Keywords: compressive-stress, virtual experiments, knowledge-network.

A Virtual Knowledge Network (VKN) as a platform for providing knowledge from and to the building and construction industry is an initiative that is launched within the Faculty of Civil Engineering of Delft University of Technology in The Netherlands. The main objective of the network is to intensify the exchange of knowledge between universities and industry. It also comprises the development of a Virtual Testing Lab (VTL) for Structural Engineers. As a pilot, a Virtual Compressive Strength (VCS) test for building material will be developed. The compressive strength is a very commonly used parameter in the design and engineering stages of construction projects and is mostly acquired from codes and standards. In case of unique or new building materials, laboratory experiments are often necessary. The introduction of a VCS testing facility, as a quickly accessible alternative for laboratory experiments will be presented in the paper.

Modern ways of communication infrastructure provide the opportunity to share knowledge and information via the World Wide Web, and to make advanced simulation models web-accessible. It opens new ways for research institutes and companies to intensify the collaboration where both sides benefit from the web-based services. Exchanging knowledge or (design) information in any stage of a construction project is associating with a unique set of services. This might comprise the exchange of documents, - like reports, films, software, etc. - or other multimedia products. One of these products could be a so-called Virtual Compressive Strength test (VCS) which is, in fact, a digital version of the experimental compressive strength test, which is very common in the world of civil engineering. The VCS consists of a simulation model for determining the compressive strength and a database filled with already executed test results. The VCS is a virtual testing instrument that is considered to be accessible via an open communication platform. More virtual testing instruments are planned for later times making this development to a so-called Virtual Testing Laboratory (VTL). Servicing the data traffic from the client towards these virtual web-based instruments is requiring a virtual platform too. This request has lead to the establishment of the so-called "Virtual Knowledge Network" (VKN).

Implementation of the VCS into the VKN environment is therefore considered as the first step into the development of a full operating service facility for the Building and Construction Industry. It is expected that the pilot version of the VCS test will provide results that look like the examples given in the Figure below. This figure illuminates the results of two concrete specimens which were submitted to a compressive force. Both the specimens are loaded until failure and both show a different failure path throughout the inner structure of the material. The two upper specimens, a) are the results of two 'real' experiments of concrete loaded by a compressive force. For the lower specimens, b) the numerical results are presented as calculated with the simulation models HYMOSTRUC [1] and Lattice [2]. The agreement between the real experiments and the numerical simulation is quite satisfactory which implicitly indicates the potential of the models.

1

Breugel, K. van, (1991), "Simulation of Hydration and Formation of Structure in Hardening Cement-Based Materials", PhD thesis, Delft University of Technology, Delft, The Netherlands.

2

Schlangen, E., (1993), "Experimental and Numerical Analysis of Fracture Processes in Concrete", PhD-thesis, TU-Delft, The Netherlands.

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