摘要：
In order to improve the seismic performance of adjacent buildings, two types of tuned inerter damper (TID) damping systems for adjacent buildings are proposed, which are composed of springs, inerter devices and dampers in serial or in parallel. The dynamic equations of TID adjacent building damping systems were derived, and the H2 norm criterion was used to optimize and adjust them, so that the system had the optimum damping performance under white noise random excitation. Taking TID frequency ratio and damping ratio as optimization parameters, the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained. The results showed that compared with the classic TMD, TID could obtain a better damping effect in the adjacent buildings. Comparing the TIDs composed of serial or parallel, it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response, while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller. Taking the adjacent building composed of two ten-story frame structures as an example, the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out. It was found that TID had a better damping effect in the full-time range compared with the classic TMD. This paper also studied the potential power of TID in adjacent buildings, which can be converted into available power resources during earthquakes.
作者机构：
[Liu, Yaru; Xiong, Lingyun] National Key Laboratory of Green and Long-Life Road Engineering in Extreme Environment (Changsha), Changsha University of Science & Technology Changsha 410114 Hunan China;[Xiong, Lingyun] Chengnan College, Changsha University of Science and Technology Changsha 410114 China;[Liu, Yaru] School of Traffic & Transportation Engineering, Changsha University of Science and Technology Changsha 410114 China;[Zeng, Qing] School of Physics & Electronic Science, Changsha University of Science and Technology Changsha 410114 China;[Lai, JianPing] Key Laboratory of Testing Technology for Manufacturing Process in Ministry of Education, State Key Laboratory of Environment-friendly Energy Materials, Southwest University of Science and Technology Mianyang 621010 China
通讯机构：
[Yaru Liu] N;National Key Laboratory of Green and Long-Life Road Engineering in Extreme Environment (Changsha), Changsha University of Science & Technology, Changsha, Hunan, China<&wdkj&>School of Traffic & Transportation Engineering, Changsha University of Science and Technology, Changsha 410114, China
摘要：
The present work investigated the effect of destabilization time on the mechanical properties and microstructure evolution of high chromium cast iron, and scanning electron microscopy and electron probe microanalysis techniques were employed. The results show that the hardness of hypoeutectic high chromium cast iron is related to the size and volume fraction of secondary carbides precipitated from the matrix. The hardness of the alloy continues to rise due to the continuous increase of the volume fraction of the secondary carbide at the initial stage of destabilization. The alloy reaches its peak hardness value at 950 °C and 1000 °C for 1 hour holding time. The solid solubility of carbon and alloying elements in the matrix increases as the holding time extends, resulting in a large number of carbides redissolved into the matrix, making the hardness of the alloy decrease; the hardness of the alloy at 14 h is less than that at 10 min. Under 1050 °C, the size and density of the secondary carbide increase significantly; extending the holding time will lead to the continuous reduction of the carbide rod that provides strength, thus, the hardness curve shows a downward trend.
摘要：
Tuned mass damper inerter (TMDI) is a device that couples traditional tuned mass dampers (TMD) with an inertial device. The inertial device produces resistance proportional to the relative acceleration at its two ends through its "inertial" constant. Due to its unique mechanical properties, TMDI has received widespread attention and application in the past twenty years. As different configurations are required in different practical situations, TMDI is still active in the research on vibration control and energy harvesting in structures. This paper provides a comprehensive review of the research status of TMDI. This work first examines the generation and important vibration control characteristics of TMDI. Then, the energy harvesting performance of electromagnetic tuned mass damper inerter (EM-TMDI) is discussed. This work emphasizes the formation of a passive dynamic vibration absorber by coupling traditional TMD with inertial devices. This paper also summarizes the design and implementation of optimal vibration control and energy harvesting for TMDI. Furthermore, this paper details the applications of TMDI in the fields of bridges and building engineering. Finally, this paper summarizes the necessity of research on tuned mass-damper-inertia, the challenges faced currently, and future research directions, such as control of parameters in electromagnetic energy harvesting TMDI systems and low-cost TMDI.
摘要：
Desiccation cracking is a major cause of shallow failure of lateritic soil slopes. Knowledge of soil tensile strength helps better understand the cracking behavior of vegetated lateritic soil. This study aims to examine the surficial cracking behavior and tensile strength of remolded lateritic soil containing horizontally arranged vetiver roots. Desiccation cracking tests, root pullout tests and direct tensile tests were performed on lateritic soil considering various porosities, degrees of saturation, and root contents. The mechanism underlying the root reinforcement was analyzed by scanning electron microscopy. The results demonstrate that adding 0.4% grass roots can reduce the crack width and crack intensity factor, and thus mitigate crack developments in lateritic soil. The interfacial shear strength exhibits a decreasing trend with increasing root diameter. As the root content increases from 0% to 1.0%, the tensile strength of lateritic soil increases to reach the peak at a root content of 0.4%-0.5% and then drops greatly. This is why the optimal root content in resisting crack development is about 0.4%. Microscopic tests show that the interfacial shear strength originates from the friction, interlocking force, cementation and capillary force between the rough root surface and surrounding soil particles. A power function-based empirical equation expressed by the root diameter and porosity is proposed to estimate the interfacial shear strength of rooted lateritic soil. Additionally, a semi-theoretical equation of the tensile strength of rooted lateritic soil is deduced based on the tensile strength of soil matrix and the interfacial shear strength between the roots and soil matrix. This equation considers the root content and root diameter distribution and is applicable to the soil of different state parameters (e.g., porosity, degree of saturation and water content). The results could provide insights into the mitigation of desiccation cracking in lateritic soil slopes with root-reinforcement technology.
通讯机构：
[Fudong Li] S;School of Mechanical and Electrical Engineering, Beijing Information Science and Technology University, Beijing 100192, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
Red clay;Wet and dry cycle;Volumetric crack rate (VCR);Ultrasonic testing;Unconfined compressive strength (UCS);Gray relational analysis
摘要：
Desiccation cracking is a common phenomenon for red clay due to alternating wet and dry weathers. The presence of cracks definitely affects the strength of the soil; however, characterizing the development of desiccation cracks inside the soil has been a challenge. The purpose of this study was to propose a method to quantify the volumetric crack rate (VCR) of red clay and investigate the influence of VCR on the unconfined compressive strength (UCS) of red clay. First, the relationship between wave speed and VCR was quantified by a prefabricated crack method to obtain the equivalent VCR (EVCR). Then, the EVCR was compared with the surface crack rate (SCR) to determine the reliability of the method. Finally, unconfined compression tests were carried out to explore the relationship between EVCR and UCS. The results show that the relationship between the prefabricated VCR and wave velocity can be described by a logarithmic equation. The calculated VCR by this equation is linearly correlated to the SCR of red clay, indicating that the logarithmic equation is effective to quantify the VCR of red clay caused by wet and dry cycles. The UCS and residual strength of red clay containing cracks reduce following an exponential function with increasing EVCR. Gray relational analysis showed that the correlation between UCS and EVCR is better than that between UCS and SCR, suggesting that it is more reliable to express the crack rate by EVCR when studying the UCS of red clay.
摘要：
Currently, the application of electromagnetic dampers in structural vibration control and energy harvesting has become increasingly widespread. The optimization research of electromagnetic dampers in building design has also received more attention. Previous studies on vibration control of building structures with electromagnetic dampers have been conducted under fixed foundations, neglecting the effect of soil-structure interaction on building structures with electromagnetic dampers. The main contribution of this paper is to fill the research gap in the study of building structural vibration control with electromagnetic dampers considering soil-structure interaction. An effective design and parameter optimization method for building structures with both soil-structure interaction and electromagnetic energy harvesting is explored. The soil-structure interaction is taken into account, and the building model with electromagnetic dampers is improved to form a coupled vibration reduction system with both structural vibration control and energy harvesting functions. The dynamic equations of the system with both structural vibration control and energy harvesting are derived and then optimized using the H2 norm criterion and Monte Carlo-mode search method. A single-layer building structure is used as an example to study the influence of soil-structure interaction on building structures equipped with electromagnetic dampers under strong earthquake action. The dynamic response and energy harvesting of building structures under earthquake action considering soil-structure interaction are analyzed and evaluated. The results show that the influence of soil-structure interaction on building structures equipped with electromagnetic dampers needs to be considered. As the soil density decreases, the dynamic response of the building structure under earthquake action becomes larger using the electromagnetic damper system. Compared to the use of fixed foundations, the energy harvesting effect of building structures with electromagnetic dampers is weakened when considering soil-structure interactions.Definition:
关键词：
Mesostructure;High temperature performance;Low temperature performance;Digital image processing;Correlation analysis
摘要：
The distribution characteristics of the mesostructure of asphalt mixtures have an important influence on the macroscopic performance of asphalt mixtures. In this study, by means of industrial computed tomography and voxel analysis, the distribution of voids and skeleton microstructure of asphalt mixture is characterized from multiple perspectives. The relationship between mesostructural characteristic parameters and macroscopic properties of asphalt mixtures was established by the indirect tensile test, uniaxial compression test, and digital image correlation test. The results show that the mesostructural distribution of the voids of different types of asphalt mixtures shows a certain degree of transverse isotropy. Air voids content and fractal dimension of voids are the mesostructural characteristic parameters that affect the cracking resistance of asphalt mixtures at low temperatures. The air voids content has a negative exponential relationship with the strength of asphalt mixture. When the void fractal dimension is 1.3, the splitting tensile strength of asphalt mixture reaches the maximum value. Skeleton structure is a mesostructure characteristic parameter that affects the high temperature stability of asphalt mixture. The lower voids in coarse aggregate skeletons and degree of anisotropy are positively correlated with the uniaxial compressive strength. After voids in coarse aggregate skeletons are lower than 35 %, the uniaxial compressive strength of asphalt mixture is significantly improved. The proposed skeleton evaluation index can effectively characterize the material composition differences of different types of asphalt mixtures. The strain cloud diagram of the digital correlation experiment shows the place where the void distribution first reached the maximum strain of about 0.003 during loading, and the high strain area corresponds to the void centroid distribution. The air voids centroid distribution is the mesostructural characteristic parameter of the indirect tensile strain distribution.
