Dims Consultants

12/03/2020

FOR ENGINEERS ONLY
WRONG OR CORRECT, AND WHY?

02/03/2019

STRUCTURAL RISK OF CONVERTING RESIDENTIAL BUILDING TO RHYTHMIC/COMMERCIAL ACTIVITIES; A CALL FOR IMMEDIATE READDRESS.
BY
ENGR. CHRISTIAN ODIMKPA
MD, DIMS CONSULTANTS LTD
Consulting Engineers and Project Planners
Shop 34, opposite Lomalinda Estate, Maryland,
Enugu.
07038252666

The words residential and commercial come from residence and commerce respectively. Hence, their difference is clear. Residential refers to place that is used for the purposes of living, whereas commercial refers to a place that is used to gain profit, or conduct activities that are other than the simple purpose of living. Residential building includes residential duplex, block of flats, bungalow, etc. while commercial building includes school, church, office, factory, auditorium, stadium, hospital, dancing hall etc.
During the stage of structural design, these different classes of buildings are loaded according to their purpose and functionalities. The residential building is considered only to serve the purpose of living , and no heavy rhythm activities shall be taking place in concomitant with the usage, therefore requires less construction materials. Commercial building is considered to accommodate many people, heavy loads and with different activities going on simultaneously, therefore requires more construction materials. The main factor causing vibration problem in a building is the resonance, which occurs when a load is exerted on a building floor at a particular frequency greater than the designed/expected load. When the natural frequency of the building floor coincides or close to the forcing frequency, vibration of the building occurs and starts giving ample warning to the user. This was exactly a case witnessed at St. Theresa’s cathedral, Nsukka, before the intervention of DIYOKES CONSULTANTS LTD, which I was the Resident Engineer supervising the reconstruction amendment. The cathedral floor podium vibrates more especially when people have flooded celebrating Mass. During our recognizance survey, we noticed that the previous design and construction done was not adequate to carry the number people currently using it. It was redesigned, reconstructed and the vibration problem stopped.
People in the school, church, dancing hall etc exerts forcing frequency ranging from 2 – 3Hz less than the natural frequency of a building which is between 3.5 – 4Hz, whereas residential is 1.0 – 1.5Hz. However, in the structural design information, the imposed load for commercial building ranges from 2.5 to 7.0KN/M2 whereas that of residential ranges from 1.5 to 2.0KN/m2. These imposed loads are described as the load that human being and other surrounding facilities exerts in every building floor. It is quite obvious that commercial building attracts more imposed load than the residential. Therefore, every commercial building should be properly designed according to the purpose i.e. church, school, auditorium, etc. In our society, we have developed a common habit of converting residential building for commercial purpose due economic challenges, thereby giving room to risk disaster. The consequences of a building collapse is so great that in most cases it takes many lives and properties. There is a need to value our lives, despite the quest to make money.
Most of the buildings built in our society today are not designed to the ultimate limit state. Many of the quacks we give out building project do not have technical and theoretical knowledge in the arrangement and design of structural elements. They give the confident that building is very easy, and it’s something anybody can do, besides once someone can do pe***ng. It’s high time we need to ask ourselves this question. If building construction is as easy as the quacks claim, why then do people struggle and pay through the nose to go to higher institution? Building construction is not only the pe***ng and laying block at the construction site. It involves meticulous planning, designing and construction. Every structural element like floor slab (decking), beam, column (pillar), foundation, stair case (step) undergoes rigorous analysis, design and detailing, before it gets to construction stage.
Residential building should not be converted to commercial activities to avoid building cracks, floor vibration and collapse. Government agencies, engineers, architects, builders etc should endavour to discourage clients from engaging in such decision. Also, an aggressive general sensitization or public awareness campaign should be fortified and propagated to urban and rural settlements its disastrous effect.
Finally, always make sure that your proposed building project is designed and supervised by a professional. Below are the pictures distinguishing the residential activities against commercial activities.
Thanks.

10/07/2018

Odimkpa Christamina
9 mins ·

Engr. Chris Odimkpa
MD, DIMS CONSULTANTS LTD
Consulting Architects, Builders, Engineers

225 Agbani road, opposite mayor bus stop
(+234) 07038252666

SEGREGATION OF CONCRETE
Segregation of concrete is separation of ingredients of concrete from each other. In good concrete, all concrete aggregates are evenly coated with sand and cement paste and forms a homogeneous mass.
During handling, transporting and placing, due to jerks and vibrations the paste of cement and sands gets separated from coarse aggregate. If concrete segregates during transit it should be remixed properly before depositing. However a concrete where initial setting time is over, should not be used.
CAUSES OF SEGREGATION OF CONCRETE:
1) Use of high water-cement ratio in concrete. This general happens in case of concrete mixed at site by unskilled workers.
2) Excessive vibration of concrete with mechanical needle vi*****rs makes heavier particles settle at bottom and lighter cement sand paste comes on top.
3) When concreting is done from height in case of underground foundations and rafts, which causes concrete to segregate.

PREVENTION OF SEGREGATION OF CONCRETE:
Wherever depth of concreting is more than 1.5 meters it should be placed through temporary inclined chutes. The angle of inclination may be kept between 1:3 and 1:2 so that concrete from top of chutes travels smoothly to bottom, use of small quantity of free water from top at intervals helps in lubricating the path of flow of concrete to bottom smoothly. The delivery end of chute should be as close as possible to the point of deposit.
Segregation in deep foundations and rafts of thickness more than 1 meter, there is every possibility of presence of segregated concrete near bottom or in center if proper supervision is not there. Such segregation can be detected by advanced method of testing like ultrasonic testing. In case of doubt random ultrasonic testing should be conducted and if it is present, designer’s opinion should be taken. This type of segregation can be rectified by pressure grounding with special chemical compounds.
After any defect rectified by pressure grouting core test has to be performed to ensure that the strength of concrete has reached to the desired level

30/06/2018

29/06/2018

PROJECT COST ESTIMATION; A tool for a timely and successful building project ex*****on.
By
Engr. Chris Odimkpa (MNSE, MIPMP, MHSE)
Managing Director
DIMS CONSULTANTS LTD
Consulting Architects, Builders, Engineers, Quantity Surveyor etc
Suite C3S, Second Floor, Alex Akporji Plaza, 225 Agbani Road, opposite Mayor Bus-Stop, Awk. Enugu.
Phone: 07038252666, 08103715407
Email: dimsconsultants@yahoo.com

Cost estimate is the process of developing an approximation of monetary resources needed to complete project activities. The key benefit of this process is that it helps to determine the amount of cost required to complete a project work.
However, before undertaking the construction of a building project, it is necessary to know the probable cost of the project which is worked out by estimation. This is done by the computation or calculation of the quantities required and expenditure likely to be incurred in the cost of the work. It commences immediately after the proposed working (Architectural, Structural, Mechanical and Electrical) drawings have been completed. These drawings present the full details including dimensions and specification of the materials to be used for the project work.
Most Clients at this stage, become so desperate to see the building going up in the site, thereby neglecting the need for the project costing. Some, because of the charge fee involved ignores to engage a qualified ESTIMATOR. They will usually prefer the builder/engineer/quack to give a rough idea of how much the project can cost. It is good to know that the result from the rough idea could be higher or lower than the total project cost, which may sometimes scares the owner away from executing the project. Cost estimation cannot be overemphasized as it determines the most economical approach to the timely completion of a project. However, the risk in neglecting this stage is just like someone who is starting up a new business, and ignores to make a feasibility studies/market survey concerning the nature of business, location, customers need, cost of sustaining the business during the emerging stage to mention but a few. It is quite obvious that if all this considerations are not captured from the onset in running the business, perhaps, the downfall starts which leads to business abandonment. Most newly established business have experienced downfall.
It’s so quite amazing to know that the fee charge for a project cost estimation is very small. It is about 2 – 5% of the total cost of the project, and this will reduce the shame and risk of cost overrun or project abandonment when properly analyzed.
KINDS OF COST ESTIMATE
Analogous Estimate: This involves using a previous work done based on size, capacity or complexity to estimate the current work. This is less time consuming in preparation, but it cannot give the client or estimator the accurate cost of that particular project, owing to the fact that the two projects may not have the same components and locations.
Parametric Estimate: This uses a statistical relationship between relevant historical data to calculate the cost of the building project.
Bottom-Up Estimate: This involves estimating the entire components of the project work. The full detailed cost analysis are carried out here, giving the accurate and most likely cost of the project.

NEED FOR COST ESTIMATION

TO AVOID PROJECT ABANDONEMENT: This is a situation whereby a project which is under construction has stopped progressing. It could be that the client does not have enough money to continue financing the project or the builder/engineer has consumed the project money recklessly. The risk of project abandonment is that arm robbers would start using the site as a place of hide out or deterioration of the building components would start emerging.
TO AVOID COST OVERUN: This is a situation whereby the money allocated for the project has finished before completing it. Most building projects experiences this cost overrun. One of the reasons could be that the accurate cost estimation was not properly carried out or there is an additional work which the extra cost becomes more than the contingency allowance provided or there is change in the market price.

BENEFITS OF COST ESTIMATION
1. The building project shall be progressing smoothly
2. The allocated project money is enough to take care of the work without affecting personal savings in the bank
3. The project is bound to complete timely
4. Adequate cost management plan is developed

ADVICE TO CLIENT
The owner should have it in mind that based on the current prices of building materials in the country, to build is very capital intensive. A step by step approach is the best way to confront the financial constraints. Firstly, get all the building drawings properly done to meet up with your dream/desire. Make sure that you have finally made all the necessary inputs you needed for the project. Request to engage the cost analysis to a professionally trained Quantity surveyor/Engineer who shall use Bill of Quantities (BOQ) or Bill of Engineering Measurement and Evaluation (BEME) to analyze the project cost, and give you the total cost base from the different stages according to the mode of construction, i.e foundation stage, floor level stages, roofing etc. These stages of work would enable you to know the stage at which your money can handle. Although this approach make take longer time, but it’s a better way of funding a private project.

ADVICE TO BUILDER/ARCHITECT/ENGINEER
What makes you a sound professional in the building industry is your ability to consider safety, economy and durability of the proposed building. Most of us out of desperate to get a contract loses our integrity and value. It is our core responsibility to advice our client on the necessary processes to get the intended project achieved. Most of the Architectural, Structural, Mechanical and Electrical drawings are freely drawn just to attract contract, and the risk becomes that the drawings would not be properly done (so many copied work, cut and join drawing). It’s high time we begin to consider the state of buildings very crucial. Lack of cost estimation leads to building failures and collapses. This is because you will be bound to do unusual things not to scare your client away, thereby violating the integrity of the building components. Cost estimation would help you to work with financial confident and assurance.

CONCLUSION
Building is one of the three (3) basic needs of a Man. The desire to have it achieved is awesome, and should be highly encouraged. But due process has to be adhered for smooth ex*****on without causing emotional/physical pain to the owner.
NOTE: Draw, Estimate and Build.
Thanks for audience!