Seismic Analysis of Open Ground Story Framed Building

The concept of open ground building (OGS) has taken its place in the Indian urban environment due to the fact that it provides the parking facility in the ground storey of the building. The cost of construction of this type of building is much less than that of a building with basement parking. Surveys of buildings failed in the past earthquakes show that this types of buildings are found to be one of the most vulnerable. The majority of buildings that failed during the Bhuj earthquake (2001) and Gujraat earthquake were of the OGS type. The collapse mechanism of such type of building is predominantly due to the formation of soft-storey in ground storey of the building. The sudden reduction in lateral stiffness and mass in the ground storey results in higher stresses in the columns of ground storey under seismic loading. In conventional design practice, the contribution of stiffness of infill walls present in upper storeys of OGS framed buildings are ignored in the structural modelling. Design based on such analysis, results in under-estimation of the bending moments and shear forces in the columns of ground storey. After Bhuj earthquake, IS 1893 code was revised in 2002, incorporating new design recommendations to address OGS framed buildings. According to this clause 7.10.3(a): “The columns and beams of the soft-storey are to be designed for the multiplication factor of 2.5 times the storey shears and moments calculated under seismic loads of bare frame”. The prescribed multiplication factor (MF) of 2.5, applicable for all OGS framed buildings, is proved to be fairly higher and suggests that all existing OGS buildings are highly vulnerable under seismic loading. The main objective of present study is the study of comparative performance of OGS buildings designed with various MFs using nonlinear analysis. As more realistic performance of the OGS building requires the modeling of stiffness and strength of the infill walls, hence they are also considered

A non-Gaussian limit for linear eigenvalue statistics of Hankel matrices

This article focuses on linear eigenvalue statistics of Hankel matrices with independent entries. Using the convergence of moments we show that the linear eigenvalue statistics of Hankel matrices for odd degree monomials with degree greater than or equal to three does not converge in distribution to a Gaussian random variable. This result is a departure from the known results, Liu, Sun and Wang (2012), Kumar and Maurya (2022), of linear eigenvalue statistics of Hankel matrices for even degree monomial test functions, where the limits were Gaussian random variables.Comment: 22 Pages, 3 figure

Efficient Tracking of Dispersion Surfaces for Printed Structures using the Method of Moments

The dispersion surfaces of printed periodic structures in layered media are efficiently computed using a full-wave method based on the periodic Method of Moments (MoM). The geometry of the dispersion surface is estimated after mapping the determinant of the periodic MoM impedance matrix over a range of frequencies and impressed phase shifts. For lossless periodic structures in the long-wavelength regime, such as lossless metasurfaces, a tracking algorithm is proposed to represent the dispersion surface as a superposition of parameterized iso-frequency curves. The mapping process of the determinant is accelerated using a specialized interpolation technique with respect to the frequency and impressed phase shifts. The algorithm combines a fast evaluation of the rapidly varying part of the periodic impedance matrix and the interpolation of the computationally intensive but slowly varying remainder. The mapping is further accelerated through the use of Macro basis functions (MBFs). The method has been first tested on lossless metasurface-type structures and validated using the commercial software CST. The specialized technique enables a drastic reduction of the number of periodic impedance matrices that needs to be explicitly computed. In the two examples considered, only 12 matrices are required to cover any phase shift and a frequency band larger than one octave. An important advantage of the proposed method is that it does not entail any approximation, so that it can be used for lossy structure and leaky waves, as demonstrated through two additional examples.Comment: Paper accepted for publication in IEEE Transactions on Antennas and Propagatio

Enhancement of spin to charge conversion efficiency at the topological surface state by inserting normal metal spacer layer in the topological insulator based heterostructure

We report efficient spin to charge conversion (SCC) in the topological insulator (TI) based heterostructure ($BiSbTe_{1.5}Se_{1.5}/Cu/Ni_{80}Fe_{20}$) by using spin-pumping technique where $BiSbTe_{1.5}Se_{1.5}$ is the TI and $Ni_{80}Fe_{20}$ is the ferromagnetic layer. The SCC, characterized by inverse Edelstein effect length ($\lambda_{IEE}$) in the TI material gets altered with an intervening Copper (Cu) layer and it depends on the interlayer thickness. The introduction of Cu layer at the interface of TI and ferromagnetic metal (FM) provides a new degree of freedom for tuning the SCC efficiency of the topological surface states. The significant enhancement of the measured spin-pumping voltage and the linewidth of ferromagnetic resonance (FMR) absorption spectra due to the insertion of Cu layer at the interface indicates a reduction in spin memory loss at the interface that resulted from the presence of exchange coupling between the surface states of TI and the local moments of ferromagnetic metal. The temperature dependence (from 8K to 300K) of the evaluated $\lambda_{IEE}$ data for all the trilayer systems, TI/Cu/FM with different Cu thickness confirms the effect of exchange coupling between the TI and FM layer on the spin to charge conversion efficiency of the topological surface state

Investigation of the potentiality of five bamboo species in biorefinery through analysis of chemical profiles

Determination of the chemical composition of biomaterial is important for their valued utilization in biorefinery. In this study, the chemical composition of five bamboo species, i.e., mitinga (Bambusa tulda), borak (Bambusa balcooa), rengoon (Thyrsostachys oliveri), orah (Dendrocalamus longispathus), and bajja (Bambusa vulgaris) were determined. The chemical characterization of these bamboo species can expedite a further study on the extraction of cellulose and lignin. alpha-cellulose content was in the range of 42.7-45.7% and Klason lignin content was 22.4-28.2%. The ash content was 1.8-4.3% for the studied five bamboo species. The alpha-cellulose and lignin content were similar to other non-timber spices. The ash content was lower than other non-timber species. Therefore, these species can be a potential source of raw material for biorefinery