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With the development of satellite remote sensing technology, satellite remote sensing data obtained by the amount will increase rapidly. Consequently, the process of Wallis transformation is faced with such challenges as large data size, high intensity, high computational complexity and large computational quantity, and so on. A fast algorithm and efficient implementation of Wallis filtering based on Compute Unified Device Architecture (CUDA) is proposed. The parallel hardware architecture and software development process of multiple graphic processing unit (multi-GPU) is introduced firstly. On the basis of the parallel architecture and hardware characteristic of GPU, some algorithms are focused on computation and optimization of multiplicative coefficients, additive coefficients and updated gray values of the image pixels to improve the computing speed, and the shared memory is used to improve the data access efficiency. The experimental results clearly show that, in the same image quality, the average acceleration rate is 107 times, and the algorithm on multi-GPU can achieve better performance.

The aim of this study is to characterize the behavior of air-concrete under triaxial compression with stress ratio α 2 = σ 2 : σ 3 = 1 : 1, while changing stress ratio α 1 = σ 1 : σ 3 from 0 to 0.2 after different cycles of freeze–thaw. 100 mm × 100 mm × 100 mm concrete cubes were tested in the experiment. Based on the experiment data, the influence of the stress ratio α 1 = σ 1 : σ 3 and the number of freeze–thaw cycles on the ultimate compressive strength σ 3 are analyzed respectively. A failure criterion expressed in terms of octahedral stress with consideration of the influence of the freeze–thaw cycles is proposed.

A simple method based on the well-known sectional analysis approach is presented to trace the structural behavior of reinforced concrete (RC) shear walls exposed to fire. It is similar to the approaches described in the existing literature but it does not require computations of moment-curvature curve group. This method can take into account material nonlinearity by use of the coupling constitutive relation of materials. Moreover, the geometric nonlinearity is considered by taking account the second-order effect of axial forces. The predictions of the proposed method are validated using experimental and analytical studies.

Traxial compressive tests on concrete samples subjected to such stress ratios as 0.1:0.25:1, 0.1:0.5:1, 0.1:0.75:1and 0.1:1:1, were performed. Based on mechanical properties measured from the tests, strength and deformation behaviors of concrete under triaxial compression were explored, and then the failure criterion was proposed. The result indicated that the bearing capacity of concrete under triaxial compression is greater than that under uniaxial stress state. Construction material can be greatly reduced considering this factor in design.

A model of attenuation of residual strength with number of cycles has been founded .In this model the constant confined stress and maximum stress of fatigue loading are both considered. 55 specimens of plain concrete are tested under biaxial compressive fatigue loading with constant confined stress. Based on the data of experiment, the coefficients of the model are determined. The residual strength attenuating curves are shown in the paper. The model can be used to predict the residual life of specimen under biaxial compressive loading with constant confined stress. The results of prediction show that the suggested method is better than the Miner rule.

Using the static and dynamic triaxial experimental machine, experimental study of the strength of wet-screened aggregate concrete are carried out under biaxial compression stress ratios, 0.25, 0.5, 0.75 and 1 after 0, 50, 100, 150, 200, 250, 300 cycles of freeze-thaw. The change of surface of wet-screened aggregate concrete specimens after different cycles of freeze-thaw are observed and described. The failure characteristic of specimens and the direction of the cracks are also observed. Based on the test data, the influence of freeze-thaw cycles and compressive stress ratio on the ultimate compressive strength and corresponding stress-strain relationship is analyzed respectively. The relationships between the ultimate compressive strength and freeze-thaw cycles, the stress ratios are given, respectively. On this basis, the unified failure criterion with consideration of the influence of freeze-thaw cycles and stress ratio is proposed. It can serve as a reference for the maintenance, design and the life prediction of ocean structures, hydraulic structures, marine structures and offshore platform in cold regions.

Utilizing the large static-dynamic triaxial test system, 7 proportional loading biaxial tensile and compressive tests of concrete were conducted. The proportional loading paths are 0 (uniaxial compression), -0.05, -0.1, -0.15, -0.2, -0.25 and ∞ (uniaxial tension). Compressive and tensile strength were measured as well as the strains at two loading directions. Considering the ratio to tension and compression, failure criteria of ordinary concrete under biaxial tension and compression was established, which has a good agreement with test value.

Little progress has been made in experimental studying on high-temperature mechanical properties of concrete under multiaxial compression. Triaxial proportional compressive tests of ordinary concrete after suffering to high temperature (200°C ~600°C) were carried out, the designed stress ratios are 0.1:0.25:1, 0.1:0.5:1, 0.1:0.75:1 and 0.1:1:1. The failure models of concrete specimens after suffering high temperature were observed. The biaxial compressive strength and deformation characteristics of which were measured. The influences of temperature and stress ratio were analyzed. On the basis of the analysis, the relationship between compressive strength and temperature as well as stress ratio was established in octahedral stress space.

Ten reinforce concrete (RC) shear walls were exposed to fire on one side. A time-temperature fire curve with a heating phase and decaying phase was used in order to simulate a natural fire. The effects of fire duration and load intensity are described in relation to the distribution of concrete temperature. Test results show that load intensity has little influence on the concrete temperature distribution. In contrast, peak temperature in the same depth is strongly affected by the fire duration.

Mechanical properties experiments of air-entraining concrete after suffered to 0, 100, 200, 300 and 400 freezing-thawing cycles were performed. The experiment method, contents and result of strength and deformation of air-entraining after freezing-thawing cycle under biaxial compression were also introduced. The relationship between the strain corresponding to peak stress and cycle of freezing-thawing as well as the relationship between compressive strength and cycle of freezing-thawing were analyzed. The failure criterion of air-entraining concrete under biaxial compression was established.

Seven beams were tested to investigate the effects of beam depth and longitudinal reinforcement ratio on the shear strength of reinforced concrete beams. To investigate the effects of beam depth on shear strength, beams of five different sizes were tested. Two beams were designed to investigate the shear behaviour of beams with small percentage of longitudinal reinforcement. In addition to an experimental investigation, a survey of data in the literature was performed to gain insight into the influence of beam depth and longitudinal reinforcement ratio. Based on test results and a data analysis, conclusions regarding the influence of beam depth and longitudinal reinforcement ratio on shear strength of reinforced concrete beams are presented herein.

The purpose of this study is to investigate the influence of specimen size and shape on compressive strength of concrete. Concrete cubes, cylinders and prisms with their size ranging from 150mm to 450mm were tested in unaxial compression. Failure patterns and the effect of specimen shape and size on compressive strength of concrete were investigated. In addition, theoretical size effect models, such as the MSEL and MFSL were used to analyze the size effect of concrete strength. It is shown that for specimens tested in this study, the two models are both applicable to predicting the compressive strength of specimens in various sizes with a reasonably good accuracy.

This work presents a study of a fatigue test and a finite element analysis on an arch bridge stainless steel suspender with threaded connections. A suspender which had a diameter of 70mm was tested under axial tensile loads range from 430kN to 700kN. The suspender was sudden failure from the thread root of the first loaded tooth in the pin after 1546609 cycles. Then, a two-dimensional axisymmetric modeling ignoring the helix angle of the thread was established with finite element software ANSYS to perform a stress analysis of the threaded connection. The stress concentration factors (SCFs) at the root of the teeth of pin were investigated under the applied external loading. The conclusive results had been drawn from the analysis including the location and the value of maximum SCF in the pin. Finally, the location and the value of the maximum von Mises stress were given. The results showed that the location of the fracture surface was consistent with the location of the maximum von Mises stress.

The effects of fire exposure, reinforcement ratio and the presence of axial load under fire on the seismic behavior of reinforced concrete (RC) shear walls were investigated. Five RC shear walls were tested under low cyclic loading. Prior to the cyclic test, three specimens were exposed to fire and two of them were also subjected to a constant axial load. Test results indicate that the ultimate load of the specimen with lower reinforcement ratio is reduced by 15.8% after exposure to elevated temperatures. While the reductions in the energy dissipation and initial stiffness are 59.2% and 51.8%, respectively, which are much higher than those in the ultimate load. However, this deterioration can be slowed down by properly increasing reinforcement due to the strength and stiffness recovery of steel bars after cooling. In addition, the combined action of elevated temperatures and axial load results in more energy dissipation than the action of fire exposure alone.

Lightweight aggregate concrete cube specimens (100 mm×100 mm×100 mm) and plate specimens (100 mm×100 mm×50 mm) were tested under biaxial compression-compression (CC) and compression-tension (CT) load combinations. For comparison, normal concrete plate specimens (100 mm×100 mm×50 mm) were tested under the same load combinations. Based on the test results, a two-level strength criterion of lightweight aggregate concrete in both octahedral stress coordinate and principal stress coordinate was suggested. The lightweight aggregate concrete cube specimens (100 mm×100 mm×100 mm) were then tested under triaxial compression-compression-compression (CCC) load combination with corresponding tests on normal concrete cube specimens (100 mm×100 mm×100 mm). The effect of intermediate principal stress on triaxial compressive strength is further examined. A “plastic flow plateau” area was apparent in principal compressive stress-strain relationships of lightweight aggregate concrete but not in normal concrete. A quadratic formula was suggested for the expression of strength criterion under triaxial compression.

Triaxial tests were performed on 100 mm × 100 mm × 100 mm cubic specimens of plain high-strength and high-performace concrete (HSHPC) at all kinds of stress ratios after exposure to normal and high temperatures of 20, 200, 300, 400, 500, and 600 °C, using a large static–dynamic true triaxial machine. Friction-reducing pads, using three layers of plastic membrane with glycerine were placed between the compressive loading plate and the specimens; the tensile loading planes of concrete samples were processed by an attrition machine, and then the samples were glued-up with the loading plate with structural glue. The failure mode characteristic of the specimens and the direction of the crack were observed and described. The three principally static strengths in the corresponding stress state were measured. The influence of the temperatures and stress ratios on the triaxial strengths of HSHPC after exposure to high temperatures was also analyzed. The experimental results showed that the uniaxial compressive strength of plain HSHPC after exposure to high temperatures does not decrease completely with the increase in temperature, the ratios of the triaxial to its uniaxial compressive strength are dependent on the brittleness–stiffness of HSHPC after different temperatures and the stress ratios. On this basis, a new failure criterion with the temperature parameters is proposed for plain HSHPC under multiaxial stress states. It provides the experimental and theoretical foundations for strength analysis of HSHPC structures subject to complex loads after subjected to a high temperature environment.

Properties of air-entrained concrete under compressive loads with constant confined stress after 0, 100, 200, 300 and 400 cycles of freeze–thaw were studied. The failure characteristic of specimens and the direction of the crack are observed. Based on the test data, the influence of freeze–thaw cycles and lateral compressive stress ratio on the ultimate compressive strength is analyzed, respectively. The relationships between the ultimate compressive strength and freeze–thaw cycles, lateral compressive stress ratio are given, respectively. The unified failure criterion with consideration of the influence of freeze–thaw cycles and stress ratio is proposed. It provides the experimental and theory foundations for strength analysis of air-entrained concrete structures subject to complex loads in cold environment.

The behavior of strength and deformation of plain concrete under triaxial compression after 0, 25, 50 and 75 cycles of freeze-thaw are experimentally studied using the static and dynamic triaxial experimental machine. The compressive strength, strain at the peak of stress and stress–strain relationship under triaxial compression were measured. The failure modes of concrete specimens are also described. The experimental results showed that the triaxial compressive strength decreased as the freeze-thaw cycles were repeated for plain concrete. The influence of the number of freeze-thaw cycles and the stress ratio on the principal compressive stresses σ 3 and corresponding strain e 3 , stress–strain relationship was analyzed. On this basis, the failure criterion of concrete under triaxial compression after freeze-thaw cycles is proposed. It can serve as a reference for the maintenance, design and the life prediction of ocean structures, hydraulic structures, marine structures and offshore platform in cold regions.

Based on the S-N relationship and statistical property of concrete static strength, a function of fatigue life of concrete,1 (a − blog N) , is found to follow the normal distribution. Thus a new probabilistic model of fatigue life distribution of concrete is presented in this paper. The model connects statistical properties of static strength and fatigue life of concrete together in theory, so it is of clear physical meaning. An experiment was conducted. The experiment was a part of the project of The State Natural Science Foundation—Failure Criterion of Plain Concrete Under Multiaxial Fatigue Loading. 2 χ -test and Kolmogorov-Smirnov test are employed to test the proposed model. Fuzzy optimization is used to compare the model with lognormal distribution. 2 χ -test, Kolmogorov-Smirnov test and fuzzy optimization are also conducted for test data from references. The results show that the new model is more flexible to fit test data.

Biaxial compressive tests of plain concrete specimens under normal temperature and suffering high temperature(200600 )were completed under four lateral constant stress rates. The tests were completed by using the large static-dynamic triaxial test system for concrete in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. The biaxial compressive strength and deformation characteristics of concrete confined by lateral stress after suffering different temperature were studied in a systematic way. On the basis of the tests, the failure criterion of concrete subjected to constant lateral compressive stress after suffering different temperature was established in the Octahedral stress space. The conclusions can provide the testing and theoretical basis for deeper study of the concrete construction subjected to biaxial compressive combined loads suffering different temperature such as chimney, building after fire and safety shell for nuclear reactor.

Fatigue tests were conducted on tapered plain concrete prism specimens under triaxial constant-amplitude tension-compression cyclic loading. The low stress of the cyclic loading was taken as 0.2fc and the upper stress ranged from 0.20ft, to 0.65ft. Three constant lateral pressures were 0. 1fc, 0.2fc and 0.3fc respectively. Based on the results, the three-stage evolution rule of the fatigue stiffness, maximum(minimum) longitudinal strain and damage were analyzed, and a unified S-N curve to calculate fatigue strength factors was worked out. The results show that the fatigue strength and fatigue life under triaxial constant-amplitude tension-compression cyclic loading are smaller than those under uniaxial fatigue condition. Moreover, the secondary strain creep rate is related to the fatigue life, a formula for describing their relation was derived. The investigation of this paper can provide information for the fatigue design of concrete structures.

Investigation shows that concrete corrosion is a common problem for ocean reinforced concrete (R.C.) structures along China’s coast. A discussion of the corrosion characteristics, based on real project cases and field surveys, is presented in this paper. These factors that might affect corrosion, such as environmental effects, construction quality, cover thickness, property of the concrete material and structure type, are evaluated. Based on the analysis of these corrosion characteristics and affecting factors, the approaches available to improve the durability of ocean R.C. structures are proposed.