Performance-based plastic design method of high-rise steel frames

Under major earthquakes, high-rise steel moment frames designed according to the current codes will experience an inelastic deformation, which is difficult to predict and control. According to the principle of work-energy balance, a performance-based plastic design (PBPD) methodology is put forward for the design of high-rise steel frames in this study. In this method, the target drift and yield mechanisms are pre-selected as key performance criteria. The design base shear in a given earthquake level is calculated based on the work-energy balance principle that the work required to push the structure monotonically to the target drift is equal to the energy needed by an equivalent single degree of freedom to reach the same state. The plastic design is utilized to design the frame components and connections so as to attain the desired yield mechanism and behavior. The method has been adopted to design a ten-story steel moment resisting frame, and has been validated by nonlinear dynamic time history analyses and pushover analysis. The results indicate that the frames develop targeted strong column sway mechanisms, and the story drifts are less than the target values, thus satisfying the anticipated performance objectives. The addressed method herein can form a basis for the performance-based plastic design of high-rise steel moment resisting frames

Experimental study on seismic behavior of steel tube confined high-strength concrete shear walls

The high strength concrete shear walls are characterized by its high bearing capacity, high stiffness but a poor deformation capacity. In order to improve the deformation capacity of these members, specimens of high-strength concrete shear wall with steel tube confined boundary elements were designed and the quasi-static tests were conducted. The failure mode, failure mechanism, deformation capacity, hysteretic behavior, stiffness degradation and energy dissipation capacity of specimens were researched. The results indicate that the steel tube boundary elements can provide an effective confinement to the wall pier and the horizontal bearing capacity of specimens dropped slowly. Under a high axial force, the vertical bearing capacity of specimens can be maintained, and the deformation and energy dissipation capacity could be obviously enhanced due to the use of steel tubes in the boundary elements. The ultimate displacement and the energy dissipation of steel tube confined high-strength concrete shear walls were increased by 27 % and 81 % respectively compared to high-strength concrete shear walls with the same axial load ratio. According to the experimental results, the calculation formula is addressed for the cross-section bearing capacity of steel tube confined high-strength concrete shear wall. As a result, it is a good practice that the steel tube confined boundary elements can be utilized at the bottom strengthening zone so as to improve the seismic performance of high-strength concrete shear walls

Analysis of Compressive Toughness and Deformability of High Ductile Fiber Reinforced Concrete

The compressive toughness evaluation index of HDC (high ductile fiber reinforced concrete) is studied through three groups of uniaxial compressive tests of HDC specimens with different fiber mixing amounts, and an equivalent analysis of their deformability is carried out, coming to the following conclusion: (1) the peak strain of HDC under uniaxial compression can be up to 3.41~3.67 times as large as that of the mortar matrix; (2) the equivalent compressive toughness index reflects the unit volume deformation energy of specimens under uniaxial compression and it can be used as the compressive toughness evaluation index of HDC; (3) the fiber bridging effect of HDC increases the equivalent compressive toughness index and the compressive deformability up to 3 times of the mortar matrix; (4) the relationship between the equivalent compressive toughness index Wcu0.85 and the fiber mixing amount φ is established according to the test results; and (5) the fiber bridging effect of the matrix in HDC can be equaling as a large number of constraint stirrups installed in the specimens, which significantly enhances the compressive toughness and the compressive deformability of specimens

Oncolytic Virus M1 Functions as a Bifunctional Checkpoint Inhibitor To Enhance the Antitumor Activity of DC Vaccine

Although promising, dendritic cell (DC) vaccines still provide limited clinical benefits, mainly due to the immunosuppressive tumor microenvironment (TME) and the lack of tumor-associated antigens (TAAs). Oncolytic virus therapy is an ideal strategy to overcome immunosuppression and expose TAAs; therefore, they may work synergistically with DC vaccines. In this study, we demonstrate that oncolytic virus M1 (OVM) can enhance the antitumor effects of DC vaccines across diverse syngeneic mouse tumor models by increasing the infiltration of CD8+ effector T cells in the TME. Mechanically, we show that tumor cells counteract DC vaccines through the SIRPα-CD47 immune checkpoint, while OVM can downregulate SIRPα in DCs and CD47 in tumor cells. Since OVM upregulates PD-L1 in DCs, combining PD-L1 blockade with DC vaccines and OVM further enhances antitumor activity. Overall, OVM strengthens the antitumor efficacy of DC vaccines by targeting the SIRPα-CD47 axis, which exerts dominant immunosuppressive effects on DC vaccines

An Extended Fourier Approach to Improve the Retrieved Leaf Area Index (LAI) in a Time Series from an Alpine Wetland

An extended Fourier approach was presented to improve the retrieved leaf area index (LAIr) of herbaceous vegetation in a time series from an alpine wetland. The retrieval was performed from the Aqua MODIS 8-day composite surface reflectance product (MYD09Q1) from day of year (DOY) 97 to 297 using a look-up table (LUT) based inversion of a two-layer canopy reflectance model (ACRM). To reduce the uncertainty (the ACRM inversion is ill-posed), we used NDVI and NIR images to reduce the influence of the soil background and the priori information to constrain the range of sensitive ACRM parameters determined using the Sobol’s method. Even so the uncertainty caused the LAIr versus time curve to oscillate. To further reduce the uncertainty, a Fourier model was fitted using the periodically LAIr results, obtaining LAIF. We note that the level of precision of the LAIF potentially may increase through removing singular points or decrease if the LAIr data were too noisy. To further improve the precision level of the LAIr, the Fourier model was extended by considering the LAIr uncertainty. The LAIr, the LAI simulated using the Fourier model, and the LAI simulated using the extended Fourier approach (LAIeF) were validated through comparisons with the field measured LAI. The R2 values were 0.68, 0.67 and 0.72, the residual sums of squares (RSS) were 3.47, 3.42 and 3.15, and the root-mean-square errors (RMSE) were 0.31, 0.30 and 0.29, respectively, on DOY 177 (early July 2011). In late August (DOY 233), the R2 values were 0.73, 0.77 and 0.79, the RSS values were 38.96, 29.25 and 27.48, and the RMSE values were 0.94, 0.81 and 0.78, respectively. The results OPEN ACCESS Remote Sens. 2014, 6 1172 demonstrate that the extended Fourier approach has the potential to increase the level of precision of estimates of the time varying LAI

Effects of obesity with reduced 25(OH)D levels on bone health in elderly Chinese people: a nationwide cross-sectional study

BackgroundObesity is often accompanied by lower 25(OH)D levels, whereas these two parameters exhibit opposite effects on bone health. It is uncertain what are the effects of lower 25(OH)D levels in obesity on bone health in elderly Chinese people.MethodsA nationally representative cross-sectional analysis of China Community-based Cohort of Osteoporosis (CCCO) was performed from 2016 to 2021, which consisted of 22,081 participants. Demographic data, disease history, Body mass index (BMI), bone mineral density (BMD), the levels of the biomarkers of vitamin D status and those of bone metabolism markers were measured for all participants (N = 22,081). The genes (rs12785878, rs10741657, rs4588, rs7041, rs2282679 and rs6013897) related to 25(OH)D transportation and metabolism were performed in a selected subgroup (N = 6008).ResultsObese subjects exhibited lower 25(OH)D levels (p < 0.05) and higher BMD (p < 0.001) compared with those of normal subjects following adjustment. The genotypes and allele frequency of rs12785878, rs10741657, rs6013897, rs2282679, rs4588 and rs7041 indicated no significant differences among three BMI groups following correction by the Bonferroni’s method (p > 0.05). The levels of total 25(OH)D (ToVD) were significantly different among the GC1F, GC1S and GC2 haplotype groups (p < 0.05). Correlation analysis indicated that ToVD levels were significantly correlated with parathyroid hormone levels, BMD, risk of osteoporosis (OP) and the concentration levels of other bone metabolism markers (p < 0.05). Generalized varying coefficient models demonstrated that the increasing BMI, ToVD levels and their interactions were positively associated with BMD outcomes (p < 0.001), whereas the reduced levels of ToVD and BMI increased the risk of OP, which was noted notably for the subjects with reduced ToVD levels (less than 20.69 ng/ml) combined with decreased BMI (less than 24.05 kg/m2).ConclusionThere was a non-linear interaction of BMI and 25(OH)D. And higher BMI accompanied by decreased 25(OH)D levels is associated with increased BMD and decreased incidence of OP, optimal ranges exist for BMI and 25(OH)D levels. The cutoff value of BMI at approximately 24.05 kg/m2 combined with an approximate value of 25(OH)D at 20.69 ng/ml are beneficial for Chinese elderly subjects

Neural correlates of consciousness and communication in disorders of consciousness

© 2015 Xingwen LiangIt is difficult to distinguish disorders of consciousness from certain disorders of communication for vegetative and minimally conscious patients who suffer from impairment of awareness and cannot produce reliable behavioural output. This thesis reviews some previous neuroimaging studies on mental imagery and brain injured patients, and presents a functional magnetic resonance imaging (fMRI) study of five patients that seeks to extend communication with them through asking them to answer simple questions with ‘yes’, ‘no’ or ‘I don’t know’ answers by performing mental imagery tasks of ‘playing tennis’, ‘navigating the home’, ‘imagining familiar faces’, and ‘counting up from 10 by 7s’. Consideration is given to how each individual’s activation map deviates from the control group map and a quantitative method of overlap, the percent overlap metric A, to classify the deviations is proposed. Promising results were found on controls with this method to infer which imagery task had been done. The full results of three tests for each participant are reported: speech comprehension capacity, mental imagery, and question-answer. Specific brain activations were observed in the first two tests: the posterior parts of superior and middle temporal cortices for ‘sentences’ in the language test; the paraphippocampal area and premotor area for navigation, superior parietal cortex and premotor area for tennis; lateral prefrontal (BA44,45), intra-parietal sulcus, and superior parietal areas for counting; frontal orbital cortex, left Broca’s area 44, and right Broca’s area 45 for faces in the imagery test. In the question-answer test, most of tennis or navigation tasks could be identified correctly when employed while answering as measured by the metric A. Although some patients produced activations in similar areas to controls for certain tasks, only two minimally conscious patients showed significant activation changes as judged by the fMRI time series for some tasks. The activation maps observed for two patients with 1.5T MRI provide independent support to the work from other groups (at 3T) on finding patients with a disorder of consciousness who can perform mental imagery tasks, which suggests broader clinical utility for the tests presented here. Given the control participant results for the mental imagery and question-answers tasks, it should be possible to at least work with locked-in patients at 1.5T. An original contribution includes consideration of the task of mental calculation. The evidence for specific pattern for counting task is provided for a group of 11 healthy participants

Uniaxial Compressive Test of High Ductile Fiber-Reinforced Concrete and Damage Constitutive Model

It has been widely recognized that the constitutive model plays an essential role in engineering application of high ductile fiber-reinforced concrete (HDC). In this research, uniaxial compressive tests were conducted on nine groups of HDC specimens with different mixture ratios and one group of mortar matrix specimens as comparison, discussing the effect of fiber content, water-cement ratio, fly ash content, and sand-binder ratio. According to the characteristics of stress-strain curve of HDC under uniaxial compression, a damage constitutive model was proposed by introducing two damage threshold parameters and then was compared with other existing models. Results indicated that the damage model curves suggested in this paper were best consistent with experimental curves and substantially demonstrate the damage evolution process as well as the cracking resistance effect of fiber bridging stress

STUDY ON VIBRATION FATIGUE OF SUBWAY VEHICLE BODY BASED ON RIGID-FLEXIBLE COUPLING DYNAMICS

The vehicle body is an important bearing structure of railway vehicles, which can bear dynamic loads from passengers and bogies. The reliability of the structure is directly related to the service safety of the vehicle.Based on the existing vehicle body standard EN12663, this paper firstly studies the static strength and fatigue strength of the vehicle body, and identifies the static weak position of the vehicle body under standard load.In order to further identify the weak position of the vehicle body under service conditions, a rigid-flexible coupling dynamic model of subway vehicle is established based on the rigid-flexible coupling dynamic theory and finite element method.Using the modal stress recovery method, the dynamic weak positions in various service modes are identified, and the vehicle modes which contribute a lot to each weak position are analyzed.Finally, based on the subway rigid-flexible coupling dynamic model, the dynamic stress characteristic of vehicle body weak position under various service conditions is analyzed, and the service life of key welds of vehicle body structure is predicted based on monte Carlo sampling and Miner linear cumulative damage theory

Shear Capacity and Failure Behavior of Steel-Reinforced High Ductile Concrete Beams

The shear behavior of six high ductile fiber reinforced concrete (HDC) beams is studied to investigate the influence of shear-span ratio and HDC mechanical property on the improvement of the shear failure mode and shear capacity of short beams. Four steel-reinforced high ductile concrete beams (SHDC) beams with different shear span ratios are tested under concentrated load at midspan. To study the effect of stirrups and steel on the shear capacity of short beams, two additional specimens without steel but one including stirrups are investigated. The main aspects of SHDC beams are discussed in detail, such as failure mode, deformability, and shear capacity. Test results show that the SHDC short beams keep high residual bearing capacity and great integrity when suffering from large deformation. It is revealed that HDC increased the shear ductility and improved the shear failure mode of short beams. A comparison with the shear equations of Chinese YB9082-2006 shows that the Chinese Code equation provides conservative estimation for HDC beams. This study proposes modifications to the equation for predicting the shear capacity of HDC beams