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Oxidative stress is a crucial factor leading to subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). Isoliquiritigenin has been verified as a powerful anti-oxidant in a variety of diseases models and can activate sirtuin 1 and nuclear factor-erythroid 2-related factor 2 (Nrf2) pathways. However, the effects of isoliquiritigenin against EBI after SAH and the underlying mechanisms remain elusive.The primary goal of this study is to verify the therapeutic effects of isoliquiritigenin on EBI after SAH and the possible molecular mechanisms.A prechiasmatic cistern SAH model in rats and a hemoglobin incubation SAH model in primary neurons were established. Isoliquiritigenin was administered after SAH induction. EX527 was employed to inhibit sirtuin 1 activation and ML385 was used to suppress Nrf2 signaling.In our study, neurological scores, brain edema, biochemical estimation, western blotting, and histopathological study were performed to explore the therapeutic action of isoliquiritigenin against SAH.Our data revealed that isoliquiritigenin significantly mitigated oxidative damage after SAH as evidenced by decreased reactive oxygen species overproduction and enhanced intrinsic anti-oxidative system. Concomitant with the reduced oxidative insults, isoliquiritigenin improved neurological function and reduced neuronal death in the early period after SAH. Additionally, isoliquiritigenin administration significantly enhanced Nrf2 and sirtuin 1 expressions. Inhibition of Nrf2 by ML385 reversed the anti-oxidative and neuroprotective effects of isoliquiritigenin against SAH. Moreover, inhibiting sirtuin 1 by EX527 pretreatment suppressed isoliquiritigenin-induced Nrf2-dependent pathway and abated the cerebroprotective effects of isoliquiritigenin. In primary cortical neurons, isoliquiritigenin treatment also ameliorated oxidative insults and repressed neuronal degeneration. The beneficial aspects of isoliquiritigenin were attributed to the promotion of sirtuin 1 and Nrf2 signaling pathways and were counteracted by EX527.Our findings suggest that isoliquiritigenin exerts cerebroprotective effects against SAH-induced oxidative insults by modulating the Nrf2-mediated anti-oxidant signaling in part through sirtuin 1 activation. Isoliquiritigenin might be a new potential drug candidate for SAH.

Objective: Intraventricular hemorrhage (IVH) is characterized by acute onset, rapid progression, and high disability and mortality rates. In this study, we investigated the clinical effect of external ventricular drainage combined with continuous lumbar drainage in IVH treatments. Methods: 114 patients with IVH treated at the Department of Neurosurgery, First Affiliated Hospital of Wannan Medical College from January 2015 to December 2017, were included in the study. Based on the different surgical methods, patients were divided into control (n=79) and study groups (n=35). The control group was treated with external ventricular drainage, whereas the study group was treated with external ventricular drainage combined with continuous lumbar drainage. The incidence of intracranial infection and hydrocephalus was compared between the two groups. The Glasgow coma scale (GCS) and the Glasgow outcome scale (GOS) were compared between the two groups 7 days postoperatively and at follow-up visits, respectively. Results: The incidence of intracranial infection and hydrocephalus in the study group was significantly lower compared with those in the control group (P

Background: This study was aimed to investigate the molecular mechanism of how melatonin interferes with hypoxia-inducible factor 1α (HIF1A) and TLR4 expression, which is implicated in the management of delayed brain injury (DBI) after subarachnoid hemorrhage (SAH). Method: Luciferase assay, real-time PCR, Western-blot analysis and immunohistochemistry (IHC) assays were utilized to explore the interaction among H19, miR-675, HIF1A and TLR4, and to evaluate the effect of MT on the expression of above transcripts in different groups. Results: MT enhanced H19 expression by promoting the transcription efficiency of H19 promoter, and HIF1A was identified as a target of miR-675. HIF1A enhanced TLR4 expression via promoting the transcription efficiency of TLR4 promoter. Furthermore, administration of MT up-regulated miR-675 but suppressed the expressions of HIF1A and TLR4. Treatment with MT alleviated neurobehavioral deficits and apoptosis induced by SAH. According to the result of IHC, HIF1A and TLR4 protein levels in the SAH group were much higher than those in the SAH+MT group. Therefore, the administration of MT increased the levels of H19 and miR-675 which have been inhibited by SAH. In a similar way, treatment with MT decreased the levels of HIF1A and TLR4 which have been enhanced by SAH. Conclusion: MT could down-regulate the expression of HIF1A and TLR4 via the H19/miR-675/HIF1A/TLR4 signaling pathway, while TLR4 is crucial to the release of pro-inflammatory cytokines. Therefore, the treatment with MT could ameliorate post-SAH DBI.

Stability of the closely star-battened member of a power transmission tower were researched in this paper, a theoretical analysis was conducted for the buckling mode of the closely star-battened member by different plate batten arrangements. The analytical method of the buckling capacity on the closely star-battened member was proposed here considering an arrangement type of the plate batten and they are compared with the results of a full-scale test. The conclusions are follows: the flexuraltorsional buckling did not happened for the closely star-battened member; the flexural buckling need to be calculated only after the strength reduction factor was considered; the stability-bearing capacity of the closely star-battened member of the line-shape type batten is slightly less than that of the cross-shape type batten; the stability-bearing capacity of the closely star-battened member can be improved when the number of bolts in the plate batten increases in a suitable extent; and the stability-bearing capacity calculated and test results agree well with each other when the stability-bearing capacity analytical method of the closely star-battened member was used to analyze the full-scale test tower. The experimental results show the calculation method is reasonable.

Pulverised coal in industrial sites and their dust can experience spontaneous combustion and self-heating, increasing the risk of fire and dust explosion. The main objective of the present study was to resolve thermal combustibility (as reflected by comprehensive combustibility index [Sn] and kinetic properties) for three types of coal (S1-BN, S2-CY, and S3-JM) through thermal analysis. The Sn values of the samples indicated a degradation in the quality of comprehensive combustibility. Apparent activation energies (Ea) at the initial stage of spontaneous coal combustion (130–300 °C) were decided through Achar and Coats–Redfern methods. Moreover, thermal susceptibility (minimum auto-ignition temperature [MAIT] and thermodynamic parameters) was evaluated using the hot plate method. The MAIT values for the three coal dust layers were 210, 220, and 300 °C. The results exhibited that heat conduction was the dominant heat transfer mode that originated the temperature distribution within the coal dust layer under the subcritical conditions for ignition; while it converted chemical reaction controlled-mode after thermal runaway. Furthermore, the results based on an improved risk matrix approach showed the S1-BN and S2-CY samples had a high self-ignition risk, whereas the S3-JM sample had a moderate ignition risk.

Syphilitic gumma involvement of the central nervous system is extremely rare and frequently misdiagnosed. The authors report a patient of a cerebral syphilitic gumma resembling a malignant brain tumor in a 62-year-old male. He was first suspected of a malignant brain tumor, but the pathological diagnosis was cerebral syphilitic gumma. This patient with unusual findings illustrates the clinical manifestations, imaging, and therapeutic aspects of cerebral syphilitic gumma.

miRNAs are important regulators of translation and have been associated with the pathogenesis of a number of cardiovascular diseases including stroke and may be possible prognostic biomarkers. The purpose of the present study was to determine the expression levels of miRNAs in the sera of subarachnoid haemorrhage (SAH) patients and to evaluate their relationships with the severity and clinical outcome of SAH. Serum samples on day 3 after the onset of SAH were subjected to microarray analysis with Exqion miRCURYTM LNA array and quantitative PCR analysis. Serum samples from SAH patients (n=60) and healthy controls (n=10) were subjected to quantitative PCR analysis. The severities and clinical outcomes of the SAH patients were evaluated with the WFNS grade and the Modified Rankin Scale (mRS). Three miRNAs, miR-502-5p, miR-1297 and miR-4320 were significantly up-regulated in the sera of SAH patients when compared with the healthy controls. The serum miR-502-5p and miR-1297 levels were significantly higher in the patients with severe SAH and a poor outcome than in those with mild SAH and a good outcome (P

A new type buckling restrained brace ensuring to work under different levels of earthquakes is analyzed in this paper. The brace is simplified by LINK elements of SAP2000. The skeleton curve of the mode is clarified. Three specimens with different slot widths are designed to evaluate the simplified model used in the software SAP2000. The evaluation work is accomplished through the software ABAQUS. The force mechanism, the hysteretic model and proposed reasonable scopes of slot widths are grasped. The numerical simulation work proves that the new type buckling restrained brace performs excellently.

Because of the predominance of construction techniques, a solid knowledge of reinforced concrete principles and rules is necessary and crucial. This study focuses on a comparative studies of different sizing standards, the Euro Code 2,the Egyptian Code 203 and the Algerian Code 93 for a rectangular reinforced concrete section subjected to simple bending in limit states and is well supported on one hand by one of the determining factors in design and on the other hand by the economy and security. The comparison of sizing standards in the limit states will assist the designer in their choice of a suitable design code.

The influential factors on synthetic seismic waves and seismic codes in China are described in detail in this paper. And the evolution of synthetic seismic waves is overviewed. The methods of synthetic ground motion in the earthquake engineering field are summarized in order to provide references for the synthetic ground motion. Based on the study situation over the world, the issues and trend are presented. Some suggestions are provided for improving the codes and standards.

Side-strengthened reinforced concrete or precast prestressed concrete beam for inadequate seismic performance is proposed in this paper. The factors are simulated by ABAQUS software for the impact of seismic performance, which are difference of material strength grade, initial load and the order of prestressing and pretightening. The strengthening technology can improve the seismic performance of side-strengthened beam. The meterials with different strength grades which used for beams give full play to their role. The initial load has little effect on the seismic performance. The way of prestressing after pretightening plays a favorable effect for the seismic performance. The simulation results can accurately reflect the impact of these factors on the side-strengthened beam.

In order to investigate the size effect and other effects on the stress-strain relationship of confined concrete, 42 specimens with different sizes and section shapes were placed under axial compression loading. Effects of key parameters such as size of specimens, tie configuration, transverse reinforcement ratio, and concrete cover were studied. The results show that for specimens with the same configuration and the same volumetric ratio of the transverse reinforcement, along with the increasing specimen size, the peak stress, peak strain and deformation of the post-peak show a down trend, however, the volumetric ratio of the transverse reinforcement is lowered, the decreasing of the peak stress is accelerated, but the decreasing of the deformation is slow down. For specimens with the same volumetric ratio but different configurations of transverse reinforcement, though the transverse reinforcement configuration becomes more complicated, the peak stress of the large size specimen does not improve more than that of the small size. However, the deformation occurs before the stress declines to 85% of peak stress, and the improvement with the grid pattern tie configuration is much greater due to size effect.

Many frame structures were damaged for the column hinge mechanism in the Wenchuan earthquake because of the biaxial seismic action. Four reinforced concrete columns with corner focus longitudinal bars were tested to improve the seismic behavior of RC columns subjected to multiaxial loading. The hysteretic behavior, skeleton curves and feature points were discussed. The results indicate that the method can improve seismic behavior of RC columns

The ground motion is multidimensional, random and uncertain in directions when earthquakes occur, so dynamic response under oblique seismic action needs to be considered in the structure design. A frame structure with different stiffness in two horizontal directions was analyzed under seismic action with different input angles. The maximum response of beams and columns was obtained. The seismic mechanism of structures under oblique seismic action was discussed.

Lots of bulidings had collapsed in Wenchuan big earthquake in 2008, one important reason is that the structure design has been launched only in X or Y axis of the building respectively, which means the oblique direction compression-bending characteristic has not been fully considered in the actual structure design process. In addition, the moment bearing strength in oblique direction is smaller than the moment strength about the principle axis of the column, so the research on bending strength calculation of biaxial/oblique compression-bending RC column is important to improve the aseismic safty of the buildings under actual earthquake effects. In this paper research achievements about bearing capacity calculation of column under oblique compression-bending action are summarized and analyzed. At last the advice for actual application has also been given.

Seismic performance of RC beam-column joints under low cyclic loading with different cycle numbers was analyzed by FEA software, to study duration effect of long period ground motion. The loading with different cycle numbers was used to simulate the duration of the ground motion. Hysteretic curves and skeleton curves of the joints were obtained. The results indicate that as the cycle number increases, the capacity and ductility of the joint declines, and the stiffness of the joint attenuates faster.

An experiment of three T-shape beam-column steel joints with intensive cover plate was conducted under low cyclic loading with different cycle numbers, to study seismic performance of the joints subjected to long-period ground motions. Effects of cycle number on mechanical performance and length of plastic hinge were analyzed. The results show that as the cycle number increases, capacity of the joint decreases, and plastic hinge of the joint develops longer which appears closer to the cover plate, and the platform of skeleton curve grows longer, and the stiffness attenuates slightly.

Based on test results of two full-scale reinforced concrete beam-column joints, carrying capacities of core areas of the joints were calculated and modified based on the strut-and-tie model. The results indicate that the capacities calculated with h-D-regions is smaller than those with h/2-D-regions, and the calculated results with h/2-D-regions agree better with the test results.

Simulation analyses of RC short columns are conducted under oblique horizontal seismic action monotonically using ABAQUS software. Concrete damaged plasticity model is used for concrete. Ideal elastic-plastic model is taken for steels. The results show that when the axial compression ratio was relatively low, the capacity of the columns increased with the increasing of load angle, because of the effect of tensile bars. For the relatively high axial compression ratio, the bearing capacity decreased with the increasing of angle, because of the effect of concrete in compression area.

Pushover anlysis of a three-story one-span space frame under oblique seismic action was conducted using ABAQUS software. The loading angle is 0°, 15°, 30° and 45° respectively. Failure mechanism of the space frame was analyzed, such as yield sequence of beam end and column end, and force-displacement curves. The results indicate that the structure loaded with angle of 0° failed when beam hinge appeared. With the increasing of load angle, the failure mechanism of frame changed from beam hinge failure to column hinge failure gradually.

The optimal treatment modalities of ruptured middle cerebral artery aneurysm are still controversial. The objective of this study is to analyze the outcomes of patients with ruptured middle cerebral artery aneurysms treated by endovascular coiling.From October 2011 to October 2015, 67 patients with 71 ruptured middle cerebral artery aneurysms received endovascular coiling in our hospital. We retrospectively reviewed the clinical, radiologic records and outcomes.Of all the 71 aneurysms (67 patients), 42 were treated by coil embolization merely, 27 by stent-assisted coiling and 2 unruptured aneurysms in patients with bilateral middle cerebral artery aneurysms without receiving treatment. Complete occlusion was achieved in 82.6% (57/69) of all the procedures. Each of incomplete and partial occlusion rates was 8.7% (6/69). Intraoperative rupture of aneurysms occurred in two procedures (2.9%). Thrombogenesis occurred in eight procedures (11.6%). Brain infarction occurred in eight patients (11.9%). Post-operative rebleeding occurred in seven patients (10.4%). Sixty-three patients were followed at a mean follow-up of 8.24 ± 7.16 months. The mortality and good outcome rate were 3.2% and 90.5%, respectively. Aneurysm recurrence occurred in 6 (13.3%) of the 45 aneurysms at a mean follow-up of 8.44 ± 7.83 months.Endovascular coiling is effective for patients with ruptured middle cerebral artery aneurysms. Individualized treatment should be assessed by experienced specialist. It is essential to perform randomized large trials to confirm the efficiency of endovascular coiling.

The method of CFRP plate reinforcement for the rigid joints with complete welding was studied using finite-element analysis. Three models were adopted in analyzed software ANSYS and they are Solid45, Combin14 and Shell181, which used to simulate steel, glue and CFRP plate respectively. The results show that the ultimate bearing capacity of rigid joints improves significantly after using CFRP reinforcement for joints. And the results also show that the level of improvement is relative to the length, width and thickness of CFRP plates.

Four prism concrete specimens with same height, same width, but different lengths is simulated in using ABAQUS FEM analysis software. The simulation work is conducted under monotonic axial compression loading, and its purpose is to research the size effect of prism concrete specimens, primarily to study the effect of specimen length on the axial compressive strength. The stress-strain relation of the specimen is analyzed. The results indicate that, for different lengths of specimens, their axial compressive strengths are quite different and the size effect on them is much obvious. The compressive strength improves gradually with the increasing of length, and size effect on transverse and vertical constraint stress of core concrete area is much distinct as well. Meanwhile, it can be obtained that the standard design method of the structures and components is conservative and of adequate security.

The Shear capacities of fourteen coupling beams are analyzed in this research by the finite element numerical simulation method. The coupling beams are designed with small span-to-depth ratios and arranged high strength steel. The results show that the shear capacities of coupling beams accord with the compression strut model. The shear capacities improve obviously through enhancing the diagonal steel bars, but they do not show significant influence through changing the strength of transverse and longitudinal bars. Comparing the results calculated by the formulas shown in the Code for Design of Concrete Structures (GB50010-2010), the results calculated by the finite element method show the gap, and it will be the key issue for further study.

To investigate the axial compressive behavior of reinforced concrete columns with strong confinement, a total of five full-scale reinforced concrete columns with stirrup characteristic values in the range 0.22~0.47 and section dimension 600mm×600mm were tested under concentric compression loading. The test results indicated that all specimens failed in a similar way. The longitudinal bars buckled in compression; the peripheral stirrups bowed out and several stirrups fractured; the cover concrete in the mid-height section of specimens spalled seriously; however, the core concrete of specimens was not crushed. The axial compressive bearing capacity and deformation ability of reinforced concrete columns could be improved by strong confinement. When specimens reached the ultimate bearing capacity, the longitudinal reinforcement yielded and provided axial bearing capacity for specimens; the transverse reinforcement reached tensile yield strength and provided effective confinement for the core concrete.

Based on the plane-section assumption, the formulas of yield moment and ultimate moment are derived for calculating high-rise RC shear wall. High-strength steels are used as transverse and longitudinal steels in boundary concealed columns of the shear wall. The practical application is performed by using the formulas derived for calculating horizontal bearing capacities of four specimens, in which one specimen used ordinary-strength steel and the others used high-strength steel. Meanwhile, the numerical simulation is carried out on the four specimens by finite element method, and the results show that the horizontal bearing capacity of the shear wall increases obviously for specimens using high-strength steel in boundary concealed column, and the simulation results of finite element method are in good agreement with formula results.

In this paper, beam ends of beam-slab-column joints installed in reinforced concrete structures are simulated using ABAQUS FEM analysis software. The simulation work is carried out under the monotonic loading. The damage factor in the plastic-damage model is adopted for describing the damage state of concrete. The failure characteristics, the distribution of cracks on the top side of slab are discussed according to the simulation results. The stresses of longitudinal bars in the slab along with different distances between the longitudinal bar and the beam are given. In reliability assessment of the numerical model, the effects of slab thickness and slab reinforcement ratio on flexural behavior of beam-slab cooperative working are conducted further more.

The paper researched on the strain, the deformation and the failure mode of hollow latticed steel columns through two experimental conditions. They were respectively about the vertical load and the horizontal load. The results showed that for the hollow latticed steel columns with upper columns, because of the stiffness of upper columns was obviously higher than the lower ones’, the upper columns were destroyed earliest under the vertical load. In addition, the columns had good horizontal bearing and deformation capacity, and the gravity second-order effects were not obvious for the columns.

3 specimens of full-scale reinforced concrete columns were tested under monotonic axial loading, in which the hoop configuration of one specimen was #, and the other two used the two-directional composite spiral hoops. The axial compressive performances of full-scale reinforced concrete columns confined by different configurations and strengths of hoops were discussed. One of the columns confined by spiral hoops used high-strength steels with the yield strength of 1000MPa as hoops, while the other two columns used ordinary-strength steel with yield strength of 400MPa. Columns confined by spiral hoops exhibited slight higher bearing capacity and better deformation ability than columns with hoop configuration #. The results also indicated that compared with the specimen used ordinary-strength hoops, the bearing capacity of the specimen used high-strength hoops was basically the same, but the deformation ability improved obviously.

The macro-synthetic fiber is widely used to prevent the cracking at concrete members. By the way of experiment that macro-synthetic fiber-reinforced concrete ductile columns comparing with the usual fiber-reinforced columns under the action of low-frequency cyclic loading, seismic performance of the columns in different form of bars were obtained. Meanwhile, the damage pattern, hysteresis curve, ductile coefficient and equivalent viscous damping coefficient of the columns could be also obtained. The results show that the macro-synthetic fiber-reinforced concrete ductile column has the better ductility and the higher post-crack energy absorption ability.

In order to study the seismic performance, of macro-synthetic fiber-reinforced concrete ductile columns, specific used as the concrete energy absorption system placed in the structure, three concrete ductile columns were constructed and tested using low-frequency cyclic loading. The damage pattern, hysteresis curve, ductile factor and equivalent viscous damping coefficient of the columns were obtained. The results show that the macro-synthetic fiber-reinforced concrete ductile column has the good ductility and the high post-crack energy absorption ability.

Experimental studies on size effect of flexural behavior of reinforced concrete beams are not carried out fully. Standard values are based on test results of small-size components, which are different from large-size components in practical engineering. For size effect on quasi-brittle materials such as concrete, related researches have been carried out for many years, but related test study combined with concrete structures or components are not sufficient. This article is based on experimental study of 13 reinforced concrete free beams, obtaining test data during different loading stage, such as carrying capacity, deflection, steel and concrete strain etc. Test results show that size effect of flexural behavior of RC free beams is mainly reflected in reinforcement yielding stage and concrete crushing stage. The negative size effect due to concrete material is not significant. Yet internal force arm and longitudinal reinforcement have a positive size effect on flexural behavior, strength and ductility reserves show a growing trend with specimen size increasing. The safety of calculation theory of bearing capacity in code is verified indirectly.

Analysis and calculation methods of reinforced concrete structure at present are based on test results of small-size component. This paper carried out test research on size effect of flexural capacity of RC cantilever beams. Sectional height of the biggest experimental specimen is 1000 mm. Obtaining detailed test data during different loading stage, such as carrying capacity, deflection, steel and concrete strain etc. Through observing test phenomenon and analyzing test data, verifying the safety to calculation formulas for ultimate bearing capacity of flexural members. Strength and ductility reserves show a growing trend with specimen size increasing.

In order to research on seismic performance of full-scale beam-column joints of RC frames under low cyclic loading, finite element software ABAQUS is used to nonlinear analysis. Analysis results show that: the process of load carrying and fracture development of beam-column joints are simulated using concrete damage plasticity model; nonlinear finite element method is easy to obtain stress-strain relationship; and can effective analyses the complex mechanical behavior of core areas of joints.

Axial compression experiments of four full-scale reinforced concrete columns of two groups were carried out. One group of three columns used high-strength steel with the yield strength of 1000MPa as reinforcement hoops, and the second group used the ordinary-strength steel with yield strength of 400MPa. The axial compressive performances between these two groups were assessed. Compared to the specimen using the ordinary-strength steel, the axial compressive bearing capacity of using the high strength steel dose not increase significantly, while the deformation ability increases greatly. The results also indicate that the stress redistributions of the hoops and the concrete sections are obvious, and long-lasting when specimens achieve the ultimate bearing capacity after the yield of the rebar and local damage of concrete materials, at this time the strain of the specimens developes a lot, especially stress - strain curves of speciments with high-strength hoop all show a wide and flat top.

Considering the structural characteristics of transmission towers, four sections of cold-formed angles with different slenderness ratios and constrained types were selected for the experimental and numerical study. Experiments and finite element analysis for the ultimate loads of the compression cold-formed angles were carried out. The finite element model well predicts the buckling behaviour of the cold-formed members. For the axial compression members, the load-strain curves as well as the ultimate loads were analyzed, and the experimental ultimate loads were compared with those of calculated by the applicable standards. It shows that the applicable standards aren’t adaptive to the strength design of the compression cold-formed members in transmission towers. Through the analysis of the experimental and FEA results, the fitting curve of the stability coefficients for the cold-formed members in transmission towers was determined. The ultimate loads calculated by the fitting curve are well agreed with the experimental values, especially for the members with relatively low slenderness ratios. Some modification suggestions were proposed for the calculation of the ultimate load for the axial compression cold-formed angle. Experimental analysis on the cold-formed members of the other five constrained types was completed, and the modification formulas of the slenderness ratios for members of different constrained types were obtained.

With the development of modern constructional technique, more attention on the size effect is paid by academics and engineers. Shear failure mechanism of reinforced concrete column is analyzed firstly, and then the advances on the size effect of reinforced concrete column is introduced. the effects of sectional size on the shear behaviors of reinforced concrete column is studied by theoretical analysis and experimental summary, and the formula of the size effect of shear resistance of reinforced concrete column is proposed.

Two kinds of imide dicarboxylic acid monomers, 4,4'-bis(trimellitimido) diphenyl ether Ⅰ and p-trimellitimido-benzoic acid Ⅱ were successfully synthesized from 4,4'-diaminodiphenyl ether and p-aminobenzoic acid with trimellitic anhydride respectively.and used to synthesize a series of new aromatic poly(amide-imide)s (PAIs) by the tri-phenyl phosphite-activated polycondensation method. The preparation of PAIs was carried out using triphenyl phosphate and pyridine symtem. The PAIs had inherent viscosities of 0.55–1.46 dL g-1. PAI films were obtained by casting their N-Methyl-2-pyrrolidone (NMP) solution. Their cast films had tensile strengths ranging from 37.4 to 83.9 MPa. The glass-transition temperatures (measured by differential scanning calorimetry) were in the range of 265-310°C. According to thermogravimetric analysis, the polymers were fairly stable up to temperature around 420°C, and 10% weight losses in the temperature range of 474-550°C in nitrogen, that showed good thermal stabilities of these polymers.

An experimental study was made of the mechanical properties of large scale confined concrete subjected to the axial compression test. Eleven tied concrete columns and six plain concrete prisms were tested. In the test, each specimen had the same transverse reinforcement configuration, and similar volumetric ratio of lateral steel, while different size. The test results in this paper indicate that the size of the specimen has no obvious relationship with the ultimate strength, however, it does affect the post-peak ductility to some extent. As a supplement to the experimental study, a finite element method was adopted to imitate the mechanical behavior of the confined concrete under axial compression. The results of the imitation in this paper indicate the confinement mechanism of large scale specimens.

Size effect, referring to mechanical properties of materials change with the geometry changes, is the basic characteristic of brittle and quasi-brittle materials. Researches show that for the concrete material, compressive strength, split tensile strength and tensile strength decrease with the size of components increases, for RC structures, size effect also exists. The development and current situation in size effect are presented from three aspects, including concrete, RC members and the application of the code. And then, the developing trends of size effect of RC members are proposed.

The paper designed three joints namely beam-column joint of reinforced concrete frame without slab and two beam-column joints of reinforced concrete frame with slab, using different loading methods (one direction and two directions) to experiment. The paper studied failure behavior, load-carrying capacity, and slab participation in flexural behavior of beam under different loading modes. Experiment shows that for the joints with slab, flexural capacity at end of the beam under two direction loads than one direction loads lows by about 10%; under one direction load, effective flange width of slab should be taken 8 times thickness, under two direction loads, effective flange width of slab should be taken 10 times thickness.

In current seismic design code of each country in the world, the mainstream of earthquake input for calculating the building is to use X and Y directions conveniently. The X and Y directions are the main axis of the building, and the strong-column weak-beam damage mechanism has been considered only followed to these main axis. However the building response in the oblique direction is higher than in the main axis, and the frequency in the oblique direction of the building is higher than the X or Y direction as well. Moreover the column usually connects with two beams in the orthogonal directions and the strength ratio of the column to beams in the oblique direction is less than in X or Y direction. Therefore it could be the major reason to cause the column-plastic-hinge damage mechanism during the earthquake. In this paper, it is discussed how the seismic input in the oblique direction influence on the strong-column weak-beam damage mechanism for RC frame through the perspectives of the dimensional mechanical analysis, cyclic loading experiment and the finite element analysis for the dimensional column-beam joint, and then proposed that considering the seismic input in the oblique direction is necessary in the future structural design in order to reach the actual strong-column weak-beam mechanism.

Experiments on reinforced concrete frame spatial joints are conducted under low level cyclic loadings.The seismic performance of the spatial joints is investigated,including failure mode,hysterisis curve, stiffness degradation,energy dissipation and displacement ductility.The experiment result shows that the column-hinge damage mechanism had happened and the bearing capactity ,energy dissipation character and displacement ductility had decreased under the oblique direction earthquake effect.The aseismic designing method should consider the oblique direction earthquake effect.

This paper presents the defects existing in shaking table control including the overshoot of displacement under low-middle frequency input using three variable parameter controls, the narrow bandwidth resulting from the performance of servo-valve and low accuracy of seismic wave reproduction because of specimen and table interaction. The effects of these factors on the stability and control accuracy of shaking table are discussed, and then the reasons of these problems existing are analyzed. The aim of this paper is to improve the stability and control accuracy of shaking table, thus, some corresponding strategies for compensation control are proposed. And a series of shaking table tests with one-story frame and two-story frame for verifying the validity of compensation control algorithm are performed.

This thesis studies deeply the crack development characteristics, failure pattern, hysteresis curve and the displacement ductility of this new prestressed precast reinforced concrete intelligent structure, by analyzing one prestressed precast reinforced concrete frame under low reversed cyclic load test. Prestressed precast reinforced concrete frame is a new assembly architecture intelligent structure. We build a model using finite element analysis software to the test piece model analysis, the analysis result agree well with the experimental results. Experimental studies indicate that this new prestressed precast reinforced concrete intelligent structure has a good seismic performance. This prestressed precast reinforced concrete frame is a new kind of structural system complying with the development of architectural industrialization, which is worthy of popularization and application in the earthquake area.