Currently, the capacity of corroded RC cylinders has been proven to significantly improve after being strengthened with carbon fiber reinforced polymer (CFRP). However, existing experimental data remains insufficient, resulting in few models available for predicting the post-strengthening capacity of corroded cylinder. The current understanding of the mechanism by which corrosion affects the mechanical properties of CFRP strengthened cylinders is also not yet clear. Against this background, this study conducted monotonic axial compression tests on CFRP-strengthened corroded RC cylinders. The experimental results indicate that while the CFRP layer predominantly controls the specimen's load-bearing capacity, the reduction in CFRP rupture strain due to increased corrosion rates should not be overlooked. When the corrosion rate reaches 35 %, the experimentally measured average rupture strain was only 65 % of the theoretical value, marking a 30 % decrease compared to non-corroded specimens. Subsequently, a predictive model for peak stress and strain of CFRPconfined corroded RC cylinders was proposed, which considers the confinement mechanisms of stirrups and CFRP as well as the degradation of CFRP rupture strain. Leveraging the existing test data, a dataset comprising 80 CFRP-strengthened corroded RC cylinder specimens was established to calibrate the key parameters in the proposed prediction model. Comparative analysis with existing models indicates that the peak stress and strain prediction model proposed in this study demonstrated the highest forecasting accuracy (the average errors for peak stress and strain were 14 % and 32.6 %, respectively), while existing other predictive models based on limited datasets suffer from a lack of universality. The experimental data and research conclusions of this article can provide reference for engineering practice and the establishment of models in subsequent research.

The seismic response of palace-style timber structures is closely related to the rocking characteristics of column. To accurately describe the dynamic characteristics of timber structures, a nonlinear rotational spring is employed to simulate the rocking behavior of column base joints under seismic excitation. Firstly, a spring-rigid rod analysis model that comprehensively considers the nonlinear properties of column base joints, mortise-tenon joints, and bracket set joints is proposed, and a simplified lumped mass model is obtained through centroid method and equivalent stiffness method. The accuracy of the simplified model is verified through shake table tests, and nonlinear dynamic response time-history analysis of the structure is conducted. Based on the verified simplified model, the influence of tenon-mortise joint reinforcement on the seismic displacement response of the structure was further investigated. It was found that carbon fiber sheets reinforcement increased the initial stiffness of the joints by 1.45 times and reduced the displacement response of the structure by 15%. Additionally, the optimal stiffness enhancement of column frame mortise-tenon joints range from 4 to 6 times.

提出了基于互相关系数和互相关峰值变化率的古建筑木结构损伤识别和定位方法.以随机振动结构的某一测点为参考点,计算其他各测点与参考点的加速度响应之间的互相关函数,将所有的最大值组成互相关峰值向量(Cross-Correlation Peak Vector,CCPV).以两组CCPV之间的互相关系数作为损伤因子对结构进行损伤识别,以结构损伤前后互相关峰值的变化率作为损伤识别指标,对结构进行损伤定位.以西安钟楼为工程背景,建立一榀木框架有限元模型进行分析.结果表明:结构损伤后,损伤因子的数值明显降低,可以有效识别结构的损伤;结构损伤前后峰值变化率最大的相邻两个测点对应着损伤单元的两个节点,可以准确确定结构的损伤位置,同时可以根据损伤因子和峰值变化率的变化范围估计结构的损伤程度.

本项目为解决现有震害评估理论方法与软件平台未考虑既有建筑耐久性损伤与设计规范差异的问题,基于大量物理模型试验、工程实测、理论分析与数值模拟,率先提出了考虑断层分布特点、近场特征和场地放大效应的西安地区强地震动场模拟预测与多变量设定地震危险性分析理论方法;系统揭示表征了多龄期建筑结构(RC结构、钢结构、砌体结构)震损破坏机理与性能劣化规律,并建立了考虑结构耐久性损伤的动力灾变多尺度高效数值建模分析方法;首次建立了可考虑我国国情的城市区域多龄期建筑时变地震易损性模型及损失评估与风险控制的成套理论技术体系,并开发出相应系统平台;率先提出基于多源异构数据的城市基础数据成套采录技术.该成果已成功综合应用与10多个大中城市及200余项工程项目中.

Bi 2 O 3 /BiOI step-scheme(S-scheme) heterojunction photocatalyst was synthesized by green calcination method, its degradation ability of methylene blue was investigated, and the photocatalytic performance of the Bi 2 O 3 /BiOI heterojunction, Bi 2 O 3 and BiOI was compared. The structure and morphology of the samples were characterized by X- ray diffraction(XRD), field emission scanning electron microscopy (FESEM), and UV-vis diffuse reflection spectrum (UV-vis DRS). The degradation rate of methylene blue was analysised by spectrophotometry, and the calculation result showed that the degradation rate of methylene blue was 97.8% in 150 minutes. The first order kinetic rate constant of 10%Bi 2 O 3 /BiOI is 0.021 8 min −1 , which are 2.37 and 2.68 times of BiOI(0.009 18 min −1 ) and Bi 2 O 3 (0.008 03 min −1 ) respectively. The calculation result shows that the work function of Bi 2 O 3 and BiOI are 3.0 eV and 6.0 eV, respectively, by density functional theory(DFT). When this S-scheme heterojunction is used as a photocatalyst, the weaker electrons in the conduction band of BiOI will be combined with the weaker holes in the Bi 2 O 3 valence band under combined effect with built-in electric field and band bending, which will retain stronger photoelectrons and holes between Bi 2 O 3 and BiOI. This may be the internal reason for the efficient degradation of tetracycline by Bi 2 O 3 /BiOI S-scheme heterostructures.

以咸丰重质碳酸钙(heavy calcium carbonate)为原料,高分子乳液为改性剂,通过干法改性制备了改性碳酸钙.采用单因素实验设计探讨了改性剂用量对碳酸钙改性效果的影响,结果分析表明,当改性温度为80℃,改性时间为50 min,转速为500 r/min,高分子乳液用量为咸丰重质碳酸钙质量的3％时,改性碳酸钙的活化率达90.8％,改性效果较好.利用FT-IR、XRD、SEM、Zeta电位对碳酸钙进行表征,结果表明,高分子乳液己成功接枝到碳酸钙表面.改性碳酸钙的特征衍射峰向高角度偏移,但高分子乳液改性并未改变响碳酸钙晶型.改性碳酸钙的Zeta电位从14.1 mV提高到29.8 mV,粒径较小,分散性有所增强.

为研究镍基单晶高温合金气膜孔结构疲劳断裂行为,将气膜孔试样在900℃、两种应力水平下进行了频率为3Hz、6Hz、10Hz的高温疲劳试验.借助扫描电子显微镜并考虑加载频率的影响分析了气膜孔结构疲劳裂纹扩展路径、裂纹微观组织特征和断口形貌特征.结果 表明不同条件下疲劳裂纹微观组织具有相似的特征,疲劳断口正断面破坏特征基本相同.加载频率对疲劳裂纹扩展及疲劳寿命有一定的影响,520MPa下疲劳寿命高于550MPa下的疲劳寿命.疲劳断裂路径的总体趋势为:裂纹从孔周萌生,先是垂直于加载轴方向扩展,然后沿与加载轴方向大致呈45°的方向扩展,局部侧断面形貌略有差异.

以MgSO4和Al2(SO4)3为原料,尿素CO(NH2)2作沉淀剂,采用均匀共沉淀法制备镁铝水滑石.利用XRD、SEM、FT-IR对产物进行表征,探讨尿素用量和晶化温度对水滑石物相组成、微观结构的影响;考察了反应条件(尿素用量和晶化温度)对水滑石吸附盐酸四环素性能的影响.结果 表明,均匀共沉淀法合成的镁铝水滑石具有特征的层状和片状结构.随尿素用量增加、温度升高,水滑石晶面层间距增加,结晶度提高.在尿素用量为n尿素∶nso42-=4∶1,晶化温度为110℃的条件下,镁铝水滑石对盐酸四环素有最好吸附效果,其吸附率为70.82％.

以绿色焙烧方法制备梯形异质结复合材料Bi2 O3/BiOI,将复合材料Bi2 O3/BiOI用于抗生素生产废水中四环素的降解,并与纯的Bi2 O3与BiOI的降解效果进行对比.以X射线衍射(XRD)、X射线光电子能谱(XPS)对Bi2 O3/BiOI样品物相组成和形貌进行表征分析,采用分光光度法测试并计算Bi2 O3/BiOI样品降解四环素,结果显示:降解率为92.4％,一级动力学常数为0.01859 min-1.密度泛函理论计算显示,Bi2 O3与BiOI的功函数分别为3.0、6.0 eV.梯形异质结复合材料Bi2 O3/BiOI在光催化反应时,在内建电场和能带弯曲的共同作用下,BiOI中导带上还原能力较弱的电子将与Bi2 O3价带中氧化能力较弱的空穴部分复合,从而保留较强还原以及氧化能力的光生电子和空穴,这可能是梯形异质结复合材料Bi2 O3/BiOI具有较高光催化活性的原因.

A damage location method for the autocorrelation peak value change rate based on the vibration response of a random vibration structure is established. To calculate the autocorrelation function of the vibration response of each measurement point, we transformed the maximum values into an autocorrelation peak vector. Under a good condition, the autocorrelation peak vector has a fixed shape; hence, it can be used as a basis for structural damage identification. The two adjacent measurement points with the largest change corresponding to the two nodes of the damage unit and the damage location are determined to calculate the change rate of the autocorrelation peak values between damaged and intact structures. When the degree of damage is 5%, the autocorrelation peak value change rate of the acceleration response on the two nodes of the damage unit is significantly greater than that of the other points, which can accurately determine the damage location, indicating that the damage location index constructed has good damage sensitivity. The damage location index can determine a single damage, as well as a double damage. The antinoise capability of the damage location index gradually improves with an increase in the degree of damage. At 45% degree of damage and signal-to-noise ratio (SNR) of 0 dB, the damage location index can still accurately determine the damage location, which has good antinoise interference capability. The Xi'an Bell Tower is used as a case study, and the feasibility of this method is verified, which provides a new method for the study of damage location of ancient timber structures.

In order to study the fatigue crack growth of directional solidified superalloy with single hole, the fatigue crack growth test of DZ125 was carried out under different stress levels. The fracture morphology of the specimens were analyzed by field emission scanning electron microscope, and the relationship between stress and life was fitted. It is found that the stress concentration around the hole and the defects lead to the crack initiation near the maximum principal stress point. The da/dN - Δ K satisfies Paris formula well.

To study the cracking process of the wall caused by differential settlement under a uniformly distributed load on the top of the wall, a laboratory model experiment was carried out on large-scale masonry specimens, and the acoustic emission (AE) technique and digital close-range industrial photogrammetry were adopted to monitor the AE signals and displacement characteristics of the masonry specimens during loading in real time. The results show that, in the case of differential settlement with small settlement on both sides and large settlement in the middle, two main cracks appear on the left and right sides of the wall, extending obliquely from bottom to top. During the loading process, damage of the wall is aggravated due to the differential settlement, and both cumulative ringing count and energy count have different periods of steep rise. With the increase in the load and activation of the AE event, the AE event becomes active, and the cumulative ringing count and cumulative energy curve have an obvious turning point, where the slope of the curve is substantially higher than that before the turning point. By using digital close-range industrial photogrammetry, it is observed that the main oblique crack on the left is mainly caused by the difference in the vertical deformation, while the main oblique crack on the right is caused by different displacements and deformation directions of the wall on both sides of the crack.

以芴、苯酚、对甲氧基苯酚和多聚甲醛为原料,采用溶液法合成了直接在芴的苯环结构上进行修饰的2个新型芴基苯并噁嗪单体3-芴基-3,4-二氢-1,3-苯并噁嗪(FBZ-1)和3-芴基-6-甲氧基-3,4-二氢-1,3-苯并噁嗪(FBZ-2).利用FT-IR,1H NMR和13C NMR对其结构进行了表征.采用示差扫描量热法(DSC)研究了2个单体的固化动力学,计算了固化反应活化能,确定了最佳固化温度.通过DSC和热重(TGA)分析了单体及其聚合物的热性能.结果 表明,FBZ-1和FBZ-2呈现出典型的热开环固化特征,放热峰顶温度(5℃·min-1的升温速率)分别为231.2℃,228.7℃,其聚合物初始热分解温度(热失重5％时)达290℃、299℃;850℃时的残炭率(Yc)达到40.9％和36.9％,极限氧指数(LOI)分别是33.86、32.26.

采用水热法合成异质结复合光催化材料BiOI/BiOBr,探究其对罗丹明B的降解能力,并与纯的BiOBr以及BiOI的降解情况进行比较.通过X射线衍射XRD、场发射扫描电子显微镜FESEM、紫外-可见漫反射光谱DRS以及稳态、瞬态荧光光谱PL等表征方法对合成的异质结复合光催化剂BiOI/BiOBr样品进行了结构、形貌、光学性质的表征.采用分光光度法分析罗丹明B的降解率,结果显示,BiOI/BiOBr异质结光催化材料对100 mg/L的罗丹明B有很好的降解能力,在40 min内对罗丹明B的降解率为100％,明显高于纯的BiOBr(80％)和BiOI(72％);其一级动力学速率常数为0.1028 min-1,分别为BiOBr(0.0403 min-1)和BiOI(0.0344 min-1)的2.6倍和3倍.这种异质结光催化剂不仅可以有效促进光生电荷分离而且可以保持复合材料的强氧化还原能力,这可能是BiOI/BiOBr异质结高效降解罗丹明B的内在原因.

采用单因素试验优化凹凸棒石用量及吸附温度对凹凸棒石/壳聚糖复合材料吸附性能的影响,并利用傅里叶红外光谱和扫描电子显微镜对复合材料进行了表征.结果表明,当凹凸棒石用量为壳聚糖质量的20％,吸附温度为25℃时,复合材料对盐酸四环素的吸附效果较好,吸附量为62. 30 mg/g.凹凸棒石表面已负载壳聚糖的含氧基团及氨基等有机基团,这是由于凹凸棒石与壳聚糖之间发生了相互作用,复合材料的表面粗糙且存在褶皱及孔隙结构,其比表面积为243. 17 m2/g,与凹凸棒石的比表面积相比,提高了60.04％.凹凸棒石/壳聚糖复合材料对盐酸四环素的吸附行为符合Langmuir等温式和准二级动力学方程,拟合计算得到的最大吸附量可以达到117.21 ～123. 04 mg/go

以咸丰重质碳酸钙为原料,硬脂酸钠为改性剂,采用干法改性制备了改性重质碳酸钙.采用正交试验设计探讨了改性温度、改性剂用量、改性时间和搅拌转速对重质碳酸钙改性效果的影响,利用FT-IR、XRD、SEM、Zeta电位对重质碳酸钙进行表征.结果分析表明,当改性温度为70℃,硬脂酸钠用量为咸丰重质碳酸钙质量的1.5％,改性时间为50 min,转速为700r/min时,硬脂酸钠改性咸丰重质碳酸钙的活化率为85.6％,改性效果较好.经过硬脂酸钠改性重质碳酸钙的红外光谱在2850cm-1和2920cm-1处出现了-CH2-对称伸缩振动和反对称伸缩振动峰,X-射线特征衍射峰向高角度偏移,Zeta电位从14.1mV提高到30.2mV,粒径较小,说明硬脂酸钠已接枝到重质碳酸钙表面,但改性并未改变碳酸钙晶型,改性重质碳酸钙具有良好的分散性.

在常压,Ca(NO3) 2-KCl溶液中,以脱硫石膏为原料,研究了聚合物大分子透明质酸转晶剂浓度和pH值对α-半水石膏晶体生长的影响.实验结果表明,pH值为5.5,转晶剂透明质酸浓度为3.0g·L-1时,制备的α-半水石膏为规整度高、分散性好的六边短柱状晶体.α-半水石膏水化硬化浆体力学性能测试显示,浆体抗压强度和抗折强度随着α-半水石膏晶体长径比减小和规整度的增加而逐渐变大,其最大值分别为58.8 MPa和28.5 MPa,属于高强石膏.

钢结构因质轻、强度高、建造方便、塑性及抗震性能好等优点越来越受到青睐.近几十年来,随着国内钢材产量及品种大幅提升,钢结构应用范围也越来越广,除传统的钢结构厂房外,钢结构也逐渐应用于高层、超高层及大跨度结构中.然而,钢结构有一个明显的缺点,即易腐蚀,暴露在大气环境中的钢结构,钢材表面会形成一种薄液膜,在干湿交替过程中对结构产生腐蚀.随着我国现代工业化进程的加快,环境问题日益突出,其中在富含SO2的酸性大气环境和富含Cl-的近海大气环境下钢材的腐蚀最为严重.钢材腐蚀不仅会造成巨大的经济损失,还会影响结构的安全稳定.钢材遭受腐蚀后,构件有效截面面积减小,强度和延性下降,不均匀腐蚀引起的锈坑会导致应力集中等,在动力荷载作用下,这些现象将引起钢材脆性断裂并影响疲劳强度,增加了钢结构风险事故发生的概率.大气环境腐蚀下钢结构性能的劣化已引起众多学者的关注.目前,国内外学者对钢材大气腐蚀的研究主要集中于:(1)钢材的大气腐蚀机理及影响因素;(2)不同大气腐蚀试验方法及其相关性;(3)钢材的大气腐蚀深度预测模型,目前虽已建立多种腐蚀深度预测模型,但要建立一种形式相对简单且精度高的预测模型仍需深入探讨;(4)大气腐蚀下钢材、钢构件的力学性能;(5)大气腐蚀下钢结构动态力学性能,此方面研究相对较少,目前国内外仍缺乏系统的报道.因此,为了明确大气环境(酸性和近海大气环境)腐蚀对钢结构性能的影响,本文对近50年国内外有关钢结构大气腐蚀的研究报道进行了评述,重点讨论了酸性、近海两种大气环境下,腐蚀对钢结构静态和动态力学性能的影响.首先分别详述了钢材在酸性(富含SO2)、近海(富含Cl-)大气环境下的腐蚀机理,以及大气腐蚀的影响因素;其次总结了钢材大气腐蚀试验方法,大气腐蚀下钢结构力学性能的相关研究;最后讨论了当前有关钢结构大气腐蚀研究的一些重要问题,并展望了今后的研究方向.

The study aims to research the influence of salt fog corrosion cycles on seismic performance of reinforced concrete (RC) frame beam-column joints in coastal atmosphere. Based on low cyclic loading tests of six RC frame beam-column joint specimens, this study analyses the failure patterns, hysteresis loops, load carrying capacity, displacement, backbone curves, and energy dissipation capacity of corrosion-damaged RC frame beam-column joints. The effect of salt fog corrosion cycles and axial compression ratios are tested repeatedly. The results show that with the same level of axial compression of the frame joint specimens, as the increase of salt fog cycles, the strength, ductility, energy dissipation, bearing capacity, and deformation capacity of joints degenerated to different degrees． When the corrosion level is the same, the stiffness degradation appeared to be more apparent as the increase of axial compression ratio. Then, the behavior degeneration rule of the RC frame beam-column joints is analyzed and formed according to the results of the test; the degeneration restoring force models of corroded RC frame beam-column joints is formed and verified based on Clough’s three-line degenerate restoring force model and the introduction to cyclic degeneration index. The results show that the restoring force model can better describe the hysteresis characteristics of the beam-column joints of corroded RC frames. The research is a theoretical reference for the seismic analysis of the RC frame structure affected by coastal atmospheric environment.

This paper presents an investigation on the rotational behaviors of fork-column Dou-Gong. Five scaled specimens in different construction forms were manufactured and tested by low reversed cyclic loading under three different vertical loads. The failure modes, envelope curve, strength degradation, deformability ratio, stiffness degeneration, and energy dissipation were assessed and compared. The results indicated that the increment of the rotational stiffness gradually decreases with increased vertical load. The relationship between rotational stiffness and vertical load can be simplicity expressed by a logarithmic function. The length, construction form, and number of linking beams are the main parameters affecting the rotational behaviors of single Dou-Gong. Reducing the length or enhancing the combined effect of the linking beams can effectively improve the bearing capacity and deformation capacity of the Dou-Gong, as well as energy dissipation capacity. The rotational behaviors of single Dou-Gong with one linking beam are worse than those of Dou-Gong linked by two beams. In addition, the double Dou-Gong exhibits better symmetry and plumper area than the single Dou-Gong, thus resulting in 109%, 78%, and 163% increment in bearing capacity, rotational stiffness, and energy dissipation, respectively. The moment-rotation curve of fork-column Dou-Gong is nearly trilinear and based on the appropriate mechanical parameters from the test results, the nonlinear hysteresis characteristics of the fork-column Dou-Gong can be simulated by an improved double-target model.