A two-stage modelling approach for the analysis of the stress distribution in anchorage zones of pre-tensioned, concrete elements

Abstract

An innovative strategy for the analysis and design of the anchorage zones of pre-tensioned, concrete girders is presented. In this approach, the bond behaviour of the prestress strands is first characterised in a small-sized beam model. A new relation between the slip and radial strain of the prestress strand is introduced and used together with the radial stress-strain relation resulting from a thick-walled cylinder model to establish the bond-slip behaviour at the steel-concrete interface. This bond behaviour is implemented in a numerical model and validated via a comparison of the computed transfer length with the results of two experimental campaigns. Next, the bond-slip relation of the small-scale model is applied in full-scale models of pre-tensioned, concrete girders to derive the stress distribution in the anchorage zones. The non-linear material behaviour of concrete is taken into account and a comparison of the numerical results with full-scale experimental data is made. An acceptable agreement is achieved between the experimental results and the numerical calculations regarding the bond behaviour and transfer lengths as well as the crack patterns and the stress values in the reinforcement bars. This efficient modelling approach allows for a full analysis of the anchorage zone based solely on the geometrical and material properties known at the design stage.

Experimental and numerical studies on the control of horizontal cracking at the ends of hollow-type pretensioned girders

“…Several earlier studies [3] showed that the main cause of horizontal end cracking is the transferring of prestressing forces from tendons to the surrounding concrete that results in stress concentration at the end-zone of the element and the control of these stresses is quite a challengeable task [3,5]. The transfer of prestressing forces from strands to concrete at the end-zone of PC-girders result in a complex stress state that can lead to concrete cracking [14].…”

“…Prestressed members are highly recommended in view of cost-effective casting in plants under higher quality control, and their durability as low maintenance structures [1]. Although, it is well-known that prestressed concrete functions well for large spans, field observations and experimental studies showed that, some types of these prestress elements exhibit horizontal end cracking due to large prestressing forces [3]. The cracks develop during the girder fabrication [4] and appear right after the prestress release process and they become noticeable at the time of lifting the girders from the prestressing bed [5].…”

Enhancement of local concrete compression performance by incorporating ultra-high performance concrete (UHPC) tube

“…, 1983). In fact, local compression problems of concrete sometimes directly determine the structural safety and overall reliability, affecting the normal use and service life of buildings (Li and Yu, 2015; Steensels et al. , 2017).…”

“…Local concentrated pressure will form vertical compression and lateral expansion in concrete, resulting in extremely complex local stress and deformation (Hawkins, 1970;Wang et al, 2022;Liu et al, 1983). In fact, local compression problems of concrete sometimes directly determine the structural safety and overall reliability, affecting the normal use and service life of buildings (Li and Yu, 2015;Steensels et al, 2017). Therefore, strengthening local compression zone has become an important research direction and attracted a considerable number of academics to study.…”

Design of Anchorage Zones of Pretensioned Concrete Girders: A Comparison of Nonlinear 3D FEM Results with Measurements on a Full Scale Beam

“…This method of modelling affects the stresses and the transmission lengths such that the model becomes irrelevant. Steensels et al [20] propose a new method of designing anchorage zones. Essentially, the strands are modelled in greater detail in terms of interaction between these elements and the concrete, with a focus on the pitch and lack-of-fit effects of the strands.…”