Substructural Approach for Assessing the Stability of Higher Fullerenes

This review describes the most significant published results devoted to the study of the nature of the higher fullerenes stability, revealing of correlations between the structural features of higher fullerene molecules and the possibility of their producing. A formalization of the substructure approach to assessing the stability of higher fullerenes is proposed, which is based on a detailed analysis of the main structural features of fullerene molecules. The developed substructure approach, together with the stability of the substructures constituting the fullerene molecule, helps to understand deeper the features of the electronic structure of fullerenes.

Analysis of the Effects of Soil on the Seismic Energy Responses of an Equipment-Structure System via Substructure Shaking Table Testing

This study investigated the real-time substructure shaking table testing (RTSSTT) of an equipment-structure-soil (ESS) system and the effects of soil on the seismic energy responses of the equipment-structure (ES) subsystem. First, the branch modal substructure approach was employed to derive the formulas needed for the RTSSTT of the ESS system. Then, individual equations for calculating the energy responses of the equipment and the structure were provided. The ES subsystem was adopted as the experimental substructure, whereas the reduced soil model was treated as the numerical substructure when the RTSSTT was performed on the ESS system. The effectiveness of the proposed testing method was demonstrated by comparing the test results with those of the integrated finite element analysis. The energy responses of the ES subsystem in the case of rigid ground (i.e., the ES system) were compared with those considering the effects of soil (i.e., the ESS system). The input energy responses of the ES subsystem were found to decrease significantly after taking the effects of soil into account. Differences due to the soil effects should be considered in the seismic design for the ES system.

Investigating the Effect of Depth and Impedance of Foundation Rock in Seismic Analysis of Gravity Dams

The inhomogenieties of the foundation can be modeled explicitly in standard FEM procedure, however, the results vary significantly with the extent of foundation block modeled and mechanism of applying the input earthquake excitation. The substructure approach provides mathematically exact solution but assumes average properties for the entire foundation as viscoelastic half space. This paper has carried out detailed investigations with varying impedance contrasts and different size of foundation block to show that the results, with suitably deconvoluted free-field ground acceleration time-history applied at the base of foundation block in the FEM approach, are in good agreement with the substructure approach. However, the other variants of the FEM approach may lead to erroneous and overestimated stresses in the dam body. As the foundation of gravity dams can generally be approximated as an equivalent homogeneous half-space, the more accurate and efficient substructure approach can be used to model the dam-foundation rock interaction (SSI) effects in most practical situations.

Substructure Damage Detection Method for Shear Structure Using Sub-Time Series and ARMAX

A local damage detection method for shear structure based on substructure approach and sub-time series superposition is proposed, which is promising for application in parallel and distributed damage detection systems. This method requires only three sensors to identify localized damage in any story of a building and it doesnt require constructing the structure models. A substructure method was used in this method to divide a complete structure into several substructures. Each substructure has a considerably smaller number of degrees of freedom (DOFs) which makes fewer requirements on the computing power of the data processing system. The algorithm is simple, which involves only algebra calculation and does not need any iterative computation. Moreover the damage detection process can be independently conducted on each substructure. Thus, this method is easy, efficient and suitable for being embedded into parallel and distributed damage detection systems. To better assess the performance of the method proposed above, experimental verification of the proposed approach has been conducted, which shows the proposed method works quite well and stably.