A slope model that shows the geogrid structural construction at the Nanning outer ring expressway is established using FLAC3D after the property of typical expansive soil in Nanning was tested. Geogrid-soil interaction in the dry-wet cycle affected zone of the slope is analyzed by thermo-mechanical coupling module in FLAC3D based on the similarity between the thermal effect of temperature variation and expansion effect of hygroscopic expansion of expansive soil. The development rule of stress, deformation, and generalized plastic strain in the turn-up geogrid flexible reinforcement of cut slope in expansive soil are obtained. The "frame hoop" mechanism of flexible reinforced cut slope in expansive soil is analyzed and verified according to the stress and deformation of the geogrid in the cut slope in the expansive soil. The results are compared with the stress, strain, and stability of untreated cut slope in expansive soil.

This paper presents a virtual uniaxial creep testing method. Different gradations were selected, and the X-ray CT was used to scan the asphalt specimens non-destructively in order to predict the deformation of asphalt mixture and verify the feasibility of the proposed method. Moreover, the finely distributed information of asphalt mixture microstructure, including aggregates, sand mastic and air voids, were captured. The 3D virtual specimen reflecting the real microscale distribution of asphalt mixture was created according to the developed 3D reconstruction theory and algorithm. Considering the Burgers visco-elastic consecutive relations of sand mastic, the visco-elastic state of sand mastic was transformed to the Prony parameters identified by finite element by using the Boltzmann superposition principle and Laplace theory. Finally, the virtual uniaxial creep testing was conducted. Results show that the predicted deformations agree well with the testing results. The proposed virtual uniaxial creep method accurately reflects different deformations for different gradations, thus overcoming the defects of conventional numerical simulation based on homogeneous specimen.

Considering the obvious wave impedance difference between dry crust and soft the phenomenon of dynamical stress mutation at the hard-soft soil interface, which is a specific performance of shell effect of dry crust in dynamic scope, is revealed by the transmission coefficient based on stress-wave theory. The attenuation law of vertical dynamic stress peak in subgrade soil under vehicle load is obtained by numerical simulation. Based on the negative exponential function characteristic of an attenuation curve, a transfer coefficient at soil layer interface is derived. This coefficient can synthetically represent the law of dynamical stress mutation. The corresponding calculation method and application range of the transfer coefficient are offered. This calculation method has simpler processing and higher precision than existing methods based on monitoring data verification. By practice validation of expressway engineering, the mechanical state of subgrade soil can be correctly evaluated, and its residual deformation can be reduced considering the dynamic response characteristic of layer interface of soft soil subgrade with dry crust.

To study the over-consolidation stress history of clay in a high-filled embankment during hierarchical compaction, indoor compaction and one-dimensional consolidation tests are performed on roadbed backfill clay. Two homemade compaction devices are used to drill into standard heavy compacted clay to prepare compacted clay samples and subsequently investigate the influence of compaction work, compaction impulse, water content, and compaction degree on over-consolidation stress history. Results provide an experimental basis to determine the parameters of an over-consolidated constitutive model. Experimental results show that compacted clays with the same compaction degree and water content can differ in stress history, and that this stress history increases as the compaction impulse per unit area builds up. Under the conditions of the same compaction work and over-consolidated formation, the compacted clay achieves the maximum compaction degree and stress history if water content is at the optimal level. If the water content deviates from the optimal level, the stress history of the compacted clay decreases, and it is more significantly affected by the compaction degree with increased water content.

To evaluate the shear lag effect of a single-box multi-cell girder with corrugated steel webs objectively and accurately, the shear lag warping displacement function of a box girder with corrugated steel webs was proposed. This function was created by combining the calculated characteristics of a single-box multi-cell concrete box girder. By using the energy variational method, the basic differential equation of twin- and triple-cell box girders with corrugated steel webs was presented with consideration to the effect of shear lag. An example was analyzed by using both the solution of FEM and the presented method to study the distribution of shear lag under concentrated load and full-span uniformly distributed load, respectively.The effect of span-width ratio on the shear lag was also discussed. Research result shows that the FEM solutions and analytical solutions are in good agreement, but differences can be observed in the junctions of roof and floor box girder with corrugated steel webs. Furthermore, the overhanging edge of the cantilever plate needs to be revised. The corresponding shear lag coefficient presented in the study can be used as a reference value of the shear lag coefficient in box girder bridges with corrugated steel webs.

To extract the temperature effect component of the dynamic strain signal through empirical mode decomposition(EMD), which presents the shape of a cycle trend measured from a bridge, the intrinsic mode function (IMF) order number by which temperature strain is constructed should be ascertained. The problem is solved on the basis of the selection of the IMF order threshold. The energy of signal of the IMF is analyzed in the time and frequency domains, and the threshold of the IMF order is acquired through a synthetic analysis of the energy catastrophe order and the correlation coefficient of the Hilbert marginal spectrum. Finally, the temperature effect component of the strain data is extracted by selecting the cycle trend of the IMF according to the IMF order threshold. The result shows that (1) the periodic trend component of a dynamic strain leads to the order catastrophe of the IMF energy from which the value range of the IMF order threshold is preliminarily determined; (2) the correlation coefficient of the IMF marginal spectrum increases rapidly to over 0.8 by analyzing the energy distribution in the frequency domain of the IMF located in a preliminarily determined range. The energy distribution patterns of last-order IMFs were consistent. By applying the method to the in-situ data, the result demonstrates that the IMF order threshold can be precisely obtained by the first correlation coefficient of the IMFs marginal spectrum of over 0.8. After the temperature effect component is extracted based on the threshold, the live load information in the dynamic strain is properly retained.

Parametric expressions of the normal and lognormal-distribution functions are derived by the maximum-likelihood method, whereas parametric expressions of the Weibull distribution function are derived by the least-square method. Based on a 48 h real-time survey of random vehicle loads on the Aizhai bridge, some parameters were analyzed and optimally fitted. These parameters were tested using the Kolmogorov-Smirnov (K-S) method to satisfy the requirements so that the optimum distribution parameters and types can be identified out according to the measured distributions. Results show that vehicles on the Aizhai bridge can be divided into seven types, with the dominant ones being the second (car) and seventh (large truck) types, accounting for 49.5% and 21.56%, respectively. Based on analytical results, the distribution characteristics of vehicle speed are as follows:(1) The speeds of the third, fourth, and fifth types of vehicles satisfy normal distribution using K-S method; (2) Although the speeds of the first, second, sixth, and seventh types of vehicles do not satisfy normal distribution using K-S method, their measured curves well fit the normal fitting curve. Thus, the normal-distribution function is suitable for the speed-distribution characteristics. Furthermore, the weight-distribution characteristics show that all types of vehicles do not satisfy the normal-distribution function, lognormal-distribution function, or Weibull function using K-S method. However, by comparing the nearest extent between the statistically measured and corresponding critical values, the weight-distribution characteristics should be applied using the normal-distribution function.

This paper presents a series of tests on the tensile, bending, welding, and threaded connection of 022Cr22Ni5Mo3N(2205) stainless steel bars. These tests prove whether the stainless steel bars have excellent mechanical properties and whether these steel bars meet technological requirements in preparing reinforcements for concrete construction. The use of stainless steel bars in concrete construction works in other highly corrosive environments, such as marine construction works, can reduce the maintenance and inspection costs and can extend the service life. Such application results in significant economic and social benefits.

The response surface method was used to construct the explicit response equation between design parameters and structure response. This method was also used to analyze the sensitivity of the parameters. Accordingly, the influence degree of various design parameters on the response of long-span cable-stayed bridge was analyzed. The sensitivity factors of the design parameters solved through the explicit response equation could show the tendency of internal force, deformation, and cable force of a long-span cable-stayed bridge under the condition of changing design parameters. These design parameters were divided into four importance ratings according to the sensitivity percentage value. This task could quantitatively distinguish the influence degree of the design parameters on the structural response. The method could provide the reference for parameter sensitivity analysis and identification of a long-span cable-stayed bridge.

Finite element analysis (FEA) and dynamic test are employed to investigate the influence of central buckles on the modal characteristics of the Aizhai bridge. The FEA result shows that (1) the longitudinal floating frequency of the bridge can be significantly raised with central buckles; (2) the influence of central buckles on anti-symmetrical lateral bending frequencies is larger than that on symmetrical mode; and (3) rigid central buckles can raise the symmetric vibration modal frequencies of main cables, whereas the flexible central buckles nearly have no effect. Further test on the dynamic behavior of the aero-elastic model of the Aizhai bridge is conducted. The result indicates that (1) the anti-symmetric lateral bending modal frequencies increase with the increasing stiffness of the central buckles; (2) central buckles have slight influence on the vertical modal frequencies; and (3) central buckles can enhance the entire stiffness and natural frequencies of suspension bridges, especially for anti-symmetric torsional and longitudinal vibration frequencies.

To study the numerical simulation method for an atmospheric boundary-layer fluctuating wind field, an ideal randomly fluctuating wind was generated by arranging structural measures, such as the roughness element, the spoiler lever, and the grille in a full-size wind field model. Some of the main parameters, such as the height of the roughness element, the spacing of the spoiler lever, and the arrangement of the grille, were analyzed. All of these parameters affected the numerical simulation results, confirmed the effect law, and suggested the possibility of a combined method of the corresponding numerical model by investigating a class C landscape atmospheric boundary-layer wind field. Simulation results satisfied the requirements of the wind structure calculation, achieved a full simulation of the boundary-layer transition, and provided a valuable stream generation method for the subsequent large eddy simulation of the flow around a structure.

A dual-target dynamic optimization model was built for the traffic signal control system of two adjacent intersections based on signal timing parameters, such as signal cycle length, green signal ratio, phase offset, coordination phase vehicle delay, dissipation quantity feature, and vehicle flow in each entrance direction to improve the operational efficiency of the system. The dual-target dynamic optimization model was established using the stratified sequencing method. The example showed that the dynamic signal control significantly increased the effectiveness of the coordination phase of through lanes. When the lengths of the road between two adjacent intersections were 200, 350 m, and 550 m, the effectiveness ratios of a through lane with a dynamic signal two-way coordination phase control were increased by 14.47%, 11.01%, and 7.91%, respectively, compared with that of a through lane with a fixed signal. Therefore, when the length of a road between two adjacent intersections was short, the phase control of two adjacent intersections should coordinate with each other. Consequently, the traffic capacity of a dynamic signal control was improved by approximately 2.85% compared with that of a fixed intersection control.

To improve the precision of short-term traffic flow prediction and to enhance the accuracy of programming as well as of traffic flow management, a novel short-term traffic flow prediction method based on similarity is proposed in this study. The similarity observed at a single point on the California expressway is examined, and the similarity on "the same day for four adjacent weeks" is higher than that on "four adjacent days." The wavelet neural network (WNN) is established on this basis; moreover, the traffic flow data regarding "the same day for four adjacent weeks" and regarding "the four adjacent days" are divided into two types. Then, more than 200 groups of data are used to train the WNN and to predict the traffic flow on the same day. Results indicate that the mean values of the mean relative estimation error (MRE), mean square percentage error (MSPE), and equalization coefficient (EC) as predicted by the first method are 8.55%, 1.32%, and 0.951 6 respectively; the corresponding mean values obtained with the second method are 13.80%, 3.71% and 0.916 8. The MRE and MSPE values generated with the first method are lower than those obtained with the second method; by contrast, the EC value of the first method is higher than that of the second method. This finding suggests that the prediction accuracy of the first method is higher than that of the second method. Accordingly, the effectiveness of the proposed method is verified.

This study aims to analyze the system security level of drop and pull transport at the level of our current policy and technology. A highway drop and pull transport system is divided into sub-systems according to risk factors. A causal relationship model was developed between the sub-systems and system safety level of drop and pull transport, and the causal feedback loop was analyzed. A system dynamics flow diagram model was established, and simulation analysis was conducted. Results show that the drop and pull transport system security level is 81.673 7 in 2013 and 89.461 3 in 2015. This rank is considered acceptable. The result also indicates that the system security level remains relatively low even with the improvement of organization scheduling, safety technical standard, and policy environment. However, the system security level will improve gradually with time. Security is needed to strengthen safety management in the early stage of development. An analysis of the sensitivity of sub-systems indicates that the policy environment and tractor safety technology level influence the overall system security level of drop and pull transport. Therefore, related policies and rules should be improved as soon as possible. Investments for the safety of drop and pull vehicles should also be increased to promote the safe and rapid development of drop and pull transport.

In this study, a 1D Brownian movement formula that considers the uncertainty of initial parameters was derived and a time-dependent model of load and structural parameters established. A model for reliability and its corresponding sensitivity analysis was proposed as well according to the residual strength distribution calculated based on the S-N characteristics of the material and on stress-strength interference theory. This model considers the effects of interaction under uncertain structural parameters and strength as well as the uncertainty of actual use. On this basis, the variation rules of initial parameters, strength, load, reliability, and its sensitivity with time are analyzed; those of reliability, failure rate, and reliability sensitivity with time were calculated when the driving axle of a vehicle was taken as an example.