Development of representative volumetric element method for analysis of interlocking brick system

This thesis examines the mechanical properties of interlocking bricks via experimental and numerical methods. It investigates compressive and shear properties (Part 1), effects of brick imperfections (Part 2), and develops a representative volumetric element method for analyzing interlocking brick systems (Part 3). Insights into the performance of interlocking brick structures, especially under varied loads and conditions, offer valuable guidelines for practical applications

Structural-semantics Guided Program Simplification for Understanding Neural Code Intelligence Models

peer reviewe

Genetic Evidence for the Association between the Early Growth Response 3 (EGR3) Gene and Schizophrenia

Recently, two genome scan meta-analysis studies have found strong evidence for the association of loci on chromosome 8p with schizophrenia. The early growth response 3 (EGR3) gene located in chromosome 8p21.3 was also found to be involved in the etiology of schizophrenia. However, subsequent studies failed to replicate this finding. To investigate the genetic role of EGR3 in Chinese patients, we genotyped four SNPs (average interval ∼2.3 kb) in the chromosome region of EGR3 in 470 Chinese schizophrenia patients and 480 healthy control subjects. The SNP rs35201266 (located in intron 1 of EGR3) showed significant differences between cases and controls in both genotype frequency distribution (P = 0.016) and allele frequency distribution (P = 0.009). Analysis of the haplotype rs35201266-rs3750192 provided significant evidence for association with schizophrenia (P = 0.0012); a significant difference was found for the common haplotype AG (P = 0.0005). Furthermore, significant associations were also found in several other two-, and three-SNP tests of haplotype analyses. The meta-analysis revealed a statistically significant association between rs35201266 and schizophrenia (P = 0.0001). In summary, our study supports the association of EGR3 with schizophrenia in our Han Chinese sample, and further functional exploration of the EGR3 gene will contribute to the molecular basis for the complex network underlying schizophrenia pathogenesis

Spectral element method for dynamic response of multilayered half medium subjected to harmonic moving load

In this paper, the spectral element method (SEM) is presented to analyze the dynamic response of a multilayered half medium subjected to a harmonic moving load. In SEM, the spectral stiffness matrix of one-node and two-node elements in the wave-number domain can be derived based on the Fourier transformation and principle of wave superposition. Then, the spectral global matrix of the model can be obtained by assembling the nodded stiffness matrices of all layers. The corresponding solution in the wave-number and frequency domain is further recovered by the Fourier series and fast Fourier transform (FFT) algorithm. At last, several numerical examples were given to validate the accuracy of the proposed method and illustrate the influence of load speed and frequency, as well as the interlayer condition of pavement, on the simulation results

Experimental and numerical studies of the shear resistance capacities of interlocking blocks

Interlocking bricks could improve construction efficiency, reduce labour cost, and provide better mechanical performance for masonry structures. Nevertheless, the shear properties of mortar-less interlocking bricks have not been systematically investigated which may impede their wide applications. In this study, the shear performance of a new type of interlocking brick is investigated in detail. Laboratory shear test is firstly conducted to study the damage and shear capacity of mortar-less (dry-stacked) interlocking bricks. Numerical model is then generated with consideration of contact imperfection and validated with test results. Intensive parametric studies are conducted to quantify the influences of material strength, axial pre-compression force, friction coefficients, and contact imperfection at brick interfaces on the shear response of interlocking prisms. The accuracy of existing methods for predicting the shear capacities of shear key by design standard and empirical formula are evaluated. Based on the numerical and laboratory results, an empirical design formula is proposed to predict the shear capacity of the interlocking brick

3D Spectral Element Solution of Multilayered Half-Space Medium with Harmonic Moving Load: Effect of Layer, Interlayer, and Loading Properties on Dynamic Response of Medium

The road pavement is a typical three-dimensional (3D) multilayered half-space medium, which consists of the surface courses, base courses, and soil subgrade/foundation. It is critical to understand the dynamic response of the road pavement under vehicular loads for improving structural design efficiency. The actual vehicular loads can be simulated as a harmonic moving load. In general, there are several methods to analyze the dynamic response of the multilayered half-space medium under harmonic moving loads, such as the boundary element method (BEM) and the finite-element method (FEM). However, the previously mentioned methods might face some unavoidable problems, for example, the numerical overflow, when the thickness of the medium is thicker, which causes the wrong result or long computing time. Therefore, the objective of this study is to develop a precise solution to solve the dynamic response of the 3D multilayered half-space medium under a harmonic moving load. In this study, a new type of 3D spectral element method (SEM) was developed and applied to the dynamic response analysis. Details of the mathematical derivation, implementation, and verification were demonstrated in the current paper. Subsequent numerical results, based on a layered road pavement structure constructed on a soil foundation, indicated that both the load speed and the frequency, the damping ratio of the structural materials, and the interlayer condition significantly impacted on the dynamic response of the structure under vehicular loads

Experimental and numerical investigation on the compressive properties of interlocking blocks

Masonry construction with interlocking bricks could effectively reduce construction time, minimize labour cost and improve construction quality. Existing interlocking bricks are mostly designed to provide easy alignment only, therefore the effect of interlocking mechanism on the mechanical performance of the interlocking block is not well investigated. This paper presents a laboratory and numerical study on the mechanical properties of a new type of interlocking brick featured with large shear keys for better mechanical performance. The theoretical compressive strength of a unit brick prism is derived using fracture mechanics theory, which is validated with laboratory compression test. Then, further tests on prisms with multiple interlocking bricks show the number of bricks strongly influences the performance of prism compressive strength. Detailed 3D numerical models of interlocking brick prisms are generated using ABAQUS. The numerical modelling results are compared with experimental test results. The damage and failure modes of the interlocking blocks are numerically and experimentally studied. Localized stress concentration at block interlocking surfaces is investigated. Parametric study is then carried out to quantify the influences of different design parameters including the number of blocks, brick surface roughness amplitude due to brick manufacturing tolerance and surface unevenness, and material strength. A modified formula based on the analytical solution is derived by fitting the numerical simulation and experimental results to predict the compressive capacity of interlocking brick prisms. A semi-empirical prediction method is also derived to predict the axial stiffness of the interlocking brick prism for use in design analysis of masonry structures made of mortar-less interlocking bricks

Analytical solution for the effect of anisotropic layers/interlayers on an elastic multi-layered medium subjected to moving load

The intent of this study was to develop an analytical solution for the mechanical behaviors associated with a three-dimensional anisotropic multi-layered medium when it is subjected to a moving load. However, for simplicity, a planar model (two-dimensional model) was used as a substitution. The anisotropic property of the structure layers was approximated as transverse isotropy. Both the interlayer conditions (bonded and sliding) between the adjacent layers and load properties including load velocity and frequency were considered in the mathematical derivation of the analytical solution. Following the mathematical derivation, implementation and verification, the analytical solutions obtained were able to successfully evaluate the mechanical behaviors of an anisotropic elastic multi-layered medium subjected to a moving load. Subsequent numerical results revealed that both the anisotropic properties and the interlayer conditions have a significant impact upon the mechanical behaviors of an elastic multi-layered medium. In contrast, due to the conditions/assumptions considered in the computations, the load velocity and frequency were found to have a negligible impact on the mechanical behavior

Assessing the mechanical responses for anisotropic multi-layered medium under harmonic moving load by Spectral Element Method (SEM)

© 2018 Elsevier Inc. The article is concerned with the mechanical responses of anisotropic multi-layered medium under harmonic moving load. An analytical solution for two-dimensional anisotropic multi-layered medium subjected to harmonic moving load is devoted via Spectral Element Method (SEM), while the anisotropic property is approximated as transverse isotropy. Starting with the constitutive equations of transversely isotropic body and the governing equations of motion based on the loading properties. The analytical spectral elements in the wavenumber domain are obtained according to the principle of wave superposition and Fourier transformation. Then, the spectral global stiffness matrix of the multi-layered medium is derived by assembling the nodded stiffness matrices of all layers depended on the different interlayer conditions between the adjacent layers, i.e. sliding and bonded. The corresponding analytical solutions are achieved by taking the Fourier series and Inverse Fast Fourier Transform (IFFT) algorithm. Finally, some examples are given to validate the accuracy of the proposed analytical solution, and to demonstrate the impact of both anisotropy, top layer thickness, interlayer conditions, and loading properties (velocity and natural frequency) on the mechanical response of the multi-layered medium