Quantity Take Off or QTO is a well known project estimating company serving to the contractors, home builders, architects, design- build firms and sub contractor trade. We are providing estimating service since 2002 with a great chronicle of success.
A building and structure has to bear not only vertical loads, but also lateral loads. This can occur due to many design or natural reasons. To counteract this lateral load, Shear Keys are used. Let us see today what exactly are shear keys and how can you use them in your construction.
A building can face a lot of lateral load due to many reasons. Some of these include earthquake loads, sliding forces, water pressure, wind pressure etc. This often occurs with bridges, retaining walls, basements, extremely tall buildings, precast buildings and culverts, masonry walls where seismic activity is stronger, and steel columns and piers.
Shear keys can be constructed by concrete in precast buildings, and of steel in steel structures. Sometimes, steel reinforcements are made to play the part of shear keys as well. They improve the lateral stability of a building.
Placement of Shear Keys: Where the shear keys will be placed differs a lot depending upon the structure they need to support. Let us discuss them below.
Bridges: In small to medium bridge structures, shear keys are placed in the abutments of the bridge. This provides lateral transverse support to the structure above during sidewise movement.
During an earthquake or similar strong lateral force application, the shear keys act as a sacrifice. Therefore, the strong seismic forces are prevented from entering the abutment piles.
They act better when they are placed on the outer side of the bridge. However, this makes them difficult to inspect or repair.
Retaining Walls: You should place shear keys at the base of retaining walls, just beneath the stem. This prevents sliding of the base during strong lateral force application.
The shear keys placed beneath the wall must be nearly twice in width than their depth for the best performance. Generally, they are 508mm by 381 mm, respectively.
Plane Table Surveying is used in ad-hoc surveying and designing situations. In this, survey fieldwork and plotting work is done simultaneously. Therefore, there is no need for office work. This is best adapted to situations where high precision is not required. Thereby, it is greatly useful for small-scale mapping operations.
Instruments used in Plane Table Surveying - The Plane Table survey method uses very simple instruments. These are available everywhere.
1. Drawing Board: It is a board made of seasoned wood. They are available in many sizes. Generally, the field work is done in 40 cm by 30 cm boards. They also use the 75 cm by 60 cm boards, for larger work. In the field, a tripod is placed under the board with a ball socket in it. This enables the surveyor to draw on the board from any angle.
2. Alidade: An alidade is basically a ruler with a telescope. This is used on the drawing board to draw lines and rays according to the field. The alidade may also have a spirit level on it.
3. Compass: A tough compass is used to find the magnetic meridian of the place. Generally, the compass used in survey work also has two bubble tubes at right angles to each other.
4. Plumbing Fork: It is a rod with a plumbob attached to one end. This is used to ensure that other equipment is aligned perfectly vertically, when needed.
5. Spirit Level: It is a tube of liquid with a bubble inside it. The tube is slightly bulging in the middle. This lets the bubble stay in the middle of the tube when the level is perfectly horizontal. This is used to make sure the drawing board, or other equipment are placed horizontally.
6. Waterproof cover: A waterproof cover is used to cover up the paper on the drawing board from rain or other splashes and dust. This is generally made of soft polythene.
There is a new construction method on the market, and it is quite cool. Called the Light Gauge Steel Frame Construction, it is successfully replacing the standard wood frame construction method. This innovative method is being widely accepted in many building designs and construction aspects.
The Light Gauge Steel Frames offer several advantages. Some of them are design flexibility, strength, sustainability, buildability, etc. This makes Light Gauge Steel Frames easier to build and much safer too. Not only that, it is also faster to build. Word to the wise, though - the light steel frame is susceptible to fire, so fire protection coating needs to be provided.
Based on ASTM standard A1003, Light Gauge Steel Frames are manufactured from structural steel sheets. These sheets are formed into ‘C’ ‘Z’ and ‘S’ shapes. This makes the structure strong and able to support heavy loads. It is also called cold formed steel. This is because of the process by which it is manufactured.
This added strength and flexibility leads Light Gauge Steel Frames to support increased spans. They can be shaped into custom openings. Moreover, they can support many different types of external facade treatments. This sheer versatility is making the Light Gauge Steel Frames very popular among modern constructors.
One thing to be noted about Light Gauge Steel Frames is they are much more susceptible to corrosion effects than standard wooden frames. For this reason, they have to be provided with zinc, aluminum or combo coatings to make them corrosion-resistant over long periods.
The external plastering work in a building project is a pretty important work because it provides the outer finish of the building. Not only that, it is the foundation for the building’s aesthetics. For these reasons, every constructor should keep in mind some basic steps in order to do it right. As such, the following checklist can be very helpful in external plastering work in building construction.
1. Clean the surface: Make sure that the external surface of the building is clean. That means the block or brick masonry and concrete surface. These should be clear of dust, oil grease, loose materials, mortar dropping, nails, wood, metal strips, etc. You should have an even, smooth surface to work on. Otherwise the bonding will not work.
2. Make scaffoldings: You need to erect a scaffolding in order to reach the entire outside surface. Conversely, you might be needing a double scaffolding as well. You have to do this without making a hole in the wall. Since in this phase you must not damage the wall in any way. However, if authorities permit, you can take support from other parts of the building.
3. Mortar and socketing: The gaps between the masonry and the beams that show on the outside needs to be filled with rich mortar. Also, you need to finish out the socketing works.
4. Chicken mesh: Then, fix a chicken mesh on the joint of RCC and masonry wall. The mesh should be 6 inches wide. Nail this mesh at 230mm intervals only.
5. Plumb measure: Use the plumb (also the line) from top to bottom to ensure the accuracy of the plastering.
The plastering here should be of a single coat of 10-12mm only. Also, you must check all the edges.
6. Handle jutting out stuff: Sometimes, a beam or a column, or other parts of construction may be budging out of the plastering. In this case, first take approval of the designer to see if you can break it off. If you can, then use a sharp chisel or hammer to break off the jutting-out portion. Also, you can use a concrete breaker in this. Do take care that it doesn’t hurt any other part of the building.
Definition of a honeycombing: Honeycombing refers to a structural fault in a RCC Structure. Honeycombed surface is the areas of the concrete surface where the coarse aggregate are eminently observable.
If precaution is not taken for honeycombed surface, the RCC structure fails to achieve optimal performance according to its design (structurally weak). Besides, it also lets damaging agents like contaminated water and air entering through the produced voids which can impact the strength of structure considerably.
Causes for Honeycombing: Honeycombing in RCC Structure is happened because of the following reasons -
1. Concrete mix is not homogenous. 2. The applicability of concrete is inadequate and not matched with its placement need. 3. Inadequate compaction to concrete. 4. Concrete flow is not dispersed to all corner due to steel congestion.
5. Concrete is set afore time prior to placing. 6. High free fall of concrete, at the time of pouring 7. Form work is not waterproof or inflexible. 8. Incorrect detailing and/or fixing of steel
How Honeycombing in Concrete can be avoided?
Check concrete production/cohesiveness from time to time to organize all concrete batches.
Tip: If it is possible to create ?ball? from the fresh concrete, a cohesive concrete mix is produced.
Concrete workability should tally with the placement need. As for example, a lightly reinforced column should contain 75mm slump, a heavily reinforced column may require 150mm slump.
Make sure that the compaction of placed concrete is perfect, vibrators should have been detached as big air bubbles stops to come out (over vibration can lead to bleeding). Various sizes (25mm, 40mm, and 60mm) of vibrator needle should have been utilized according to RCC sections.
Functioning as a system of steps leading people from one level of the building to another, a staircase is a pretty complex building element. This is because staircases have particular geometry and function. Everything about this building element needs to be carefully planned because of that.
The dimensions of the steps and regulations of the heights and widths of the steps need to be carefully maintained. Not only that, you need to pay attention to the material being used as well.
In this article we will discuss the standard staircase dimensions today.
In staircase design, concrete offers great reliability in terms of load-bearing and production benefits. Geometry requirements, heat resistance and tensile strength, all can be fulfilled by using concrete. The staircases that are made of in-situ concrete can be adapted to any building plans on site.
On the other hand, precast staircases are not as flexible and can only be fitted into predefined design dimensions specific for that staircase design.
However, one advantage of using precast staircases is that they can be produced efficiently, faster and more cleanly than in-situ staircases.
It goes without saying that special attention must be paid to the basic dimensions of the stair breadth and rises. You should also need to take care of dividing the staircase with proper landings in order to enable resting places in a long climb. The number of steps without an intermediate landing should be counted in this matter.
Staircase dimensions are an important part of staircase safety. This page covers all of the important staircase measurements and a mistake to watch out for.
Staircase design has to account for the human step sizes and the comfortable distance a human foot can travel vertically.
The tread size is dictated by the average adult foot size. Though it is not necessary to fit your entire foot on the stairs, it should be kept as close as possible in order to keep it as safe as possible. The standard tread size is 10 inches minimum, or 25.4 centimeters.
A pier is kind of a big brother to a column. It is a support structure holding up great loads, and can take a lot of tensile strains as well. Piers are constructed in a dry place by digging out the soil in a large diameter hole and then filling it with reinforcements and concrete. A pile greater than 0.6 meter in diameter becomes a pier.
The pier foundation transfers the load on the pier to the ground via the bearing. It is generally a shallow structure placed on top of sound rock layer. Hard soil is also good for pier foundation construction provided they can take the load.
Which type of pier foundation will be used depends upon the depth of the hard bed, nature of soil, and the superimposed load.
Masonry or Concrete Pier Foundation
The name comes from the pier being made of concrete. Precast sections are manufactured in-situ or in facility. Then they are driven into the ground at location. The sections are generally reinforced with steel wires. At the bottom, a cast steel shoe is provided to hold the structure better and to transfer the load well. The cross sections of these piers are generally no more than 30-50 centimeters and they are no taller than 20 meters.
Drilled Caisson Pier Foundation
A drilled caisson is a large compressed member subjected to an axial load. The load is at the top and the reaction is at the bottom. These can be concrete caisson with enlarged bottom, a steel pipe caisson with concrete filled in it, or a concrete body caisson with a steel pipe core.
In this construction video tutorial, you will learn how to compute quantity of tiles required in building rooms or bathrooms.
Initially, you have to determine the area of the room where the tiles will be placed. Suppose, there is an L-shaped room and it is divided as part A and part B.
Length of room A = 3 meter Breadth of room A = 2 meter Length of room B = 6 meter Breadth of room B = 2 meter
At first, calculate the area of A as follow :- Area = Length x Breadth After putting the above values of room A, we get Area = 3 x 2 = 6 square meter
Then, calculate the area of B as follow :- Area = Length x Breadth After putting the above values of room A, we get Area = 6 x 2 = 12 square meter
Therefore, total area = area of A + area of B = 6 + 12 = 18 square meter Suppose the length of one tile = 600 mm = 0.6 m and breadth = 600 mm = 0.6 m So, area of one tile = length x breadth = 0.6 x 0.6 = 0.36 square meter There, no. of required tiles = Total Area / Area Of One Tile = 18 / 0.36 = 50 Nos. (approx)
The first step in any construction project is to prepare a visual plan for the building. This is called the drawing, a visual representation of the project with dimensions and appropriations so that civil engineers can understand what the architect actually wants them to build.
To make sure there is no misinterpretations, one needs to follow some basic steps to understand the drawing. Here is a brief guide on how to study civil engineering drawings.
Familiarize the Scale
You have to understand exactly how large the objects are going to be in real life from the drawing itself. In a civil engineering drawing, the scale is maintained religiously all throughout the documents.
Generally the scale is 1/4th or 1/8th, but there may be other variations as well. Sometimes one set of plans may contain different scales on different pages if they need to depict very large and small objects at once.
You must be able to understand at a glance the real scale of the object from the drawings.
This is an exclusive excel template that is based on daily work report of the employees. Any person who is self employed or performing as an employee in a company, it is required to maintain day-to-day work reports as well as generate them on daily basis to organize records concerning all the works executed by you throughout working hours.
To prove your worth and ensure that you are a responsible employee to your employer, it is necessary to send report about your work on day-to-day basis as you are completing the works entrusted to you as well sending reporting on it devoid of any delay on a regular basis.
Daily work report means a document of details of work accomplished by you in a day. Either your supervisor, manager or employer inquire you to provide information on what you carry out every day or not, creating a daily work report is a perfect way to keep tracing of the work done by you.
The industrial buildings such as godowns and factory floors are often low rise structures with few or none internal walls. In such buildings, special Care needs to be taken while designing industrial roof trusses, since large spans need to support the entire roofing system without intermittent support. Trusses with roof covering materials make up of the entire roofing assembly here.
What are Trusses? Trusses are triangular formation of metal sections, usually used to span large lengths in space instead of solid girders. The external load apply mostly axial forces on the members in a truss. Depending upon how the force is applied, trusses can be designed in the following two ways:
Plane Trusses: where the external load is placed on the plane of the truss.
Space Trusses: where the external load can be applied to any three-dimensional space within.
How are Trusses Built? Trusses mostly consist of axially loaded members to support loads. The reason for this that when steel members are subjected to axial forces, they perform better in bearing that load, than members that are in flexure. This is because the cross-section of such a system is uniformly stressed under axial forces.
Trusses are very common in most architecture. Mostly used to span long distances, they are well suited to bear the load of single-storey industrial buildings. They can also be designed to bear gravity loads in long span floors. For the same reason they are also mounted to bear loads of long span bridges.
It is essential for the constructors to have good quality material for their building project. Compromises in the quality of construction material can cause severe results leading to serious repercussions. One of the most important materials of a building is the steel reinforcements used in concrete columns, beams, and other structures.
The quality of steel received on site determines the strength of the structure with steel reinforcements inside it; so it is imperative that you check the steel quality right on the project site to ensure that your building will be made out of materials capable of handling the load.
Observations on Steel on Site:
1. Cleanliness: The reinforcements that you receive in the field must be clean ones. Dust, rust, earth, mild scales, paint, oil, grease or any similar coating clinging to the bars is detrimental to the bonding between reinforcement and concrete. Also, these contaminants can cause corrosion in the structure. For this reason, you must make sure that the steel bars and other reinforcements you receive are clean. Point to note: a little rusting on the bars is considered to be helpful in forming better bonds with the concrete. But excessive rusting and/or scaling is absolutely harmful for the building.
2. Manufacturer Marking: The bars should have their steel grade, manufacturer name/logo, brand name, diameter etc should be embossed on themselves. Do check if you have received everything of the same type as you expected.
3. Bending the Bars: When satisfied with the above, proceed to the Bend Test to examine the actual capabilities of the steel you have received on site, under realistic strain.
a. Bend Test: This test should be carried out as per the specifications in IS 1599 and you should use mandrels of size specified in IS 1786. The rebar sample should be bent in 180 degrees, results recorded, and then proceed to bending it 180 degrees.
Sometimes, it is required to move a building from one place to another location. This can be required for a number of reasons, like change of land, replanning of facility or even natural causes. In such situations, a process called Structure Relocation comes into play.
Relocation of a structure essentially involves three steps. The first is to disassemble the existing structure - you need to tear the building down systematically, preserving as much material and objects as you can. The second step is transporting the disassembled building blocks to the intended target location.
This may need the involvement of heavy transport support if the location is far away. Of course, if the location is within the same property then this step reduces next to zero. The last and the most important step is to reassemble the building back again at the target location using the same building blocks from the previous structure and maybe some extra materials.
Sometimes if the building is small enough and light enough, it can be picked up as a whole and transported to the new location with minimal disassembly and reconstruction necessary. If the move is within the same piece of property, the move can be done by rolling it on temporary rails or rollers. For long distance moves, generally heavy-duty flatbed trucks are used. Though in that case many complications may arise on the way, like roadside obstacles like narrow zones, and overhead obstacles like low-hanging branches and cables.
Columns are essential support structures that are almost inevitably used in any construction projects. From ancient times, columns have been an indispensable part of erecting buildings, them being one of the most important load-bearing members. Obviously, one needs to be careful while designing such important structures.
As per the construction sciences and technologies, there are many rules applicable to specific columnar structures. However, there are some few basic rules of column designing that all engineers can keep in mind while designing most types of columns and similar vertical supports.
Today, we will discuss these important thumb rules of column design in this article. Needless to say, columns need to be designed keeping in mind the total amount of forces acting on the structure. But also, keeping these basic guidelines in mind can prevent architects and engineers from making silly mistakes.
Rule 1: Essentially, the size of the columns would depend upon the total amount of forces acting on the column. In short you can consider this as the total load on a column. This will make or break the column, so you need to be ensuring that your columns design can withhold this entire load and anything else that may come later.
That is, the total load on a column may be not only the weight of the structure that it bears, but also the movable materials that structure will bear. For example, while designing a multi-storied godown, you will need to care about not only the weight of the floor and the walls and the roof, but more also, the weight of the goods that are going to be stored on that floor. This can get pretty great in case of solid materials.
Reinforcement Detailing in Slabs and Beams performs a vital role in a construction process to provide durability and strength to the structure. It also helps out in the cost optimization for the project. A structure’s cover to reinforcement, length of the reinforcement, it’s curtailment, number and diameter should all be clearly defined by the detailing of the reinforcement of the concrete beams and slabs.
Consider a generic concrete slab or beam, supported via simple means. This structure would experience the maximum bending moment at the center of the span. The shear force will come at a distance of d/2 from the face of the support (where d = effective depth of the slab or the beam).
This indicates clearly that the bending reinforcement is required at the center of the span, where the bending moment occurs, not at the support. Whereas the support should be reinforced to withhold the shearing forces.
Therefore, it would not be necessary to cover the full length of the structure in tension reinforcement. In fact, as much as 50% of the reinforcement can be curtailed at suitable locations. They can also be repurposed as shear reinforcements by bending them upwords.