Civil Engineering Program

CVE 400

SUMMER PRACTICE REPORT

Name of Student : ALİ CAN OKUR

ID Number : 1728955

Name of Company : İNPRO Mühendislik Müşavirlik

İnş. San. ve Tic. Ltd. Şti.

Date of Submission : 19.10.2015

TABLE OF CONTENTS

1. INTRODUCTION........................................................................................................................4

2. IFORMATION ABOUT THE COMPANY:..............................................................................4

3. STEPS OF BRIDGE DESIGN:..................................................................................................5

3.1. Material Selection:................................................................................................................5

3.2. Modeling Stage :..................................................................................................................6

3.3. Structural Analysis :...........................................................................................................12

3.4. Final Design :......................................................................................................................23

4. CONCLUSION :.........................................................................................................................25

LIST OF FIGURES

Figure 1. Material selection........................................................................................................6

Figure 2 Abutment Structure at Auto-CAD environment..........................................................6

Figure 3. Dimensions of an Abutment........................................................................................7

figure 4. Finished bridge structure..............................................................................................8

figure 5. Elevation view of abutment..........................................................................................8

figure 6 Pile Information.............................................................................................................8

Figure 7. Area Sections...............................................................................................................9

Figure 8. An abutment structure with pile foundation..............................................................11

Figure 9.Dimension and unit weight information.....................................................................13

Figure 10.Dead load Calculations.............................................................................................13

Figure 11.Force Assigning process...........................................................................................14

Figure 12. Dead Load locations................................................................................................15

Figure 13. Joint Load assigning................................................................................................16

Figure 14. Area load assigning.................................................................................................17

Figure 15. Load patterns defined on SAP2000.........................................................................18

Figure 16. Displacement and rotation values............................................................................19

Figure 17. Shear force and moment heat maps for foundation.................................................20

Figure 18. Shear force and moment heat maps for structural wall...........................................20

Figure 19. Shear force diagram for piles and girder flange......................................................21

Figure 20. Moment diagram for piles and girder flange...........................................................21

Figure 21. Analysis results on MS. Excel sheet........................................................................22

Figure 22. Reinforcement calculations 1..................................................................................23

Figure 23. Reinforcement calculations 2..................................................................................24

Figure 24. Reinforcement calculations 3..................................................................................25

1. INTRODUCTION

After completing CVE 300 summer practice at the construction site, the aim of this summer

practice, which is CVE 400, is to gain knowledge and experience in design office.

After some research I decided to perform my summer practice in INPRO Engineering and

Consultancy Company to learn how I can use my theoretical knowledge in pratic.

I started my summer practice on August 17 and finished on September 11.During my

summer practice I worked with the bridge department of the company and tried to understand

the steps and important points about the design of a bridge structure. Throughout the summer

practice I used AUTO-CAD, SAP2000 and some excel sheet that are prepared by the

engineers in the company. I tried to understand the basic of the specifications of Turkish

General Directorate of Highways and AASHTO.

In this report, I tried to transfer my observations, impressions and knowledge about a design

office and design steps of construction project that I learn from my summer practice.

2. IFORMATION ABOUT THE COMPANY:

INPRO Engineering and Consultancy is a design company that generally provides

engineering and consultancy services for transportation, infrastructure and industrial projects.

The company was established in 2003 and since then they completed over 250 bridge

projects, 450 km roadway projects, 35 level crossing structures and 140 level crossing

projects. As far as I observed, the company has 2 main departments: bridge and roadway

departments. During my summer practice, I worked with the bridge department, which consist

of 10 civil engineers and four technicians.

3. STEPS OF BRIDGE DESIGN:

During my summer practice, I worked on abutment structures. Design steps of an

abutment structure can be listed as:

Material selection

Modeling stage

Structural analysis

Final design

All stages of the design are done according to the codes listed below.

AASHTO – Standard specifications for highway bridges

ACI – American reinforced concrete specification

TS 500 – Turkish reinforced concrete specification

TS 3233 –Turkish pre-stressed concrete specification

DIN 1072 – German bridge loads specification

DIN 1075- German bridge specification

DIN 4227- German pre-stressed concrete specification

3.1. Material Selection:

In every construction process, one of the most important stages is determining the correct

material for the project needs, which have to be strong, durable and also economical. Material

selection is done according to the Turkish, American and German specifications. Concrete

grade has to be BS20 (C20) or BS25 (C25), reinforcing steel grade has to be S220 or S420,

and pre-stressed concrete grade has to be BS40 (C40), BS45 (C45) or BS50 (C50).

Figure 1. Material selection

3.2. Modeling Stage :

At that stage of the design process aim is to create a virtual model for that specific part

according to the drawings. Most important part at the modeling stage is try to reflect the site

conditions as much as possible to the real case.

For modeling Stage Auto-CAD and SAP2000 environments are used. Dimensions of the

abutment structures are taken from Auto-CAD file and a virtual abutment structure was

created at the SAP 2000 environment.

Figure.

Abutment Structure at Auto-CAD environment

There are two abutment structures at the both side of the road that cross pass the bridge .By

using the tools in Auto-CAD the dimensions of the structure is determined .(Fig.2.)

From Fig.3. an abutment structure in roughly U shape structure the yellow lines represent the

margin lines for the bridge structure .Yellow lines shows the margin for road and the outer

yellow lines shows the sidewalks. Light blue lines shows the abutment structure . Structure

shown in Fig.3. has a pile foundations and piles are shown with the orange lines . Locations of

piles are determined and indicated whit the green lines . First stage of modeling is to read all

this details from Auto-CAD file and transfer it to the SAP2000 environment.

The main function of abutment structure is they act like a support for the bridge structure

above them, for this abutment it has a pile foundation and this determined after the

geotechnical investigation of the soil by standard or cone penetration test . Also type and size

of abutment structure is also important for determination of the foundation of the abutment.

Figure 3. Dimensions of an Abutment

Figure 4. Finished bridge structure

Fig.4. shows a complete version of a bridge structure and span of the bridge is made by using

pre-stressed concrete beams which are stay above the abutments that are located two sides of

the roads. Also after abutment is finished the inner parts of the structure is filled with soil and

the pressure of soil will be also calculating at the structural analysis stage.

By the help of the elevation view in Fig.5. We can determine the height of the structure for

modeling. Inspection of Fig.5. Is important because this figure shows the elevation of

different part of abutment structure like foundation , elevation (elevasyon) and shield(kalkan)

which are different parts of the structure . For the abutment structure in Fig.5. Has mat

foundation when pile foundation or mixed foundation is used length of the piles also be

determined from the Auto-CAD files. From Fig.6. On the right side detailed pile information.

Figure 5. Elevation view of abutment

After all dimensions are determined from the Auto-CAD files, virtual copy of the structure

can be created at the SAP2000 environment. When virtual copy was created to get better

results from the software , abutment structure represented as 0.5 -0.5(m) square shell

elements . By assembling those shell elements whole abutment structure is tried to virtually

created. Another important point while abutment structure was created is that; shell elements

was assembled trough the centerlines of the walls of the structure, it is important because,

when you get dimensions from the Auto-CAD file you need to pay attention to the centerline

dimensions.

Figure 7. Area Sections

From Fig.7. There are several different sections defined for different parts of the structure.

Since different parts has different section properties proper sections needs to be selected for

shell elements on the structure . From Fig.7.there are 8 different section options for this

abutment structure. Main difference between sections basically explained as their rigidity

Figure 6. Pile Information

modulus are different from each other related with their locations in the structure. Fig.7.

shows joining locations of elevation wall and foundation is in different color, this is because

section properties at that location is different then the other parts of the elevation wall and the

foundation .The idea behind that section difference is that since these locations is near to the

joining point of elevation wall and foundation they represented in software as rigid as possible

so these rigid locations named as ELEVASYON RIJ. and TEMEL RIJ. in the software with

higher rigidity modulus then other parts .

For the assembling process as it mentioned before a 0.5-0.5 m shell element was created at the

beginning, after that for the example in the Fig.7. Auto-CAD drawings for examined and all

the dimensions of the abutment was determined. Then the square shell element that was

created before copied by using offset tool in the software. For instance figure 5 shows the

height of the elevation wall of the structure in Figure 7 and it is around 11 m so if you check

the Fig.7.there are 22 square shell elements along the longitudinal direction. If the dimensions

couldn’t divide by the 0.5 properly we can obtain our structural element by changing the

coordinates of the last shell element. In order to do that operation navigation tool that in the

lower right corner in the software can be used and that tool can be seen in the Figure 8.By

using the coordinates that are provided by navigation tool can be used as guide to complete

correct structure. By using that approach abutment structures was created in the software.

By using shell element abutments with mat foundations can easily be created in the software

but abutments with pile foundations and mixed foundations for the pile part at the foundation

a different approach is used. After pile length was determined from the Auto-CAD file by

using frame tool in the SAP2000 software a 1m long part of the pile was created. After that

using same offsetting tool whole pile foundations is created. Another important point while

creating the piles is that the locations of the piles also be checked from the Auto CAD file and

assemble the correct positions on the abutment structure. In Figure 8 an abutment structure

with pile foundation is shown.

Figure 8. An abutment structure with pile foundation

For the last step of modeling stage, springs are placed beneath the mat foundation and around

the piles if pile foundation exist in the structure. Main purpose of placing this springs is to

simulate effect of soil beneath the foundation or round the piles. In order to do that in a proper

way springs are placed in uniformly manner and this springs show reactions in all 3

dimensions (x-y-z). Reactions that springs are show directly related with the spring constant

that they possess. After springs are placed spring constants were entered to the system and

these constants were increased in every 10-20 m depending on the soil condition and

geotechnical investigation. The determination of spring constants as the engineers in the

company said related with the soil condition and results came from soil investigation test like

CPT (Cone Penetration Test) or SPT (Standard Penetration Test). After that point the

abutment model that worked on so far is ready for the structural analysis stage.

3.3. Structural Analysis :

In order to do the structural analysis first step that needs to be done is the determination of the

loads that acting on the abutment structure. This loads are classified as Dead Load (WDL),

Live Load (WL), Wind Load, Earthquake load, Breaking Load and Lateral Earth

Pressure .This loads were calculated according to various specifications listed below.

Live Load – YKİTŞ(1.3.3)- Turkish General Directorate of Highways Bridge

Specifications

Breaking Load - YKİTŞ(1.3.17) - Turkish General Directorate of Highways

Bridge Specifications

Wind Load - YKİTŞ(1.3.14) - Turkish General Directorate of Highways

Bridge Specifications

Earthquake Load – AASHTO SSHB 1992

Lateral Earth Pressure – YKİTŞ(1.3.22)- Turkish General Directorate of

Highways Bridge Specifications

This load calculations were based on the specifications above and at the company they use

some Excel Macro’s to calculate those loads easily but the idea behind those Excel Macro’s

are used same basis that mentioned in the specifications. In a more detailed manner Dead

Load calculation done according to steps below.

When Dead Load were calculated we need to calculate the forces that are permanently acting

on the structure for a bridge structure these permanent forces acting on abutment structures

can be listed as :

Weight of the Pre-stressed beams

Weight of the bridge floor (Both concrete and asphalt)

Weight of the curb

Weight of the bridge railings

All of these forces above are related with the dimensions of the bridge structure. For the

bridge floor calculation the span length of the bridge, slab and asphalt thicknesses and some

unit weight values needs to be known.

A

After that information was determined from Auto-CAD for all parameter above forces were

calculated in unit weight fashion with a unit of KN/m. For the next step all that unit weights

were summed and multiplied with the span length and Dead Load (WDL) for the bridge

structure were calculated .Since a bridge span stay on top of two abutment structures by

dividing final number by 2 final Dead Load value per an abutment was calculated.

Figure 9. Dimension and unit weight informationFigure 9.Dimension and unit weight information

Figure 10. Dead load Calculations

For the other load types this calculations were done according to specifications that were used

for that specific load type. As mentioned before while these calculations were done Microsoft

Excel were used and only thing that needs to be done was to enter dimension values to excel

sheet. Another important point for load determination process was determining the direction

of those forces. All of these forces were calculated in order to conduct a structural analysis in

the SAP2000 environment. While these forces were entered to the system another important

point is direction of these forces. In the SAP2000 environment you need both direction and

the magnitude of these forces to get a good result from the structural analysis.

In the process of entering forces in to the system there are two different approaches for

different kind of force types. Depending on the force type there are two types of forces; joint

loads and area loads while using the system , two different approaches using for joint loads

and area loads. For joint loads Dead Load, Live Load , Wind Load , Breaking Load and for

area loads Earth Pressure and Earthquake Loads can be listed .

For the joint load entering process there are some important points needs to be considered. At

first these dead loads due to weight of pre-stressed beams, bridge floor and all the other

elements above the abutment structure. Since pre-stressed beams are in direct contact with

the abutment structures, dead loads will transfer to abutment structure through the locations

that pre-stressed beams located as a result of that joint force locations that dead loads placed

in the SAP2000 environment can be taken as locations of pre-stressed beams. At the end

locations and numbers of joint loads were the same with the locations and number of pre-

stressed beams. While joint forces were entered to the system number of beams need to be

determined and same amount of joint force needs to be define on the abutment structure.

These Joint forces need to be placed as much homogenous as possible.

Joint loads were placed between top finishing point of ELEVASYON and start of point of

KALKAN layers that are modeled before. These points are locations of elastomers.

Elastomers are a load transfer mechanism that placed top of ELEVASYON layer and transfer

Dead Load to abutment structure. From the Figure below doted points indicate the points

where Dead Loads were applied in the SAP2000 environment. Also by investigating figure

that can be seen there are 16 pre-stressed concrete beams were used in the structure.

Figure 11. Force Assigning processFigure 11. Force Assigning process

Figure 12. Dead Load locations

By using Assign tool in the SAP2000 environment that can be seen from the Fig.11. we can

assign joint forces to the system and as mentioned before location of the forces are important.

After doing these two steps magnitude and the direction of the forces need to be defined to the

system. While directions of these forces were defined global coordinate system were used in

the software. At this step when magnitudes were entering to the system a load pattern needs to

be selected, by doing that you can easily check and control the forces for the different actions.

These load patterns were defined on the system before and before entering a load correct load

pattern need to be selected and magnitude and direction information were entered to the

system. Another important point is that while different loads were added to the same point for

example: Dead Loads and Live Loads, since the loads applied into the same location from the

panel at the Fig.13. load pattern name was changed to the related load type and also by

enabling to replace existing loads by options segment in the same panel each load was

assigned to its own load pattern.

Area loads were entered in to the software by using a different approach. As it mentioned

before by using “Assign” toolbar area loads were selected. Area loads can be defined as the

loads acting on the areas like earthquake loading and lateral earth pressure .As mentioned in

the joint loads in the case of area loads first thing that needs to be done is selection of the

areas that loads were applied . After areas were selected like the case in the joint loads from

the panel corresponding load type were selected and data were entered into the software .Also

Fig.11. shows the initial parts of the area load assigning process.

Figure 13. Joint Load assigning

From the Fig.14. that can be seen while area loads were entered to the system there is no

magnitude or direction component need to be added to the system .Reason behind is that,

since the forces which were defined as area loads, are the loads that couldn’t be defined using

a direction and a magnitude value, rather than that these forces were entered to the system

using different approaches. For example; when lateral earth pressure was entered to the

system from the panel correct load pattern was selected and by joint pattern option enabled

then by the boxes below again corresponding load type was selected and as the multiplier “-

1” was entered. In order to do all calculations correctly an important trick that need to be done

is, since we are working on an abutment structure it has a certain height. As mentioned before

after abutment structure done on the site “U” shaped part will be filled with soil that’s why

effect of the lateral earth pressure is considered. Because earth pressure is increases from top

to bottom of the structure we type “-1”. Another point is that when lateral pressure was

assigned to the structure move the top point in the structure to ground level which is “0” m

then assign the lateral earth pressure. This moving process is mainly related with how the

Figure 14. Area load assigning

lateral earth pressure was defined in the software. Like lateral earth pressure , earthquake

loading also defined as areal loading and the only difference between those two loading , in

earthquake loading as multiplier “1” was typed in to the system again due to the definition of

the earthquake loading in the software.

In the software any kind of loading can be defined and modified .According to Fig.15. there

are various of load patterns defined in the structure and these can be used without any

modification in the time of need.

After modelling and load assigning parts were finished now the virtual copy of the abutment

structure was ready for the structural analysıs part by using analyzing tools available in the

software. After some time from the start of analysıs result were ready for further inspection.

Immediately after the software finishes structural analysis in the screen the structure that

modeled in the previous stage was available and if any adverse condition or structural defect

occurred after the structural analysis result these are shown in the modelled structure. Also in

the screen if you move your mouse to the joint points in the structure displacement and

rotation values were shown in the screen and that can be seen from figure below. From the

Fig.16. that can be seen there are 3 displacement and 3 rotation values these 3 parameters

Figure 15. Load patterns defined on SAP2000

were with respect to the global x , global y and global z axis. Furthermore there are some

deformations in the abutment structure can be seen in the corner of the structure.

For further inspections moments, normal forces and shear forces acting on the structure can be

listed or can be shown on the structure as heat map formation. This inspections can be done

for whole structure or can be done by separately for the structural elements in the abutment

structure. Mat foundation, structural walls and pile foundations can be inspect separately from

each other. This structural analysis were done using Load and Resistance Factor Design

(LRFD) and each combination defined in the system after loads were entered the system

software done the structural analysis according to those load combinations and shown in the

figures below . Fig.17. shows the different moment and shear forces acting on the mat

foundation by the effect of different load combinations. As can be seen in the Fig.17. all 4

combinations results different effects on the structure to be o the safe side reinforcement

design were done taking the most critical values from the all possible combinations.

Figure 16. Displacement and rotation values

Furthermore from Fig.18. same things can be seen and the same procedure was repeated for

the structural walls that can be seen in the Fig.18 .

Figure 17. Shear force and moment heat maps for foundation

Figures above shows the moments and shear forces acting on a mat foundation and structural

walls of an abutment structure. These two components were defined as shells in SAP2000

environment .As mentioned before pile foundations were represented by frame elements and

those moments and forces can also be shown on the pile as well as on Microsoft excel. From

the figure below forces and moments acting on the piles and girder flange can be seen. While

abutment structure was constructed in the need of pile foundation; after piles were constructed

all piles were connected to each other with the girder flange so in the analysis they are shown

together.

Figure 18. Shear force and moment heat maps for structural wall

Figure 19. Moment diagram for piles and girder flange

Figure 20. Shear force diagram for piles and girder flange

Other than showing these analysis result on the structure as heat map we can export analysis

result to Microsoft Excel and see them in a more organized fashion. In order to do that ,after

structural analysis were done analysıs result could be shown in a tabulated format by using

display tool and clicking show tables option from that point results were tabulated from the

file options this tables can be exported to the Microsoft Excel . By using the features of the

Microsoft Excel this result can be re-arranged in to desired format. From the figure it is easier

to see the load combinations and corresponding moment, normal and shear forces.

Figure 21. Analysis results on MS. Excel sheet

3.4. Final Design :

After structural analysis part was finished, moment, normal force and shear force values were

available to be used in further in the final design part. For this stage the main purpose of the

calculations is to obtain amount of the reinforcement steel that used in the structure. For that

calculations in the company they use some Microsoft Excel macros that were prepared before

by using AASHTO Bridge Design Specifications. Idea behind those Excel sheets are same

with the knowledge that are learnt from the Reinforced Concrete lesson.

From the structural analysis results moments are available , concrete grade and steel grade

were taken from data available in the excel sheet .After that moment value were entered to the

system and also section dimensions were entered to the system from the Fig.22. the

parameters that can be changed by the users were indicated by red color. Moment value,

dimensions and steel diameter and amount are the parameters that can be changed by users.

Figure 22. Reinforcement calculations 1

From Fig.23. ρ b represent the balanced steel ration and its basically As/(bw*d) after this

calculations were done ρ max value were calculated, from the reinforced concrete course ρ max=

0.85*ρ b beyond that limit our design started to lose its ductility beyond this limit is not

allowed so at the and this number is a check for our design .

From the Fig.23. when ρ max was calculated they multiply ρ b with 0.75 that would be done in

order to be on the safe side. By doing so at the end more conservative ρ max value was

obtained.

For the last part moment capacity of our structure and the moment that our structure was

exposed were compared and by changing the amount of steel the moment capacity that can be

withstand to applied moments. Also as mentioned in the Fig.23. resisting moment was

calculated by Mn= A steel * f y * (d-(k1*c)/2). From the figure moment carrying capacity

calculated as 1622.96 KN.m and this is bigger than applied moment. For the last check ρ max

and calculated ρ values were compared and since ρ is smaller than ρ max this design can be

acceptable.

Figure 23. Reinforcement calculations 2

From the Fig.24. that can be seen shear design and design against cracking was done

accordingly. In order to do that shear force was taken from structural analysis results and at

the end shear capacity and shear force that been applied to the structure was compared and

design was acceptable .

4. CONCLUSION :

This report contains four main parts; introduction, company history, structural analysis and

conclusion furthermore detailed information about modeling and structural analysis stage was

given. During my internship, project related with bridge design and its structural analysis was

examined and basics of SAP2000 structural analysis software was tried to be learn and

understood. Also I have gained experience on running of a design office. This is important

because I want to connect my theoretical knowledge with practical one as well. Moreover, at

the end of the my summer practice I was able to increase both communication and group

working skills .Furthermore I was able to learn the importance of the design part of the project

and by getting involved in the working of an office I tried to understood the paperwork that

done with ministries as well. Also sawing the working conditions on a project office help to

decide what I was done after graduation.

Figure 24. Reinforcement calculations 3

REFERENCES

AASHTO LRFD 2012 Bridge Design Specifications, AASHTO Publications Staff (2012), 6th edition.

Ersoy, U., Özcebe, G., and Tankut, T. (2003). Reinforced Concrete. Metu Press.

Güngor G., Aşık I. , Fekardan H. , Demir E. (2013), Turkish General Directorate of Highways Bridge

Specifications, Revised version.

INPRO engineering (2014).” Institutional and Projects.” < http://www.inprotr.com> (Oct. 16, 2015).

INPRO Engineering and Consultancy Company Manavgat – Akseki road Üzümdere Bridge Structural

Analysis Report (2014)