The scattering of SH waves by a finite crack with a superposition-based diffraction technique     

Camilo Valencia  Juan Gomez  Juan Jaramillo  Mario Saenz  Juan Vergara 《Studia Geophysica et Geodaetica》2017,61(1):93-114

The problem of diffraction of cylindrical and plane horizontally polarized shear waves (SH waves) by a finite crack embedded in a plane bidimensional elastic full-space is revisited. Particularly, we construct an approximate solution by the addition of independent diffracted terms. In our method the derivation of the fundamental case of a semi-infinite crack obtained as a degenerate case of a generalized wedge is first considered. This result is then used as a building block to compute the diffraction of the main incident waves. The interaction between the opposite edges of the crack is later considered in terms of a series, one term at a time until a desired tolerance is reached. Moreover, we propose a procedure to determine the number of required interactions as a function of frequency. The solution derived with the superposition technique is shown to be effective at low and high frequencies and as shown by comparisons with a direct boundary element method software, highly accurate solutions are obtained after retaining just a few terms of the infinite series.  相似文献   

Proposal of design rules for ductile X-CBFS in the framework of EUROCODE 8     

Silvia Costanzo  Mario D'Aniello  Raffaele Landolfo 《地震工程与结构动力学》2019,48(1):124-151

Cross concentrically braced frames (X-CBFs) are commonly used as primary seismic resisting system, owing to their large lateral stiffness, simplicity of design, and relatively low constructional cost. Current EN 1998-1 provides design rules theoretically aiming at developing ductile global plastic mechanism, namely enforcing plastic deformations in the diagonal members, while the remaining structural members and connections should elastically behave. However, as widely demonstrated by many existing studies, the design and the corresponding seismic performance of EC8-compliant X-CBFs are generally affected by several criticisms, eg, difficulties in sizing of diagonal members, massive and non-economical structures, and poor seismic behavior. In light of these considerations, the research activity presented in this paper is addressed to revise the design rules and requirements given EN 1998-1 for X-CBFs to simplify the design process and to improve the ductility and the dissipative capacity of this structural system. Hence, design rules are proposed for the next version of EN 1998-1 and numerically validated by means of nonlinear dynamic analyses.  相似文献