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Tuesday, November 27, 2018

November 27, 2018

Structural Design of Swimming Pools and Underground Water Tanks



I spent a large part of the last few months developing the contents of this booklet on 'Structural Design of Underground Water Tanks and Swimming Pools' (According to the Eurocodes). Water is necessary for survival of mankind, but in one way or another, water is relatively scarce. We all know that rain does not fall continuously, and for water to be available for usage in homes, it will have to be fetched/pumped from the stream, or harvested during rainfall, or dug up from the ground. As a result, survival instincts made man to create different means of storing water in order to face the periods of scarcity.

One of the alternatives of storing water is the use of reinforced concrete structures which may be buried under the ground, supported on the ground surface, or elevated above the ground surface. Civil engineers have been at the forefront of designing these infrastructures in order to meet accepted performance criteria. One of the profound requirements of water tanks is water tightness, which can be related to the serviceability limit state requirement of cracking, amongst other factors.



The publication highlighted above focuses on the use of reinforced concrete for construction of underground water tanks and swimming pools. All the factors usually considered in the design of underground water retaining structures such as geotechnical analysis, modelling, loading, structural analysis, and structural design were all presented in an objective manner to the reader. Also, the use of Staad Pro Software was explored in detail on how it can be used to model and analyse tanks and swimming pools. 

I am going to use the screenshots below to show you some of the contents, with hope that you will find it interesting. The images are arranged in no specific order.
























I also paid serious attention to how water tightness can achieved on site through careful and standard construction practices. In addition to this 167 pages booklet, I also developed excel spreadsheets that can help make calculation of crackwidths faster, and Staad Pro video tutorials, peradventure you want to master the use of the software. Kindly see screenshot below;


For this reason, there are three different packages that can be purchased to match different levels of interest in the content.

PACKAGE 1 (STANDARD)        COST: NGN 2,000
(1) 167 pages booklet on Structural Analysis of Swimming Pools and Underground Water Tanks (in PDF)

PACKAGE 2 (ADVANCED)       COST: NGN 3,500
(1) 167 pages booklet on Structural Analysis of Swimming Pools and Underground Water Tanks (in PDF)
(2) Staad Pro Video Tutorial on Modelling and Analysis of Underground Water Tanks

PACKAGE 3 (SOPHISTICATED)    COST: NGN 5,000
(1) 167 pages booklet on Structural Analysis of Swimming Pools and Underground Water Tanks (in PDF)
(2) Staad Pro Video Tutorial on Modelling and Analysis of Underground Water Tanks
(3) MS Excel Spreadsheet for design of slabs, and calculation of crackwidths

All purchases will be delivered via mail within 24 hours of purchase.


To purchase any of the packages, click HERE


Thank you, and God bless you.

For more information;
Call: +2348060307054
WhatsApp: +2347053638996
E-mail: rankiesubani@gmail.com

Friday, August 24, 2018

August 24, 2018

How will you describe this system of forces?


What is the best description that you will give to this system of forces?




(a) Coplanar parallel system of concurrent forces
(b) Non-coplanar parallel system of non-concurrent forces
(c) Coplanar non-parallel system of concurrent forces
(d) Non-coplanar non-parallel system of non-concurrent forces

E-mail: info@structville.com
WhatsApp: +2347053638996

Are you looking for where you can make free downloads of publications? Visit Structville Research for all your free downloads.

STRUCTVILLE REINFORCED CONCRETE DESIGN MANUAL
We have this very affordable design manual available...


Do you want to preview the book, click PREVIEW
To download full textbook, click HERE

Tuesday, August 21, 2018

August 21, 2018

Is This Ultimate or Serviceability Limit State Failure?

Kindly look at the image carefully, and lend your professional opinion if the failure of the building will be categorized under ultimate or serviceability limit state. By posting and discussing your opinion on the comment section, I am very certain that knowledge and deeper understanding of this topic will be enhanced.

Thank you very much.




E-mail: info@structville.com
WhatsApp: +2347053638996

Are you looking for where you can make free downloads of publications? Visit Structville Research for all your free downloads.

STRUCTVILLE REINFORCED CONCRETE DESIGN MANUAL
We have this very affordable design manual available...


Do you want to preview the book, click PREVIEW
To download full textbook, click HERE

Saturday, August 18, 2018

August 18, 2018

Aspects of Modelling of Shear Walls

Shear walls are structural elements usually employed in tall buildings to assist in resisting lateral loads. Shear walls can be solid or pierced (coupled), depending on their location in the building. In the design of  tall buildings, structural engineers normally throw the entire lateral load (say wind action) to the shear walls, which means that the columns will not be relied on for lateral stability. In a more practical scenario however, the shear walls and columns interact in resisting lateral loads, which can be taken into account.

Thursday, August 16, 2018

August 16, 2018

A brief Presentation on Flexural Buckling of Columns

Introduction
When structural members are subjected to compressive forces, the members may fail before the compressive resistance (A.fy) is reached. This premature failure is usually caused by secondary bending effects such as imperfections, eccentricity of loading, asymmetry of the cross-section etc. In such cases, the failure mode is normally buckling, and this is unlike when the member is subjected to tensile forces, where the member will generally fail when the stress in the cross-section exceeds the ultimate strength of the material. Members subjected to tensile forces are inherently stable.

Tuesday, August 14, 2018

August 14, 2018

Structural Design of Cantilever Slabs - Solved Example



Cantilever slabs are common features in buildings due to the need to have bigger spaces at upper floors. To achieve this, architects normally extend the slab beyond the ground floor building line, thereby forming a cantilever. In this post, we are going to show how we can analyse and design cantilever slabs subjected to floor load and block work load.

Wednesday, August 8, 2018

August 08, 2018

How to Calculate the Quantity of Mortar for Laying Blocks


Engineers, site managers, and quantity surveyors are always faced with the challenge of specifying as accurately as possible, the quantity of materials needed to execute a specific item of work. In this post, we are going to explain how you can estimate the quantity of mortar (cement and sand) needed to lay blocks per square metre of wall.
August 08, 2018

Analysis and Design of Pedestrian Bridge Using Staad Pro


Pedestrian bridges (footbridges) are structures designed to enable human beings cross over obstacles such as busy highways, water bodies, gullies, etc. There are several variations of foot bridges based on structural configuration and materials. Modern footbridges are increasingly becoming elements of street beautification, with a view on sustainability and environmental friendliness. In this post, a simple pedestrian bridge has been modelled on Staad Pro software, and the result of internal stresses due to crowd load on the bridge presented.

Saturday, August 4, 2018

August 04, 2018

Bonding of Old and New Concrete


In construction, there always comes a time when there is need to bond old hardened concrete (substrate) with fresh concrete topping/overlay. This post aims to explain how to bond old and fresh concrete successfully, and also review the strength of  interfacial bond between old and new concrete based on already carried out experimental works.




Bonding is very important for adequate performance of finished concrete when fresh concrete topping is used to overlay an existing hardened concrete. This construction feature is usually found during bridge deck construction, concrete pavement, precast filigree slab, pile caps (in some cases) etc. The truth is that adequate bonding is not always guaranteed between the two layers, unless adequate precautions are taken.

For adequate bonding, it is very important to prepare the surface of the substrate adequately. The preparation of the surface usually involves roughening the surface, and removal of all dirt, oil, grease, loosened or unbonded portions of the existing concrete. By implication, the surface of the substrate should be hard, firm, clean, and free from loosened particles. This can be achieved by the use of chipping hammers, wire brushing the surface etc. After this is done, the exposed concrete surface can be cleaned by using pressurised clean water, air, etc. The man hours involved depends on the area of the surface, location, and the ease of cleaning (e.g reinforcement interference).

Precast Filigran Slab





After surface preparation, there is usually need to apply bonding agent on the surface of the existing concrete in order to facilitate the bonding. Epoxy based bonding agents are very popular for such operations. It is recommended that bonding agent is applied prior to casting the fresh concrete.  In essence, the procedure should be 'wet-to-wet' as the bonding agent should not be allowed to dry before the fresh concrete topping is placed.

Hardened Concrete With Bonding Agent Ready for Topping/Overlay
In a research carried out by Vandhiyan and Kathiravan (2017), the compressive strength of monolithic and bonded concrete was compared using 150mm x 150mm cube specimens at 28 days. With epoxy based bonding agent, the compressive strength of the bonded concrete was about 5% less than the monolithic strength, while without bonding agent, the compressive strength was about 28% less than the monolithic compressive strength.

Research has also shown that the moisture condition of the substrate affects the shear bond strength of bonded concrete. Shin and Wan (2010) investigated the interfacial bond strength of old and new concrete considering saturated surface dry (SSD) and air dry conditions. Saturated surface dry is  condition that can be described as the concrete containing moisture that is equal to its potential absorption, without the surface being wet or damp. At water/cement ratio of 0.45 (for the topping concrete), the shear bond strength at the interface was about 44% greater when the substrate was at SSD condition than when it was air dry. At water/cement ratio of 0.6 for the topping layer, an increase in shear bond strength was recorded, but there was a reduction in the compressive strength of the concrete.

So the recommendation in this article is that when casting a topping layer of fresh concrete on old concrete, adhere to the following guidelines;

(1) Prepare the surface properly
(2) Make sure that the substrate is at saturated surface dry condition
(3) Use a bonding agent and follow the manufacturer's technical recommendation properly.

Thank you for visiting Structville today, and God bless.

References
Vandhiyan R., Kathiravan M. (2017): Effect Of Bonding Chemical On Bond Strength Between Old And New Concrete. SSRG International Journal of Civil Engineering- (ICRTCETM-2017) - Special Issue – April 2017 ISSN : 2348 – 8352 pp 129-134

H-C. Shin,  Z. Wan (2010): Interfacial shear bond strength between old and new concrete. Fracture Mechanics of Concrete and Concrete Structures - Assessment, Durability, Monitoring and Retrofitting of Concrete Structures- B. H. Oh, et al. (eds) ⓒ 2010 Korea Concrete Institute, Seoul, ISBN 978-89-5708-181-5 pp 1195 - 1200



Thursday, August 2, 2018

August 02, 2018

Meet the Winners of Structville Design Competition

In the month of May, we announced the commencement of Structville Design Competition, where civil engineering students and serving NYSC members from various universities and polytechnics in Nigeria competed for small tokens in the design of reinforced concrete structures. The exercise was aimed at developing the interest of students in Structural Design, and preparing them for excellence in the field of structural engineering. You can view the details of the competition below;
August 02, 2018

A simpler Approach to the Design of Ground Beams Using Staad Pro


Ground beams are employed in reinforced concrete substructures for a lot of reasons. Ground beams can be differentiated from plinth beams due to a slight variation in the purpose of their construction. Plinth beams are used to connect (chain) separate pad bases together, and blockwork can be built off from the plinth beams. On the other hand, ground beams are designed mainly for the purpose of receiving load from ground floor slab or raft, alongside other functions as envisaged by the designer.

Monday, July 23, 2018

Friday, July 20, 2018

July 20, 2018

Comparative Design of Staircase Using StaadPro and Manual Calculations


Staircases provide simple solutions for vertical circulation in a building. In this post, we are going to model a simple  staircase using finite element plates, and compare the answer with manual calculations in which we assume the staircase to be a simply supported beam. The aim of this post is to verify the results obtained from the different procedures, and give reinforced concrete designers a little idea about the results to expect from their assumptions.

Tuesday, July 3, 2018

July 03, 2018

Structville Design Challenge Results (1st Edition)


On 14th of May, 2018, Structville Integrated Services announced the commencement of Structville Design Challenge for civil engineering students in Nigeria. (If you missed it, you can read post HERE). By the special grace of God, the competition has come and gone, and I wish to appreciate everyone who participated in the exercise.




The price money goes as follows;
1st position - NGN 10,000
2nd position - NGN 3,000
3rd position - NGN 2,000

Competition Details
Total number of successful applicants = 20
Total number of scripts submitted by dead line = 14
Total number of accepted scripts = 12
Total number of assessed scripts = 12

Rationale
Human capacity building in Nigeria has become a necessity, and we must all wake up to that fact. The motivation to start up something is one thing, but staying motivated to finish it up is another thing. The main aim of this competition was to steer the younger generation to a path of creativity, curiosity, technical capacity, problem solving, and tenacity. It was also designed to make them optimistic and look forward to a wonderful career in structural engineering.

While assessing the scripts, I made a lot of observations, and I will briefly summarise them using the points below;



(1) A lot of participants disregarded the first instruction of the exercise which was to pay attention to details. A lot of people lost marks by assuming weight of finishes, when the details of the finishes were clearly specified. Other people quoted values and formulars without properly referencing them. This affected a lot of people.

(2) In most cases, there was poor reading and interpretation of the architectural drawing. All those who modified the structure significantly lost a lot of marks.  However, I saw a lot of brilliance in some people with the way they managed the complexities of the architectural drawing, and produced a very good design. Some others came up with interesting GA's that are stable and buildable, but not very economical, so they lost marks in that aspect. For some others, they came up with GA's that are good, but did not reflect it properly in their analysis.

(3) No single person from South-East or South-South part of Nigeria participated in the exercise. I hope to see more of them next time.

(4) Finally, structural design is not about evaluating  M/fcubd2 and providing 2Y16, but it is more about the processes that led to the result, and the ability to execute the design economically, with adequate reliability.

So this is the result of the challenge;

I wish to say a very big congratulations to the winners;

1st Position - USMAN UMAR (Ahmadu Bello University, Zaria)
2nd Position - Ogungbire Adedolapo (Osun State University, Osogbo)
3rd Position - Olajide Bukoye (Federal Polytechnic Offa, Kwara State)

We will be celebrating them with their certificates and prize money in our next post. Structville will engage all the participants with corrections, recommendations, and discussion on all aspects of the design. Thank you, and God bless you.