Tag Archives: Construction

A Quick Peak at Construction Induction Training

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Construction induction training extends far beyond being simply the application of common sense and conscientious safety measures. It is the law. Every contractor and all contractor employee must attend occupational health and safety training as per the prescribed amount before being cleared to operate on any site in any capacity. There is also a legal obligation for those that are self-employed to make certain that the complete this training as well.

All work performed by these individuals or under their guidance must be performed in a manner that remains compliant with the rules and regulations as they were introduced in induction training. The operation of sites must follow these mandates as well. All measures protect workers, their hire and those individuals that may be within a reasonable distance of the construction site.

The design and implementation of emergency management procedures will be attended to within the courses. The instructor will help plan for the implementation of arranged reporting procedures as well. Companies will also learn to delegate leaders according to specific areas of occupational health and safety.

Employers will be notified of their obligation to provide a safe environment for work and the necessary accommodations that this includes. As employees are taught to operate according to standard health and safety procedures they can begin to assist in the every day maintenance of their work environment. There are additional employer health and safety obligations that will be defined as well.

It is an unavoidable obligation that all employers make certain to make provisions for every employee to undergo sufficient construction induction training. This will help create a safe place in which business can be conducted and lessen the amount of money that companies will lose on work related accidents. It is also better assurance for the safety of those that will be within the area of construction or around it.

Precast Concrete Construction

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In the mid-nineties, I was heading a civil design department for a large EPC contractor in South East Asia. We had received an order to build a paper plant.

The primary building in a paper plant is the paper machine building. A typical paper machine building is about 300 m long. The building typically has two floors, one at ground level, and one at about 7.5 m level. The paper machine is installed on a foundation that is not connected to the building. The machine is accessible from the machine hall at 7.50 m level. This building houses other complex and heavy machinery and has very stringent requirements with respect to quality, structural design and stability. The roof is high up and some of the sections of this building are subject to temperatures between 50 to 60 0 C. A large overhead crane straddles the upstairs machine hall. The differential settlement in the paper machine foundation has to be less than one mm and overall settlement at any point less than 1.25 mm. This building, with all its components and the equipment foundations, normally takes 18 months to build.

Our managing director was an innovative man and constantly sought ideas to speed up construction. One day, he called me to his office and showed me an article narrating about a company in the US that had developed techniques to build a paper machine building using pre cast elements. This paper machine building was completed in a record time of 6 months, said the article. We appointed the US company as our consultants and they did the engineering with the help of our engineers in our office. We built our paper machine building in a year cutting down the time by about six months. This was despite a delay of about three months due to the learning curve and the time required for setting up a precast plant.

Thus began my twenty two years long association with pre-cast concrete. My old company has built several large industrial plants and other structures since then.

In many first world countries pre cast elements for bridges, culverts have been standardized. Pre-casting units are located near major cities that supply these elements to the construction sites. This not only reduces the construction time but also the design time as one uses standard elements whose properties are known.

There are variations of the precast concrete construction such as tilt up construction, module fitments etc.

I have often wondered why India, with so much construction needed in the all the sectors of construction, has not embraced this technique. Apart from other issues like need for repetition, unfriendly taxation, requirement of transport or lifting machinery etc., I think our engineers have not given a serious thought to developing this technique.

I would like to share some of my learnings.

1. Planning is Paramount: The structure to be built from precast elements has to be broken down in elements, in a pre-determined configuration. It is like making the pieces of a jigsaw puzzle that when put together will form the completed puzzle. It can be a combination of standard and non-standard pieces.

2. God is in details: Each element thus planned has to be detailed out to fit all the elements on all its sides and the embedment required for utilities.

3. Design the Construction and Construct the design: Normal structural engineering practice of designing the final product and leaving the “How?” to the construction personnel, does not work in precast. The structural engineer has to stay involved in the process of pre casting, erection and placement.

To the best of my knowledge, IS codes do not have specific provisions for pre cast structures unlike ACI or BS codes. Some of the clauses in ACI can be substituted by provisions in their supplementary publications. Such provisions have to be applied judiciously after a proper assessment of the stages in the service life of the element. A foremost expert on pre-casting once said “Applying provisions of R.C.C code to pre-casting would be like playing tennis with a baseball bat”

The structural design for a precast element is done for various stages of in its early life. Multiple level checks are required till the element is placed, more checks are required if it is a pre-stressed element with partial un-bonding of tendons.

4. Joints can cause headaches: Resolving and configuring a joint between precast elements can be an arduous task. It becomes a heuristic process to balance between the structural requirement, functionality with respect to basic consideration as water tightness, and the size of the elements to which an element in consideration is attached. Joints have to be constructed the way they have been envisaged.

5. Cutting off ears because they stick out, not only impairs hearing but also creates difficulty in wearing spectacles: This is known to occur frequently where architectural requirements are of primary importance. Typically some architects do not like some essential arrangements created for better joints. Doing away with these “hindering” details may lead to reduced functionality of the joints or the elements. Expensive alternate arrangements are required to restore functionality.

6. Construction Methodology can make or break a project: Many years ago, a large bulk warehouse with pre-cast pre stressed concrete bow string girders as roof trusses was being constructed in India for a fertilizer plant. Out of twelve bowstring girders, six broke while being lifted while the others were erected smoothly. Designs were checked and double checked and checked again. This was before the easy availability of the sophisticated finite element analysis that we have today. It finally dawned on someone that the bow string girders broke because a girder while being lifted in tandem by two cranes, twisted out of plane due to different rates of lifting. A structural engineer designing precast elements should, therefore, have the knowledge of the lifting process.

7. Quality is the watchword: Consistent Quality of production is one of the arguments put forward by the advocates of precast. But many a mismatches, rejections and failures have occurred due to watching only the quality of concrete and giving less importance to placement of reinforcement embeds and the dimensional tolerances.

8. A one rupee increase in the production cost can mean a crore of rupees at the end: Due the repetitive nature of the cost of pre-casting a lot of thought has to be given to use any “nice to have” component. While the most obvious cost elements related to concrete are watched vigilantly, a small embed or a detail, that is incorporated in the design and casting of an element for a probable use, escapes attention. Such an embed that was proposed to be used and has been cast in the element has already added to the cost of producing the element. When a number of such elements are cast, the expenditure can be substantial. If such redundancy if not eliminated in time, it can waste lakhs of rupees.

Construction Tools – Types and Usage

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It refer to the various kinds of tools and equipments used for building and construction purposes. It has always been an integral part of the construction and building industry as it is unimaginable to construct a building without these tools. In fact, for every single activity at a construction site one invariably needs one or the other kind of construction tool to start up the work.

It is also important as there needs to be a definite and appropriate tool for every activity during the construction of a building. Its range from the lighter equipments like sand screening machine, air compressor, brick making machine to large, heavy equipments like cranes, dozers, haulers etc. Every builder or constructor looks for durable tools which last long in the rough and tough conditions of a construction site. Thus, construction tool manufacturers too work on the principle of providing reliable tools to serve the requirements of the site workers in the best possible manner.

Discussed here are some of the basic construction tools which are generally used at a construction site:

Excavators

Excavators refer to the heavy construction machines used for the purpose of pushing or lifting heavy objects from one place to another. This particular construction tool simplifies the mammoth and tiring task of moving the large objects on a construction site.

Sand Screening Machine

Sand screening machine is used for screening sand to get rid of dust, dirt and slit from sand. Generally constructors prefer vibratory screening machine as it can sieve both wet as well as dry sand.

Concrete Mixers

Concrete mixers are needed for mixing the cement consisting of sand and gravel with water. Together these ingredients form a homogeneous mixture of concrete. The anatomy of a concrete mixer comprises of a rotating drum used for mixing the ingredients. Though some mixers also carry hoopers which make the job of mixing all the more easier.

Jaw Crusher

Jaw crushers are used for crushing heavy stones and rocks into smaller pieces so as to make them usable for construction purposes. The sizes of this construction tool vary as per the nature of job it has been assigned to.

Scrapers

Scraper is a multipurpose mechanical construction equipment. This one single equipment is capable of doing three different tasks at a site i.e. excavating, digging and hauling. It is one versatile construction tool which digs the site, loads, hauls and dumps the scrap thereafter. It is instrumental in preparing construction sites.

Cranes

Cranes again account into the heavy construction machinery. These are used for lifting heavy materials from one place to another. Cranes form an integral part of the construction tools as these simplify the task of transporting heavy materials to and fro to a great extent.

Boring Machines

Boring machines are the machines used for the purpose of digging holes of precise diameters and depth in hard rocky surfaces or even in to metal equipments and buildings. This construction tool is used quite often at the construction sites.