Hydropneumbox: yesterday, today, tomorrow

Викладено історію розвитку гідроприводу, як найважливішого засобу механізації і автоматизації виробничих процесів. Відзначено внесок вітчизняних вчених у становлення теорії гідравлічного і пневматичного привод у як науки. Підкреслено провідну роль України в розробці та виробництві елементів і систем гідропневмоприводів. Показані нові тенденції і принципи функціонування мехатронних гідропневмосистем, які забезпечили широкомасштабне впровадження їх в гнучкі автоматизовані виробництва.The prerequisites and history of the emergence and development of industrial hydraulic drive as the most important means of mechanization and automation of production processes is outlined. The contribution of domestic scientists in the process of establishing the theory of hydraulic and pneumatic actuator as science is noted. The leading role of Ukraine both in the past and in the post-Soviet space in the development and production of elements and systems of hydro-pneumatic actuators is underlined, the main enterprise-developers and manufacturers of this equipment are listed. Much attention is paid to the modern stage of development of this industry as an integral part of mechatronic systems. New trends and principles of the functioning of mechatronic hydropneumatic systems are shown, which ensured their large-scale introduction into flexible automated production. Examples of modern elements of mechatronic hydropneumatic systems and schemes of their use in industrial processes are given

Overview of the service life and maintenance problem probabilistic design

The service life of a building or structure is determined by the design and construction in combination with the ageing and the maintenance during use. To get grip on this combination it has advantage to present the functioning of the building or the structure on a performance level. As ageing will influence the performance, the combined effect of performance and ageing should be considered. By requiring a minimum limit for the performance the end of the service life or the moment when maintenance is necessary can be defined

The DuraCrete approach

In the past years much efforts have been spent on a new design approach for the durability of existing and new concrete structures. The results of these efforts can be seen in recent work of several international scientific committees of Rilem, CEB, CIB and FIER These have finally resulted in the Brite/Euram project DuraCrete where a design manual has been developed for a service life design of concrete structures. The new design method is based on performances (both serviceability and ultimate limit states), reliability and a distinct design service life. This is in contrast with the conventional design approach, that is based on deem-to-satisfy rules, mainly to prevent degradation of the concrete

Overview of the development of service life design for concrete structures

After the introduction of reinforced concrete it was believed that the material was extremely durable. Soon it was found that reinforced concrete could have serious durability problems and that special care should be taken to avoid them. Durability became a design issue

Design of concrete structures for durability. Example: Chloride penetration in the lining of a bored tunnel

The present design method for durability of concrete is based on a set of rules that give no objective in-sight in the service life to expect from the concrete structure. An objective comparison between different durability measures is therefor not possible. Especially if the lack of durability can lead to victims and high economic losses this is not acceptable. But even lack of seráceability and premature repair is inac-ceptable if methods are available to avoid this

Duracrete: Service life design for concrete structures

In the past decades much effort has been put into the improvement of the durability of concrete structures. This has resulted in a reasonable understanding of the main degradation processes or in experience with measures to prevent degradation. The results of this effort can be found in the present concrete codes and in manuals on durability design. The design rules are in general presented as deem-to-satisfy mies. If the mies are followed it may be assumed that the structure is durable. The present approach does not give direct insight in the service life, the necessary maintenance or the probability of premature failure. Further it is clear that lack of durability can have an influence on the structural behaviour. The direct relationship between durability and safety and serviceability of concrete structures has however not been made in the concrete codes. In the Brite-EuRam project `DuraCrete' the durability design has been developed into a service life design based on performances and on reliability for reinforced concrete structures. This offers the possibility to present the design on the same level as the structural design that has also been based on performances and reliability. The structural and service life design can even be integrated. The `DuraCrete' approach offers good opportunities for the service life design of other structural materials and building material

Durability and service life design of concrete structures. Experiences and the way to prove in The Netherlands

After the introduction of reinforced concrete it was believed that the material was extremely durable. Soon it was found however, that reinforced concrete could have serious durability problems and that special care should be taken to avoid them. Durability became an issue

Performance based durability design of a bored tunnel with concrete lining

Design for durability is gradually changing from a deem-to-satisfy approach to a performance based approach. The conventional building codes give in principle only construction rules. If these rules are fulfilled, it is assumed that the structure will have an adequate durability. But specifications concerning dura-bility in codes are still on an empirical base. The performances, the service life, and the amount of mainte-nance are however not explicitly specified