Structural Concrete, Vol. 3, no. 2, June 2002

Written on 19 August 2011.

Friction between concrete and slipform panel during slipforming

Kjell T. Fosså, Norwegian University of Science and Technology, Trondheim, Norway
Magne Maage, Selmer Skanska AS, Oslo, Norway

Tests are carried out in a vertical slipform rig in order to identify the main parameters affecting the lifting stress (friction) during lifting of the slipform panel. The results show that there is an almost linear correlation between the net lifting stress and the effective pressure. This means that the net lifting stress can be calculated based on the effective pressure by using the friction law. The lifting stress is affected by both the particle shape of the aggregates, roughness of the slipform panel and the workability in the early phase. The results also show that lower air content and a finer pore system (finer particle size distribution and higher particle concentration) in the concrete will result in a higher maximum lifting stress (friction). Also a lower lifting height or lower frequency will increase the lifting stress. It is assumed that higher lifting stress will increase the risk for surface damages during lifting of the slipform.

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

Written on 19 August 2011.

"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

Written on 19 August 2011.

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

Written on 19 August 2011.

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. 3, no. 1, March 2002

Written on 19 August 2011.

Editorial: premieres Jean-Phillipe Fuzier, Editor-in-Chief

No abstract.

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

Written on 19 August 2011.

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.