Comportamiento de anclajes postinstalados adhesivos en concreto liviano estructural de alta resistencia, sometidos a cargas de tensión y corte

Abstract

Anchors are widely used today to join or support metal structures to concrete. In this union, there is a transfer of forces both in the elements that are joined (concrete and the metallic element) and in the transmitting elements (bolts). Detachment may occur in concrete and shear failure or shear failure may occur. Currently there is a wide variety of anchors and fastening systems, including gas fastening and adhesive technologies.

This investigation will offer a comparison of the values of the resistant load of an anchor using the current regulations respect to the experimental values of the failure load made to the post-installed adhesive anchors.

In order to achieve it, an experimental program was proposed in which the behavior of post-installed anchors in lightweight structural concrete will be analyzed, for this, 27 solid concrete slabs were built, on which 201 threaded bars were anchored, where 162 of these anchors were tested at tension loads, while the remaining 39 were tested at shear.

The results obtained will be compared with the equations that determine the resistance of the anchors through the formulation established in the current normatives, as well as the expected failure mode of the anchors before different geometric configurations.

A program was proposed to determine the tensile and shear capacities of adhesive post-installed anchors with threaded rods in high strength structural lightweight concrete with 1.82 T / m3 specific weight, using AnchorFix300 epoxy provided by Sika, for this purpose 27 slabs were cast (9 for tension-confined tests, 9 for tests not confined to tension and 9 for shear tests) of thicknesses of 10 cm, 15 cm and 20 cm where threaded rods with diameters 3/8 ", 1/2" and 5/8 "anchored at 5cm, 10 cm and 15 cm; the anchors have separated threefold depth of the anchor. The results of the tests were compared with the data calculated using the ACI 318-19 equations and it was concluded that 1) For post-installed anchors with anchor depths greater than 100 mm, the equations of the American regulation ACI 318-19 well predict the fails to use 3/8”, 1/2” and 5/8” threaded rods anchored in lightweight concrete, 2) In unconfined anchors in lightweight concrete for 1/2” and 5/8” threaded rods, the predominant failure is the removal of the concrete, regardless of its anchorage length, however, the values obtained from the tensile force differ from the results of the equations but are not far from these values, 3) The greater the diameter and the greater the depth of the anchorage, the less variation there is in the theoretical results vs. the experimental results.