192 CONCRETE FRAME BRIDGE IMPACTED BY MINING DEFORMATIONS P. Bętkowski, S. Pradelok, M. Salamak Silesian University of Technology, Faculty of Civil Engineering, Gliwice, POLAND. e-mail: piotr.betkowski@polsl.pl, stefan.pradelok@polsl.pl, marek.salamak@polsl.pl SUMMARY Computational analysis of influences of mining exploitation on a certain frame bridge are described in this paper. Mining deformations of the ground cause internal additional forces in structures. Due to the frame structure of the object, it is necessary to pay special attention to interaction of the structure and ground, i.e. the existence of internal additional forces in the structure. Distribution of inner strengths in the structure is determined in these elements of the object which are important for safety. The method of changing the static scheme as a technical solution, which adapted the construction to take additional loads from mining deformations of the area, is discussed. The example of computational analysis is given. A system of monitoring will make it possible to control the risk of the structure's failure. Keywords: mining, monitoring, maintenance and revitalization of concrete bridges. 1. INTRODUCTION The economy of Poland firmly relies on hard bituminous coal. Hard bituminous coal is exploited both for energetic purposes and for households. In the area of Upper Silesia there are many concrete bridges with a static scheme of frame [1], [2]. Such bridge objects were often built in 1950s and 1960s, during the intensive economic development of the region connected with coal mining. Owing to the progressive change in the location of mining areas, part of these objects, not designed for the impact of mining, are located in regions subjected to influences of mining deformations. These bridge objects, although over 50 years old, are often in a good technical condition. Significant deformations of the area are a difficult problem for crisp concrete structures. The way of protecting a frame bridge object from mining influences by creating a flexible joint in the place on the connection of beams and pillars is described in the paper. 2. PROTECTION A CONSTRUCTION FROM MINING INFLUENCES The admissible level of internal forces in construction is calculated by comparing internal forces for which this object was designed [3] and the forces that appear in the structure as a result of mining influences and actual loads [4]. This operation allows estimating the distribution and value of internal forces from all loads which were analyzed in the past, in the times when the object was designed, and compare these forces with results obtained for actual loads, mining influences, the change static scheme. Such analysis is more reliable than the calculation of stress with many uncertain and often doubtful data (for example lack of acquired knowledge to identify the kind and distribution of reinforced bars). This paper describes the method of protecting a bridge frame object by changing the static scheme - creating flexible joint in the place on beams' and pillars' cutting close to girders (changing of the static scheme follows) and reinforcing pillars with steel angle bar put in angles of poles, so that construction (girders, slab) will be working as continuous beam. The way of creating conditions for making flexible joints in the place where pillars and girders connect (stiffening the head of the pillars with a frame of steel angle and cutting the jacket of rebar pillars right under the girders: width and depth cutting a notch for 40 mm and filling the crack with silicone) is given.