Design Requirements for Reinforced Concrete Masonry as per IS codes.

Masonry Unit.

Minimum compressive strength of masonry units used in reinforced masonry shall not be less than 7Mpa. Steel reinforcement of grade Fe 415 or less shall be used

Concrete.

At least M20 grade concrete should be used.

Minimum cover for steel reinforcement is 15mm top and bottom cover; 20mm for side cover.

Mortar Bed.

High strength mortars H1 or H2 shall be used in mortar bed.

Structural Continuity.

Where floor transfer horizontal forces to wall, there must be proper anchorage of steel reinforcement from floor to wall reinforcement.

Effective Span.

For simply supported/continuous members the smaller of;

  • Distance between centers of supports.
  • Clear distance between supports plus and effective depth, d.

For cantilever; the greater of;

  • Distance between the end of the cantilever and the centre of support.
  • Distance between the end of the cantilever and the face of support plus half its effective depth whichever is greater.

Slenderness Ratio. Walls/Columns.

Ratio of effective height Hef to effective thickness Tef for walls should not exceed 27. For columns; 20

7 Popular Commercial Civil Engineering Software

You are a Civil Engineer or Civil Engineering student, and you are asking yourself; ” of all the civil engineering softwares out there, which ones can I study/purchase?. Well this article is for you. I will be dividing the list of software into 2 sections. The first section for general 2D & 3D Modelling/ drafting/ design and the second section for structural modelling, calculation and design. Here are Popular  commercial civil engineering software you can buy to enhance your understanding and productivity

SECTION 1  General 2D & 3D Modelling/ drafting/ design software.

AUTOCAD

Autocad is a general technical drawing software made by Autodesk. It is very good for creating 2D drawings.You can easily produce all types of building/civil engineering drawings with this great software. This software is worldwide industry standard. In fact, you must have and learn it!. It is quite expensive but there are cheaper versions like the Autocad LT.

You can also get a free one year license on Autocad, check out this OFFICIAL AUTODESK WEBSITE for details.

REVIT

Revit is a coordinated 3D / 2D modelling software great for creating Civil engineering and architectural drawings. It is a BIM software, that is; Building Information Modelling  software.With this software, you start modelling in either 2D or 3D but actually you are modelling in 2D and 3D at the same time. This is the no. 1 software for Architects. It is an Autodesk product which means you can get a free one year license or try it for 30 days.

CIVIL 3D

Civil 3D  is a software for creating various types of civil engineering drawings. It is also owned by Autodesk.You can produce 2D and 3D drawings with this great software. Types of drawings you can produce with this software include;

Building plans, survey plans, site design drawings, rail design drawings, contour drawings, road/highway design drawings, drainage system drawings, city master plans, maps, and much more. 

For pricing of Autocad, revit civil 3D and other Autodesk products, you can check their PRICES HERE. All Autodesk software come with 30 day free trials. If you are eligible you can also get a one year free student of educator license.

SECTION 2. Structural modelling, calculation and design software

CSC ORION

CSC orion is a reinforced concrete structural and design software. It automates the design of concrete buildings from start to finish. It can design any shape of reinforced concrete structure and supports a lot of building codes. CSC orion is now part of Tekla. Telka is company that produces civil and structural engineering software. For more information visit Telka Website

PROKON

Prokon is a software for the automated analysis, design and detailing of a wide range of structures. You can use the software to design reinforced concrete, timber and steel structure. Prokon is popular and used in over 80 countries. You can try prokon software free for 30 days.  Click HERE for pricing.

QUICK STRUCTURE.

Quick structure is a software that automates the analysis, design and detailing of reinforced concrete structures. It can automate the production of calculation sheets and final drawings into drawing sheets. It very easy to use and much cheaper compared to other software listed so far. Click HERE for pricing.

STAAD PRO.

STAAD Pro is a software for the analysis and design of any type and size of structure.It can design steel, concrete, timber, aluminum, and cold-formed steel structures using over 90 international design codes. Click HERE for pricing.

There are many other civil engineering softwares out there that are very good. The ones highlighted in this article is based on their popularity and age.

The Natural and Built up Environment as it relates to land Acquisition.

A built up Environment (Courtesy Google Maps)
A built up Environment (Courtesy Google Maps)

There are many economic  factors to consider before a decision is taking on land acquisition in a particular location. A proper knowledge of the environment, government/vendor restrictions is essential in order to avoid pitfalls.

What is a natural environment ?

A natural environment is an environment that has not been tampered by the actions of man. On the other hand, a built up environment is a natural environment that has been changed considerably by man’s action.

In a natural environment you will often see vegetation including various sizes of trees, wildlife, natural waterways, and rocks. But in a built up environment man alters the natural environment to build houses, roads, water conductors and so on.

Natural and built up environment as it relates to acquiring of a landed property.

The acquiring of a landed property will usually precede the construction of a building on it. The location of the land is important as it has a considerable effect on the cost of the building.

It may cost more to acquire a landed property in a built up environment however, the presence of access roads, water and electricity would make the building constructed economically viable.

On the other hand it may cost less to acquire a land in a more natural or less developed environment but may cost more to build and use the building. This is because this kind of environment is characterised by undeveloped roads, thick vegetation, limited or lack of social amenities.

Other environmental considerations include;

  • Town Planning requirements and building regulations
  • Land restrictions by vendor
  • Adjoining buildings or land
  • Use of building
  • Daylight and view aspects

The physical features around or within the land property should also be taking into consideration. Things to be look out for include:

Land level; is the land level or is it slope. If sloped how steep is it. It may usually cost more to build on a land that is sloped.

Vegetation: how intense is the vegetation?, How many trees are present and how big?. Considerable amount may be spent on removal of vegetation.

Condition of soil: what type of soil is present?, is it swampy, clayey, waterlogged, rocky, sandy etc. these may have a considerable impact on cost of foundation for the building.

Other physical conditions include;

  • Size of land
  • Natural waterways, lakes, ponds, streams and rivers.
  • Approach and access roads
  • Shape of land
  • Services available
  • Climatic conditions
  • Restrictions such as right of way, tree preservations

Design steps to be followed for an Unreinforced Masonry Wall as per IS 1905(1987)

Here are the design steps to be followed for an unreinforced masonry wall.

  1. Estimate the self weight and imposed loads. See IS 875 part 1&2 on how to go about it.
  2. Estimate the eccentricity ratio taking moments about the centerline of the wall. You can use the equation stated below to calculate eccentricity ratio. WE=w1e1+w2e2 where W is the weight of the masonry wall and E is the eccentricity. Eccentricity ratio is E divided by thickness of the wall.
  3. Estimate the effective height, length and thickness of the wall.
  4. Calculate slenderness ratio as the lesser of the 2; effective height / effective thickness or effective length / effective thickness.
  5. With the eccentricity and slenderness ratios; estimate the stress reduction factor from the code . If necessary you can also estimate area reduction factor and shape modification factor.
  6. Calculate the compressive stress of the wall based on the wall load. Then divide by stress reduction factor, to arrive at the basic compressive stress required.
  7. Apply increase in  basic compressive stress if eccentricity is significant. Increase of up to 25% is allowed by the code
  8. With the help of TABLE 8 of the IS code 1905,and using the basic compressive stress, chose the appropriate unit strength and mortar mix required.

Introduction into seismic design of buildings.

This article was written based on Indian building codes.

Response reduction factor R for buildings in seismic design.

In the seismic design (earthquake) of masonry structures, design forces can be reduced by an R factor for seismic design. This factor is called response reduction factor. The R factor depends on the type of structure. Generally the R values are lower for unreinforced masonry structures and higher for reinforced masonry structures. For R factor related to the type of structure you are designing, consult the building code. In seismic zones or zones prone to earthquakes, the building code will specify the general requirements and type of building to be built.

Seismic weight.

 Seismic weight is the weight of the building that will participate in developing inertial forces during an earthquake. That is the calculated weight based on dead and live loads that will participate in the event of an earthquake.

Importance factor (I) in seismic design

Similar to the response reduction factor, importance factor is also used to adjust the design forces used in seismic design. The I factor increases based on how important the building is. The I  factor is based on whether the building is public or private. For the same kind of building the I factor is increased for public buildings. This is because there is tendency for much more people to be on this type building at the same time.

Design seismic coefficient (Ah)

The design seismic coefficient is calculated based on several factors. These factors are; seismic zone factor, response reduction factor, importance factor and spectral ratio.

As per the Indian building code, Seismic coefficient ;

Ah =(Z/2)(Sa/g)/(R/I) .

Z is seismic zone factor, Sa/g is spectral ratio, R is response reduction factor and I is importance factor.

General requirement for buildings to resist seismic vibrations.

  • Slenderness of the building should be limited as much as possible. This should reduce the possibility of bulking under vertical loads.
  • Building should provide adequate stability against overturning from horizontal forces.

The above points can be achieved if the building is properly designed and adequately  braced using beams, columns, cross walls and buttresses where appropriate.

Hydroelectric Power Systems

hyro electric dam
Hydro electric dam

Hydroelectric power plants convert potential and kinetic energy of water into electricity.

In hydroelectric production, potential energy of water is created by the construction of large dams. The dams hold the water at a greater height than the water level at the turbines.

Water is the greatest contributor of renewable energy to the world electricity generating system.

The common unit of measurement used to indicate the installed capacity of a hydroelectric power station is Megawatts.

Types of hydroelectric power plants

Based of design, hydro electric power plants are broadly divided into 2 types;

  1. Impoundment power plant
  2. Diversion power plant.

In the impoundment type of power plant, All water coming into the plant is dammed. The dammed water creates the head needed to power the hydro plant.

Impoundment  type of Hydro dam
Impoundment type of Hydro dam

In the diversion type, the water coming to the plant is partially dammed, some water is allowed to flow back into the river immediately while the rest is used to power the hydro plant.

Head and tail water

 In a hydro power plant system, the dammed water upstream is known as Head water and the water on the other side of the dam is known as Tail water. The difference between the top of the head water and that of the tail water is called pressure head.

Components of hydroelectric power plant

Trash rack; when water is coming fresh from the dam it needs to be cleared of big debris such as wood , plastic bags etc. the duty of the trash rack is to remove these.

Inlet gate; after water have been processed to remove debris, it then passed through the inlet gate. The inlet gate is used to regulate water flow into the turbines

Water conductors; water conductors are equipment used to convey water within the hydo electric power system. Example include; penstock, draft tube, scroll case, spill way, canals etc.

Penstock; the main pipe that conveys water to the turbine is known as penstock. It is a pressurized water conductor.

Spill way;  a spillway is a water conductor used to prevent overflow of dammed water

Runner; the runner is part of the turbine system and it rotates as water from the penstock passes through it at high pressure

Power house; the power house houses the turbine, electric generators, transformers and other electric generating equipment

Open air switch yard; when the electrical transmission equipment is installed in open air, it is called an open air switch yard.

How a hydroelectric turbine works

Water with high pressure head on the upstream side of the dam is lead through large penstock pipe. Before the water get to the turbine it passes through a scroll case. The scroll case is a large curved pipe that helps the flowing water to efficiently rotate the turbine. The turbine is connected to the generator through a shaft. so  as the turbine rotates, the connected generator also rotates  producing electricity.

Advantages of hydroelectric power plant.

  1. It is a completely green process
  2. It is a very efficient way of generating electricity.

Disadvantages of hydroelectric power plant

1. It is always necessary for settlement around the dammed area relocate. This is because water required to run hydroelectric plants is extremely large and dammed water will cause flooding of the settlement.

2. It is capital intensive. This is because the hydro dams constructed are extremely large.

Types of hydro power plants

  1. Impoundment type power plant. This type of power plant utilizes a dam to impound large amount of flowing river water. The dammed water is the potential energy necessary to power the hydro plant. The different type of dams that could be used include; gravity, reinforced concrete, buttress, rock filled or earth dams.
  2. Diversion type power plant( run of the river). In this case, the river water is partially dammed, only part of the flowing water is utilized to produce electricity.
  3. Tidal water plant. This process works based on tidal action of water. it helps create a height difference on either side of the turbine, this pressure difference cause water to flow through the turbine rotating it.
  4. Pumped storage power plant. This type of plant basically consists of very large reservoir of water held at a very high level. The stored water is then made to flow downwards through a penstock pipe to run the turbine and generate electricity. After reservoir is depleted, the water is pumped back again and the whole process is repeated. Pumped storage power plant is a type of standby power generator.Its acts as a supplement and is usually made available to the national grid during peak hours

Types of turbines

Broadly of two types;

  1. Reaction turbine
  2. Impulse turbine

The reaction turbine are pressure turbines. When water flow through this turbine, it creates a pressure differential which causes the turbine to rotate.

Impulse turbine are pressure-less turbines. It rotates due to the kinetic energy given to it by a jet of water as its hits the blades.

Types of turbine runners

There are many types of turbine runners, however, the 3 most commonly used are;

  1. Kaplan runner
  2. Francis runner
  3. Pelton runner

Kaplan runners are types of turbine runners that can operate with medium to high water flows and efficient at low pressure heads. Kaplan runners are reaction  runners because the pressure difference of the water flowing through the blades causes it to rotate.

Kaplan runner
Kaplan runner

Francis runners  are reaction runners and can operate within a wider range of pressure heads than the Kaplan runners.

Francis runner
Francis runner

Pelton runners are only adequate for very high flows and operates within a narrower range compared to the Kaplan and Francis runners.

pelton runner
Pelton runner