Betonarme inşaat kalıpları

Abstract

Betonarme inşaat kalıpları eğer gerektiği gibi boyutlandırılıp, dizayn edilmez ise sonuçları çok pahalı kazalara neden olabilecekleri gibi, gayri ekonomik maliyetlere neden olarak istenmeyen dudumların ortaya çıkmasınada neden olabilir. Bu maksat ile doğru dizayn ve boyutlandırma yapabilmek için öncelikle kalıpta nasıl ekonomi sağlanacağı incelenmiştir. Hata yapılmasını engellemek için kalıp malzeme ve bağlantı elemanları ana başlıklar halinde incelenmiş, kalıp boyutlandırılmasında kullanılan yük hesap ilkeleri ve bağıntılar teker teker ele alınmıştır. Binanın bütün elemanları (temel, betonarme perde, kolon, döşeme) için yukarıda adı geçen bağıntılardan hareket ederek dizayn örnekleri verilmiş ve kolay dizayn yapabilmek amacı ile tablolar çıkarılmıştır. Bütün bunlar dışında endüstriyel kalıp sistemleri ele alınmış dizayn ve hesap ilkeleri incelenerek konvansiyonel usûl ile mukayesesi yapılmıştır. Ayrıca tez kapsamı dışı olan ama faydalı bir takım bilgiler ek olarak tezin en sonunda derlenmiştir.

The subject matter may consist of a small residence construction or a dam project; whatever it is, the main material of civil engineering is the concrete. The concrete will behave like a plastic material and in a short time after its preparation it will start solidifying in order to turn out to be a good supporting element. In this sate, we can shape the concrete in every form we desire. Lie call the combination of these elements, used to shape the concrete in the desired form, under the common name of formwork. When the concrete is placed in the formwork, it will first exercise a certain load. This load will be exercised in the form of hydrostatic load on such elements like wall, column, foundation, side of beam and on other elements such as slab and bottom of beam it will be in the form of weight. Therefore, it has to be balanced with the elements we can name as tie-rod in the vertical elements existing in the formwork and so must be done the same with the elements we can call scaffolding and prop when the horizontal elements are concerned. Shortly, the formwork of reinforced concrete construction will be conposed of two main elements: 1- Formwork 2- Support When both vertical and horizontal structure elements are concerned, the formworks are constituted out ot three parts : 1- Sheatering 2- Vertical struts (in order to support the loads acting on sheatering and to prevent slop) 3- Horizontal struts in order to support the loads acting on Vertical struts and to prevent slop) Supports help to balance in a predeterminated may the transmitted loads acting on horizontal elements. On the vertical elements the load is balanced by passing some tie-rods through both sides of formwork. And on the horizontal structural elements, the load is transmitted to a solid ground by supporting the horizontal struts with some elements like scaffolding or props. The maximum care must be taken in balancing the loads created by the concrete, whatever would be the form of the load. Therefore this balancing process can't be carried out by simple guessing, on the contrary a minute and careful calculation must be made. Formuork for concrete structure are designed, dimensioned and manufactured in the verv same way as the other constraction elements. If this process is not done by a competent engineer in a controlled way; 1- The formworc system will not be able to resist the loads and consequently it will either cause huge failures or end up with deformation. Both results will bring a substantial Idss of labor and money and the repercussion of the failure will be hard the restore. 2- Or, the formwork system will be unnecessarily built up with excessive component, which will bring up an uneconomical result and this will cause a waste of scarce resources. Thanks to developments in the cement industry in the mineteenth centur, in the years of 1840 the first samples of reinforced concrete structure began to appear. It is also possible to accept this date as the first application of reinforced concrete structure in the history. Back in those times, as formwork material, wood has been used given that it was an easy material to treat and shape. Nowadays, this method is still holding it's particularity of beeing used wildly. In convantional method, the formwork was used to be mounted entirely in wooden material. In first application even the support were made of wood whreas later, due to development in steel industry related tD this field of application, manif acturing the supports out of steel has gained a larger application as a method. Hence, at the begining of 1900's, we encounter the convantional method where this time the mixture of wood and steel was used. -x- Right after the end of the second world war in Europe begins a period of the highly accelerated duelling constractions. As a result, in countries like England, Germany, France where the steel industry was considerably advanced, first time in the history appear the formworks made copletely of steel. Particularly in this period because of the construction of countless number of standart buildings we witness the innovation of TUNE "L" formwork system manifactured entirely out of steel. Although the TUNE "L" formwork system has been accepted as a reform in the recidence constructin field, since there has not been any other application field this system has gradualy lost momentum and finaly almost abandoned in Europe. Since -the system other than TUNE "L" formuork have been dificult to be applied, in 1950s, other system have been develoed with sheatering in wood and other components in steel. In the same period, due to some inconveniences of wood stated below, first applications on the plywood start to emerge: i- less usage of wood sheatering, ii- the need of frequent rectification of wood sheatering. iii- unability to create smooth concrete surface. The rapid technological development in the wood industry taken place in 1950s and 1960s, helped modular wooden elements to be guther developed. In nowadays technology, the modular formwork systems are composed out of these elements. These reasons why advanced wooden products find extensive field of application are: 1- Easiness of their usage, 2- Their multiusability, 3- Their considerable rigidity. Even though the steel material seems to possess these particularities at the first glance, in fact it is a system quite hard to use and treat. Besides, steel has the property of quick deformation. And in this case its reusability is not possible or making other uses of steel requires great expenses. -xi- Another advantage of modular formwork is that they provide important savings. In fact, the conventional formuork system, as investment cost, is relativly cheaper than both steel formwok systems and wood-steel composit modular formwork systems. Moreover, formwork system made completely of steel are comparatively cheaper than woodsteel composit modular formwork systems. From the beginnig of the second half of the twentieth century, labour and time turned out to be more expencive than other factors. All industrial pruducts under development have always had to bring an enswer to question of how the duration can be shortened and how less labour force can be employed. This is the same case for the construction sactor which is the vital sector in a country's economy. To that end, a big variety of constraction machines, equipment and so forth have been developed. Industrial formwork systems always' kept pace with this development process. But, in developing and under developed countries and even in same developed countries Those system have difficulties in finding wide application possibilities. Since labor cost is very cheap in Turkey using advanced industrial systems have been indispensable in big projects, and its application hasgradually been widespread. Actually, big companies are using these systems even in their smallest projects. But medium-sized and small firms are still using convantional formwork systems or steel formwork systems. In this subject, the best solution is still preceived as the least costing solution. This reasoning is absolutly wrong. In the first parts Df this thesis, applied and theoretical solutions are scrutinized to eliminate this ill reasoning. As a result it is determined that the best solution is not the cheapest solution. This guessination must not be reached by trial and error. On the contrary, firs of all a "METHOD DF CONSTRACTION" must be elaborated. Dorking with the material and equipment most appropriate to this method will bring up the most economical result. After this examination, a general approach has been brought to components used in convantional formwork systems. In this chapter, elements of modular formwork system are mentioned in detail. Hence, advantages and disadvantages are presented in comparison. Then, in order to prevent faulty design, it is pointed out how the formwork system could be calculated and also the effects of concrete acting on the formwork. The physical and mechanical properties that a formwork has to possess are clearly stressed. ?Xll- Towards the end of the thesis, constraction elements are examined one by one so that the most economical solution could be obtained. While doing so, a comparison has been carried out betuieen convantional formuork system and advanced modular formuork systems. In the final part of the thesis, though they are excluded by the scobe of the thesis, the most important informations related to the subject are examined thoroughly in the form of appendices.