelling of the bridge for the high amplitude testing due to earthquake loading, was conducting using LUSAS. This was conducted to determine the accuracy of bridge design due to earthquake loading and to develop a model to use for further studies.
Based on the objective of this study, it can be expected that, from LUSAS analysis, the bridge design can be obtain and classification earthquake condition and loading can be identify.
The available analysis tools were successful in estimating the nonlinear response of a concrete bridge structure with flexure dominated columns from the preyield state up to failure. The LUSAS model which explicitly accounted for bond-slip rotation at column ends.
To investigate the effects of multidirectional seismic excitation on the dynamic response of reinforced concrete bridge columns, an earthquake simulation test and a series of dynamic analyses were conducted.
4.2 STRESS ANALYSIS
4.2.1 Normal Stress Contour
4.2.2 Shear Stress Contour
4.3 DEFORMATION OF EARTHQUAKE EFFECT TO THE BRIDGE PIER
4.3 SEISMIC ANALYSIS
A number of computer models of the Jejambat Kepong Bridge were created, analyzed and compared to evaluate the structural response of the bridge under earthquake loading. All models were linear elastic in LUSAS.
4.3.1 Free Vibration Analysis
The free vibration analysis considered five modes. The periods of structure are shown in table 4.1.
Table 4.1: 5 natural periods of Jejambat Kepong
No
Period(sec)
1
2
3
4
5
4.3.2 Time History Analysis
In this analysis, the effect of time history analysis at surface with PGA 0.012 was applied to two dimensional analyses. The maximum axial, shear and bending moment forces and maximum displacement at bridge pier and deck can be seen in table 4.2 and 4.3. The maximum displacements are presented by U1 and U3 as horizontal and vertical displacement.
Table 4.2: The results of 3 dimensional time history analysis
COMPONENT
VALUE
Maximum axial force pier
-
Maximum shear force pier
-
Maximum BM pier
-
Table 4.3: The maximum vertical and horizontal displacement for TH-3D analysis
Maximum Displacement
(mm)
Pier
U1
U3
