Ultimate Shear Force of an Any Anchor Group Post-Installed into Concrete

Abstract

This paper is devoted to the fastening system that consists of a number of anchors of approximately equal effective embedment depth, called “anchor group”, embedded into hardened concrete, used to transmit forces transverse to the anchors from an attachment to the concrete. The anchor group is far from the edges and is subjected to no more than marginal axial forces. Being post-installed, rather than cast-in, the embedded end of each anchor is not hooked, and no nuts, washers, or plates are attached to the embedded shaft. The paper focuses on the transverse forces that can be transmitted across an anchor group from an attachment to the concrete. The paper provides an analytical model for predicting the maximum (ultimate) shear force that an anchor group can bear, thus called “shear strength”. The model hence allows the structural designer to predict the shear strength of an anchor group post-installed into concrete. The model is based on five mechanical assumptions, which were established from a wide-ranging numerical analysis. Model predictions turned out to be, on average, 20% lower than the results of experiments performed on cast-in anchor groups borrowed from literature. The comparison verifies model accuracy, considering that the tested anchor groups benefitted from the extra-strength furnished by nuts and washers attached to the embedded shaft. Model predictions were also compared to code provisions; the former resulted to be up to one third of the latter. The paper presents and comments those comparisons, as well as all mathematical development. Applications of the model to wide-ranging case studies is presented and discussed as well.

Overall and Local Wind Loads on Post-Installed Elevator Shaft of Existing Buildings

“…Marinkovic et al [11] investigated the degree of damage in buildings after earthquakes and found that masonry infill walls, which were used in some elevator shaft areas instead of reinforced concrete shear walls, led to the insufficient seismic performance of the structures. Some studies on post-installed concrete anchors [12] and the seismic analysis of existing reinforced buildings [13] provide a reference for the mechanical performance analysis of the post-installed elevator shafts of existing buildings. Zhou et al [14] studied the seismic performance of a light wood structure and found that the use of a masonry elevator shaft in a light wood structure can significantly reduce the displacement at the top of the structure and improve seismic performance.…”