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Showing 12 results for Wang

KWang-Suek Oh, Tae-Hyung Kim,
Volume 11, Issue 2 (Transaction B: Geotechnical Engineering 2013)

This study was conducted to determine the effect of vibration on the curing and compressive strength of lightweight air-trapped

soil (ATS). ATS is manufactured by mixing cement with water and sand and injecting bubbles into the mixture. It is light as

compared to regular soil, can reduce the weight on the ground, and has high fluidity. If ATS is used at construction sites with

many vibration sources, such as pile driving, blasting, and construction machinery, the effect of vibration needs to be seriously

considered. If a road is expanded using ATS to reduce traffic congestion, the ATS quality may decrease because of vibration

generated by traffic moving on the road. In particular, because ATS contains many air bubbles and needs time for curing, the

effect of vibration can be greater than expected. Therefore, the effect of vibration on ATS was evaluated during the curing process

by conducting unconfined compression tests on samples prepared with different values of variables including vibration velocity,

starting vibration time, and mixing ratio. Vibration velocities of 0.25 and 0.50 cm/s did not greatly affect the strength. However,

vibration velocities of above 2.50 cm/s significantly affected the decrease in strength, and the starting vibration time also had a

clear effect on specimens cured for less than 2 hours.

Jui-Chao Kuo, Teng-Yi Kuo, Cheng-Han Wu, Shih-Heng Tung, Ming-Hsiang Shih , Wen-Pei Sung, Weng-Sing HWang,
Volume 12, Issue 2 (Transaction A: Civil Engineering, June 2014)

In this study digital image correlation (DIC) technique combined with a high speed video system was used to predict movement of particles in a water model. Comparing with Particle-image velocimetry (PIV) technique, it provides a low cost alternative approach to visualize flow fields and was successfully employed to predict the movement of particles in a water model at different submergence depth using gas injection. As the submergence depth increases, the number of the exposed eye is reduced accordingly. At 26.4 cm submergence depth, an exposed eye was found at 1/3 of the submergence depth, whereas two exposed eyes were observed at 1/2 depth and near the bottom wall at 24 cm submergence depth.
H. Qi, D. Wang, P. Chen, Y. M. Bie,
Volume 12, Issue 3 (Transaction A: Civil Engineering September 2014)

A structural model for urban arterial road is proposed. It describes the road traffic dynamics in a disaggregated way. The structural model mainly includes: (1) a link traffic model that tracks the traffic waves cyclically. Traffic waves within each cycle are captured by three characteristic points. These points are formed by the encounter of different traffic waves. (2) a proportional line model which is used to split the overall outflow into different turning flow. The model is derived directly from first-in-first-out (FIFO) principle. (3) a spillover component that deals with channelized section queue overflow and (4) a traffic flow performance index component that outputs macroscopic and microscopic level indexes. These indexes include delay, stops, queue length and vehicle trajectory, travel time. The former three can be used in traffic flow optimization and the latter two are valuable in vehicle emission evaluation. Simulation results show that with the increasing of numerical resolution, traditional CTM model gradually converges to our model.
D. F. Cao, W. J. Ge, B. Y. Wang, Y. M. Tu,
Volume 13, Issue 1 (Transaction A: Civil Engineering March 2015)

In order to investigate the flexural behaviors of RC beams after freeze-thaw cycles, compressive strength test of concrete cubes after 0, 50, 100, 125 freeze-thaw cycles were made, and static flexural experiment of 48 RC beams after 0, 50, 100, 125 freeze-thaw cycles were made. The relationships of relative compressive strength, mass loss rate, relative dynamic elastic modulus and numbers of freeze-thaw cycles were analyzed. The influences of different numbers of freeze-thaw cycles on the flexural behaviors of RC beams with different concrete grades were studied. The results show that concrete cubes’ mass, relative dynamic elastic modulus and compressive strength decrease with the increasing of freeze-thaw cycles, and high-strength grade concrete could slow down the damage caused by freeze-thaw cycles. Experimental values of test beams stiffness under short-term load were smaller than theory value. Some under-reinforced RC beams occurs over-reinforced failure mode after freeze-thaw cycles. Boundary reinforcement ratio of RC beams after certain numbers of freeze-thaw cycles was derived and its correctness was verified by experiment. Current code for design of concrete structures about crack load and ultimate load are still suitable for RC beams after freeze-thaw cycles.
K. Wang, S.f. Yuan, D.f. Cao, W.z. Zheng,
Volume 13, Issue 2 (Transaction A: Civil Engineering June 2015)

This paper describes experimental and numerical investigations on two specimens of frames composed of steel reinforced concrete beam and angle-steel concrete column under horizontal low cyclic loading. Based on the test results, the relationship curves of the horizontal load-displacement and the failure modes are acquired. Meanwhile the hysteretic behaviors, skeleton curves, stiffness degradation, energy dissipation, residential deformation of the two specimens are studied. Nonlinear structural analysis program OpenSEES is employed to predict the experimental curves. Using the verified numerical model, the influences of slenderness ratio, axial compression ratio, steel ratio of column, cross-section moment resistance of I-shaped steel in beam, ratio of longitudinal rebars of beam and prestressing level on skeleton curves are investigated. The results indicated that the two specimens exhibited the favorable ductility and energy dissipation capacity, and the beam depth could be reduced to improve service function because of the application of the prestress. The ultimate horizontal load decreases with the increase of column slenderness ratio, and firstly increases then decreases with the increase of axial compression ratio. In the meantime, the descent segment of skeleton curve is smooth with the increase of column slenderness ratio, and becomes steeper with the increase of axial compression ratio.
Z.y. Wang, Q.y. Wang,
Volume 13, Issue 4 (Transaction A: Civil Engineering December 2015)

This paper presents a finite element analysis and its related experimental test of corrugated steel web beams subjected to fatigue loading. A particular focus in this study was set on the fatigue failure arising from the web-to-flange welded joint of the corrugated steel web beam. A detailed three-dimensional finite element model which explicitly includes the geometry of the web-to-flange welds along the corrugated web was developed to simulate the test corrugated web beam. The finite element model is verified by comparing with related fatigue experimental test results. The effective notch stress approach was also applied to analyse the web-to-flange welded joint replicating the local critical region in the corrugated web beam. The fatigue strength of the web-to-flange welded joint was evaluated and compared numerically by considering the stress distribution at potential fatigue crack initiation location. The fatigue life of the corrugated web beam was assessed numerically by incorporating material S-N relation and employing fracture mechanics approach. The comparison with the fatigue test results show that it is possible to expect the fatigue crack failure arising at the weld root or weld toe corresponding to the sections with reference angle using the effective notch stress analysis. The range of these predictions was evaluated by comparing with fatigue test results with accuracy and can be considered between AASHTO fatigue categories B and B’. The parametric notch stress analysis incorporating the influences of corrugation angle was performed and demonstrates it is possible to expect the fatigue crack failure arising at the weld root or weld toe. Finally, a practical solution for possible fatigue life enhancement of such structure is proposed by decreasing the corrugation angle or smoothing the intersection geometry of the corrugated web is suggested together with a moderate increase of the flange thickness.

H.s. Qi, Y. Y, Dian Hai Wang, Y.m. Bie,
Volume 13, Issue 4 (Transaction A: Civil Engineering December 2015)

Abstract: Gridlock is an extreme traffic state where vehicle cannot move at all. This research studies the development of gridlock by theoretical and numerical analysis. It is shown that the development of gridlock can be divided into several stages. The core of the development is the evolution of congestion loop. A congestion loop is comprised of a number of consecutively connected spillover links. The evolution of a congestion loop always tends to be stable, i.e. the state of all related links tends to be identical.. Under the stable condition, traffic states of all links are identical. A novel concept, “virtual signal” is proposed to describe the queue propagation and spillover during the stabilization. Simulation results show that congestion propagates in an accelerated way. The prevention of the first congestion loop is crucial. The achieved results have potential use for future network traffic control design and field applications

Dongfang Ma, Fengjie Fu, Weiming Zhao, Dianhai Wang, Sheng Jin,
Volume 14, Issue 5 (Transaction A: Civil Engineering 2016)

The purpose of this paper is to improve the intelligence and universality of classical method for gating control in the SCOOT system. Firstly, we introduce a method to identify spillovers, and use the occupancy threshold for spillover recognition to trigger this special control logic. Then we present an influence rate model for links upstream of the bottleneck link, and a share ratio model for the downstream links, after analyzing the interrelationship of the traffic flows among adjacent traffic links. With known threshold values for the influence rate and share ratio, we propose a rule and process for selecting the intersections that should be included in the sub-area of the gating control. Thirdly, we determine total capacity adjustments for the incoming and outgoing streams of bottleneck links, with the aim of dissipating the queue to a permissible length within a given period of time. After that, the apportion models for the total adjustments among different paths and links are presented, along with the correlation coefficients of the traffic flows between the bottleneck link and the other links. Next, we ascertain the capacity decrements and increments for the gated and benefiting streams, and define the optimization schemes so as to calculate splits for the gated and benefiting intersections. Finally, we evaluate the advanced method using a VISSIM simulation. The results show that new control method brings significant and positive effects to the bottleneck link itself and to the entire control area.

Tao Ma, Hao Wang, Yongli Zhao, Xiaoming Huang, Siqi Wang,
Volume 15, Issue 2 (Transaction A: Civil Engineering 2017)

This study evaluated the effects of Warm Mix Asphalt (WMA) additives on the compaction temperature and properties of Crumb Rubber Modified (CRM) asphalt binder and mixture. Two different WMA additives (named as Sas and Evm) were used to prepare warm-mix CRM asphalt binder and mixture. The viscosity of different warm-mix CRM asphalt binders and mastics were measured at different temperatures. The rheological and mechanical properties of different warm-mix CRM asphalt binders were tested. At the mixture level, the volumetric properties of different warm-mix CRM asphalt mixtures were experimented by Gyratory compactor at different temperatures and the performance of different warm-mix CRM asphalt mixtures were evaluated. It was found that, both of the two WMA additives could lower the compaction temperatures of CRM asphalt mixtures by 10°C~20°C. However, they have different influences on rheological properties of CRM binder and performance of CRM mixture. The Sas warm-mix additive can improve the anti-rutting performance of CRM mixture but may degrade its low-temperature performance and moisture stability. The Evm warm-mix additive has no adverse effects on the high-temperature and low-temperature performance of CRM asphalt mixtures and can improve its moisture stability.

Zhechao Wang, Ron C. K. Wong, Liping Qiao, Wenge Qiu,
Volume 15, Issue 3 (Transaction B: Geotechnical Engineering 2017)

The effects of effective stress and void ratio on the secondary compressibility of the sandy and clayey soils were investigated in this study. The coefficient of secondary compression of Ottawa sand in single stage and stepwise loading tests increases with effective vertical stress while that of saturated kaolinite decreases with effective vertical stress. Multi-staged loading tests showed that at a given effective stress, the higher the void ratios of the soils, the higher the coefficients of secondary compression of the soils are. It was concluded that the secondary compressibility of a soil depends on not only the effective stress, but also the void ratio of the soil. A general relationship between the coefficient of secondary compression, and effective stress and void ratio was proposed for soil. The discrepancy of the dependency of secondary compressibility on effective stress for different soils was well explained using this relationship, moreover, the quasi-overconsolidated state of clayed soil induced by time effect and the effect of surcharge preloading on the secondary compressibility of soft ground were discussed in light of the general relationship.

Yang Wang, Kai Su, Hegao Wu, Zhongdong Qian,
Volume 15, Issue 4 (Transaction A: Civil Engineering 2017)

The reinforced concrete bifurcation in hydropower station is consistently under high internal water pressure, and its diameter is usually larger than common duct junctions. In order to diminish or to decrease the heavy plastic zone and stress concentration, structure rounding is commonly used on bifurcation. This will bring some changes to the flow characteristic of bifurcation, and it is an interesting attempt to figure out the influence of structure rounding optimization. The Realizable k-ε model was employed in Computational Fluid Dynamics numerical simulation. The water pressure distribution was compared quantitatively at several certain sections. Furthermore, uneven pressure is analyzed by relative standard deviation. Hydraulic characteristics are discussed as well, including flow pattern, excavation volume and head loss in different working conditions. The results indicate that the pressure of pipe wall is uneven, and the maximum and minimum pressure value has a differential of 0.3% - 1.2% compared to relative static water pressure. The pressure unevenness will increase after structure rounding, and it has a positive correlation with structure rounding radius. At the same time, it is more reasonable for structure rounding in obtuse angle region than that in acute angle region, on account of well-distributed flow conditions and better economic benefit.

Xiaolei Chen, Jianping Fu, Feng Xue, Xiaofeng Wang,
Volume 15, Issue 4 (Transaction A: Civil Engineering 2017)

This paper presents a comparative numerical research on the overall seismic behavior of RC frames with different types of rebars (normal versus high strength rebar). A nonlinear numerical model is developed and is validated using experimental results. Comparing the numerical and experimental behaviors shows that the developed model is capable of describing the hysteretic behavior and plastic hinges development of the experimental RC frames with various strength longitudinal steel bars. The validated model is then used, considering the influences of axial load ratios and volumetric ratios of longitudinal rebars of column, to investigate the effects of reinforcement strength on the overall seismic behavior of RC frames. The simulation results indicate that utilizing high strength reinforcement can improve the structural resilience, reduce residual deformation and achieve favorable distribution pattern of plastic hinges on beams and columns. The frames reinforced with normal and high strength steel bars have comparable overall deformation capacity. The effect of axial load ratio on the energy dissipation, hysteretic curves and ultimate lateral load of frames with different strength rebars is similar. In addition, increasing the volumetric ratios of longitudinal rebars can increase the ultimate lateral load of frame and improve the plastic hinge distribution of frame.

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