Abstract
Lap splices are part of virtually every structure made of reinforced concrete. As loads need to be transferred safely along these discontinuities, numerous studies focused on their strength. However, even though they are traditionally placed also in highly loaded regions of elements, which are potentially undergoing plastic deformations, little attention has been paid to their load-deformation behaviour and deformation capacity. This study presents a sound mechanical model based on the established Tension Chord Model to assess the load-deformation behaviour of lap splices. A thorough analysis of the load transfer mechanism reveals that the major part of the load is transferred at the beginning and the end of a lap splice. Therefore, the lap splice acts as a double reinforced tensile element over a considerable length, which drastically reduces its deformation capacity to less than half of the minimum value expected for adjacent parts. This especially needs to be addressed in performance-based design methods, where the deformation demand is compared to the existing deformation capacity. The theoretical results are validated with a recently conducted experimental campaign, exhibiting excellent agreement of model and experimental data. Besides a comprehensive analysis of the influencing parameters, a simplified modelling approach for practical applications and design recommendations for new structures are presented in this publication.
Highlights
This study presents a sound mechanical model based on the established Tension Chord Model to assess the loaddeformation behaviour of lap splices
This especially needs to be addressed in performance-based design methods, where the deformation demand is compared to the existing deformation capacity
Lap splices are an indispensable element of reinforced concrete structures, as it is typically impossible to place the entire reinforcement as continuous bars
Summary
Lap splices are an indispensable element of reinforced concrete structures, as it is typically impossible to place the entire reinforcement as continuous bars. Examples are cantilever retaining walls, where the rein forcement is commonly spliced just above the construction joint between footing and wall, or monolithically connected bridge piers, where lap splices can typically be found at the joints between foundation and pier, and between pier and bridge deck These zones should provide sufficient ductility in both cases, as either the loading depends on the deformation (earth pressure for retaining walls) or as rotation capacity is needed in performance-based design (earthquake loading for bridges). Steel stress at crack for boundary element in Case I and II at cracking load τb0, τb1 Bond stress if reinforcing bar is elastic (0) and plastic (1), respectively Their experiments aimed at investigating the influence of lap splice length, confining reinforcement and loading history on the deformation capacity of lap splices. A simplified modelling approach and design recommendations are deduced
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