| 種別 | Paper |
| 主題 | ON PERFORATION OF CONCRETE SLABS PRODUCED BY IMPACTS |
| 副題 | |
| 筆頭著者 | Wojciech RADOMSKI （Kanazawa University） |
| 連名者1 | Hiroshi MASUYA（Kanazawa University） |
| 連名者2 | |
| 連名者3 | |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 13 |
| 号 | 2 |
| 先頭ページ | 1045 |
| 末尾ページ | 1050 |
| 年度 | 1991 |
| 要旨 | INTRODUCTION It is known that many of various concrete structures are subjected to impact or impulsive loads, particularly, in most cases these types of loads may occur accidentally. However, the investigations of dynamic behaviours of concrete structural members are rather limited compared to research on their static behaviours, thereby the knowledge on the dynamic problems concerning these members is so far incomplete. The phenomena produced by the impact loads in the structural concrete elements are very complex. They may be in general characterized as wave and local effects. In this paper the study is focused on the local effects. The most important local impact effects produced by the missiles in concrete structural elements are the following: penetration, perforation, scabbing and spalling. Penetration is the displacement of missile into the element. It is measured by the depth of the crater formed at the zone of impact. Perforation means ”full penetration”. The missile passes through the element with or without exit velocity. Scabbing is the peeling off from the back face of the element opposite to the impact face. Spalling is the ejection of materia1 elements from the front face of the element (i.e. the face on which the missile hits). The paper deals with some problems concerning the perforation of the concrete slabs produced by impact loads. It requires to define so called perforation thickness of a structural element. Perforation thickness is the maximum thickness of a structural element which a missile with a given impact velocity will completely penetrate. Theoretically, the exit velocity of the missile is equal to zero. For concrete, the perforation thickness is considerably greater than the penetration depth due to scabbing of concrete from the back face of the element. Determination of the perforation thickness for the concrete structural elements is very important for the safety design of many structures in which the impact loads may occur. The perforation thickness of the concrete structural elements has been determined experimentally so far by various authors and several empirical formulae for prediction of this thickness have been formulated, as discussed below. CONCLUSION The research problems concerning the perforation of concrete slabs under the impact loads are not well developed, especially in the theory. It is due to the very complex phenomena produced by impacts in these members and due to heterogeneity of the material, particularly in the case of SFRC elements. On the base of the results presented above, the following conclusions can be drawn. 1) The empirical formulae for the prediction of perforation thickness of the concrete and reinforced concrete slabs have been verified, during the last decade and may be useful for applications. 2) In spite of SFRC is a very appropriate material for applications in the various structures subjected to the impact loads, the lack of the formulae for the prediction of perforation thickness of SFRC slabs can be noticed. 3) The author’s original formula for the prediction of perforation thickness of SFRC slabs seems to be very promising but requires further experimental verification. 4) As not expected, the steel fibres seem to be more effective than meshes with respect to the perforation toughness of the slabs. However, this observation requires further investigation. |
| PDFファイル名 | 013-01-2178.pdf |