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Structural Concrete, Vol. 3, no. 1, March 2002

"Inspectionability" of bridges

Jorge de Brito, Technical University of Lisbon, Portugal
Sonia Santos, BRISA, Portugal
Fernando A. Branco, Technical University of Lisbon, Portugal

Guidelines that relate to the design of concrete road and railway bridges are presented in this paper in order to guarantee the durability of bridges through easier inspection procedures -- the concept of inspectionability. The main characteristics that must be conferred on these structures, in order to facilitate access to all of their elements which are most prone to inspection/maintenance, are defined. In this context, access to the bridge elements and the equipment installed (bearings and joints) is paramount. The inspection auxiliary means are classified by traditional methods, by specific design detailing and by specific inspection equipment. Each of these groups is described and examples of their use are presented.

Structural Concrete, Vol. 3, no. 1, March 2002

Comparison of structural characteristics for different types of cable-supported prestressed concrete bridges

H. Otsuka, Graduate School of Civil Engineering, Kyushu University
T. Wakasa, New Structural Engineering Ltd
J. Ogata, Ingerosec Corporation
W. Yabuki, Graduate School of Civil Engineering, Kyushu University
D. Takemura, Graduate School of Civil Engineering, Kyushu University

Following recent developments in prestressed concrete bridges, this paper examines extradosed and cable-stayed structures, particularly with regard to the evaluation of seismic performance and the economical considerations in a seismic region, and provides designers with guidance for choosing the most appropriate structure.

Structural Concrete, Vol. 3, no. 1, March 2002

The added value and profit of concrete research and development

J. Moksnes, Honorary president fib, Norway
M. Maage, Selmer Skanska, Norway

This paper presents the costs and the associated added value and profit for a selection of concrete research and development (R&D) programmes in Norway during 1980-2000. The estimated figures give a ratio of added value, or return on investments, to costs equal to 19. This ratio is remarkably high and demonstrates that industry based R&D can be a profitable investment. The major beneficiaries of the added value are the clients of the industry and society, through reduced costs and better products and solutions.

Structural Concrete, Vol. 4, no. 4, December 2003

Development of material to be used for bearing pad in precast concrete connections

Mounir Khalil El Debs, University of Sao Paulo at Sao Carlos, Brazil
Aline da Silva Ramos Barboza, Federal University of Alagoas, Brazil
Anamaria Malachini Miotto, Tuiuti University of Parana, Brazil

Bearing pads are used in precast concrete connections to provide a more uniform distribution of contact stresses over the bearing areas and to allow relative movements between precast concrete elements, in order to prevent cracking at the connection area. This paper presents the study of an alternative material made with styrene-butadiene latex modified on Portland cement mortar, polymeric fibres, and, eventually, lightweight aggregate (vermiculite). The developed material showed a good compression strength and low elasticity modulus. These characteristics make it suitable for use as bearing pads in precast concrete connections, such as beam-to-column connections or wall-to-wall connections. The paper shows the main characteristics of this material and the application and tests on: (a) beam-to-column connections and (b) samples that reproduce a wall-to-wall connection.

Structural Concrete, Vol. 4, no. 4, December 2003

Size-effect experiments on concrete in compression

Stefan L. Burtscher, University of Technology, Vienna
Johann Kollegger, University of Technology, Vienna

It is well known from literature that heterogeneous granular materials exhibit a size effect under tensile loading. Thus, the strength determined in experiments is not a material property. Some experiments have been performed regarding the size effect in tension whereas very few experiments have been performed in compression. However, compressive loading of concrete is more important because concrete is applied in structural systems to carry load in compression and not in tension. Furthermore, a compressive failure in a load-carrying member is more brittle, and in most cases more dangerous, than a tensile failure. Experimental investigations on the size effect are therefore needed. Experiments from literature on column-like specimens under compressive loading were performed up to a size range of 1:4. The size range of a series of geometrically equal specimens is given by the amplification factor of a characteristic dimension from the smallest to the largest specimen size. Obviously large size ranges are advantageous for experimental studies on size effect. The largest size range (1:16) of experiments on concrete under compressive loading carried out so far will be presented in this paper. This series was performed in one of the largest testing facilities available. A size effect on nominal strength was detected. The results are compared with the two most common size-effect laws.

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