Vibration suppression analysis of a long-span cable-stayed bridge based on earthquake-wind-traffic-bridge coupled system

Xinfeng Yin,Yong Liu,Wanli Yan,Yang Liu,Zhou Huang 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.4

Wind and earthquake loads may cause strong vibrations in large-span cable-stayed bridges, leading to the inability of the bridge to operate normally. An improved Pounding Tuned Mass Damper (PTMD) system was designed to improve the safety of the large-span cable-stayed bridge. The vibration control effect of the improved PTMD system on the large-span cablestayed bridge under the combined action of earthquake-wind-traffic was studied. Furthermore, the impact of different parameters on the vibration suppression performance of the improved PTMD system was analyzed. The numerical results indicate that the PTMD system is very effective in suppressing the displacements of the bridge caused by both the traffic-wind coupling and traffic-earthquake coupling. Moreover, the number, mass ratio, pounding stiffness, and gap values have a significant influence on the vibration suppression performance of the improved PTMD system. When the number of PTMD is increased from 3 to 9, the vibration reduction ratio of the vertical displacement is increased from 25.39% to 48.05%. As the mass ratio changes from 0.5% to 2%, the vibration reduction ratio increases significantly from 22.23% to 53.30%.

Solidification of uranium mill tailings by MBS-MICP and environmental implications

Niu Qianjin,Li Chunguang,Liu Zhenzhong,Li Yongmei,Meng Shuo,He Xinqi,Liu Xinfeng,Wang Wenji,He Meijiao,Yang Xiaolei,Liu Qi,Liu Longcheng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

Uranium mill tailing ponds (UMTPs) are risk source of debris flow and a critical source of environmental U and Rn pollution. The technology of microbial induced calcium carbonate precipitation (MICP) has been extensively studied on reinforcement of UMTs, while little attention has been paid to the effects of MICP on U & Rn release, especially when incorporation of metakaolin and bacillus subtilis (MBS). In this study, the reinforcement and U & Rn immobilization role of MBS -MICP solidification in different grouting cycle for uranium mill tailings (UMTs) was comprehensively investigated. The results showed that under the action of about 166.7 g/L metakaolin and ~50% bacillus subtilis, the solidification cycle of MICP was shortened by 50%, the solidified bodies became brittle, and the axial stress increased by up to 7.9%, and U immobilization rates and Rn exhalation rates decrease by 12.6% and 0.8%, respectively. Therefore, the incorporation of MBS can enhance the triaxial compressive strength and improve the immobilization capacity of U and Rn of the UMTs bodies solidified during MICP, due to the reduction of pore volume and surface area, the formation of more crystals general gypsum and gismondine, as well as the enhancing of coprecipitation and encapsulation capacity

Hypolipidemic effect of soluble dietary fibers prepared from Asparagus officinalis and their effects on the modulation of intestinal microbiota

Miansong Zhang,Mengke Yao,Airong Jia,Yaping Shi,Xinfeng Bai,Xue Liu,Tingting Cui,Xin Liu,Changheng Liu 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.13

The soluble dietary fiber from Asparagus officinalis(ASDF) was successively prepared using enzymolysiscombined with spray-drying technology. Highperformanceliquid chromatography analysis showed thatASDF contained two polysaccharide fractions with theaverage molecular weight of 2.77 9 105 and6.44 9 103 Da, and was composed of mannose, rhamnose,galacturonic acid, glucose, galactose, and arabinose with amolecular ratio of 19.93:1.02:1.94:32.17:1.00:1.91,respectively. ASDF showed potential in vitro antioxidantactivities. The oral administration of ASDF significantlyreduced the levels of total cholesterol, triglyceride, andlow-density lipoprotein cholesterol in HD-induced miceserum. Furthermore, 16S rRNA gene sequencing analysisshowed that ASDF significantly affected the compositionof intestinal microbiota, especially reducing the Firmicutes/Bacteroidotetes ratio and the relative abundances ofDesulfobacterota, Proteobacteria, Actinobacteriota andincreasing that of Muribaculaceae, Bacteroides, and Alloprevotella. These results demonstrated that the intake ofASDF could regulate intestinal microbiota and serum lipidlevels in hyperlipidemic conditions.

The mediating role of atrial fibrillation in causal associations between risk factors and stroke: a Mendelian randomization study

Shanmei Qin(Shanmei Qin),Mengmeng Wang(Mengmeng Wang),Dipender Gill(Dipender Gill ),Zhizhong Zhang(Zhizhong Zhang),Xinfeng Liu(Xinfeng Liu) 한국역학회 2024 Epidemiology and Health Vol.46 No.-

Vibration behaviors of a damaged bridge under moving vehicular loads

Xinfeng Yin,Yang Liu,Bo Kong 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.2

A large number of bridges were built several decades ago, and most of which have gradually suffered serious deteriorations or damage due to the increasing traffic loads, environmental effects, and inadequate maintenance. However, very few studies were conducted to investigate the vibration behaviors of a damaged bridge under moving vehicles. In this paper, the vibration behaviors of such vehicle-bridge system are investigated in details, in which the effects of the concrete cracks and bridge surface roughness are particularly considered. Specifically, two vehicle models are introduced, i.e., a simplified four degree-of-freedoms (DOFs) vehicle model and a more complex seven DOFs vehicle model, respectively. The bridges are modeled in two types, including a single-span uniform beam and a full scale reinforced concrete high-pier bridge, respectively. The crack zone in the reinforced concrete bridge is considered by a damage function. The bridge and vehicle coupled equations are established by combining the equations of motion of both the bridge and vehicles using the displacement relationship and interaction force relationship at the contact points between the tires and bridge. The numerical simulations and verifications show that the proposed modeling method can rationally simulate the vibration behaviors of the damaged bridge under moving vehicles; the effect of cracks on the impact factors is very small and can be neglected for the bridge with none roughness, however, the effect of cracks on the impact factors is very significant and cannot be neglected for the bridge with roughness.

Impact factors of an old bridge under moving vehicular loads

Liu, Yang,Yin, Xinfeng,Zhang, Jianren,Cai, C.S. Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.3

This paper presents a new method to study the impact factor of an old bridge based on the model updating technique. Using the genetic algorithm (GA) by minimizing an objective function of the residuals between the measured and predicted responses, the bridge and vehicle coupled vibration models were updated. Based on the displacement relationship and the interaction force relationship at the contact patches, the vehicle-bridge coupled system can be established by combining the equations of motion of both the bridge and vehicles. The simulated results show that the present method can simulate precisely the response of the tested bridge; compared with the other bridge codes, the impact factor specified by the bridge code of AASHTO (LRFD) is the most conservative one, and the value of Chinese highway bridge design code (CHBDC) is the lowest; for the large majority of old bridges whose road surface conditions have deteriorated, calculating the impact factor with the bridge codes cannot ensure the reliable results.

Vibration Suppression Analysis of a Long-Span Bridge Subjected to Combined Service and Extreme Loads

Xinfeng Yin,Wanli Yan,Qian Liao,Xiang Chen,Yang Liu 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.5

The long-span bridge structures are loaded by service loads including traffic and/or wind loads almost every day. The earthquake load may occur on the bridges simultaneously except for these two common service loads. The vibration response of long-span bridges under earthquake and service loads usually exceeds the expected values. Therefore, the suppressed system should be extensively studied to control the vibration of the bridges. In the work, a pounding tuned mass damper (PTMD) system was designed, which can be effectively used for the dissipation of impact energy. It is mainly made up of a tuned mass and an additional limit device. Based on the earthquake/wind/traffic/bridge coupled system, the numerical simulation of multiple PTMDs (MPTMDs) was carried out. Different parameters of MPTMDs were studied including different numbers, mass ratio, pounding stiffness, and the gap values. The simulations show that the MPTMDs are very effective in suppressing the displacements of the bridge caused by both the traffic flows/wind and traffic/earthquake, and the suppressing effectiveness for bridge vibration under traffic and earthquake is more than that under traffic and wind.

Ride comfort of the bridge-traffic-wind coupled system considering bridge surface deterioration

Liu, Yang,Yin, Xinfeng,Deng, Lu,Cai, C.S. Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.23 No.1

In the present study, a new methodology is presented to study the ride comfort and bridge responses of a long-span bridge-traffic-wind coupled vibration system considering stochastic characteristics of traffic flow and bridge surface progressive deterioration. A three-dimensional vehicle model with 24 degrees-of-freedoms (DOFs) including a three-dimensional non-linear suspension seat model and the longitudinal vibration of the vehicle is firstly presented to study the ride comfort. An improved cellular automaton (CA) model considering the influence of the next-nearest neighbor vehicles and a progressive deterioration model for bridge surface roughness are firstly introduced. Based on the equivalent dynamic vehicle model approach, the bridge-traffic-wind coupled equations are established by combining the equations of motion of both the bridge and vehicles in traffic using the displacement relationship and interaction force relationship at the patch contact. The numerical simulations show that the proposed method can simulate rationally the ride comfort and bridge responses of the bridge-traffic-wind coupled system; and the vertical, lateral, and longitudinal vibrations of the driver seat model can affect significantly the driver's comfort, as expected.

Impact factors of an old bridge under moving vehicular loads

Yang Liu,Xinfeng Yin,Jianren Zhang,C.S. Cai 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.3

This paper presents a new method to study the impact factor of an old bridge based on the model updating technique. Using the genetic algorithm (GA) by minimizing an objective function of the residuals between the measured and predicted responses, the bridge and vehicle coupled vibration models were updated. Based on the displacement relationship and the interaction force relationship at the contact patches, the vehicle-bridge coupled system can be established by combining the equations of motion of both the bridge and vehicles. The simulated results show that the present method can simulate precisely the response of the tested bridge; compared with the other bridge codes, the impact factor specified by the bridge code of AASHTO (LRFD) is the most conservative one, and the value of Chinese highway bridge design code (CHBDC) is the lowest; for the large majority of old bridges whose road surface conditions have deteriorated, calculating the impact factor with the bridge codes cannot ensure the reliable results.

Influence of Injection System Parameters on Combustion Noise of a Small Power Non-Road Diesel Engine

Zhou Xinfeng,Ma Zhihao,Liu Yuna,Li Ao 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.5

Combustion noise accounts for a large proportion of diesel engine noise. On the premise of not increasing the cost of diesel engine, the injection system parameters such as dynamic fuel supply advance angle and needle valve opening pressure are optimized, and the influence of the above parameters on the in-cylinder pressure, rate of pressure rise, in-cylinder pressure level (CPL) spectrum and high frequency pressure oscillation is analyzed. The study shows that reducing the dynamic fuel supply advance angle can effectively reduce the combustion noise, and appropriately increasing the needle valve opening pressure can also reduce the combustion noise. After the optimization of injection parameters, the combustion noise of the diesel engine with an electronically controlled VE pump-tube-nozzle injection system is significantly reduced compared with the prototype engine, and can reach the same level of combustion noise as the diesel engine with the common rail system without deterioration of fuel economy and emission performance. The experimental study can provide technical reference for diesel engines in the selection of injection system parameters and the optimization of combustion noise in the improvement stage.