Behavior and design of fastenings with headed anchors at the edge under tension and shear load

ABSTRACT: In the present paper the theoretical aspects and the application of the non-linear finite element program MASA for analysis of anchorages placed at an edge of a concrete block are discussed. After an introduction the structure of the finite element (FE) code is briefly described. The results of the simulations are shown and compared with experimental data. They confirm that the FE code is able to simulate realistically the behavior of anchorages. Subsequently a parametric study is caITied out and the results are discussed

Application of Post-Installed Anchors for Seismic Retrofit of RC Beam-Column Joints: Design Method

Paper 106Many reinforced concrete (RC) structures, built in seismic-prone countries before the introduction of the modern seismic oriented codes and usually designed for gravity loads only, necessitate an upgrade in terms of strength and ductility against lateral loading. In this paper the possibility of using post-installed anchors for seismic retrofit solutions is investigated. Post-installed anchors are usually fast and easy to install and they represent a valuable low-invasive solution to transfer high loads with quite low costs. The retrofit of RC beam-column connections with a diagonal haunch element fastened to the existing structural element using post-installed anchors is proposed. The design method based on experimental and analytical investigations is presented. Particular focus is given to the requirements in terms of load displacement characteristics, i.e. stiffness on the post-installed anchors

Development of seismic retrofit technique of RC Frame using fully fastened haunch elements: Static to dynamic testing

In this paper an innovative method for seismic retrofitting of poorly detailed reinforced concrete beam-column joints and structures using haunch type elements connected with post-installed anchors is discussed. During an earthquake, the global behaviour of the structure significantly depends on behaviour of the beam-column connections, but no special emphasis was given to that till the eighty’s. Therefore, it is recognized that the joints of old and non-seismically detailed structures are more vulnerable and behave poorly under the earthquakes compared to the joints of new and seismically detailed structures. Thus, often the joints of such old structures require retrofitting in order to deliver better response during earthquakes. A relatively new technique for retrofitting the beam-column connections using steel diagonal elements to prevent a brittle failure of the joint core was investigated by mean of experiments on beam-column joints under quasi-cyclic loads and numerical simulations. Highly encouraging results were obtained that proved the efficacy of the system in improving the seismic behaviour of poorly detailed joints. In order to prove their usefulness at the structural level under dynamic loads, shake table tests on 2-D frames are planned. This paper presents the main results of the quasi-static cyclic tests carried out for seismic retrofitting of RC beam-column joints using haunch elements and the further research planned at the structural level. The strengths, limitations and the open issues of the proposed method are discussed in brief

Three-dimensional Modelling of Poorly Detailed RC Frame Joints

This paper presents preliminary work on three-dimensional numerical modelling of seismic strengthening measures for poorly detailed reinforced concrete frames, primarily designed for gravity loads, as was typical in seismic-prone countries before the introduction of more advanced seismic codes in the early 1970s. These buildings are at risk due to inadequate structural detailing, deficiencies in reinforcement anchorage and the absence of measures to prevent brittle failure modes. Representative beam-column joints tested experimentally at the University of Pavia are analyzed using a continuum finite element program specially developed for detailed modelling of fracture in quasi-brittle materials. The microplane material model with relaxed kinematic constraint is used for the concrete. In the first stage of this work, which is presented in this paper, the proper modelling of the behaviour of smooth reinforcement with hooked ends, as well as the accurate representation of brittle shear failure modes in joints, are of particular interest. In the second stage of the project, strengthening measures that incorporate post-installed anchors for connection to the existing structure will be assessed