Experimental and numerical study regarding H-steel all-bolted connection steel frame with composite wall boards

H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were studied.The failure modes,hysteresis curves,bearing capacity,ductility,energy dissipation capacity,stiffness degradation and strain distribution were discussed.The calculation method of structural theoretical internal force was presented.The results showed that the overall structural seismic performance was better,and the structural ductility met the demands of elastic-plastic inter-story drift angle for seismic design.The H-steel weak-axis connection structure obtained better energy dissipation capacity,and its bearing capacity and stiffness were slightly different from the strong-axis connection.The heat preservation and decoration performance of composite wallboard and the all-bolted connection of the steel frame realized prefabrication during the whole construction period.The plastic hinge of the steel beam can be moved outwards because of the L-angles,which effectively avoids stress concentration in joint areas and expands the plastic hinge range.The errors between the theoretical structural capacity calculated by the plastic analysis method and the test results were within 2.44%.In addition,structural failure mechanisms and bearing capacities were verified by the finite element(FE)analysis,and the effects of the main parameters on the structures were investigated.The FE verification results were the same as in the test.The research results provide theoretical support and technical guidance for the application of thermal insulation and decorative composite wall panels in H-shaped steel all-bolted steel frames.

Numerical Investigation of the Thermal Behavior of a System with a Partition Wall Incorporating a Phase Change Material

The work deals with the thermal behavior of a conventional partition wall incorporating a phase change material(PCM).The wall separates two environments with different thermal properties.The first one is conditioned,while the adjacent space is characterized by a temperature that changes sinusoidally in time.The effect of the PCM is assessed through a comparative analysis of the cases with and without PCM.The performances are evaluated in terms of dimensionless energy stored within the wall,comfort temperature and variations of these quantities as a function of the amount of PCM and its emplacement.

Shear resistance performance of steel-concrete-steel composite shear wall

For a deeper understanding of the shear resistance performance of the steel-concrete-steel composite shear wall, the main influence factors such as the thicknesses of the steel plates and the concrete, the strength grades of the concrete and the span-depth ratios of the composite wall, which have impacts on the shear resistance performance of the composite shear wail, are analyzed by the numerical simulation method. Meanwhile, the simplified calculation formulae of the initial elastic lateral-resisting stiffness and the shear bearing capacity of the composite shear wall are also proposed. The research shows that with the increase in the thicknesses of the steel plates and the concrete and the increase in the strength grades of the concrete, the shear performance of the shear wall improves obviously; the span-depth ratios of the composite wall have a significant effect on the initial elastic lateral- resisting stiffness, but a small effect on the shear bearing capacity. Comparing the results of the simplified calculation formulae with those of the nonlinear finite element method, it is obvious that the presented formulae are reasonable and meet the real force state of the structure. These conclusions can serve as a preliminary design reference for the steel-concrete- steel composite shear wall.

Experimental and analytical study on seismic behavior of steel-concrete multienergy dissipation composite shear walls

In this paper, a steel-concrete multi-energy dissipation composite shear wall, comprised of steel-reinforced concrete （SRC） columns, steel plate （SP） deep beams, a concrete wall and energy dissipation strips, is proposed. In order to study the multi-energy dissipation behavior and restorability after an earthquake, two stages of low cyclic loading tests were carded out on ten test specimens. In the first stage, test on five specimens with different number of SP deep beams was carried out, and the test lasted until the displacement drift reached 2%. In the second stage, thin SPs were welded to both sides of the five specimens tested in the first stage, and the same test was carried out on the repaired specimens （designated as new specimens）. The load-bearing capacity, stiffness, ductility, hysteretic behavior and failure characteristics were analyzed for both stages and the results are discussed herein. Extrapolating from these results, strength calculation models and formulas are proposed herein and simulations using ABAQUS carried out, they show good agreement with the test results. The study demonstrates that SRC columns, SP deep beams, concrete wall and energy dissipation strips cooperate well and play an important role in energy dissipation. In addition, this study shows that the shear wall has good recoverability after an earthquake, and that the welding of thin SP＇s to repair a deformed wall is a practicable technique.

A case study on behaviors of composite soil nailed wall with bored piles in a deep excavation

A complete case of a deep excavation was explored. According to the practical working conditions, a 3D non-linear finite element procedure is used to simulate a deep excavation supported by the composite soil nailed wall with bored piles in soft soil. The modified cam clay model is employed as the constitutive relationship of the soil in the numerical simulation. Results from the numerical analysis are fitted well with the field data, which indicate that the research approach used is reliable. Based on the field data and numerical results of the deep excavation supported by four different patterns of the composite soil nailed wall, the significant corner effect is founded in the 3D deep excavation. If bored piles or soil anchors are considered in the composite soil nailed wall, they are beneficial to decreasing deformations and internal forces of bored piles, cement mixing piles, soil anchors, soil nailings and soil around the deep excavation. Besides, the effects due to bored piles are more significant than those deduced from soil anchors. All mentioned above prove that the composite soil nailed wall with bored piles is feasible in the deep excavation.

Lateral load-carrying capacity analyses of composite shear walls with double steel plates and filled concrete with binding bars

A method is developed to predict the lateral load-carrying capacity of composite shear walls with double steel plates and filled concrete with binding bars(SCBs). Nonlinear finite element models of SCBs were established by using the finite element tool, Abaqus. Tie constraints were used to connect the binding bars and the steel plates. Surface-to-surface contact provided by the Abaqus was used to simulate the interaction between the steel plate and the core concrete. The established models could predict the lateral load-carrying capacity of SCBs with a reasonable degree of accuracy. A calculation method was developed by superposition principle to predict the lateral load-carrying capacity of SCBs for the engineering application. The concrete confined by steel plates and binding bars is under multi-axial compression; therefore, its shear strength was calculated by using the Guo-Wang concrete failure criterion. The shear strength of the steel plates of SCBs was calculated by using the von Mises yielding criterion without considering buckling. Results of the developed method are in good agreement with the testing and finite element results.

Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

A composite shear wall concept based on concrete filled steel tube （CFST） columns and steel plate （SP） deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements： CFST columns; SP deep beams; and reinforced concrete （RC） strips. The RC strips are intended to allow the core structural elements - the CFST columns and SP deep beams - to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

Experimental study on axial compressive behaviors of prefabricated composite thermal insulation walls after single-side fire exposure

The axial bearing capacity of prefabricated composite walls composed of inner and outer concrete wythes,expandable polystyrene(EPS)boards and steel sleeve connectors is investigated.An experimental study on the axial bearing capacity of four prefabricated composite walls after fire treatment is carried out.Two of the prefabricated composite walls are normal-temperature specimens,and the others are treated with fire.The damage modes and crack development are observed,and the axial bearing capacity,lateral deformation of the specimens,and the concrete and reinforcing bar strain are tested.The results show that the ultimate bearing capacity of specimens after a fire is less than that of normal-temperature specimens;when the insulation board thicknesses are 40 mm and 60 mm,the decrease amplitudes are 20.8%and 16.8%,respectively.The maximum lateral deformation of specimens after a fire is greater than that of normal-temperature specimens,and under the same level of load,the lateral deformation increases as the insulation board thickness increases.Moreover,the strain values of the concrete and reinforcing bars of specimens after a fire are greater than those of normal-temperature specimens,and the strain values increase as the thickness of insulation board increases.

Shear-resistant behavior of light composite shear wall

Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan.The analysis results show that this kind of composite wall panel works very well,and can be regarded as a solid panel.The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play.Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.

Experimental study on out-of-plane seismic performance of precast composite sidewalls of utility tunnel with grouting-sleeve joints

The precast composite reinforced concrete wall with the advantages of fewer joints,superior impermeability and rapid construction provides an efficient and environmental friendly alternative in the construction of underground utility tunnels in the last few years.To investigate the seismic performance of precast concrete composite walls of utility tunnels with grouting-sleeve connection under out-ofplane loads,a series of quasi-static cyclic tests were performed on the full-scale sidewall specimens with different axial compression ratios in this study.The experimental results including the failure modes,crack distributions,and the influence of different connections on the out-of-plane seismic performance of precast concrete composite wall were carefully examined and compared with those from the cyclic tests of the cast-in-place sidewalls of the utility tunnel.The test results show that the seismic performance of the precast concrete composite sidewall specimen,such as the hysteresis curves,the ultimate bearing capacity,stiffness degradation pattern and the ductility ratio,is basically the same as that of the cast-in-place specimen,indicating that the seismic performance of the prefabricated structure is equivalent to that of the cast-in-place structure.Moreover,the grouting-sleeves of the joints can effectively transfer the reinforcement stress until the failure of the precast concrete composite sidewall specimens,which exhibits excellent out-of-plane ductility and serviceability.

Shear-Resistant Behavior Analysis of Light Composite Shear Walls

Shear test results for a composite wall panel in a light composite structure system are compared with test results for shear walls in Japan in this paper. The analysis results show that this kind of composite wall panel works very well, and can be regarded as a solid panel. The composite wall panel with a hidden frame is essential for bringing its effect on shear resistance into full play. Comprehensive analysis of the shear-resistant behavior of the composite wall panel suggests that the shear of the composite shear wall panel can be controlled by the cracking strength of the web shearing diagonal crack.

Numerical Study of Classical and Composite Solar Walls by TRNSYS

The laboratory LAMTI has worked for several years on the study and the optimization of the thermal performances of passive solar walls like solar Trombe wall. These components of the buildings envelope have very complex behaviour because they are the seat of various coupled heat transfers modes and are subjected to the random variations of the meteorological parameters. Using the finite difference method （FDM） and starting from experimental results recorded during several years, a simulation model was developed and validated concerning the ＂composite＂ Trombe wall. In order to make this work more accessible to the community of the heat engineers, it appears interesting to build a simulation model which can be integrated into the library of elements of the TRNSYS software. A ＂Type＂ was thus carried out and the results obtained compared with those of the FDM model. In this work we compare the obtained results with these two numerical ways. The assumptions and the results of simulations are also confronted with those of an existing module in TRNSYS （Type 36） established for the ＂classical＂ Trombe wall. The study shows that the models that we developed are very precise and that certain assumptions must be used with a lot of precautions. The advantages of the composite Trombe solar wall compared to the Classical Trombe wall are highlighted for cold and/or cloudy climates.

Numerical characteristics of the full operator hybrid simulation method

The full operator method （FOM） has been proposed to overcome some of the shortcomings of the commonly used operator splitting method （OSM）. In particular, the FOM is improved by increasing the accuracy of both the predictor and corrector using the estimated tangent stiffness of the tested structure. The numerical characteristics of the FOM, including stability and accuracy, are investigated in this study. It is shown that FOM is conditionally stable. The stability and accuracy characteristics are dependent on the accuracy of the estimated tangent stiffness and the parameters associated with the acceleration variation in the time-stepping integration method. Mass-spring systems with different types of nonlinearity, including hardening, stiffening, and softening behavior, are used to evaluate the performance of the FOM. It is found that the FOM can capture these types of nonlinearity with satisfactory accuracy. Using a prototype 12-story composite coupled wall system, the influences of the strong nonlinearity of the system as well as the displacement control errors from hydraulic actuators on the performance of the FOM are explored. The results show that the FOM is capable of generating reasonably accurate results despite the presence of strong structural nonlinearity and displacement control errors.

Experimental research on the seismic behavior of CSPSWs connected to frame beams

The seismic performance of composite steel plate shear walls （CSPSWs） that consist of a steel plate shear wall （SPSW） with reinforced concrete （RC） panels attached to one or both sides by means of bolts or connectors is experimentally studied. The shear wall is connected to the frame beams but not to the columns. This arrangement restrains the possible out-of-plane buckling of the thin-walled steel plate, thus significantly increasing the bearing capacity and ductility of the overall wall, and prevents the premature overall or local buckling failure of the frame columns. From a practical viewpoint, these solutions can provide open space in a floor as this type of composite shear walls with a relatively small aspect ratio can be placed parallel along a bay. In this study, four CSPSWs and one SPSW were tested and the results showed that both CSPSWs and SPSW possessed good ductility. For SPSW alone, the buckling appeared and resulted in a decrease of bearing capacity and energy dissipation capacity. In addition, welding stiffeners at corners were shown to be an effective way to increase the energy dissipation capacity of CSPSWs.

Assessment of fodder quality of leaves of multipurpose trees in subtropical humid climate of India

The leaves of 12 species （Acacia auriculiformis, Albizzia procera, Dalbergia sissoo, Gliricidia maculata, Leucaena leuco- cephala, Samanea saman, Azadirachta indica, Eucalyptus hybrida, Gmelina arborea, Michelia champaca, Morus alba, and Tectona grandis） of Multipurpose trees and shrubs （MPTs） grown in the agroforestry arboretum were evaluated for their nutritional characteristics in terms of proximate composition, cell wall constituents, total tannins, major （Ca and P） and trace minerals （Fe, Cu, Zn, Mn and Co）, in vitro dry matter and organic matter digestibility （IVDMD and IVOMD） and metabolisable energy （ME） values. There were significant （P〈0.01） variations among MPTs for all parameters studied. The average values of （92.02±0.30）%, （16.00±0.74）%, （3.05±0.13）%, （18.97±1.07）%, （54.00±1.12）% and （7.98 ± 0.30）% （DM basis） were observed for OM （organic matter）, CP （crude protein）, EE （ether extract）, CF （crude fibre）, NFE （nitrogen-free extract） and total ash, respectively. Leguminous trees had high CP compared to nonleguminous ones （18.30% vs 13.70%）. The mean values for cell wall constituents viz., NDF （neutral detergent fibre）, ADF （acid detergent fibre）, hemi cellulose, cellulose and ADL （acid detergent lignin） were found to be （52.48±1.05）%, （31.72±0.97）%, （20.76±0.88）%, （16.97±0.70）% and （9.57±0.62）%, respectively. The total tannin contents averaged （4.22±0.32）%. The ratio of Ca to P was quite wider. The levels of Fe and Mn were adequate to rich in all the MPTs while many of the tree species possessed P, Cu, Zn and Co level below the critical limits for the animals. The average IVDMD and IVOMD values were found to be （48.96±1.30）% and （50.69±1.36）%, respectively. The ME value averaged （6.95i-0.11） MJ·kg-1 DM. The CP content had significant positive correlation with IVDMD, IVOMD and ME val- ues while NDF, ADF, ADL and total tannins showed negative correlations with these three parameters. Based on the results, Leucaena Leucocephala could be considered as good quality fodder as it had the highest level of IVDMD/IVOMD （65.20%/67.66%） and ME （7.95 MJ·kg-1 DM） while G. maculata, M. alba, A. indica, D. sissoo and S. saman were of medium type and rest of poor quality.

Microstructure and Properties of Cement Foams Prepared by Magnesium Oxychloride Cement

Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams（MOCF） with various MgO powders and water mixture ratios were studied. Their infl uences on compressive strength, water absorption and resistance of MOCF were also discussed in detail. The experimental results indicated that moderate and slight excess MgO powders（MgO/MgCl2 molar ratios from 5.1 to 7） were beneficial to the formation of excellent microstructure of MOCF, but increasing water contents（H2O/MgO mass ratios from 0.9 to 1.29） might result in opposite conclusions. The microstructure of MOCF produced with moderate and slight excess MgO powders could enhance the compressive strength, while serious excess MgO powders addition（MgO/MgCl2 molar ratios = 9） would destroy the cell wall structures, and therefore decrease the strength of the system. Although MOCF produced with excess MgO powders could decrease the water absorption, its softening coefficient was lower than that of the material produced with moderate MgO powders. This might be due to the instability of phase 5, the volume expansion and cracking of cell walls as immersed the sample into water.

Effect of Chitin Treatment on Softening of Actinidia arguta

[Objectives] This study was conducted to discuss the effect of chitin treatment on softening of Actinidia arguta Huanyou No. 1 as the test material.[Methods]Huanyou No. 1 was sprayed with chitin,and the changes of some physiological and biochemical indexes in fruit softening were investigated. [Results]Chitin treatment significantly improved single fruit weight,increased soluble solid content,but decreased titratable acid content and significantly reduced the content of cellulose and hemicellulose; and the chitin treatment significantly inhibited the breakdown of pectin,cellulose and hemicellulose,and inhibited the activities of PG enzyme and β-Gal enzyme. [Conclusions] Chitin spray treatment could increase the yield of A. arguta,and improve its quality and storage property.

Sound Insulation Performance of Structural Wood Wall Integrated with Wood Plastic Composite

The sound insulation performance is an important technical index for evaluating the physical property of the building wall.Three kinds of structural wood walls integrated with wood plastic composite(WPC)were designed.And the sound insulation performance of the walls was studied.The results showed that for the wall that constructed by the WPC as the wall studs,compared with the one that constructed by the pine wood as the wall studs,the deviation of their sound insulation was lower than±3 dB.The wall’s external panel material had significant effect on the wall’s sound insulation property,and the contribution of the wood-plastic panel to the sound insulation was much higher than that of the polyvinyl chloride(PVC)plastic hanging board.The surrounding sealing quality of the wall’s external panel material had an important influence on the sound insulation effect of the building wall,and the panel of the wood plastic interior wall had less influence on the sound insulation performance of the wall.Taking the sound-absorbing cotton or non-woven fabric as elastic strips was an effective technical measure to improve the sound insulation performance of the walls.The sound insulation was improved by 2.4 dB and 3.1dB respectively after the correction of pink noise spectrum,and increased by 2.8 dB and 3.6 dB respectively after the correction of traffic noise spectrum.

Wood forming tissue-specific expression of PdSuSy and HCHL increases holocellulose content and improves saccharification in Populus

Development of strategies to deconstruct lignocellulosic biomass in tree species is essential for biofuels and biomaterials production.We applied a wood forming tissue-specific system in a hybrid poplar to express both PdSuSy(a sucrose synthase gene from Populus deltoides×P.euramericana that has not been functionally characterized)and HCHL(the hydroxycinnamoyl-CoA hydratase-lyase gene from Pseudomonas fluorescens,which inhibits lignin polymerization in Arabidopsis).The PdSuSy-HCHL overexpression poplars correspondingly driven by the promoters of Arabidopsis AtCesA7 and AtC4 H resulted in a significant increase in cellulose(>8%),xylan(>12%)and glucose(>29%)content,accompanying a reduction in galacturonic acid(>36%)content,compared to control plants.The saccharification efficiency of these overexpression poplars was dramatically increased by up to 27%,but total lignin content was unaffected.These transgenic poplars showed inhibited growth characteristics,including>16%reduced plant height,>10% reduced number of internodes,and>18% reduced fresh weight after growth of 4 months,possibly due to relatively low expression of HCHL in secondary xylem.Our results demonstrate the structural complexity and interaction of the cell wall polymers in wood tissue and outline a potential method to increase biomass saccharification in woody species.

Identification of Quantitative Trait Loci Affecting Hemicellulose Characteristics Based on Cell Wall Composition in a Wild and Cultivated Rice Species

Cell wall hemicellulosic polysaccharides are structurally complex and diverse. Knowledge about the synthesis of cell wall hemicelluloses and their biological roles is limited. Quantitative trait loci （QTL） mapping is a helpful tool for the dissection of complex phenotypes for gene identification. In this study, we exploited the natural variation in cell wall monosaccharide levels between a common wild rice, Yuanj, and an elite indica cultivar, Teqing, and performed QTL map- ping with their introgression lines （ILs）. Chemical analyses conducted on the culms of Yuanj and TeqJng showed that the major alterations are found in glucose and xylose levels, which are correlated with specific hemicellulosic polymers. Gly- cosidic linkage examination revealed that, in Yuanj, an increase in glucose content results from a higher level of mixed linkage I^-glucan （MLG）, whereas a reduction in xylose content reflects a low level of xylan backbone and a varied arabi- noxylan （AX） structure. Seventeen QTLs for monosaccharides have been identified through composition analysis of the culm residues of 95 core ILs. Four major QTLs affecting xylose and glucose levels are responsible for 19 and 21% of the phenotypic variance, respectively. This study provides a unique resource for the genetic dissection of rice cell wall forma- tion and remodeling in the vegetative organs.