Abstract:Elastic modulus is one of the most important indexes to reflect material stiffness. Raining and freeze-thaw lead brick masonry to be in the state of unsaturated water freeze-thaw. The experiment aims to obtain the elastic modulus of ancient bricks under various unsaturated water freeze-thaw. The brick samples were put in the environmental chamber to carry out raining and freeze-thaw action. The experiment including saturated coefficient, saturated degree, dynamic elastic modulus and relative elastic modulus were carried out for these samples. Results show that the dynamic elastic modulus of the samples obviously decreases when saturated degree is equal to or larger than 60%; the elastic modulus of the samples have no significant change when saturated degree is less than 60%, and the samples break when their saturated degree reached a certain value. This paper also discusses parameters like limit saturated degree, which reflect the freeze-thaw resistance for ancient bricks.

Abstract:The effect of freeze-thaw cycle to the bonding performance between steel bar and fly ash concrete was analysed through pull-out test to steel bars attached strain gages inside. The results of pull-out test under different number of freeze-thaw cycle show that the bonding strength between steel bar and concrete decrease as the content of fly ash increasing; when the content of fly ash stay the same, with the number of freeze-thaw cycle increasing, the concrete compressive strength decline, and the bonding strength decrease; as the fly ash replacement rate stay 40%, with the number of freeze-thaw cycle increasing, the ultimate bonding strength decreased speed reduce, and the free end displacement corresponding to the ultimate bonding strength increase, which shows that mixed with a large number of fly ash can remit the freeze-thaw damage phenomenon, the bonding performance of reinforced concrete specimens under freeze-thaw environment is improved.

Abstract:The results of reanalyzing the testing method of sintered brick mortar rebound show that the carbonation depth has slight influence on the mortar rebound. Based on the results and analysis performed by Origin8.0,a sintered brick mortar rebound curve was shown between Standard mortar test block strength and mortar rebound value without considering the carbonation depth.

Abstract:Parallel Strand Bamboo (PSB) is a biocomposite composed of long narrow parallel bamboo strands which are adhesively bonded under high pressure. It has more and more attractive structural applications in building and construction engineering. It’s important to well understand the stress-strain relationship to develop the constitutive law and conduct the nonlinear analysis of PSB structures. The PSB was treated as an transversely isotropic composite in the experiment and the uniaxial parameters in each main material axis and the pure shearing parameters in each main material plane were proposed, and the corresponding stress-strain relationships of each stress state were also established. The results show that compared with common used woods in construction engineering, PSB has higher strengths with less variability. Strength of tension parallel to grain is nearly as twice as that of compression parallel to grain. In perpendicular to grain direction, the strength of tension is much lower than the that of compression. Shearing in transverse-to-grain plane presents lowest modulus and strength than those shearing in other two directions. The shearing strength in perpendicular to grain is as about 3 times as that of shearing in parallel to grain direction. The stress-strain relationships and the failure modes of PSB are significantly depended on the way in which the fiber participated. In parallel to grain direction, tensile damage almost entirely contributes to the broken of fibers, which shows the highest strength and brittle behavior among all stress states. In other cases, when the expending of failure cracks are restricted by fibers, the damage presents progressive process and higher strength, and the stress-strain relationships exhibit linearity in the earliear life while turn to nonlinearity in the later life of the specimens. When damages take place in matrix or in fiber-matrix interface without fibers involved in, the material shows lower strength, and the stress-strain curves present linear and brittle behavior.

Abstract:To study effects of deck roughness and large attack angle on vortex-induced vibration, wind tunnel test has been performed. First, deck roughness was obtained in numeric simulation and according to which, the best match sandpapers were selected for the experiment. Tests of bridge section model were performed with different kinds of attack angles and bridge deck roughness. The results show that the vertical and torsional vortex-induced vibration of flat steel box girder with a large aspect ratio increase at the large attack angle. When the bridge locates in the mountains, it is necessary to do bridge section model test at large attack angle. Deck roughness can reduce the vertical and torsional vortex-induced vibration.Deck roughness has influence on vortex-induced vibration which increases correspondingly with the decrease of the attack angle. Response of torsional vortex-induced vibration is more sensitive to deck roughness, and its range is greater than that of vertical vortex-induced vibration. The accuracy of deck roughness affects the reliability of wind tunnel test.

Abstract:The temporary supporting system also referred as time-dependent structural system during construction, consist of early-age reinforced concrete structures and formwork supporting system. It bears the load including the new concrete weight and the live construction load. A model of continuous beam with spring supports is put forward to analyze the mechanical characteristics of the reinforced concrete structures during construction. Based on-site measuring data, effective bearing area of members were used as statistical objects to calculate statistical parameters of live construction load of concrete buildings. By referring todomestic and foreign achievements, the the standard value of the live construction load was inverted with 95% reliability and standard value of live construction load of 2.5 kN/m 2. is recommended .

Abstract:An accelerated carbonation experimental analysis on carbonation resistance behavior of recycled concrete was carried out. The influence of recycled coarse aggregate replacement ratios, water cement ratios, cement content, the strength of natural concrete and the kinds of mineral admixture on the carbonation resistance of recycled concrete was studied. The results show that the carbonation depth decreases with the increase of water cement ratios and recycled coarse aggregate replacement ratios, while it increases with the growth of strength of natural concrete and cement content.Moreover, the addition of mineral admixture replacing cement partially can also decrease the carbonation depth of recycled concrete. Based on the current prediction models of natural concrete carbonation depth, the prediction model of recycled concrete carbonation depth wasestablished through regression analysis of experimental data from this paper and the results of the model agreed well with the experimental results from other researchers in China.

Abstract:A new adobe wall structure was proposed and mechanisms and seismic behavior were studied. Three pieces of the specimen of the new adobe wall structure were designed. Vertical loads and low cycle horizontal loads were applied on the specimen in order to study the failure process, failure mode, hysteretic curve and skeleton curve feature. The horizontal bearing capacity and deformation capacity of the wall were also examined. Meanwhile, attention was paid to the influence of the seismic details of the wall structure on anti-seismic capacity. Test results show that the failure mode of the new adobe wall is similar to that of reinforced concrete masonry wall. The new adobe wall has favorable bearing capacity and deformation capacity. In addition, its anti-seismic performance is affected by the new seismic measures, in particular the connection. Compared with the theoretical calculation results, it is feasible to build a two-story structure housing by the new adobe wall in the 7 degree fortification regions.

Abstract:Comparision of resistant behavior was made between two kinds of seismic strengthening methods for the single-story brick-wood structure with brick columns representative of existing rural buildings in Beijing, through shaking table tests on large-scale models. According to the seismic damages of unreinforced model test, the seismic strengthening measures were proposed, which included: (1) addition of a concrete window frame to increase the lateral stiffness of front longitudinal wall, (2) strengthening the walls, brick columns and under-window walls by using cement mortar to increase the carrying and deformation capacity, (3) addition steel ring beam to enhance the robustness of the structure. The results of testing damage and the dynamic characteristics parameters, such as, dynamic frequency, structural damping, acceleration dynamic coefficient, hysteresis curve etc., showed that the reinforcement measures significantly increased the seismic resistance of this kind of brick-wood structure. At same time, the reinforcement measures could achieve the seismic design target of “operational under minor earthquakes, repairable damage under design basis earthquakes, and collapse prevention under rare earthquakes.”

Abstract:When structure using energy dissipating device suffers from earthquake, its core materials will first go into the plastic yield stage and consume earthquake input energy by hysteretic deformation to protect the main structure. Therefore, the numerical simulation of core materials constitutive relation is the basis of seismic analysis and design with dissipation device. Theconstitutive relation of energy dissipation device under monotonic loading and cyclic loading elastic-plastic seismic response of the structure with energy dissipation device were investigated in the numerical simulation of monotonic constitutive relation, cyclic constitutive relation and skeleton curve of SN490B steel. The simulations include the four stages which are elastic stage, collapse stage, strain-hardening stage and secondary flow plastic stage of core material using Esmaeily-Xiao secondary flow plasticity model; the constitutive response of core materials under cyclic loading using combined hardening; the skeleton curve using the Ramberg-Osgood model, dimensionless Ramberg-Osgood skeleton curve model and double-linear model. Based on finite element software ABAQUS combined with numerical simulation parameters, numerical simulation of 16 different cyclic loading tests was conducted and compared with the test results. The results show that: mathematical model can be used to simulate the monotonic constitutive response, cyclic constitutive response and cyclic skeleton curve of SN490B steel accurately. Numerical simulation and experimental results fit well.

Abstract:Based on the characteristics of microstructure of foamed mixture lightweight soil using river sludge (FMLSS), the strength properties and failure mechanism of FMLSS are studied. The results show that when water content of FMLSS is constant,with the increase of bubble incorporation internal average equivalent aperture, the percentage of porosity area of FMLSS present linear increasing trend, while all of them decrease with the increase of cement incorporation. With the increase of bubble incorporation，the size uniformity of pore in FMLSS reduces, while improve with the increase of cement incorporation. The strength of FMLSS has obvious correlations with the microscopic parameters of FMLSS such as the equivalent aperture and uniformity of pore distribution. The results provided basis for the study of the strength of FMLSS and the mechanism of the damage.

Abstract:According to the urgent requirements for the winter heating in a rural residential in Chongqing, it has set up air-source heat pump heating system experiment platform. From the perspective of supply and return water temperature, power consumption, heat supply and coefficient of performance (COP), it has analyzed the system performance factors and phase characteristics (including starting, stable operation and whole stage) during operation, and the system has been very different characteristics in this three stages. Primarily, the initial temperature of the starting phase has obviously influenced COP of the system and when defrosting, it has a 25% drop in performance of the system. For stable operation of the stage, the performance and the initial temperature are not related. Reducing the set temperature, the COP has increased significantly, when there has been a good outdoor condition. Overall, COP in starting stage is the highest, then the whole stage, and COP of stable operation is lowest.

Abstract:A micro environment monitoring system has been developed to quantify the impact of micro environmental parameters on color decay of color paintings’ at Chinese classical garden. The environment parameters including temperature, humidity, velocity and sunlight in micro environment is a were recorded for the whole year at the Summer Palace. Besides, the color parameters of color painting were recorded periodically. Then fit curve graphs were obtained with dominant wavelength, excitation purity and luminance changed over time. Comparative analysis of micro environmental test data and color decay curve revealed that the temperature, humidity and wind speed has slight impact on the color of color painting, while sunlight is the dominant factor responsible for the color decay of painting. The extents to which the sunlight affect dominant wavelength, excitation purity and luminancewere different.are different on and impact of sunlight on different colors are different.

Abstract:To reveal the changing process of drivers’ pupil size during driving were carried out into of tunnels, experiments eight drivers drived into four tunnels at different time. And their pupil size were recorded with eye tracker in the driving process. The recorded raw data by eye tracker was analyzed, wavelet transforms method was taken to process the data, and the pupil size changing curves of drivers when they drive into tunnels. From the curves analysis, it has been found that the individual difference exist on different drivers’ pupil size; There was a degree of randomness of pupil sizes amone repeated test of the same driver; the drivers’ pupil enlarged gradually when they driving into tunnels, and enlarged violently nearby tunnel’s threshold; the pupil size changing tendency of different driver exists some difference; drivers’ pupil size was influence not only by adaptation luminance, but also by their psychological factors.

Abstract:The rapid development of city lighting and the population of LED have brought us excessive artificial outdoor light. Now there is no effective limitation for it. Based on subjective survey and objective measurement, we got the residents’subjective evaluation and the optical parameter of the light trespass, and identified 4 trespass sources, 5 classic factors(brightness, color, dynamic mode, light-emitting time and area) and 3 major trespass types (brightness trespass, colored trespass, dynamic trespass)of light trespass. And the parameter range was given to the main trespass factors of the 3 types light trespass.

Abstract:There is short of reliable methods to determine typical elements’ reference luminance at tunnel portals in a certain area. In order to solve this problem, the measured data of luminous climate of a year in Chongqing was firstly used to investigate the reflection of vertical illuminance on the typical elements’ luminance. The influencing factors were studied to develop the mathematical models of vertical conversion luminous efficacy and clearness index as well as solar altitude in four directions. Compared with the data collected inanother year in Chongqing, model shows relatively high precision. On the base of long-term continuous measurement of solar radiation and weather conditions among the luminous climate data, this method could be used to determine typical elements’ reference luminance at tunnel portals effectively and relatively accurately.

Abstract:The working principle of active chilled beams (ACBs) was analyzed on the basis of unlimited space jet theory and cooler heat exchanger theory. Inducement ventilation model and cooler heat exchanger model were built under the assumptions. The two models were combined to establish ACBs model. Primary air volume, secondary air volume, water side heat transfer amount etc were measured in five specified static pressure value. Induction ratio and refrigerating capacity were selected as two standards of ACBs performance parameters. The results of the consistency and differences of theoretical value with practical value verified the established model.

Abstract:n order to estimate the impact of groundwater advection on the performance of borehole heat exchangers under the intermittent operational mode, the solution of soil temperature response were programmed on the basis of the moving line heat source model and superposition principle by using MATLAB. The heat transfer processes of single borehole in the soil under the intermittent operational and continuous operational modes under the influence of groundwater advection were analyzed. Results show that the temperature change in the soil around borehole is influenced by the coupling of pipe heat flux, the soil thermal physical properties and the real advection velocity andespecially under the intermittent operation, the effect was significant.

Abstract:Ecological construction experience of traditional dwellings has been widely recognized. The construction technology of traditional houses on thermal environment has unique characteristics in Bayu region because of its special topography and climate. A rural earth building in Jiangjin district, Chongqing was used as the research object. Field measurement was carried out to record the residential indoor thermal environment throughout the year. and the data was adopted in numerical simulation analysis to evaluate indoor thermal conditions The results showed that the earth wall was more effective to for improve thermal environment in summer and indoor thermal environment in winter was far worse than that in summer. The attic space in earth building had significantly positive affect on indoor thermal environment because of its heat preservation in winter and heat insulation in summer.

Abstract:A time domain recursive algorithm was used to solve the model of coupled heat and moisture transfer equation through building wall. The calculation was carried out by using algorithm in wood.The recursive algorithm and the finite volume algorithm were separately used in the time and space domains respectively to obtain the linear equations of recursive form. The results were compared with that of finite difference algorithm and showed that the result of algorithm agreed with that of the finite difference algorithm, analytical solution and experimental data. The algorithm can be used to solve coupled heat and moisture transfer model in porous media. The change of the time step has slight effects on results and increasing time step would reduce the calculating time .