Doctor of Philosophy (PhD)
Civil and Environmental Engineering and Construction
First Committee Member
Second Committee Member
Third Committee Member
Fourth Committee Member
Fifth Committee Member
The composite masonry prism test is a common laboratory test to determine the compressive strength of a set of masonry prisms (f’mt) to verify that the composite masonry prism assembly, and more importantly, the constituent materials, are providing adequate strength. While constructing masonry structures, the subcontractors, designers, and inspectors rarely provide continuous supervision or inspection of the construction process. Accordingly, verification of grout mix design, mixed proportions, proper installation of blocks, placement of mortar, dimensions of joints, etc. are more traditionally performed on a periodic basis instead. However, through the use and review of the composite masonry prism test results, designers can be assured that the quality of the masonry walls in terms of sufficient strength and workmanship is achieved. That said, performing the composite masonry prism test requires substantial time, energy, and effort in part because the results of the test are not available until weeks or months after materials have been incorporated into the project. When results produce a potential failure of the assembly materials to meet strength, an in-depth analysis (and usually an argument or two) ensues. Since time and, consequently, cost, are often considered crucial factors for construction projects, development of increasingly economical verification and reliable design validation methods, with reduced likelihood of critical path delay, is necessary to predict f'mt instead of using the time-consuming, contentious, and costly traditional method. This study considers the application of an experimentally calibrated simulation and numerical model with FLAC3D software to predict f'mt and corresponding elastic modulus (Em) of the grouted masonry prisms made of hollow concrete masonry units (CMU). By employing a laboratory-based experimental program, CMU, mortar, and grout are used to build the grouted composite masonry prisms. The quality of the mortar, the lot of the block and the skill of the mason are each held constant for all samples and sample sets. Each composite prism specimen consists of two stacked and mortared blocks, which were then grouted solid. After standard curing, prisms were reduced by saw-cutting, capped with molten sulfur for uniform load distribution, instrumented for data collection and finally tested to failure under uniaxial, unconfined compression. Corresponding grout compressive strength and strain data was collected using similar experimental methodology. The strain hardening/softening Mohr-Coulomb constitutive model was selected for modeling the composite masonry prism in FLAC3D. After the calibration of the simulation in FLAC3D using the experimental data, a numerical model was developed, both of which produced acceptable sensitivity and reliability analysis when f'mt was predicted using only f’g and Em of grout.
University of Nevada, Las Vegas
Bristow, James, "Application of Experimentally Calibrated Numerical Models for Prediction of Composite Masonry Prism Strength" (2022). UNLV Theses, Dissertations, Professional Papers, and Capstones. 4576.
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