Laboratory and In Situ Calibrations of New Flat Jack Method for Assessing Masonry Shear Characteristics

Abstract

The test methods currently used to assess the shear characteristics of masonry structures does not fit with the execution of in situ tests on existing buildings (especially heritage buildings) because they are usually strongly destructive. Furthermore the method of preparation of the sample causes damages that can reduce the mechanical characteristics of the masonry: for these reasons there are significant doubts about the effective representativeness of the results obtained from these methods. A new in situ testing technique (named FJ-SCT Method) has been developed by the authors based on the use of flat jacks to apply the horizontal load: this allows a great reduction in the impact of the test and therefore it makes the testing technique applicable on existing buildings. A calibration campaign was performed both in laboratory using a special testing frame and in situ (on Italian buildings seriously damaged by the 2012 Emilia earthquake) to evaluate the operability of the defined procedures. This campaign proved the technique to be reliable, the procedures to be efficient and effective and the results to be repeatable. The damages produced to the masonry by this test technique are limited, justified by the level of the results obtained and they can be easily repaired. The analysis of the calibration results, the proposal for the processing of shear strength data and the comparison with reference shear values taken from the Italian codes will be hereafter discussed.