Monotonic and cyclic testing of clay brick and lime mortar masonry in compression

Abstract

This research presents an experimental programme on the mechanical characterization of masonry under monotonic and cyclic uniaxial compression. Two different types of standard specimens, running bond walls and stack bond prisms, were built using handmade clay bricks and hydraulic lime mortar. The experimental results are compared and discussed in terms of strength, stiffness and deformability. It was observed that the two specimen types provided very similar results on both strength and stiffness. Cyclic loading tests carried out on a set of samples provided new experimental evidence on the stiffness degradation, loss of load carrying capacity for increasing irreversible compressive strains and energy dissipation. The paper presents eventually a thorough discussion about the comparison between the obtained experimental results with available predictive models for strength, stiffness and fracture energy of masonry under monotonic and cyclic compression loading.

Macro scale material characterisation in support of meso scale modelling of masonry under uniaxial in-plane loading

“…The compressive strength of the wallettes in the present case study appears to be atypical for lime/cement mortar masonry. The expected compressive strength normally lies between that of the units and the mortar in uniaxial compression (Drougkas et al, 2019b;Segura et al, 2018). The reason behind this low strength of the wallettes is not entirely clear, although it has been previously noted in experimental campaigns with low to moderate strength bricks coupled with moderate to high strength mortars (Binda et al, 1988;Gumaste et al, 2007;Kaushik et al, 2007;Sarangapani et al, 2005).…”

“…As such the second approach is far more appealing and straightforward in execution. Substantial complexity arises from size effects influencing the mechanical testing, the compressive strength in particular (Drougkas et al, 2016;Segura et al, 2018). This can affect both the units, from which it is difficult to extract compression samples with proper dimension ratios, and mortars, which may have different properties in stand-alone samples and in the joint.…”

Simulation of the in-plane structural behavior of unreinforced masonry walls and buildings using DEM

“…Each independent model is subjected to a monotonically increasing lateral force at the points matching with the locations of the horizontal loads applied during the testing. it is difficult to estimate the stiffness of the masonry based on its compression strength due to the high variability in the experimental data, which can be expressed considering lower and upper bounds of 200 ′ and 350 ′ for lime mortarclay brick masonry, as discussed in [54,55]. In this study, Young's modulus of the masonry is approximately estimated based on the mean compression strength of masonry prism as ≈ 225 ′ .…”

Experimental and Analytical Study of Masonry Subjected to Uniaxial Cyclic Compression

“…The formulation to simulate the masonry cyclic behaviour was derived from the concrete cyclic analytical model proposed by the same researchers [ 24 ]. The envelop curve of the model is represented by the compression damage using a parameter which characterises the material damage in each cycle.…”

“…The research studies dedicated to experimentally or analytically examine the masonry cyclic compression characteristics are rarely compared to the studies dedicated to investigate the monotonic compression characteristics. Only few studies exist across different masonry types [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. It is commonly understood that the masonry cyclic compressive strength is moderately less than the corresponding monotonic strength, and the axial deformation capacity derived from cyclic tests is relatively higher than the equivalent monotonically tested masonry.…”