The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and t...The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and tends to be constant after 25 days regardless of the restraining conditions. The mixture ratio of expansive cement and restraining conditions are the main factors affecting expansive deformation. Self-stress can be obtained when the expansive deformation is restrained. The higher self-stress could be obtained when the expensive concrete is restrained by steel tube. For specimens under steel tube restraining, the wall thickness and the length of the steel tube have important influence on self-stress. Both the radial self-stress and axial self-stress in concrete core increase when wall thickness or length of the steel tube increases.展开更多
Through the experiments of 7 T-section composite beams, steel fiber reinforced self-stressing concrete （SFRSC） as the composite beam in the composite layer was studied under the hogging bending. The tests simulated ...Through the experiments of 7 T-section composite beams, steel fiber reinforced self-stressing concrete （SFRSC） as the composite beam in the composite layer was studied under the hogging bending. The tests simulated composite layer tensile strain under the hogging bending of inverted loading composite beams, giving the relationship under the different fatigue stress ratios between fatigue cycles and steel bar’s stress range, crack width, stiffness loss and damage, etc., in composite layer. This article established fatigue life equation, and analyzed SFRSC reinforced mechanism to crack width and stiffness loss. The results show that SFRSC as the composite beam concrete has excellent properties of crack resistance and tensile, can reinforce the fatigue crack width and stiffness loss of composite beams, and improve the durability and in normal use of composite beams in the hogging bending zone.展开更多
Combining with the technology of self-compacting concrete, self-stressing concrete and concrete-filled steel tube, we can get self-compacting and self-stressing concrete-filled steel tube. In order to study the expans...Combining with the technology of self-compacting concrete, self-stressing concrete and concrete-filled steel tube, we can get self-compacting and self-stressing concrete-filled steel tube. In order to study the expansive mechanism of self-stressing concrete, the continuous observation of 47 days on six specimens was carried on. The specimens have different steel area to concrete area ratio. The expansive process in hoop and axial direction were studied, and the expansive mechanism was discussed too. The experimental results identify that the creep and elastic deformation take a large proportion in effective free expansion. The calculating formulas of self-stress in hoop and axial directions were presented here.展开更多
The use of relaxation techniques in daily life is an effective means for the self-management of stress. Acupressure is a traditional technique where pressure is applied to acupuncture points instead of puncturing the ...The use of relaxation techniques in daily life is an effective means for the self-management of stress. Acupressure is a traditional technique where pressure is applied to acupuncture points instead of puncturing the skin. Self-administered acupressure is a potential method for dealing with stress. The effect of self-administered acupressure on anxiety has been examined but whether it can reduce perceived stress over longer periods is unknown. This study aimed to examine whether a self-administered, four-week acupressure intervention would reduce perceived stress over the past month. Fifteen male and nine female college students (age, 28.9 ± 8.51 yr) majoring in acupuncture and moxibustion medicine were randomly assigned to self-acupressure (AG) and control groups (CG). AG participants were instructed to conduct five sessions of acupressure in the morning, midday, and night. Each session included pressing six acupressure points on the neck (three points on the left and right side each) for five seconds. CG participants were asked to spend their daily life as usual. The outcome was the perceived stress level during the past month, which was assessed using a reliable and valid four-item scale. Perceived stress was measured at baseline, two weeks later, and after intervention. The stress level did not significantly differ between the two groups at baseline. In the AG, the stress level decreased from baseline to two weeks later and remained constant until the end of intervention. The stress level was significantly lower in the AG than in the CG only after intervention. These results provided initial evidence that self-administered acupressure reduces perceived stress over the past month.展开更多
Objective: To determine how self-compassion and empathy might influence the degree of burnout, secondary traumatic stress and compassion satisfaction among medical students and residents. Methods: Cross-sectional surv...Objective: To determine how self-compassion and empathy might influence the degree of burnout, secondary traumatic stress and compassion satisfaction among medical students and residents. Methods: Cross-sectional survey of medical students and select residency programs at Henry Ford Hospital in Detroit, Michigan. Respondents completed the Professional Quality of Life Scale (burnout, secondary traumatic stress and compassion satisfaction), Neff’s Self-Compassion Scale, and the empathic concern and personal distress subscales of the Interpersonal Reactivity Index. Results: The response rate was 28.6%. 23.9% and 27.3% of medical trainees reported high levels of burnout and secondary traumatic stress, respectively. Females reported greater empathy but lower self-compassion than males. Greater concern for others and oneself and lower personal distress predicted greater pleasure derived from professional work. Less concern for others and lower concern for oneself predicted greater burnout. Conclusions: Compassion for oneself and for others within their care appears to ameliorate burnout and can increase professional satisfaction. Initiatives to foster empathy and self-compassion may enhance individual well-being.展开更多
Requirements of self-compacting concrete （SCC） applied in pre-stressed mass concrete structures include high fluidity, high elastic modulus, low adiabatic temperature rise and low drying shrinkage, which cannot be s...Requirements of self-compacting concrete （SCC） applied in pre-stressed mass concrete structures include high fluidity, high elastic modulus, low adiabatic temperature rise and low drying shrinkage, which cannot be satisfied by ordinary SCC. In this study, in order to solve the problem, a few principles of SCC design were proposed and the effects of binder amount, fly ash （FA） substitution, aggregate content and gradation on the workability, temperature rise, drying shrinkage and elastic modulus of SCC were investigated. The results and analysis indicate that the primary factor influencing the fluidity was paste content, and the main methods improving the elastic modulusof SCC were a lower sand ratio and an optimized coarse aggregate gradation. Lower adiabatic temperature rise and drying shrinkage were beneficial for decreasing the cement content. Further, based on the optimization of mixture, a C50 grade SCC （with binder amount of only 480 kg/ m3, fly ash substitution of 40%, sand ratio of 51% and proper coarse aggregate gradation （Vs.~0 mm： V10-16 ram： V16.20 mm= 30%： 30%：40%）） with superior workability was successfully prepared. The temperature rise and drying shrinkage of the prepared SCC were significantly reduced, and the elastic modulus reached 37.6 GPa at 28 d.展开更多
Since a self-elevating platform often works in water for a long time, the lattice leg is largely influenced by wave and current. The amplitude of leg joint stresses is a very important factor for the fatigue life of t...Since a self-elevating platform often works in water for a long time, the lattice leg is largely influenced by wave and current. The amplitude of leg joint stresses is a very important factor for the fatigue life of the platform. However, there are not many researches having been done on the mechanism and dynamic stress analysis of these leg joints. This paper focuses on the dynamic stress analysis and suppression methods of the leg joints of self-elevating platforms. Firstly, the dynamic stresses of the lattice leg joints are analyzed for a self-elevating platform by use of the 5th-order Stokes wave theory. Secondly, the axial and bending stresses are studied due to their large contributions to total stresses. And then, different joint types are considered and the leg-hull interface stiffness is analyzed for the improvement of the joint dynamic stress amplitude. Finally, some useful conclusions are drawn for the optimization design of the self-elevating platform.展开更多
The Self-Similar Crack Expansion (SSCE) method is proposed to evaluate stress intensity factors at crack tips, whereby stress intensity factors of a crack can be determined by the crack opening displacement over the c...The Self-Similar Crack Expansion (SSCE) method is proposed to evaluate stress intensity factors at crack tips, whereby stress intensity factors of a crack can be determined by the crack opening displacement over the crack, not just by the local displacement around the crack tip. The crack expansion rate is estimated by taking advantage of the crack self-similarity. Therefore, the accuracy of the calculation is improved. The singular integrals on crack tip elements are also analyzed and are precisely evaluated in terms of a special integral analysis. Combination of these two techniques greatly increases the accuracy in estimating the stress distribution around the crack tip. A variety of two-dimensional cracks, such as subsurface cracks, edge cracks, and their interactions are calculated in terms of the self-similar expansion rate. Solutions are satisfied with errors less than 0.5% as compared with the analytical solutions. Based on the calculations of the crack interactions, a theory for crack interactions is proposed such that for a group of aligned cracks the summation of the square of SIFs at the right tips of cracks is always equal to that at the left tips of cracks. This theory was proved by the mehtod of Self-Similar Crack Expansion in this paper.展开更多
Post-Traumatic Stress Disorder (PTSD) is widely known in our society. The symptoms of PTSD are particularly believed to occur predominantly in children. We believe that Yogo teachers, who play a role in maintaining an...Post-Traumatic Stress Disorder (PTSD) is widely known in our society. The symptoms of PTSD are particularly believed to occur predominantly in children. We believe that Yogo teachers, who play a role in maintaining and promoting the health of children, are expected to provide appropriate support for children with a tendency for PTSD. In this study, we investigated the tendency for PTSD in students at University, as well as self-esteem related to depression and anxiety. Furthermore, we clarified the relationship between PTSD and self-esteem and examined the support provided by Yogo teachers. As a result, it was found that the higher the tendency for PTSD, the lower the self-esteem. We believe that the onset of PTSD causes a decline in memory ability and attentional function, which interferes with one’s life and leads to self-denial, resulting in a decline in self-esteem among those with a high tendency for PTSD. These results suggest that Yogo teachers should provide support to prevent the onset of PTSD in child students due to accidents, incidents, natural disasters, etc., as well as support to prevent the decline in self-esteem associated with the onset of PTSD.展开更多
Background: Cognitive restructuring and imagery modification for posttraumatic stress disorder (CRIM-PTSD) is a new intervention that involves only three sessions and focuses on the self-concept. It combines cognitive...Background: Cognitive restructuring and imagery modification for posttraumatic stress disorder (CRIM-PTSD) is a new intervention that involves only three sessions and focuses on the self-concept. It combines cognitive restructuring of core trauma-related dysfunctional beliefs and mental imagery. The effectiveness of CRIM-PTSD has recently been demonstrated in a pilot study. Method: This article presents a step-by-step description of the administration of CRIM-PTSD in a female survivor of childhood sexual abuse (CSA) suffering from PTSD and major depressive disorder related to strong self-blame. Results: The intervention showed substantial reductions in PTSD symptoms and depression in the patient comparable to those observed in the pilot study. Conclusions: CRIM-PTSD might provide an economical tool for reducing PTSD symptoms when only a short time is available for intervention. Furthermore, this tool could be included in well-established PTSD treatments. In addition to the pilot study, a randomized controlled trial is needed to further explore the feasibility and effectiveness of this short intervention.展开更多
Self-Compacting concrete is a concrete that is able to flow and consolidate under its own weight, completely fill the formwork even in the presence of dense reinforcement, whilst maintaining homogeneity and without th...Self-Compacting concrete is a concrete that is able to flow and consolidate under its own weight, completely fill the formwork even in the presence of dense reinforcement, whilst maintaining homogeneity and without the need for any additional compaction. Self-Compacting concrete is achieved by using high proportions of powder content and super?plasticizers. Due to this, pronounced thermal cracking is anticipated. Thermal cracking in concrete structures is of great concern. The objective of this research is to carry out experiments and investigate fresh and hardened properties of SCC developed using a blend of ordinary Portland cement and ground granulated blast furnace slag (GGBFS), to evaluate the applicability of Japan Concrete Institute (JCI) model?equations and?to find out any similarities and differences between Self-?Compacting concrete and normal vibrated concrete—Portland blast furnace slag concrete class B. Thermal stress analysis of the proposed Self-Compacting concrete and normal vibrated concretes were investigated by simulation using 3D FEM analysis. To carry out these objectives, concrete properties such as autogenous shrinkage, adiabatic temperature rise, drying shrinkage, modulus of elasticity, splitting tensile strength and compressive strength were determined through experiments. From experimental results, it was observed that except for the fresh properties, the hardened properties of Self-Compacting exhibit similar characteristics to those of normal vibrated concrete at almost similar water to binder ratios. It was also established that Self-Compacting concrete at W/B of 32% with a 50% replacement of ground granulated blast furnace slag has better thermal cracking resistance than SCC with 30% GGBFS replacement. It is also found that provided the relevant constants are derived from experimental data, JCI model equations can be applied successfully to evaluate hardened properties of Self-Compacting concrete.展开更多
基金Funded by the NSFC (No.50578027)the Key Subject Foundation of Henan Province (No.504906)the Doctor Foundation of Henan Polytechnic University (No.B2009-2)
文摘The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and tends to be constant after 25 days regardless of the restraining conditions. The mixture ratio of expansive cement and restraining conditions are the main factors affecting expansive deformation. Self-stress can be obtained when the expansive deformation is restrained. The higher self-stress could be obtained when the expensive concrete is restrained by steel tube. For specimens under steel tube restraining, the wall thickness and the length of the steel tube have important influence on self-stress. Both the radial self-stress and axial self-stress in concrete core increase when wall thickness or length of the steel tube increases.
基金Project supported by the Science and Technology of Department of Communications of Liaoning Province (Grant No.200514)the Science and Technology of Department of Education of Liaoning Province (Grant No.L2010378)
文摘Through the experiments of 7 T-section composite beams, steel fiber reinforced self-stressing concrete （SFRSC） as the composite beam in the composite layer was studied under the hogging bending. The tests simulated composite layer tensile strain under the hogging bending of inverted loading composite beams, giving the relationship under the different fatigue stress ratios between fatigue cycles and steel bar’s stress range, crack width, stiffness loss and damage, etc., in composite layer. This article established fatigue life equation, and analyzed SFRSC reinforced mechanism to crack width and stiffness loss. The results show that SFRSC as the composite beam concrete has excellent properties of crack resistance and tensile, can reinforce the fatigue crack width and stiffness loss of composite beams, and improve the durability and in normal use of composite beams in the hogging bending zone.
基金the National Natural Science Foundation of China (50578027)
文摘Combining with the technology of self-compacting concrete, self-stressing concrete and concrete-filled steel tube, we can get self-compacting and self-stressing concrete-filled steel tube. In order to study the expansive mechanism of self-stressing concrete, the continuous observation of 47 days on six specimens was carried on. The specimens have different steel area to concrete area ratio. The expansive process in hoop and axial direction were studied, and the expansive mechanism was discussed too. The experimental results identify that the creep and elastic deformation take a large proportion in effective free expansion. The calculating formulas of self-stress in hoop and axial directions were presented here.
文摘The use of relaxation techniques in daily life is an effective means for the self-management of stress. Acupressure is a traditional technique where pressure is applied to acupuncture points instead of puncturing the skin. Self-administered acupressure is a potential method for dealing with stress. The effect of self-administered acupressure on anxiety has been examined but whether it can reduce perceived stress over longer periods is unknown. This study aimed to examine whether a self-administered, four-week acupressure intervention would reduce perceived stress over the past month. Fifteen male and nine female college students (age, 28.9 ± 8.51 yr) majoring in acupuncture and moxibustion medicine were randomly assigned to self-acupressure (AG) and control groups (CG). AG participants were instructed to conduct five sessions of acupressure in the morning, midday, and night. Each session included pressing six acupressure points on the neck (three points on the left and right side each) for five seconds. CG participants were asked to spend their daily life as usual. The outcome was the perceived stress level during the past month, which was assessed using a reliable and valid four-item scale. Perceived stress was measured at baseline, two weeks later, and after intervention. The stress level did not significantly differ between the two groups at baseline. In the AG, the stress level decreased from baseline to two weeks later and remained constant until the end of intervention. The stress level was significantly lower in the AG than in the CG only after intervention. These results provided initial evidence that self-administered acupressure reduces perceived stress over the past month.
文摘Objective: To determine how self-compassion and empathy might influence the degree of burnout, secondary traumatic stress and compassion satisfaction among medical students and residents. Methods: Cross-sectional survey of medical students and select residency programs at Henry Ford Hospital in Detroit, Michigan. Respondents completed the Professional Quality of Life Scale (burnout, secondary traumatic stress and compassion satisfaction), Neff’s Self-Compassion Scale, and the empathic concern and personal distress subscales of the Interpersonal Reactivity Index. Results: The response rate was 28.6%. 23.9% and 27.3% of medical trainees reported high levels of burnout and secondary traumatic stress, respectively. Females reported greater empathy but lower self-compassion than males. Greater concern for others and oneself and lower personal distress predicted greater pleasure derived from professional work. Less concern for others and lower concern for oneself predicted greater burnout. Conclusions: Compassion for oneself and for others within their care appears to ameliorate burnout and can increase professional satisfaction. Initiatives to foster empathy and self-compassion may enhance individual well-being.
基金Funded by National Natural Science Foundation of China(Nos.U1134008 and 51302090)the Fundamental Research Funds for the Central Universities(No.2015ZJ0005)
文摘Requirements of self-compacting concrete （SCC） applied in pre-stressed mass concrete structures include high fluidity, high elastic modulus, low adiabatic temperature rise and low drying shrinkage, which cannot be satisfied by ordinary SCC. In this study, in order to solve the problem, a few principles of SCC design were proposed and the effects of binder amount, fly ash （FA） substitution, aggregate content and gradation on the workability, temperature rise, drying shrinkage and elastic modulus of SCC were investigated. The results and analysis indicate that the primary factor influencing the fluidity was paste content, and the main methods improving the elastic modulusof SCC were a lower sand ratio and an optimized coarse aggregate gradation. Lower adiabatic temperature rise and drying shrinkage were beneficial for decreasing the cement content. Further, based on the optimization of mixture, a C50 grade SCC （with binder amount of only 480 kg/ m3, fly ash substitution of 40%, sand ratio of 51% and proper coarse aggregate gradation （Vs.~0 mm： V10-16 ram： V16.20 mm= 30%： 30%：40%）） with superior workability was successfully prepared. The temperature rise and drying shrinkage of the prepared SCC were significantly reduced, and the elastic modulus reached 37.6 GPa at 28 d.
基金supported by the Shanghai Science Foundation of Important Projects for Post Doctoral Research, China (Grant No. 09R21421600)
文摘Since a self-elevating platform often works in water for a long time, the lattice leg is largely influenced by wave and current. The amplitude of leg joint stresses is a very important factor for the fatigue life of the platform. However, there are not many researches having been done on the mechanism and dynamic stress analysis of these leg joints. This paper focuses on the dynamic stress analysis and suppression methods of the leg joints of self-elevating platforms. Firstly, the dynamic stresses of the lattice leg joints are analyzed for a self-elevating platform by use of the 5th-order Stokes wave theory. Secondly, the axial and bending stresses are studied due to their large contributions to total stresses. And then, different joint types are considered and the leg-hull interface stiffness is analyzed for the improvement of the joint dynamic stress amplitude. Finally, some useful conclusions are drawn for the optimization design of the self-elevating platform.
文摘The Self-Similar Crack Expansion (SSCE) method is proposed to evaluate stress intensity factors at crack tips, whereby stress intensity factors of a crack can be determined by the crack opening displacement over the crack, not just by the local displacement around the crack tip. The crack expansion rate is estimated by taking advantage of the crack self-similarity. Therefore, the accuracy of the calculation is improved. The singular integrals on crack tip elements are also analyzed and are precisely evaluated in terms of a special integral analysis. Combination of these two techniques greatly increases the accuracy in estimating the stress distribution around the crack tip. A variety of two-dimensional cracks, such as subsurface cracks, edge cracks, and their interactions are calculated in terms of the self-similar expansion rate. Solutions are satisfied with errors less than 0.5% as compared with the analytical solutions. Based on the calculations of the crack interactions, a theory for crack interactions is proposed such that for a group of aligned cracks the summation of the square of SIFs at the right tips of cracks is always equal to that at the left tips of cracks. This theory was proved by the mehtod of Self-Similar Crack Expansion in this paper.
文摘Post-Traumatic Stress Disorder (PTSD) is widely known in our society. The symptoms of PTSD are particularly believed to occur predominantly in children. We believe that Yogo teachers, who play a role in maintaining and promoting the health of children, are expected to provide appropriate support for children with a tendency for PTSD. In this study, we investigated the tendency for PTSD in students at University, as well as self-esteem related to depression and anxiety. Furthermore, we clarified the relationship between PTSD and self-esteem and examined the support provided by Yogo teachers. As a result, it was found that the higher the tendency for PTSD, the lower the self-esteem. We believe that the onset of PTSD causes a decline in memory ability and attentional function, which interferes with one’s life and leads to self-denial, resulting in a decline in self-esteem among those with a high tendency for PTSD. These results suggest that Yogo teachers should provide support to prevent the onset of PTSD in child students due to accidents, incidents, natural disasters, etc., as well as support to prevent the decline in self-esteem associated with the onset of PTSD.
文摘Background: Cognitive restructuring and imagery modification for posttraumatic stress disorder (CRIM-PTSD) is a new intervention that involves only three sessions and focuses on the self-concept. It combines cognitive restructuring of core trauma-related dysfunctional beliefs and mental imagery. The effectiveness of CRIM-PTSD has recently been demonstrated in a pilot study. Method: This article presents a step-by-step description of the administration of CRIM-PTSD in a female survivor of childhood sexual abuse (CSA) suffering from PTSD and major depressive disorder related to strong self-blame. Results: The intervention showed substantial reductions in PTSD symptoms and depression in the patient comparable to those observed in the pilot study. Conclusions: CRIM-PTSD might provide an economical tool for reducing PTSD symptoms when only a short time is available for intervention. Furthermore, this tool could be included in well-established PTSD treatments. In addition to the pilot study, a randomized controlled trial is needed to further explore the feasibility and effectiveness of this short intervention.
文摘Self-Compacting concrete is a concrete that is able to flow and consolidate under its own weight, completely fill the formwork even in the presence of dense reinforcement, whilst maintaining homogeneity and without the need for any additional compaction. Self-Compacting concrete is achieved by using high proportions of powder content and super?plasticizers. Due to this, pronounced thermal cracking is anticipated. Thermal cracking in concrete structures is of great concern. The objective of this research is to carry out experiments and investigate fresh and hardened properties of SCC developed using a blend of ordinary Portland cement and ground granulated blast furnace slag (GGBFS), to evaluate the applicability of Japan Concrete Institute (JCI) model?equations and?to find out any similarities and differences between Self-?Compacting concrete and normal vibrated concrete—Portland blast furnace slag concrete class B. Thermal stress analysis of the proposed Self-Compacting concrete and normal vibrated concretes were investigated by simulation using 3D FEM analysis. To carry out these objectives, concrete properties such as autogenous shrinkage, adiabatic temperature rise, drying shrinkage, modulus of elasticity, splitting tensile strength and compressive strength were determined through experiments. From experimental results, it was observed that except for the fresh properties, the hardened properties of Self-Compacting exhibit similar characteristics to those of normal vibrated concrete at almost similar water to binder ratios. It was also established that Self-Compacting concrete at W/B of 32% with a 50% replacement of ground granulated blast furnace slag has better thermal cracking resistance than SCC with 30% GGBFS replacement. It is also found that provided the relevant constants are derived from experimental data, JCI model equations can be applied successfully to evaluate hardened properties of Self-Compacting concrete.
