In the mid-nineties, I was heading a civil style and design office for a massive EPC contractor in South East Asia. We experienced obtained an order to make a paper plant.

The primary creating in a paper plant is the paper device creating. A usual paper equipment constructing is about 300 m lengthy. The creating ordinarily has two flooring, just one at floor level, and 1 at about 7.5 m amount. The paper machine is put in on a basis that is not connected to the constructing. The machine is obtainable from the equipment corridor at 7.50 m degree. This developing residences other complex and major machinery and has extremely stringent prerequisites with regard to quality, structural design and security. The roof is substantial up and some of the sections of this developing are issue to temperatures among 50 to 60 C. A huge overhead crane straddles the upstairs machine hall. The differential settlement in the paper machine basis has to be much less than one mm and all round settlement at any stage much less than 1.25 mm. This developing, with all its factors and the equipment foundations, typically usually takes 18 months to establish.

Our handling director was an ground breaking person and continuously sought strategies to pace up building. One particular day, he termed me to his office environment and showed me an report narrating about a firm in the US that experienced made approaches to build a paper device making utilizing pre cast aspects. This paper equipment developing was accomplished in a history time of 6 months, reported the write-up. We appointed the US corporation as our consultants and they did the engineering with the assist of our engineers in our office environment. We built our paper device building in a 12 months reducing down the time by about 6 months. This was despite a delay of about a few months thanks to the studying curve and the time necessary for setting up a precast plant.

Consequently started my twenty two years extensive association with pre-solid concrete. My aged business has developed a number of huge industrial vegetation and other buildings due to the fact then.

In numerous to start with world international locations pre cast components for bridges, culverts have been standardized. Pre-casting units are positioned close to major towns that source these things to the design internet sites. This not only lessens the building time but also the design and style time as a person utilizes normal components whose houses are regarded.

There are variants of the precast concrete design this kind of as tilt up building, module fitments and so on.

I have often puzzled why India, with so significantly building desired in the all the sectors of construction, has not embraced this strategy. Aside from other concerns like will need for repetition, unfriendly taxation, need of transport or lifting equipment etcetera., I assume our engineers have not given a serious believed to creating this technique.

I would like to share some of my learnings.

1. Organizing is Paramount: The structure to be developed from precast elements has to be broken down in factors, in a pre-identified configuration. It is like building the pieces of a jigsaw puzzle that when set collectively will kind the completed puzzle. It can be a blend of common and non-normal parts.

2. God is in particulars: Just about every component as a result planned has to be comprehensive out to healthy all the aspects on all its sides and the embedment demanded for utilities.

3. Style and design the Construction and Build the structure: Regular structural engineering exercise of building the final item and leaving the “How?” to the development personnel, does not perform in precast. The structural engineer has to continue to be concerned in the approach of pre casting, erection and placement.

To the best of my knowledge, IS codes do not have unique provisions for pre solid constructions contrary to ACI or BS codes. Some of the clauses in ACI can be substituted by provisions in their supplementary publications. This kind of provisions have to be used judiciously right after a appropriate assessment of the levels in the services lifetime of the component. A foremost qualified on pre-casting the moment claimed “Implementing provisions of R.C.C code to pre-casting would be like participating in tennis with a baseball bat”

The structural design and style for a precast component is carried out for numerous levels of in its early lifetime. Many degree checks are demanded till the element is placed, additional checks are required if it is a pre-stressed element with partial un-bonding of tendons.

4. Joints can bring about complications: Resolving and configuring a joint involving precast factors can be an arduous undertaking. It gets to be a heuristic system to equilibrium amongst the structural prerequisite, performance with respect to primary thing to consider as h2o tightness, and the size of the aspects to which an factor in consideration is hooked up. Joints have to be manufactured the way they have been envisaged.

5. Chopping off ears since they stick out, not only impairs hearing but also creates issue in donning spectacles: This is identified to manifest commonly wherever architectural needs are of principal value. Generally some architects do not like some vital arrangements designed for much better joints. Undertaking absent with these “hindering” details might direct to lessened functionality of the joints or the elements. Pricey alternate preparations are essential to restore functionality.

6. Construction Methodology can make or break a job: Lots of many years ago, a massive bulk warehouse with pre-forged pre stressed concrete bow string girders as roof trusses was remaining manufactured in India for a fertilizer plant. Out of twelve bowstring girders, 6 broke although becoming lifted though the others were erected efficiently. Styles were being checked and double checked and checked all over again. This was prior to the straightforward availability of the advanced finite element assessment that we have right now. It last but not least dawned on an individual that the bow string girders broke simply because a girder while staying lifted in tandem by two cranes, twisted out of aircraft because of to distinctive rates of lifting. A structural engineer developing precast things really should, as a result, have the information of the lifting process.

7. Good quality is the watchword: Reliable Top quality of manufacturing is one of the arguments put forward by the advocates of precast. But quite a few a mismatches, rejections and failures have occurred due to watching only the high-quality of concrete and providing much less great importance to placement of reinforcement embeds and the dimensional tolerances.

8. A one particular rupee enhance in the creation price can suggest a crore of rupees at the conclusion: Because of the repetitive character of the charge of pre-casting a great deal of believed has to be specified to use any “great to have” part. When the most clear charge things connected to concrete are watched vigilantly, a modest embed or a detail, that is included in the design and casting of an element for a possible use, escapes interest. This sort of an embed that was proposed to be employed and has been forged in the factor has previously extra to the price of producing the element. When a amount of this kind of factors are cast, the expenditure can be sizeable. If these kinds of redundancy if not eradicated in time, it can squander lakhs of rupees.