Search

Glass fibre reinforced polymer (GFRP) pipelines are widely used in civil and offshore engineering owing to their good mechanical performance and light weight. However, typical structural problems, such as low radial stiffness, are still existing in the GFRP pipelines. In this paper, a novel GFRP sandwiched pipeline structure with a stiffened core was designed and was integrally fabricated by a newly developed multistage filament winding (MFW) technique. The radial stiffness of the GFRP stiffened pipe was investigated through a combination of theoretical, numerical and experimental methods. It was found the structural layer formed by GFRP webs combined with foam blocks effectively increase the stiffness with a considerable weight reduction for the newly proposed pipe structure. In addition, the mechanical behaviour of the stiffened pipe was precisely predicted by the adopted theoretical method and the proposed numerical model. Based on the validated model, the structural stability under confined load of the GFRP stiffened pipe was numerically studied and the failure map was constructed as a function of the related geometric parameters. The results provided a new concept for the pipeline structural design and a guidance for the geometric optimization of the proposed pipeline configuration. • A novel GFRP sandwiched pipe with stiffened core was designed to achieve the light-weight pipeline design. • An integrated fabrication technique, namely multi-stage winding, was developed to manufacture the stiffened pipe. • The stiffened pipe achieved a full use of structural layers, featured by a composite failure rather than a delamination. • The stiffened pipe achieved around 67% weight reduction comparing to the mortar pipe at the same stiffness level. [ABSTRACT FROM AUTHOR]

• Blast tests were conducted to study the combined loading effects and failure characteristics of two-way RC slabs. • Numerical simulation based on FEM-SPH (finite elements-smoothed particle hydrodynamics) method is in good agreement with experiments. • The effect of the standoff distances on the damage of the RC slabs is discussed, and analytical expressions are derived. This paper aims at investigation of failure characteristic of RC slabs under combined blast and fragment loading. With experimental device designed, blast tests were conducted to study the combined loading effects and failure characteristics of two-way RC slabs. Numerical studies based on FEM-SPH (finite elements-smoothed particle hydrodynamics) method were carried out and good agreement was obtained between numerical simulation and the testing results. The validated numerical model is then used to carry out parametric studies on damage classification. It is demonstrated that there was spall damage, penetration, crack and fragment in concrete slabs under combined loading. Besides, both explosive mass and standoff distance have profound effects on RC slab damage. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced composites (CFRP) and porous lattice structures possess the advantages of high specific strength and outstanding energy absorption efficiency. However, the structures combining their merits for underwater explosion protection receives little attention, and the underlying mechanics are still not clear. In this work, a CFRP-lattice sandwich structure is proposed, and its responses subjected to the underwater shock wave loading is studied via the finite element code ABAQUS/Explicit. The numerical results are first validated by the existing experiments (Huang et al., 2016), and the influences of the geometrical and load factors on the deformation modes and energy absorption performances are further explored. Results shows that with the variation of the load intensity and structural configuration, the failure modes of the plates can be mainly divided into three types. The failure occurs in the middle layer of the metal porous lattice core along the thickness direction. The thickness of the back plate has a greater influence on the overall deformation of the structure than that of the front plate. When the thickness of the back plate increases, the energy absorption of the front plate increases first and then decreases under the condition of a small shock wave load. The impact resistance of composite sandwich structure is the result of the coupling of core layer and plates. The proportion of energy absorption of each layer is affected by the form of structural energy transfer. The work of this paper provides guidance for the design of underwater protective equipment. • A novel CFRP-lattice sandwich structure was proposed. • The numerical and experiments results were in good agreement. • Three deformation modes of CFRP-lattice sandwich structure were summarized. • The effect of the geometrical factors and loading conditions on the energy absorption and deformation resistance performance were explored. • 71 various configurations were taken into consideration. [ABSTRACT FROM AUTHOR]

In the context of global warming, most researches have been conducted on health influences of heat waves, with limited understanding of health impacts of cold spells, especially for developing countries. We collected daily mortality and meteorological data for 31 capital cities across China during the maximum period of 2007–2013. A quasi-Poisson regression model combined with a distributed lag non-linear model was used to estimate the short-term effects of cold spells on mortality in cold seasons (November to March). 19 definitions of cold spell were clearly compared, including three definitions from the China Meteorological Administration (CMA) and 16 definitions by combining two temperature indicators (daily minimum and mean temperature), two temperature thresholds (3rd and 5th percentile) and four durations of at least 2–5 days. Then, a random effect meta-analysis was applied to pool the effect estimates at national level. Furthermore, a stratified analysis was constructed to identify the vulnerable subpopulations to cold spells. The definition, in which daily mean temperature falls below 5th percentile for at least two consecutive days, produced the optimum model fit performance. Generally, the mortality risk increased to the maximum after 3–6 days' exposure to cold spell and then leveled off in the next 3 weeks. The pooled relative risks (RR) of non-accidental mortality for cold spells were 1.03 (95% CI: 1.01–1.05), 1.27 (1.19–1.35) and 1.55 (1.40–1.70) at lag 0, lag 0–14 and lag 0–27 days, respectively. The greatest effect estimates of cold spells were found among total respiratory diseases and COPD, with RR of 1.88 (1.65–2.11) and 1.88 (1.58–2.19), respectively. The elderly, less-educated individuals and residents in southern China were more vulnerable to cold spells. There are remarkable mortality effects of cold spells, with effect estimates varying with the definition of cold spell and subpopulations. Using the official definition of cold spells may fail to capture the mortality risk associated with cold spells. These findings may facilitate the development of cold alert warning system and preventive actions to the vulnerable populations. • This is the first multicity study to comprehensively examine health-related cold spell definitions in China. • Using the official cold spell definition failed to capture its mortality risk around China. • The elderly, respiratory patients, less-educated persons and residents in southern China were more vulnerable to cold spells. [ABSTRACT FROM AUTHOR]

This paper designs two chiral compression–twist coupling lattice structures with positive Poisson's ratio (PPR) and negative Poisson's ratio (NPR), and studies their compressive mechanical behaviors. Experiments and finite element (FE) simulations under the quasi-static load are firstly done. Compared to the PPR case, the maximum rotation of the lattice structure with the NPR effect is increased over 40%. Then dynamic compressive mechanical behaviors of the PPR and NPR lattice structures are investigated with different velocities of loads. Impact resistance performances of present structures are further researched, and gradient designs are introduced to improve the impact resistance performance. It is found that different Poisson's ratios show great effects on quasi-static and dynamic mechanical behaviors. As the velocity of load increases, both the initial deformation region and initial compact region are closer to the side of the applied load. Under the middle velocity load, the NPR lattice structure shows the smaller initial peak stress but less energy absorption. With the further increase of load velocity, the PPR lattice structure presents both the better energy absorption and smaller stress peak. The positive gradient (PG) rises the energy absorption, while the negative gradient (NG) abates the peak stress. As the NG design is used, the peak stress of the NPR lattice structure decreases from 23.3 MPa to 16.5 MPa. Besides, gradient designs diminish discrepancies of mechanical behaviors caused by different Poisson's ratios. • Two new chiral compression–twist coupling structures are designed and fabricated. • Quasi-static tests are done and gained results can be used as benchmark solution. • Dynamic compressive behaviors of the structures are studied for the first time. • Compression processes show new phenomena and meaningful conclusions are gained. • Gradient designs are introduced and the impact resistance performances are improved. [ABSTRACT FROM AUTHOR]

• Explore the impact of hourly temperature variability in 31 Chinese capital cities. • Investigate the time window of hourly temperature variability. • 5.47% of non-accidental mortality could be attributed to temperature variability. • Female, old, or undereducated people were more affected by temperature variability. • Effect of temperature variability may be modified by season and temperature zone. In the context of ongoing climate change, temperature variability (TV) has been considered as an important trigger of death. However, evidence of association between mortality and hourly temperature variability (HTV) is scarce at the multi-city level, and the time window of health effects of HTV is lack of investigation. This study aims at quantifying the mortality risk and burden of HTV and exploring subpopulations susceptible to HTV from a large-scale multi-city perspective. Data on daily number of deaths and meteorology were collected for 31 Chinese major cities during 2007–2013. HTV was calculated as the standard deviation of hourly temperature within a few days. The optimal exposure period of HTV was chosen according to multiple scientific criteria. A quasi-Poisson regression combined with distributed lag nonlinear model was used to assess the city-specific HTV-mortality associations. Then, meta-analysis was further applied to pool city-specific effect estimates. Finally, we calculated the fraction of mortality attributable to HTV. Stratification analyses were conducted by individual characteristics (i.e. age, sex, and educational attainment), season, and region. HTV calculated in a relatively long-time window like 18 d (HTV 0–17) could capture the impact of HTV adequately. Per 1 °C raise of HTV 0–17 associated with 1.38% (95%CI: 0.77, 1.99) increase of non-accidental mortality. During the study period, 5.47% (95%CI: 1.06, 9.64) of non-accidental mortality could be attributed to HTV. The females, the elderly, and individuals with low education level were more susceptible to HTV than their counterparts, respectively. Moreover, a stronger HTV-mortality association was observed in individuals who live in warmer season and temperature zone. HTV is associated with a considerable mortality burden, which may be modified by season, geographic and individual-level factors. Our findings highlight the practical importance of establishing early warning systems and promoting health education to mitigate the impacts of temperature variability. [ABSTRACT FROM AUTHOR]