2 results for Jensen, J.P.

  • Experimental Investigation of Existing Hollowcore Seating Connection Seismic Behaviour Pre and Post Retrofit Intervention,

    Jensen, J.P.; Bull, D.K.; Pampanin, S. (2007)

    Conference Contributions - Published
    University of Canterbury Library

    In the recent past a number of issues regarding the seismic performance of typical existing hollowcore floor systems have been raised. The most concerning of these is the vulnerability to loss of vertical support of the floor system at the end floor to seating beam connection. This vulnerability arises due to incompatibilities between the floor system and intrinsic deformations of the neighbouring seismic frames. In a previous contribution by the authors (Jensen et al 2006), a conceptual retrofit strategy for existing hollowcore seating connections was proposed. This paper provides an experimental validation of that strategy through quasi-static cyclic testing of alternative seating connection configurations, adopting varying seating lengths. In general, unfavourable performance was exhibited by the existing seating connections, resulting in loss of vertical support of the hollowcore unit. In contrast, when additional seating and selective weakening retrofit approaches were implemented, a higher level of seismic performance leading to collapse prevention was achieved. In conclusion, issues and uncertainties associated with the evaluation of the likely failure mechanism, as well as the definition of an appropriate retrofit intervention are discussed.

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  • Conceptual retrofit strategy for existing hollowcore seating connections

    Jensen, J.P.; Bull, D.K.; Pampanin, S. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    Previous research regarding the seismic performance of existing precast hollowcore floor and ductile lateral frame systems has highlighted several behavioural uncertainties. In particular poor seismic performance due to deformation incompatibilities between the floor diaphragm and frame seismic resisting system have become apparent. Significant rotation and displacement demand on the floor systems due to frame beam elongation, seating beam rotation, and longitudinal perimeter vertical displacement have been identified as the main sources of undesirable damage. As a result the structural integrity at hollowcore seating and perimeter connection interfaces can be jeopardised, potentially leading to a partial or even complete floor collapse. In this paper an overview of expected compatibility issues is given while providing suggestions for conceptual low-invasive retrofit strategies. Particular focus will be given to the experimental investigation on the vulnerability of and suggested retrofit solutions for hollow core-seating connections. The Quasi-static experimental testing procedure focusing on a series of as-built and retrofitted specimens, reproducing a hollowcore-toseating- beam connection with traditionally adopted details will be presented. Both seating rotation due to the imposed lateral drift and beam elongation effects are simulated in the applied testing set-up. Simplified analysis and modelling aspects regarding the connection behaviour are discussed; expected damage and performance criteria associated with the alternative existing or retrofit solution are also tentatively indicated.

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