Experimental study of damage evolution in cuboid stirrup-confined concrete

This paper presents an experimental study on cuboid stirrup-confined concrete specimens under uniaxial monotonic loading and cyclic loading. The effects of stirrup volume ratio, stirrup yield strength, and concrete strength on damage evolution of the stirrup-confined concrete were investigated. The experimental results showed that the strength and ductility of concrete are improved by appropriate arrangement of the stirrup confinement. Firstly, with the increase of the stirrup volume ratio, the damage evolution of concrete can be relatively restrained. Secondly, higher stirrup yield strength usually leads to larger confining pressures and slower damage evolution. In contrast, higher concrete strength leads to higher brittleness, which accelerates damage evolution. Based on the experimental data, a plastic strain expression is obtained through curve fitting, and a damage evolution equation for stirrup-confined concrete is proposed by introducing a confinement factor (C). The comparisons results demonstrated that the proposed damage evolution curve can accurately describe the experimental results.

Modelling of the stiffness evolution of truss core structures damaged by plastic buckling

A finite element study based on 1D beam element model is performed in order to investigate the mechanical behavior of an elasto-plastic beam loaded in axial compression over its buckling limit. The mode of loading is related to the damage of truss-cored beams in truss-cored laminates. The analysis takes into account the effects of geometry and material properties. The results of the FEM analysis are used for developing a simple mechanical model based on the basic Euler-Bernoulli beam theory and accounts for the beam compressibility. The model uses phenomenological functions containing parameters related to the basic material and geometrical properties. The presented model is developed in the form of closed solution which does not require complex numerical methods or extensive parametric studies. Predictions of the compressive stiffness degradation of truss-cored composites are made with the proposed model and compared with the results of FEM simulations. The error of the stiffness prediction with respect to the FEM results is within 10% over a 5 fold range of stiffness.

Simulation of progressive damage in composites using the enhanced embedded element technique

Analysis of complex composite structures requires a fine contiguous mesh of threedimensional (3D) solid elements. The embedded element technique is a promising technique for predicting stiffness and stress. This paper presents a new method for enhancing the embedded element with continuum damage mechanics methods for predicting the evolution of damage in fiber reinforced composite structures. Comparison of the model prediction with experimental results reveals an excellent correlation between the tensile strength of quasi-isotropic laminate with an open hole. The embedded element technique allows the fiber reinforcement and matrix domains to be meshed independently and failure is evaluated separately in each domain. The enhanced embedded element approach allows the failure modes to be observed, specifically, the evolution of matrix cracking and fiber rupture. Compared to the traditional contiguous mesh finite element method, the present modelling technique demonstrates a clear advantage in predicting the experimentally observed failure modes and accurate characterisation of intralaminar fracture.

Evolution and significance of the regeneration reserve heritage landscape of Broken Hill: history, values and significance

In 1991, the National Trust of NSW classified the Regeneration Reserves surrounding the City of Broken Hill as an essential cultural heritage asset of the City of Broken Hill, and in 2015 the City of Broken Hill, including the reserves, were elevated to the National Heritage List under the Commonwealth's Environment Protection and Biodiversity Conservation Act 1999. This tract of land, and its proponents, Albert and Margaret Morris, are recognised as pioneers of arid zone revegetation science in Australia; a point noted in the National Heritage List citation. They created at Broken Hill a unique revegetation ‘greenbelt’ of national ecological, landscape architectural and town planning significance. The Morris’ led the advancement of arid zone botanical investigation and taxonomic inquiry, propagation innovation, and revegetation sciencein the 1920s-40s in Australia and applied this spatially. Their research and practical applications, in crafting the regeneration reserves around Broken Hill, demonstrated the need for landscape harmonisation to occur to reduce erosion and dust damage to human and mining activities alike. This pioneering research and practice informs and underpins much arid zone mine reclamation and revegetation work in Australia today. This paper reviews the historical evolution of this cultural landscape, its integral importance to the cultural heritage and mining history of the City of Broken Hill, and its inclusion as part of the Broken Hill National Heritage List citation.