Sharif Digital Repository

In spite of existing comprehensive studies on the behavior of steel plate shear wall (SPSW), some aspects of the SPSW have remained unknown, yet. One of the important aspects that is unknown is the crack effect on the SPSW behavior in linear and nonlinear zones. Some experimental studies have been reported that SPSWs were fractured due to crack propagation. Therefore, the crack effect on the behavior of SPSW should be accounted in considering of SPSW behavior. Although the effect of crack on the thin SPSW has been investigated to a limited extent numerically, stiffened SPSPW, especially diagonally stiffened SPSW, has not been studied. In doing so, in this paper, the effect of crack effect on... 

This paper aims at investigating free vibrations and stability of double-walled carbon nanotube (DWCNT)-based spinning nanobearings. The so-called nanobearing consists of two coaxial carbon nanotubes (CNTs) where either of the two CNTs can be a rotor while the other takes the role of stator. Euler–Bernoulli beam model along with the Eringen’s nonlocal theory of elasticity are employed to obtain governing equations of transverse vibrations for the CNTs. The coupling of the two CNTs originates from the van-der-Waals (vdW) forcing present in the interface of the two CNTs. The coupling is taken into account as distributed spring foundation with an equivalent elastic stiffness. Based on the... 

In steel tub girder bridges, end diaphragms transmit vertical and lateral loads to the substructure. Vulnerable response of steel diaphragms in recent strong ground motions has encouraged the researchers to work on their application as seismic force reducing devices for design and retrofitting of bridges. This study is an attempt to achieve a ductile diaphragm behavior under seismic actions by using existing internal end plate diaphragm of steel tub girder bridges. Considerable elastic stiffness and dominant shear behavior of the end diaphragm has made it a suitable choice for such behavior under seismic actions. Nonlinear quasi-static analyses using nineteen different finite element models... 

In the present study, the in-plane elastic stiffness coefficients of graphene within the framework of first strain gradient theory are calculated on the basis of an accurate molecular mechanics model. To this end, a Wigner–Seitz primitive cell is adopted. Additionally, the first strain gradient theory for graphene with trigonal crystal system is formulated and the relation between elastic stiffness coefficients and molecular mechanics parameters are calculated. Thus, the ongoing research challenge on providing the accurate mechanical properties of graphene is addressed herein. Using results obtained, the in-plane free vibration of graphene is studied and a detailed numerical investigation is... 

In the present study, the in-plane elastic stiffness coefficients of graphene within the framework of first strain gradient theory are calculated on the basis of an accurate molecular mechanics model. To this end, a Wigner–Seitz primitive cell is adopted. Additionally, the first strain gradient theory for graphene with trigonal crystal system is formulated and the relation between elastic stiffness coefficients and molecular mechanics parameters are calculated. Thus, the ongoing research challenge on providing the accurate mechanical properties of graphene is addressed herein. Using results obtained, the in-plane free vibration of graphene is studied and a detailed numerical investigation is... 

Young’s modulus (E) is one of the most important parameters in the mechanical properties of solid materials. Young’s modulus is proportional to the stress and strain values. There are several experimental and theoretical methods for gaining Young’s modulus values, such as stress–strain curves in compression and tensile tests, electromagnetic-acoustic resonance, ultrasonic pulse echo and density functional theory (DFT) in different basis sets. Apparently, preparing specimens for measuring Young’s modulus through the experimental methods is not convenient and it is time-consuming. In addition, for calculating Young’s modulus values by software, presumptions of data and structures are needed.... 

The Endurance Time (ET) method is a new dynamic pushover procedure in which structures are subjected to gradually intensifying acceleration functions and their performance is assessed based on the length of the time interval that they can satisfy required performance objectives. In this paper, the accuracy of the Endurance Time method in estimating average deformation demands of low and medium rise steel frames using ETASOf series of ET acceleration functions has been investigated. The precision of the ET method in predicting the response of steel frames in nonlinear analysis is investigated by considering a simple set of moment-resisting frames. An elastic-perfectly-plastic material model...