Internship report on substructure and superstructure works of construction project

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W e a r e b o r n o f a l l t h e t h i n g s w e k n o w !

2015 GC 2007 EC

Institute of Technology

College of Engineering

Civil Engineering

Department

Four Month Internship Report

Abdirashid Mohamed Dahir

ID: ENGR/952/04

Debre Berhan University


Copyright ©Abdirashid Mohamed Dahir, 2015

No part of this internship report may be reproduced, transmitted, utilized or stored in

any form or by any means without prior written permission from the writer


DECLARATION

I, Abdirashid Mohamed Dahir, hereby declare that this internship report is

submitted by me under the guidance of my mentor Alemu Diribsa and supervision of

Bashir Mohamed Barik. I assure that the report contains actual events and facts that

were observed and performed during my internship practice program. All the

contents are my own and have not been submitted to any other institute.

Mentor:_________________________________________ Signature__________

Supervisor:______________________________________ Signature__________

Student:_________________________________________ Signature__________


List of Tables

Table-1 Major Activities and Stretch objectives of the Bureau………………..Page 11

Table-2 Customers and Expectations of the Bureau……………………….……....Page 12

Table-3 Design Team…………………………………………………………………………….Page 12

Table-4 Contracts and Construction Administration Team……………………...Page 14

Table-5 Process Owner………………………………………………………………………….Page 17

Table-6 Concrete Cover…………………………………………………………………………Page 35

Table-7 Concrete Classes……………………………………………………………………….Page 35

Table-8 Reinforcing Bars and Their Applications………………………………….…Page 36

Table-9 Recommended Slumps for Various Types of Construction………….Page 49


Table of Contents DECLARATION ............................................................................................................................................... 2

List of Tables ................................................................................................................................................. 3

Acknowledgement ........................................................................................................................................ 6

Executive Summary ....................................................................................................................................... 7

ACRONYMS ................................................................................................................................................... 8

Background of the Bureau ............................................................................................................................ 9

1.1 Brief Details ......................................................................................................................................... 9

1.2 Main products and services of Bureau ............................................................................................... 9

1.3 Main Customers and End Users of the Products and Services ......................................................... 12

1.4 Overall Organization and Work Flow ................................................................................................ 12

2- Overall Internship Experience ................................................................................................................. 18

2.1 How I got into the company ............................................................................................................. 18

2.2 The sections that I had been working in ........................................................................................... 19

2.3 Introduction to the Sites ................................................................................................................... 20

2.3.1 Introduction to Palace and Staff Residence ............................................................................... 20

2.3.1.1 Construction Materials, Quality Assurances and Tests ........................................................... 20

2.3.1.2 Storage Process and Construction Equipment ....................................................................... 21

2.3.1.3 Concrete Mixing ...................................................................................................................... 24

2.3.1.4 Engineering Problems at Presidential Palace Site ................................................................... 26

2.3.1.5 Substructure and Foundation Works ...................................................................................... 28

2.3.1.6 Solid Slab and Grade Beams [Staff Residence] ....................................................................... 35

2.3.1.7 Floor System [Presidential Palace] .......................................................................................... 38

2.3.1.8 Roofing System [Presidential Palace]...................................................................................... 42

2.3.1.9 Tests on the Site ...................................................................................................................... 48

2.3.1.10 Total Station Operation ........................................................................................................ 50

3-Overal Internship Benefits ....................................................................................................................... 54

3.1 Improvement of Practical Skills ......................................................................................................... 54

3.2 Theoretical Knowledge Upgrading .................................................................................................... 54

3.3 Interpersonal Communication .......................................................................................................... 55

3.4 Team Playing Skills ............................................................................................................................ 55


3.5 Leadership Skills ................................................................................................................................ 56

3.6 Work Ethics ....................................................................................................................................... 56

3.7 Entrepreneurship Skills ..................................................................................................................... 56

4-CONCLUSION ........................................................................................................................................... 57

5-RECOMMENDATION ................................................................................................................................ 58

6-REFERENCES ............................................................................................................................................. 59

7-APPENDICES ............................................................................................................................................. 60


Acknowledgement

Firstly, all praise due to almighty GOD for the generation of ideas solely expressed in this

report, in depth analysis of engineering problems and possible solution, at last the

publishing and above all the everlasting mercy.

I would like to express my profound gratitude for the excellent guidance, hearty

acceptance, constant cooperation and warm welcome of Eng. Asad Omar Hussein, the

Deputy Chief of Ethiopian Somali Urban Development, Construction and Industry Bureau.

Special thanks also go to Eng. Bashir Mohamed and Eng. Mohamed Omar who tirelessly

helped me cope with different engineering problems during my stay with Urban

Development Bureau in Jigjiga. Both worked with me as supervisors and I was able to share

my ideas on engineering problems with them.

I am grateful to my advisor Alemu Diribse who really showed off greater willingness in

helping me remain updated and for his corrective measures in the course of the internship

program.

Lastly, I should not forget to thank Ato Abraham and Highway Engineer Samson Kibret of

Best Consulting Engineers P.L.C, the company that undertook the design project of Jigjiga

asphalt roads for their encouraging feedbacks and invaluable contribution.


Executive Summary In summary this report sheds light on my internship practice program at Ethiopian Somali

Urban Development, Construction and Industry Bureau in Jigjiga, the capital of Zone 5

where I have maintained four-month presence. Primarily, although I was assigned to

Roads Construction Enterprise, the delay in the projects forced me to strike contract with

the governmental Bureau which welcomed me with open arms upon my application.

I translated theories at class into practice not only as intern but also I played consulting

role in the construction of Presidential palace in the outskirts of Jigjiga, three storey staff

residence in Jigjiga University and the design of four lane-one way urban roads in Jigjiga.

In the first part of this report, I have discussed the background of hosting Agency- Urban

Development, Construction and Industry Bureau which is among the regional

implementing bureaus with the aim of enhancing infrastructure and integrated housing

development in the Somali region of Ethiopia. Consulting services and role by the Bureau

as client in some construction projects are also part of the first section of this report.

Second part of the report divulges my overall internship experience, for instance how got

into the company, the section of the company I have worked in, the workflow of the section,

tasks being executed, challenges I faced and the possible solutions to the problems

encountered during the internship practice program.

Third, the detailed report exposes overall benefits I have gained during the internship

when it comes to the improvement in practical skills, upgrade of theoretical knowledge,

interpersonal communication skills, team playing skills, understanding of ethics and

organizational and entrepreneurship skills.

Finally, I have given recommendations to the hosting Bureau and concluded my report with

paragraphs summarizing practical skills on the sites over the last four months.


ACRONYMS

AUTOCAD-Automated Computer Aided Design

BSc-Bachelor of Science

DBU-Debre Berhan University

DPC-Damp Proof Coarse

EBS-Easting Back Sight

EBCS-Ethiopian Building Code Standard

ENG-Engineer

ESUDCIB-Ethiopian Somali Urban Development, Construction and Industry Bureau

-Yield Strength of Steel bars

GC-Gregorian Calendar

GPS-Global Positioning System

NBS-Northing Back Sight

OPC-Ordinary Portland Cement

PLC-Private Limited Company

PPC-Pozzoloni Portland Cement

PVC-Polymerized Vinyl Chloride

SAP-Structural Analysis Program

UTM-Universal Transverse Mercator


Background of the Bureau

1.1 Brief Details

Ethiopian Somali Urban Development, Construction and Industry Bureau is an

implementing body tasked with administration of settlements in urban cities, expansion of

houses and infrastructure and inter urban rural linkage to play a great role in the region’s

economic and social development to reduce poverty.

Bureau aspires to establish better construction quality and good urban governance system

through rapid and sustainable development.

Ethiopian Somali Urban Development, Construction and Industry Bureau leads accountable

institution by organizing and integrating supportive community-based organization in

public and private sectors while designing sustainable capacity building system which

enhances urban good governance, efficient and effective service delivery, building better

construction industry and service capacity.

1.2 Main products and services of Bureau

Designing – sub team

Design preparation service

Job list preparation and approval service

Checking and approval of design

Adaptation of design

Consultation service

Contract and construction administrations sub- team

Preparation of bid document

Contract agreement

Selling of bid document

Payment service

. Preparation of bid document

. Interim payment

. Final payment

. Payment certificate

Variation work service

Additional work service

Construction material’s price escalation service

Solving conflicts b/n contractors and consultants

Performance bond document service

Temporary & final construction acceptance service

Construction material’s market price assessment


Performance evaluation service

Contactors license service

Consultants license service

Professionals license service

Certificate of occupancy

Answering for technical support

Answering for arithmetic check

Laboratory service

Site surveying service

Soil test service

Construction material test service

Table 1-Major Activities and stretch objectives of the process

S/No Major activities Stretch Objectives

1. Design

preparation

Preparing a new design within High level building 7-20 Mill in 90 days.

Quality of 90%

Middle level building 4-7Mill 60 days. Quality of 90%

Low level building <4 Mill 30days. Quality of 90%

Extra high level building greater than 20 Mill in as per schedule.

Quality of 90%


2. Design

approval

Approving design within High level building 7-20 Mill in 7 days.

Quality of 90%

Middle level building 4-7 Mill in 4 days. Quality of 90%

Low level building <4 Mill in 2 days. Quality of 90%

Extra high level building greater than 20 Mill in 15 days. Quality of 90%

3. Bidding

process

Selecting and categorization of capable contractors within 15 days using IT technology.

4. Supervision

and

inspection

process

We make supervision and provide report within 3 days for concerned sector. Quality of 100%.

5. Payment

process

Finishing the payment and approval within 7 days.

6. Registration

of

contractors&

consultants

Finishing the registration within ½ day.


1.3 Main Customers and End Users of the Products and Services

Table 2-Customers and Expectations

S/No Customers Need and expectation

1.

Regional

sector

Bureau

and

Woredas

Approving designs in short period of time. To get completed design which satisfy their need with

scheduled tie. Processing and approving of the payment to be fast and

transparent. To get capable contractor. To respond claims on time and in transparency way. Project to supervise each activity to get quality building &

supervision on projects

2.

Contractors

and

consultant

Payment process to be fast. The site hands over to on time. To get complete design on time. To get fast response to their claims or disputes.

3.

Investors

Approving designs on time

1.4 Overall Organization and Work Flow

Work flow goes to the following three teams

Table-3 Design Team

S/N Position name Minimum

requirement

Respective role remark

1 Surveyor Adv. Diploma in

surveying

2 Architect Bsc In Architecture Preparation architectural design

Check architectural design

Prepare design contra document








5 Structural

Engineer

BSC In Civil Engineer

Preparation of structural design

Prepare project TOR Checking structural

design

6 Structural

Engineer




design

7 Structural

Engineer




8 Electrical

Engineer

Bsc Electrical

Engineer

Preparation of electrical design

Checking electrical of design

9 Electrical

Engineer

Bsc Electrical

Engineer



10 Electrical

Engineer

Bsc Electrical

Engineer



11 Drafts Man Bsc In Drafting Or

Advance Diploma With


3 Year Experience



3 Year Experience



3 Year Experience

14 Sanitary Engineer BSC In Sanitary

Engineer

Preparation of sanitary design Checking sanitary design


Engineer

Preparation of sanitary design

Checking sanitary design


Engineer

Preparation of sanitary design

Checking of sanitary design

17 Quantity Surveyor Advance Diploma Civil

Engineering Or

Related Field

Preparation of BOQ Checking BOQ


Engineering Or

Related Field



Engineering Or

Related Field


Table-4 Contracts and Construction Administration Team

S/N Position name Minimum requirement Respective role remark


1 construction

engineer

BSC Civil Engineering Or

Related Field Advance

Diploma Civil

Engineering Or Related

Field

Evaluation of contracts

Supervising construction

Checking & approve variation

Solving disagreement Checking & approve

time extension Performing temporary

& final acceptance Registration of

construction. Consultants as well as providing professional license

2 construction

engineer



Diploma Civil


Field

3 construction

engineer



Diploma Civil


Field








4 construction

engineer



Diploma Civil





Field




& final acceptance Registration of construction.

Consultants as well as

providing professional

license

5 construction

engineer



Diploma Civil


Field








6 construction

engineer



Diploma Civil


Field









Table-5 Process Owner

S/

N

Position name Minimum requirement Respective role remark

2 Secretary Diploma In Secretarial

Science

Responsible to the process

owner

Prepare different letter,

write and transfer to the

concerned bodies.

Examine documents,

written letters and

transfers to the concerned

bodies.

Give reception to the

customer and other stake

holders accordingly and

make to meet with core

process owner.

Manage and transfers all

materials from the

process owner to the

concerned body

Take attendance from

team in the process

Perform other assigned

work by the process

owner


2- OVERALL INTERNSHIP EXPERIENCE

2.1 How I got into the company

It was not a painstaking process for me to simply get into ESUDCIB. Before applying

to the governmental body, in March 2014 GC I signed an agreement with Roads

Construction Enterprise and at the time, the General Manager of the Enterprise

Guled Ahmed Ali told me that I will gain practical experience from the construction

of rural roads outside the capital of Zone 5 Jigjiga. Working under difficult

circumstances is always welcome and Highway sector has an important role to play

in Ethiopia and in Africa at large.

Shortly after the holistic exam, in line with my previous agreement with Roads

Construction enterprise, I directly arrived in Jigjiga to get involved in projects

pertaining to the design and construction of roads; unfortunately I couldn’t get into

the company since the regional government temporarily put the projects across

Zone 5 on hold.

It took a few weeks for me to make a shift in hosting company [as per the

acceptance of the Bureau] and the roads construction enterprise encouraged me to

join the implementing body which was undertaking huge projects in Jigjiga.

The following days, I had a meeting with Eng. Asad Omar Hussein, the highest

governing deputy chief of the Bureau who immediately assigned me to the site

where a new presidential palace were being built under the supervision of

professional engineers.

As I was intern from Debre Berhan University, I enjoyed wider recognition and open

cooperation from the team of engineers with the Bureau. I used to learn a lot about

the designs and construction of buildings from them.

The presidential palace was under progress and the contractors were erecting

superstructure elements, meaning that I was unable to see the substructures, like

foundation works. Nonetheless, I managed to work with K2N architecture and

Engineering consultancy P.L.C on the foundation of three storey 18-blokcs meant as

staff residence in Jigjiga University following consultations with the Bureau.

In the last month of the internship program, I had been part of a technical

committee appointed to review the engineering report of Best Consulting Engineers


P.L.C. I drafted a seven page evaluation report on the engineering designs and

reports of the consultancy.

2.2 The sections that I had been working in

I had been working on the side of the consultant and my role was not only limited to

visiting sites and practically understanding the job but my role was also to make

some designs, quantity takeoffs and study designs.

Among the tasks entrusted in me are as follows:

1-Supervision of Jigjiga Presidential palace, including inspection of construction

progress and the quality of construction materials.

2-Reading of Designs of the buildings under construction and ensuring whether the

design is met on the site.

3-Cooperating with foremen under the guidance of Bureau supervisor on the

prevailing problems.

4-Generation of new ideas and proposal of solutions if challenges come into being

on the construction site.

5-Preparation of takeoffs for the plans of new construction projects.

6-Supervision of construction of staff residence in Jigjiga University.

7-Review into engineering report by Best Consulting Engineers P.L.C, on four lane

divided urban roads that will be constructed in Jigjiga city.

8- Introduction of comments on the much-needed engineering tasks.

9-As surveyor using Total Station equipment.

During my internship program, I paid special attention to:

Condition of plastering

Visible cracks due to the self-weight and live loads imposed on the structure by

construction workers

Severe failures in the structure

The condition of Portland cement

Concrete mix

Whether foreman assigns workers to their respective tasks


2.3 Introduction to the Sites

2.3.1 Introduction to Palace and Staff Residence

Presidential place and staff residence are found in Jigjiga, the capital city of Somali region of

Ethiopia. Presidential palace is now 80% completed and substructure works were

completed before my arrival while 3 storey 18 blocks staff residence is under construction

and nearly 20% completed.

2.3.1.1 Construction Materials, Quality Assurances and Tests

-Cement

-Selected Materials

-Fine Aggregates

-Coarse Aggregates

-Reinforcement Bars

-Nails

-Tying Wires

-Form Works

-Timber Scaffolds

As I worked on two different sites, construction materials were similar to each other but

the most important issue, regarding the tests for quality assurance was matter under

spotlight. On Site one where presidential palace is being built tests were either pre-

conducted or suspended due to physical observations being made by engineers. But on Site

Two, where staff residence is being built, I found that Addis Ababa-based Engineering

Consultancy employed two empirical tests:

1-Slump Test

2-Compressive Strength Test

For every concrete mix, the consultancy PLC staffers used to test the compressive strength

of the concrete. If the concrete fails to satisfy the required compressive strength,

demolition will come into being for the sake of quality assurance. All compressive strength

tests were conducted in Dire Dawa.

Six test cubes of each (15cm*15cm*15cm) are taken for each test. At least one test is

taken whenever the concrete mix is less than 50m3, and at least two tests are taken to

test for a concrete mix greater than50m3. Out of the six cubes, three will be tested for 7

days strength which should be greater than 70% of the compressive strength of the 28th

day strength, and the rest will be tested for the 28days compressive strength which should

fulfil the required strength.


Criterion for Design

Function- the structure should give any of the services it was intended for. It should be possible to have unrestricted and unhindered use of the structure for the purpose for which it is built. Crack, deflection and vibration of the structure should be within the service limits.

Safety- the structure should be safe against any possible failure during its intended time of use. It should fulfill requirements set by building codes. It should follow the codes of practice for loading, materials, design and construction.

Durability- the structure should be able to stand for a time it is intended to serve for.

Economy-The design work should take into account not only the cost of materials but also the applicability, the time required to build, the cost of temporary structures, the cost of maintenance.

Appearance (aesthetic value) - it should have a satisfying appearance/ look. The design should consider the effect of cracking, leaking, staining, flaking, etc.

2.3.1.2 Storage Process and Construction Equipment

Upon my arrival at the site, I decided to learn a lot about the construction materials and

equipment since engineers are required to be acquainted with the knowledge of equipment

and store keeping on the site. Various materials such as cement, PVC, metallic pipes and

paints have varying shelf lives and different ways are employed while keeping them in halls

mainly constructed of Galvanized Corrugated Steel Sheet [BWG 34], the low-quality sheets

for economic reasons.

Figure 1: Photo 1: Indicates cement bags resting on the ground & Photo 2: Cement Bags placed above the ground at nearly 30cm


The site engineer told me that the shelf life of cement is 6 months and if it surpasses

duration of six months, it can’t be used for the concrete and mortar mixes.

The following factors are taken into account while storing concrete in the temporary camps

of contractors.

Flooding/ the depth of flowing water when it rains

Humidity and moisture

Why placed above the ground?

Because cement is more liable to be inundated by liquids including rain water and

moist soil on which cement bags rest.

Figure 2: Photo 1 [Presidential Palace] Factors like flooding should be considered and the height depends on the amount of precipitation Photo 2: Like cement, PVC and electrical conduits are not laid on the ground

Below are the construction equipment found on Staff Residence Site


Figure 3: Orange-branded Back Hoe excavates the ground to minimize labour cost and throws excavated soil into the Damp Truck…….R: Electric vibrators help construction workers expand concrete in plastic state, more importantly in this case for the concrete cover of footing reinforcement

Figure 4: Fixed Concrete mixer has the capacity of holding 2 bags of cement, 6 boxes of course aggregates and 4 boxes of fine aggregates at a time for C25 concrete while R: Concrete hauler transports fresh concrete from the fixed mixer to the intended destination

Compactors


Figure 5: Simple compactors reduce the volume of backfill soil by compaction while R: similarly rollers or caterpillars are compactors and a machine that is mainly used for increasing the bearing capacity of soil on roads and sometimes the site of buildings

2.3.1.3 Concrete Mixing

I took a look back at concrete work on the construction site to see if the procedure

complies with university lessons, particularly lessons pertaining to construction materials.

On the site that I visited [Presidential Palace] the concrete mix was important part since the

building was Reinforced Concrete structure [Residential Building plus assembly building].

Figure 6: Crew members await workers collecting fine and course aggregates in estimating box…R: The photographic image presents everybody with 50 x 40 x 18 measuring box that was used during volume batching of concrete mix

Batching

Al though two types of batching are used: 1) Weight Batching 2) Volume Batching, the

most important one, Weight Batching has never been used on my site but Volume

Batching was predominant and workers were employing measuring box with dimensions:

50 cm X 40 cm X 16 cm for C30 Concrete

50 cm X 40 cm X 18 cm for C25 Concrete


50 cm x 40 cm x 20 cm for C15 Concrete

Ratio Proportioning

1:2:3 for C30 Concrete [Highly Specialized Work]

1:2:4 for C25 Concrete [Strong Work]

1:2:5 for C 15 Concrete [ General Purpose Work]

1:4:6 for Lean concrete [Sub base Material]

To get concrete consisting of 50kg-Net-weight National-branded cement bag, three

measuring boxes of coarse aggregates and two measuring boxes of fine aggregates.

Procedure of mixing

Approximately 18 liters of water is poured into the concrete mixer

Cement Pack is cut into two pieces to make handling simple and

subsequently added to the water

Pozzoloni Portland cement [PPC]

Concrete Formula

Dry:

-1 Part Portland Cement

-2 parts medium or coarse sand

-3 part Gravel or rock

Urban Development Bureau brought National-branded Pozzoloni Portland Cement (PPC) with 32.5 R Strength Class to the site because it is cheaper when compared with Ordinary Portland Cement [OPC] with 42.5 R Strength Class.

The pozzolanic materials commonly used are volcanic ash, calcined clay, fly ash, and silica fumes.

The Portland Pozzolana Cement is ideal for general construction which does not required high early strength. Commonly, it is ideally suited for constructions such as hydraulic structures, mass concrete works, marine structures, masonry mortars and plastering, under aggressive conditions, and all other applications where Ordinary Portland Cement (OPC) is used.

Typical concrete sets in about 6 hours and develops a compressive strength of 8 MPa in 24 hours. The strength rises to 15 MPa at 3 days, 23 MPa at 1 week, 35 MPa at 4 weeks and 41


MPa at 3 months. In principle, the strength continues to rise slowly as long as water is available for continued hydration

Figure 7: National-branded Pozzoloni Portland Cement used for concrete on the construction site

The construction works did a good job to at least avoid poor handling, placing and

compaction of fresh concrete and in less than 30 minutes, the process was over for setting

and hardening of plastic material.

Curing was also the most important practice after concrete being placed, the curing was

aimed at preventing concrete from surface cracks due to the rapid loss of water and

increase the strength of concrete.

2.3.1.4 Engineering Problems at Presidential Palace Site

On the site of the construction, I saw problems emanating from segregation and

bleeding

No test was performed on the concrete, e.g slump test for workability

The project lacked mix design and perhaps, it could have affected quality control of

concrete

Vibrators were not used effectively for the compaction of concrete, thus the chance

for segregation was high but it also led to slab defects as concrete cover of the upper

floor slab became non-existence according to the below photo.


Figure 8: Honey comb [Mortar fails to fill voids between Coarse Aggregate particles] and Voids [Concrete fails to fill areas in the form work] Defects

2.3.1.4.1 Causes

Stiff and Unworkable Concrete

Segregation

Congested Rebar

Insufficient Consolidation

Improper Placing Practices

2.3.1.4.2 Weak Crushing Strength Coarse Aggregates

On the site, engineer feels that Coarse Aggregate is the most important ingredient in the

concrete since it is different from Mortars due the presence of course aggregate. One thing

that I can draw from my experience falls into the strength of course aggregate which is

required to match the strength of concrete itself.

As I have worked with the consulting firm side, I found a course aggregate with low

crushing strength due to the following reasons.

-It simply crushed when pressed between thumb and a finger

-Appearances such as the surface cracks and sieve-like characteristics proved weaknesses


Figure 9: Low crushing strength Aggregate

2.3.1.5 Substructure and Foundation Works

Since I understood a lot about the superstructure, I asked Urban Development Bureau to let

me work with K2N Architecture and Engineering Consultancy plc which was undertaking

the construction of G+3 Staff residence buildings inside Jigjiga University.

I started observing site clearance operation, including Setting out, excavations for footing

pads, Placement of lean concrete and formwork of footings, placement of concrete in

formwork, attaching columns to footing re-bars, Backfilling, Profile Floor Levelling and

Grade Beams.

To meet the exact Profile Floor Level [+/-0+00], you need to fix profile boards at a distance

of 2m from the outside edge of the masonry wall where the excavation will take place.

Perpendicularity is given much attention to avoid disturbances and improper centerlines

during the excavation of ground for shallow foundations.

Main function of the lean concrete is to provide the uniform surface to the foundation

concrete and to prevent the direct contact of foundation concrete from the soil. Lean

concrete is used under the foundations.


2.3.1.5.1 Tasks Executed

Minimum Depth of Boreholes for Site Investigation?

As a consultant I suggested that the minimum depth of excavation can be derived from this

formula

Where D=Depth of Boring

S=Number of stories

In our case, we were constructing G+ 3 building [3 Storey building], henceforth. From

previous records, we found that the type of soil is block cotton soil, which could result in

failure and differential settlement, therefore we agreed to increase the width of footing for

punching shear.


It is impossible to achieve a depth of 12.94m:

The footing dimensions=1500mm X 1500mm

Footing Depth=550mm

Foundation Depth=2730mm

Rebar Size=Grade 60 14mm Diameter

Concrete Cover=50mm

Steel Grade=

=300

Column Dimensions=400mmX250mm

250mm of working space was needed each side

Figure 10:From physical observation, I understood that the relative density of soil was small [Low Dense Soil], Depth of Foundation could have been increased [Photo 2] & Photo 3 shows lean concrete poured into the excavated holes

Development Length Check

To achieve higher bond between the concrete and steel, you need to bend the re-bars for

bond strength. Why for development Length? In the tension zone, Concrete-Steel

interface form Bond Stress, if not achieved bars pull out of concrete and tension drops to

Zero.

The sufficient length into which bars extend concrete is known as ‘Development Length’.

We usually apply this principle when designing Footing re-bars. I have checked the bars of

the foundation for development length, which is unavoidable at all costs during the

construction of foundation footings.


Where ᶲ=Diameter of the bars

Yield Strength of Reinforcement Bars

On my site:

Rebar Size=Grade 60 14mm Diameter

For Concrete C-25

2 X Fctd(Design Stress of Concrete in Tension) =Fbd

Fctd=1 Fbd for deformed bars [>Diameter 6) =2x1=2MPa


Figure 11: Footing Re-bars are bent up for bond strength to create strong bond between Concrete and Steel

In Ethiopia, the most commonly used steel bars are S-300 with Fyd=260.87MPa


The amount of soil dug up from the site during the excavation is not almost important and

to make sure that future backfill soil is good at compaction, Cart Away concept is

introduced during the preparation of Quantity Take-off material. Over 80% of backfill

constitutes selected materials and expenses are in turn incurred.

Figure 12: Materials are selected for better compaction, strength and good texture

Columns are fixed to the footing bars by transferring lines from string lines to the ground

through plumb-bob and nails are also attached to wooden form work. It is noteworthy to

mention that Verandas Footing Pads carry smaller load than other footings of the G+3

building.


Figure 13: Columns are directly attached to footing re-bares [Photo 1], Concrete is

poured into the footing only [Photo 2] & without casting the column concrete forms

the footing pad only [Photo 3]

Footings remain 24 hours in the form work, to continue hydration process in order to

attain high strength curing lasts seven days and followed by backfilling.

Figure 14: Photos show curing techniques for footing pad and columns


2.3.1.6 Solid Slab and Grade Beams [Staff Residence]

Solid Slabs For any structural element, the following guidelines are important and it should be applied to the structure while designing and constructing.

Shear is maximum at support

Moment is minimum or zero for pinned and roller supported structures at supports

Stirrups [Vertical stirrups] that are most commonly used carry shear above the

concrete capacity

Inclined stirrups not used for buildings prone to seismic loads

T and Inverted L beams –T sections are very advantageous in simply supported

span to resist positive bending moment. Inverted L sections resist negative bending

moment in cantilever beam.

Table-6 Concrete Cover

Member Concrete Cover

Beam 25mm Moderate

Slab 15mm Mild

Footing 50mm Severe

One-way slab: Reinforcement in one direction [Transverse for Bending Moment] but

practically it is non-existent due to architectural reasons.

Two-way slab: Reinforcement in two directions

Main Mesh Reinforcement

Secondary Mesh Reinforcement

Table-7 Concrete Classes


Table-8 Reinforcing Bars and their applications

Except for 6 mm diameter bars, reinforcing bars have ribs that create strong bond with

concrete.

Slabs transfer floor loads to the support by flexure and of the three types of slabs namely-

Solid Slab, Ribbed Slab and flat slabs-I saw Solid slabs which are divided into strips, say

middle strip and edge strips and reinforcement is provided in both directions.

Maximum bending moment is found in the middle strip where positive reinforcement and

T sections are found while 50% of the strips are extended into the support. I learned that

negative bars are terminated at a distance of L/3 from the respective centerline of the

supports.

Engineers prefer yielding steel at first to collapse in concrete.

Grade Beams

There is a direct relationship between ground floor slabs and grade beams. Grade beams

are similar to other beams supporting slabs but needs some structural considerations and

important concepts are introduced while on site and also in office.


Figure 15 the Ground is levelled up to Profile Floor Level [PFL] before grade beam is

being laid

Once footings and columns are completed, foundation masonry wall constructed of stone

and cement mortar is erected. Grade beams directly rest on the masonry wall and now the

concrete.

Isolation of Ground floor Slab: During my stay on the site, I came across the concept of

isolating ground floor slab from the grade beam. Unlike first floor and second floor slabs,

ground floor slabs don’t carry flexural stress but since concrete is weak in tension, you

need to avoid severe cracking that would result from tension above the concrete capacity

and Expansion joint materials are placed between grade beam and ground floor slab.

Grade beams are not doubly reinforced structures but hanger bars run longitudinally in the

nominal compression zone for vertical stirrups to be fixed and allocated properly. In fact

Negative bars are provided in the tension zone like cantilever beams.


Figure 16: Negative bars resist negative bending moment due to the pressure by soil on the masonry wall on which grade beams rest

2.3.1.7 Floor System [Presidential Palace]

During the flooring, I raised a number of questions, particularly the observation of solid

floor which direly rests on the ground. For example, the importance of Damp Proof Courses

(DPCs) and how such materials help floor system resist moisture and dampness into the

pavement.

I took a serious note on the following procedures:-

Floor Layering

Figure 17: Soil constituting a depth of 150mm above the ground level is compacted manually

Soil, either Natural or selected soil material is sprayed on the floor area, the depth of the

soil is almost 150mm above the ground level and a rod in a can filled with concrete helps

construction workers level the soil to a desired depth.


Figure 18: Trachytic Hardcore materials used as Damp Proof Course (DPC) during floor layering

Figure 19: Basaltic gravel is also used as an alternative Damp Proof Course (Material) over the course of floor layering


Hardcore or from Geologic perspective, Granite rocks are important in the layering of solid

floor due their resistance to dampness and moisture. The hardcore layer occupies a depth

of 250mm.

Hardcore exists in two forms, namely 1) Trachytic Hardcore [Granite] 2) Basaltic Hardcore

Rock.

Merits of Hardcore on the site

1-Strengthened and solidified the base of the building by resisting the pressure of dead and live loads acting on the building.

2) Saved cost of construction, for example during the application of hardcore, the volume occupied by the hard core if it were to be concrete would have cost more.

3) I do expect in future, it would reduce movement of water up to the floor surface.

Figure 20: After the hardcore is finished, Reinforcing steel with 8mm diameter is applied to the surface to let floor system withstand tensile forces


Before the concrete was poured over the hardcore, a process called ‘blinding’ is employed. Since it is quite troublesome placing concrete on the hardcore directly, three options existed for us on the site 1) the use of a thin layer of very dry coarse concrete that could be spread over it, 2) the use of a thin layer of coarse clinker (powder), and 3) the use of ash. This blinding layer, or coat is about 50 mm thick, and on it the site concrete is spread and finished with a true level top surface. The diameter of reinforcing steel used in the field is 8mm while the total depth of floor became 50cm:-

1) Compacting the selected backfill material with a layer not more than 25 2) 25cm of Hardcore/ 20 Hardcore plus 5cm of blinding material 3) 10cm of concrete

Figure 21: While casting concrete, it is lined just to ensure that alignment is

correct and surface is levelled appropriately


2.3.1.8 Roofing System [Presidential Palace]

Roof constitutes the upper most part of the building. It was really carrying a special interest

for me to see how roof covering are selected and supports including rafters, kingposts,

struts and purlins are built prior to the placement of Galvanized Corrugated Steel Sheets.

The most abundant roof covering on my site was Galvanized [Steel with zinc for rusting]

Corrugated Steel Sheet and at least I encountered some problems regarding the quality

control.

Figure 22: Galvanized Corrugated Steel Sheet, USG where G=Gauge 0.376mm

Types of roofs on the site

-Corrugated Metal Sheets

-RC Slabs

-Clay Tiles

There have been pitched roofs, closed couple roofs and trussed steel roofs for assembly

structures.


Figure 23: The presidential offices exhibit Hip roofs, just pitched since rainfall is abundant in Jigjiga

For halls

-Steel Truss span-18.4m

-Spacing 4.5m


Figure 24: Assembly buildings require steel trusses unlike others due the width of the building

If the roof is to be constructed as a concrete roof, it will be designed as a slab. While if a sloped roof, say with EGA SHEET cover, supported with truss it will requires its own design procedure. For steel truss like this, the truss members should be designed using design software to check the safety of the truss and its ability to withstand excessive deflection. The loads that are considered in the analysis and design of truss include:- 1-Roof Cover Load 2-Wind Load 3-Live Load [According to EBCS 2] 4-Self Weight of Truss Members and Purlins 5-Additional Imposed Loads [If Any] The loads are applied at joints as concentrated loads and the truss is analyzed. The reactions from the truss have to be transferred to the structure. For steel truss, since it can have a longer span between the trusses, the load transfer will be directly into columns. But in case of wood truss, the span between trusses is limited, so the roof loads will be transferred to beams as a concentrated load at certain intervals.


Figure 25: Photo 1: Steel trusses Photo 2: Welded Steel trusses Photo 3: Less corrugated Ega Sheets, thicker than more Galvanized Corrugated Steel sheet

Figure 26: BWG 34-0.2mm used for stores while USG 28-0.376mm is used as roof covering

Drainage System

Like the formal structures, buildings require more credible drainage system to avoid

failures resulting from poor drainage.


At the construction sites, Flat sheets are either used as gutters or down pipes and let rain

water flow through pipe-like systems attached to the side-building.

Parapets

Figure 27: Parapets are part of the structural elements that form a building Photo 1: Before concrete casting Photo 2: After placement of concrete

Parapets are structural elements in the building during concrete casting. They are directly

attached to the reinforcement mesh of the slab due to the presence of loadings.

Among the loads on the parapets are: Dead loads [Self Weight], Hydrostatic Loads [When

raining] and occasionally lateral loads resulted by wind loads on the roof covering.

After concrete is casted, hollow concrete blocks at a depth of 40cm are constructed to help

parapets retain rain water.

Dimensions of the blocks [40X20X15 CM].


Gutters

Figure 28

Photo 1: Workers attend to non-corrugated/ Flat sheets to find exact dimensions required

Photo 2: Prepared Gutter on roof top

Photo 3: Upper most part of a roof covering with opening

Photo 4: Hidden Roof gutters due to aesthetic purposes

Quantity Take off for roofs

Without taking labour and material costs into account, it’s necessary for engineers to

understand how to calculate the surface area of roof on a given building.

At first, I found the following interesting

Angle of the Roof, Rise-and-Run of roofs

Width of the Roof and Overhang of the roof

Area= Two Sides X Length of the rafter X Length

of the Building


2.3.1.9 Tests on the Site

Slump Test

Figure 29

Photo 1 indicates preparation after [photo 6 resulted in collapsible slump

Photo 2 shows concrete poured into the slump cone

Photo 3 unveils compaction of concrete with tamping rod

Photo 4 exposes how I carefully lifted the cone after the compaction of three layers

got finished

Photo 5 I measured the slump of the concrete/True Slump

Photo 6 is the first test of collapsible slump

For the construction of footing and columns, I decided to perform Slump Test to ensure

whether the concrete is workable enough or not.


Apparatus

Slump Cone/Metallic Mould with 20cm bottom diameter, 10 cm top diameter and

30 cm height.

Wooden base plate

Steel Tamping road with 16mm diameter and 60 cm length

Wheelbarrow

Procedure

I took a sample concrete on wheelbarrow from the mobile concrete truck

Prior to the test, wooden base plate was washed with water to avoid moisture

absorption

I placed three layers of concrete in the slump cone, each tamped 25 times with steel

rod

I carefully lifted the slump cone, just to avoid unintentional collapse

Result

First test resulted in collapsible slump due to the following reasons -Poor compaction by the foreman

-Large amount of water in the concrete

Second test resulted in true slump of 7 cm /70mm satisfactory for footings and

columns according to the following table

Table-9 Recommended Slumps for Various Types of Construction

TYPES OF CONSTRUCTION SLUMP CM.

Maximum* Minimum

Reinforced foundation walls and footings 8 2

Plain, footings, caissons, and substructure walls 8 2

Beams and reinforced walls 10 2

Building columns 10 2

Pavements and slabs 8 2

Heavy mass concrete 8 2


Recommendation

Since the first test led to collapsible slump, the only solution is to leave it and again

proportion concrete ingredients.

2.3.1.10 Total Station Operation

Definition: Electronic Survey Equipment is used to perform horizontal and vertical measurements in reference to a grid system (e.g. UTM, mine grid). Well in the first place, it’s noteworthy to mention that different types of Total station are available on markets so in my case, I operated Sokkia CX Series. Like theodolite you need to adjust tripod, optical plummet to the target (Bench March/ Occupy station) and also to use foot screws. Below is the display panel of my total station after I exactly placed it on the occupy station and centred the circular bulb.

Figure 30


Here we have one task to do to achieve higher accuracy; through the foot screws at 180 one

needs to eliminate tilt of Y by two foot screws and tilt of X by one foot screw. Again make

90 degree rotation and repeat the same procedure.

Function Keys

Figure 31

Function Keys are important in many ways, particularly in identifying the kind of project

you are expected to execute. Below are function and ESC buttons for showing off the pages.

Create Job[F3], from the job selection, select job with 0 data if not, then go to

F1 [Job List] ,delete a job and again choose job

DATA COLLECTION VIA TOTAL STATION

Select Data

Prepare occupy station [Point over which the total station is placed] with Easting,

Northing and Z [Elevation], for almost all cases, we employed Garmin GPS to find

E=257955, N=1034958 and Z=1672 of occupy station

Again on Data, click BS Data to find second reference position, you will see Angle or

Coordinate, we do prefer Coordinate Method, and GPS is again used for BS to

achieve accuracy, data is inserted into the equipment.

EBS=257910

NBS=1034989

ZBS=1670-----Ok button

Height of instrument is measured using steel tape and heigh of the prism pole is

written in the display screen.


To check out your work, now take Back Sight reading, shoot the prism pole and hit

F1[REC] to get accurate reading

Place your prism pole over various stations by keeping your total station over the

occupy station until prism-hold gets lost due to rough terrain and existence of

mountains.

DATA TRANSFER

Figure 32


As you can see from the above photographic image, you can transfer

the collected data to flash disk or to the computer with the help of USB

and specific software. Fortunately, nowadays total stations have own

system to let surveyors receive data in a simple manner.

Hit F2 [USB], Select S type, Select Save Data, among the different jobs

available on the display panel, choose your task and click ok, wait for a

while moving into the storage device.

Transfer to Excel as CSV [Comma Delaminate] format and save [Below

is the data]

X Y z

267952.4 1034958 1672.285

267952.4 1034958 1672.285

267952.4 1034958 1672.285

267952.4 1034958 1672.285

267952.4 1034958 1672.285


3-OVERALL INTERNSHIP BENEFITS

3.1 Improvement of Practical Skills

In the last four months, I was able to improve my practical skills and understand

how works are executed on the construction sites. Below are practical skills I gained

during the internship program:-

Installation of scaffolds and false work

Types of formwork, releasing agents and their design

Concrete mixing, procedures, handling, placement and casting

The meaning of the term 1:2:3 in concrete mix

Reinforcement Placement, types of re-bars, curtailment, and lab length.

Casting of solid slabs, design of negative bars and positive bars and storage of

concrete and other construction materials.

Operation of Total Station

Empirical tests on concrete including slump and compressive strength test

Roof covering, quality assurance of roof coverings, quantity takeoff, drainage

system of buildings and design of steel trusses for assembly buildings

Floor systems and the reasons behind reinforcement mesh of ground floor

slabs

Understanding grade beam and expansion joints

Inspection of aggregates

Development length in foundation works

Construction Equipment and physical observation in line with engineering

perspectives

Designing in Autocad, SAP, ETABS and EAGLE POINT

3.2 Theoretical Knowledge Upgrading

Practical skills on the construction sites upgraded my theoretical knowledge as I came

across new components in construction industry, for example:

The concept of parapets and Grade Beams

Generation of scientific reasoning for practical problems

Construction Equipment and Materials

The concept of cart away in takeoff sheets and estimation of re-bars for structural

elements

Reading and Understanding working drawings


3.3 Interpersonal Communication

The site is far more different from the University where we solely use scientific reasons. I

managed to interact with many people with different backgrounds and languages. I had a

working relationship with supervisors, office engineers, project managers, foremen and

even construction workers.

You may find new words at the site but I coped with both the horizontal and vertical

communication between different groups involved in the two projects.

Benefits of communication skills on the site

Suggestions and orders for foremen and construction workers

Sharing ideas

Co-managing daily activities

Respects for attitudes

Decision-making while resolving engineering problems

3.4 Team Playing Skills

I used to join my colleagues from other universities to discuss engineering problems and

possible solutions. At the same time, as a team member and fresh consultant with Urban

Development, Construction and Industry Bureau I cooperated with professional engineers

on a number of occasions by:

Respecting suggestions

Sharing ideas open-mindedly

Communicating effectively

Approaching issues from a constructive point of view

Listening seriously

Seeking accuracy at all times


3.5 Leadership Skills

During the internship program, I benefited from many leadership skills from the offices in

the Bureau to the construction sites. At office, I took a serious note on the orders from

Urban Development, Construction and Industry Bureau head to contract administration

team and engineers.

On the site, orders by project managers for keeping materials properly were important and

foremen remained accountable to both engineers of the contractors and consultancy.

Controlling everything on the site under the watch of contactor and work flow at office play

crucial role in the timely completion of projects.

3.6 Work Ethics

In construction industry, you need to develop healthy working environment and double

productivity through punctuality, honesty by avoiding corruption and bias, cooperation,

office discipline without disturbing working condition and reliability.

3.7 Entrepreneurship Skills

Al though I was working on the side of the consulting Bureau, I came across some

entrepreneurship skills including resource utilization in profitable manner in a given

period of time and the importance of manpower and construction equipment.

The obvious goal of the Bureau was to improve the standards in place for housing and

construction of high-quality buildings in the Somali region of Ethiopia.


4-CONCLUSION I have found the internship program interesting as it provided me with the necessary skills

required by civil engineers at site and in office. It was an opportunity for me to interact

with different people including professional engineers who at least contributed their

guidance to me.

It was something of highly valued to work for Ethiopian Somali Urban Development,

Construction and Industry Bureau on the construction of two key projects -Jigjiga

Presidential Palace and staff residence in Jigjiga University.

The consulting body directed me towards tough tasks but those with appropriate

theoretical knowledge could have overcome the engineering problems over the course of

the internship.

I gained not only practical but also theoretical knowledge by perceiving different

challenges on site and putting what I studied at class into practice.

At least, if you go on internship with high-class company or institution, you will get

acquainted with the translation of something in books into action.

I learned what do self-confidence, team playing, organizational skills, upgrade of

theoretical knowledge mean to the engineer?

Once and for all, let me say internship is far more fascinating than many things and

complies with real life situation.


5-RECOMMENDATION

Ethiopian Somali Urban Development, Construction and Industry Bureau where I

maintained presence for nearly four months needs to increase the number of civil and

construction engineers. Despite impressive work flow, the shortage of experienced

engineers was challenging matter.

The setting up of modern laboratory, publishing of soil testing manual and training of

technicians remain crucial because of the critical tasks ahead for the Bureau.

The delays in construction could only be avoided if contractors are scolded legally and held

accountable for the mishaps.

On site two, the staff residence of Jigjiga University, I recommend both the consulting firm

and contractor to provide space to practicing students and ease the restrictive control.

As long term and short term plan, consultancies are in dire need of relevant expertise and

laboratories to come up with quality assurances and scrutinize the contractors whenever

problems arise with varying intensities.


6-REFERENCES

Debre Berhan University, ‘Lecture Notes’,[Unpublished]

Ethiopian Somali Urban Development, Construction and Industry Bureau,

‘Company Profile’ 2007 [Unpublished]

Foundation Analysis and Design, ‘Joseph E. Bowles’, 5th Edition

Ministry of Works and Urban Development, ‘Ethiopian Building Code Standard;

EBCS-1-EBCS-8’,1995

S. S Ray, ‘Reinforced Concrete Design and Analysis’, 1995

Techniques of Writing and Editing Educational Materials, ‘Tesfaye Ejigu Tefera’, 1st

Edition


7-APPENDICES

Timber Formwork & Steel Formwork

Oil is used as releasing agent during the initial fixing and at a later date when workers remove temporary support from the hardened concrete


If the work can’t be accessed from the ground, construction workers need to use scaffolds to build upper parts

Documents

Internship report on substructure and superstructure works of construction project