We devise a multiple crack weight (MCW) method for the accurate and effective solution of strongly interacting cracks by meshless numerical methods. The MCW method constructs weight functions around cracks so that they simultaneously characterize all the cracks present in the single nodal domain of influence. This approach reduces the number of nodes necessary to achieve sufficient accuracy and consequently it decreases the computational effort. Numerical examples demonstrate that the method allows an accurate solution of multiple cracks problems. Convergence of the method is analyzed and discussed.

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In the last decade several different approaches have been developed to study arbitrary static and dynamic cracks. Among these methods meshless techniques play an important role. These methods provide an accurate solution of a wide range of fracture mechanics problems while traditional methods such as finite element and boundary element have limitations. We wish to increase the accuracy of the meshless approximations without increasing the nodal density. This is done by an appropriate modification of the weight function near crack tips. Earlier attempts still had limitations that result in a lack of accuracy, especially in the case when a linear basis is used. In this work a new technique, the spiral weight, is introduced that minimizes the drawbacks of existing methods. Numerical examples show that the spiral weight method is more efficient than existing methods, when using a linear basis, for the solution of crack problems.

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Acoustic Emission (AE) nondestructive tests have attracted great interest for their use in the determination of structural properties and behavior of reinforced concrete (RC) elements. One of the applications this method can contribute to is in high-strength concrete (HSC) columns. These elements have a great advantage in the lower stories of high-rise buildings. However, the premature failure of the concrete cover and the brittleness nature of the failure is of a concern for engineers. This paper presents a study on the AE monitoring of HSC columns subjected to compressive axial loading. The study consists of four large-scale reinforced HSC columns with different confinement reinforcement and height. It is shown that the AE distributions in the columns are categorized by three stages. Moreover, the levels of loads reached at the first AE macro event are similar to the lower range levels of the nominal axial compressive strengths of the tested specimens, while the majority of macro AE events are located at the concrete cover. Based on the results of this study, AE monitoring can provide indications for the damage and load levels attained by reinforced high-strength concrete columns subjected to compressive axial loading.