Abstract-In order to provide a new approximated method for the preliminary design, tub-in-tube structure is simplified as a double cantilever beam system with compatible horizontal displacement at each floor along one of orthogonal direction of structure. According to the linear elastic assumption, the fluctuation equations of tubes, the equilibrium of floor and displacement compatibility conditions, the spectrum of dynamic response of structure such as displacement, rotation angle, bending moment and shear force of two tubes are expressed by a transfer vector with 6 dimensionless elements. The equations to solve seismic response, natural frequency and mode shape of structure are finally derived by taking into account the boundary condition of structure. This method has 8 parameters in each storey and is suitable for structure with different storey parameters. With the aid of Fast Fourier Transform, it can provide time history solution for displacement, rotation angle, bending moment and shear force of every tube at the top and bottom of each storey. During the preliminary design, the designer can use this method to realize a satisfied design efficiently.
Concrete cracking and interface slip decrease the bending stiffness of steel-concrete composite beams (SCCBs) in the negative moment region. To evaluate this decrease in the stiffness of SCCBs, a static differential equation is used to derive analytical expressions of interface slip and deflection. Based on the static load test results for SCCBs, the influence of concrete cracking and interface slip on the stiffness is analyzed. A linear stiffness reduction method is proposed for calculating the stiffness of SCCBs in the negative moment region after the concrete undergoes cracking. The proposed method can be used in engineering applications as it enables the facile and accurate calculation of the deflection and slip and the changes in stiffness of SCCBs in the negative moment region. The method can also be used for predicting and evaluating performance in the field of structural design.
People can simulate extreme hydrodynamic conditions in a laboratory facility by interfering a numbers of regular waves at a certain point in space and time, which is focused wave. It is obviously higher and steeper than any other wave, e.g. regular or irregular waves, within the propagating wave group. The focused wave occurs at a designed point both in space and time. It represents an event with a large return period which would take a long time to reproduce within a random wave sequence. The focused wave, representing of a large wave occurring in a random sea, is quite frequently used to investigate wave loading on marine or coastal structures. However, most research only employ one single focused wave group. Taking the randomness of the wave-structure interaction, repeated tests would be suggested by some textbooks or codes to eliminate the odd results. However, it would take more time to conduct those tests no matter in the laboratory or in the numerical simulations.
In our present work, we use a novel method to experimentally generate several focused wave group with different focus time but same focus point at the same time to obtain multi-focused wave groups. The wave elevation and water particle kinematics are measured. The influence of peak frequency, frequency resolution and period of focused wave group are checked and discussed. The results show that present method can generate stable and repeatable focused wave groups in the wave flume.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.