Understanding Simply Supported and Continuous Analysis /Design in Reinforced Concrete

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Simply supported design means you are designing reinforced concrete structure span by span. This type of design assumes that there is no transfer of moments between spans. For instance, in the design of a reinforced concrete frame structure consisting of 4 spans, using simply supported design method, you design each span separately.

The bending moment diagram for a reinforced concrete frame structure shown below consisting of 4 spans and designed using the simply supported method would look like this;

You should always use the ultimate load combination of (1.4gk + 1.6qk) in calculating design loading during analysis. Note that gk refers to dead load , while qk refers to live load.

Simply supported design is hand calculation friendly, you only need a scientific calculator to help you.

Simply supported design is a conservative type of design and in some cases may not produce an economic design.

Continuous design means you are analyzing and then designing structure as a whole. Since a reinforced concrete structure consist of slab, beams and columns, it means you are analyzing all together.

In continuous analysis and design, it is assumed that there is transfer of moments between spans or structural elements. Typical bending moment diagram for a structure consisting of 4 spans and designed as continuous would look like this;

Also in continuous analysis/ design, using only the ultimate load combination of 1.4gk +1.6qk sometimes do not give the result which can be described as worst case, various load combinations of dead, live and wind loads (where appropriate) need to be applied on the structure to determine the worst possible case under which the structure is safe.

While it is possible to analyze a structure as a whole using moment distribution, manually or by hand calculation, it is not practicable because it is tedious. Structural engineers who still design manually often divide the whole structure into sections consisting of 3 to 5 spans , then analyze and design each section separately until the whole structure is covered, and with the aid of structural analysis programs, the process has been made easier.

The use of computer in structural analysis and design cannot be over emphasized, computer can implement the use of moment distribution or finite element method to analyze and design a whole structure in minutes.

Structural Analysis to BS 8110 with Excel.

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Structural analysis which involves strenuous mathematical calculations is a core skill required for civil and structural engineers. Almost every project handled by a civil/ structural engineer will involve structural analysis.

Structural analysis can be very tedious and when there are many projects to be done, moving from one mathematical calculation to the other may eventually lead to frustration and then errors.

There are many structural analysis/ design software available that make analysis and design very easy, however , there are free structural analysis software available which can ease analysis and design, one of them is the RC 21 Sub-frame analysis excel program (RC 21) developed by reinforced concrete council UK.

RC 21 Sub- Frame Analysis

RC 21 analyses reinforced concrete frame structures to BS 8110. While the United Kingdom no longer uses the BS 8110 and adopted the Euro code, BS 8110 is still being used in many African countries, and also other countries outside Africa.

RC 21 analyses reinforced concrete elements based on input parameters to determine design moments and shear forces necessary to further calculate amount of reinforcement required.

You can watch the video on how RC21 works, by clicking the my youtube video link below.

https://www.youtube.com/watch?v=kkTyB3cFkn4

RC 21 can analyze slab, beams and columns. It can analyze up to six spans and seven supports.

RC 21 can analyse up to six spans

Input parameters required for analysis to complete include;

Dead and live loads.

Span (slab/beam length)

Beam/slab/column section dimensions (size)

End conditions

Load factor

Colum height above/below beam level.

Results calculated include design slab, beam and column moments and shear forces. RC 21 considers 3 load cases and calculates design moments based on worse case loading. RC 21 is a free excel program, to down load, you can visit the following URL; REINFORCED CONCRETE FRAME ANALYSIS TO BS 8110.

You can also directly view and download RC 21 by clicking HERE

The excel program will open in your browser, to download finally, click the download icon at top right of your screen.

RC 21;Click download icon at top right of screen

Reinforced concrete frame analysis spreadsheet to BS 8110

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reinforced concrete frame analysis spreadsheet program to bs 8110
Reinforced concrete frame analysis spreadsheet

RCC21 sub-frame analysis is a spreadsheet program to calculate design moments for reinforced concrete elements such as slabs, beams and columns. The spread sheet program uses moment distribution method and considers critical load cases in the calculation of design moments.

reinforced concrete analysis spread sheet to bs 8110

It can analyze up to six spans and determines beam and column moments, and also slab moments as the case may be.

Just click image above to download Rcc 21

Generally for analysis to complete, you will be required to input span lengths, beam or slab section dimensions, dead and imposed loads, column height above and below beam section, column section dimensions and much more.

Reinforced Concrete Design Excel Spreadsheet.

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The reinforced concrete design spreadsheet (RCC11) is a program built to design reinforced concrete elements to BS8110. It was developed by the reinforced concrete council. The spreadsheet can be used to design slabs, beams and columns.

For slabs, the design moments needs to have been calculated prior to design. Slabs can be designed as simply supported, continuous or cantilever.

The same goes for beams; design moments need to have been calculated prior to designing with spreadsheet. Beams can be designed as simply supported or continuous span.

Reinforcement for beam shear can also be calculated with the spreadsheet.

Columns can also be designed with this excellent spreadsheet. Axial loads and any moments needs to have been calculated prior to designing with the spreadsheet program.

This excel spreadsheet program will basically calculate amount of reinforcement required and check that all other conditions are met in accordance with BS 8110 code.

Download RCC11

To download more Reinforced concrete council design spreadsheets, CLICK HERE

What to check for when buying a used car

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If you don’t have enough money to purchase a new car. Purchasing a used car outright may be a good option. However, you should be much more careful when making a purchase for a used car. Buying a used car comes with the high risk of unexpected repairs which may not be economical for you in the long run.

Make sure you buy a car you can afford and save money for minor repairs.

It is cheaper to buy a used car from the owner than from a car dealer.

Carefully check for these things in a used car before you buy;

  1. Start the car and listen to sound of the engine. Confirm that the engine sound is smooth and white or black smoke is not coming out of the exhausts.
  2. Check underneath the car for any sign of oil leakage be it engine or transmission oil leakage. Oil leakage can be a sign of minor or major problem.
  3. Check all the car safety features, such as brakes, headlights, indicator lights, horns, and wipers and so on.
  4. Test drive the car and check out the performance of brakes, gears, steering, suspension, shock absorbers. Also drive the car up a hill and note its performance.
  5. You must confirm that the car engine and transmission are in good condition as these are the most expensive parts of the car to replace.
  6. If car engine is emitting black smoke, strongly consider not buying the car.
  7. Check that the car interior is not too worn out.
  8. If you decide to buy the car, make sure you collect all documents relating to the car from the owner, make sure you confirm the real ownership of the car.
  9. You can also check the vehicle history report using the car’s VIN. VIN is the car’s unique vehicle identification number usually located in a metal strip on the dashboard or the driver side door. note that VIN is the same as FRAME or CHASSIS number.You can check your car history at websites such as carfax.com or autocheck.com.

What you need to know about MTN’s LUMOS MOBILE ELECTRICITY

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                                          Lumos Mobile Electricity

Lumos mobile electricity comes packaged with;

  • 80W solar panel
  • One indoor unit (unit that stores electricity charge generated from solar panel)
  • 2 led bulbs
  • Usb and pin phone charger
  • DC to AC Converter

Lumos mobile electricity specifications.

300Wh Lumos Smart Solar PayGo  indoorUnit (MTN Yellow Box)

80W Solar Panel with cable

Two USB ports (5V DC / 2.1A)

60W DC to AC Converter (60W Inverter)

Two Bright LED Bulbs

Four DC Output jacks (12V / 2A)

Two Car Cigarette Sockets (12V / 8A)

6 hours Charge Time (Bright Day)

How it works.

Solar panel charges the battery in the indoor unit using energy from the sun.

(the solar panel must be installed on the roof to maximize energy use of the sun.)

You plug your electrical appliance to charged indoor unit.

Lomos Mobile Electricity System

 

 

What lumos mobile electricity can power;

Radio

Dc fan

Charge mobile phone

Small LED/LCD tvs (up to 14 inches)

Laptop

Hair clippers

Dc light bulb

Small 60W AC  standing fan

Lumos Mobile Electricity and some appliances it can power

What lumos mobile electricity cannot power;

Air conditioner

Water heater

Electric kettle

Electric cooker

Desktop computer

Microwave oven

Blender

Ceiling fan

Refrigerator

Washing machine and other heavy electrical appliances.

Cost and fees.

As of writing, you can get the unit for 20,000 naira at any MTN office and

Pay subscription fees daily, weekly or monthly;

1 day:  230 naira

10 days: 1800 naira

20 days: 3300 naira

1 month: 4500 naira

3 months: 12,600 naira

1 year: 46,720 naira

5 years: 219,000 naira

In short, you are paying installmentally for a period of 5 years.

You must pay for at least 20 days usage every month. After regular use for 5 years, the system becomes fully yours.

How to get Lumos Mobile Electricity.

Sign up at any MTN office with;

Your MTN Sim card

Valid ID card

2 guarantors

Install with the help of qualified/authorized professional.

Pay for electricity use using your MTN charged mobile phone 

How long lumos mobile electricity lasts when powering appliances.

This is the most frequently asked question. Depending on the number of valid appliances connected to the unit, when fully charged, can power appliances for 2- 8 hours. For very small appliances such as charging of phone and laptop, the device can be powering up these devices for almost 24hrs assuming a very bright day. The 2 led bulbs that comes with the unit can be powered up for 5 hours assuming the device is fully charged. It is best to use lumos mobile electricity to power only DC appliances for maximum enjoyment.

Is obtaining lumos mobile electricity worth it.

For low income earners; YES, the unit should cost around 200, 000 naira as onetime payment, so for those that can’t afford that much can obtain the unit with a downtime payment of 20,000 naira plus subscription fees of between 3,300 – 4500 monthly payments for the next five years. Also the system will be serviced free of charge during those five years as long as you don’t void the warranty.

For high income earners; NO, there are better solar/inverter alternatives  out there starting from around 150,000 naira onetime payment.