Older areas in the city are now generally characterized by road congestion, obsolete facilities, low disaster prevention capability, and so on. To accurately and efficiently improve the quality of the living environment in the urban old settlements, this paper proposes a resilience evaluation method for old neighborhoods based on cloud modeling. Based on the toughness theory, this paper obtains 30 groups of representative characteristics data of old neighborhoods in Xi'an City, Shaanxi Province, China, through field research and determines 4 first-level indicators, 9 second-level indicators, and 30 third-level indicators of architectural toughness, facility toughness, environmental toughness, and personnel toughness by referring to relevant literature and combining with the suggestions of relevant experts to constitute the evaluation index system of the old neighborhoods. The analytic hierarchy process is used to determine the subjective weight of each indicator, the entropy weight method and maximum entropy relative entropy criterion combination method is used to determine the objective weight, the final weight is determined by the combination of the weighting method, and MATLAB (version R2018b) is used to construct a cloud model based on the evaluation of the toughness of the old neighborhood. Based on this model, this paper selects the old neighborhood in Xi'an City, Shaanxi Province-Wanqing Lane neighborhood, for toughness evaluation, and the results obtained can more accurately reflect the toughness of the neighborhood. At the same time, the study shows that the evaluation model established offers a certain degree of effectiveness and applicability.

In this study, the damage modes, hysteresis curves, and changes in characteristic loads of the models obtained from experiments in both positive and negative directions are analyzed, and the results show that the T-type recycled aggregate concrete short-leg shear walls have excellent seismic performance. Meanwhile, with the increase of the replacement rate of recycled coarse aggregate, the indexes such as hysteresis performance gradually improved; with the increase of axial compression ratio, the indexes gradually decreased. Finally, the formula for calculating the normal section ultimate bearing capacity of T-type RAC short-legged shear wall was established through experimental analysis, and the formula for calculating the horizontal ultimate bearing capacity was derived on the basis of this formula, and the horizontal ultimate bearing capacity of the four models was calculated by using the established formula, and the average error was only 9.45

A new type of assembled shear wall with energy dissipation and seismic damping function was proposed for the damage mechanism and weak points of typical assembled shear wall structures under strong earthquake effects. Using a combination of model tests and numerical simulations, four new assembled shear wall specimens with a scaling ratio of 1:1.54 and a shear-to-span ratio of 1.52 were designed and fabricated. The corresponding seismic performance tests were carried out. The effects of the number of bolts, axial compression ratio and longitudinal reinforcement ratio of edge members on the damage mode, hysteresis performance, bearing capacity, deformation performance, stiffness degradation and energy dissipation capacity of the specimens were systematically analyzed. The test results show that the damage mode of each specimen is basically the same as that of the common shear wall with the same shear-to-span ratio, which is bending-shear type damage However, the new assembled shear wall has more excellent hysteresis performance and energy dissipation capacity. Friction between the steel plates of the horizontal joints consumes a lot of energy and further inhibits wall damage. The energy dissipation value at the point of destruction of the wall is significantly higher than that of ordinary cast-in-place wall. The energy consumption value of the specimen PFSW is about 6 times that of a cast-in-place wall. When the number of bolts decreases, hysteresis performance decreases and wall deformation increases. The decrease of axial pressure ratio or longitudinal reinforcement ratio of edge members leads to the decrease of bearing capacity and increase of ultimate displacement of shear wall. Finally, the finite element model of the corresponding specimens was established by ABAQUS software. The simulation results were in good agreement with the test results, which indicated the correctness of the proposed model. And it can be applied to the analysis of new assembled shear walls.

In view of the problem that the current evaluation of prefabricated buildings in China focuses more on the ‘assembly rate’, this paper puts forward a green assessment method suitable for prefabricated buildings in China, which determines the evaluation index system according to four aspects: green design, intelligent construction, assembled building quality and comprehensive benefit. In addition, the decision making trial and evaluation laboratory method is used to optimise the index weight, and then the analytic hierarchy process–entropy weight method is used to determine the weight of the index system, and the evaluation index set is quantified and graded. Finally, taking the Hutuo Village public rental housing project in Xi’an City of Shaanxi Province as an example, this paper uses the evaluation method to conduct a green assessment and gives suggestions for improvement in each stage of the project.

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Based on the construction advantages of dry connection mode of precast shear wall with high-strength bolts, steel plates and other components, a new type of prefabricated shear wall with the function of friction energy dissipation was proposed. Three shear wall specimens with the scale ratio of 1.54 were designed, and the control parameters were the axial compression ratio and the longitudinal reinforcement ratio of edge components. The quasi-static tests were carried out and the results show that the final failure mode of the three specimens are similar, which is the bending-shear failure that diagonal cracks in the wall develop to the concrete spalling in the compression area. The reduction of axial compression ratio or longitudinal reinforcement ratio of edge components have adverse effects on the seismic performance of the new prefabricated shear wall, which is manifested in the weakening of hysteretic performance and the reduction of ultimate bearing capacity. Combined with the finite element analysis results, the five-fold skeleton model and restoring force model of the new prefabricated shear wall were established. The proposed restoring force model is in good agreement with the test results, which can provide reference for the elasto-plastic seismic response analysis of the new prefabricated shear wall.

为增强装配式剪力墙的耗能能力,提高其施工效益,提出一种具有摩擦抗剪与耗能功能的新型装配式剪力墙结构,并进行了抗震性能试验.为弥补试件数量不足以及精确确定最优起滑荷载的设计需求,结合新型装配式剪力墙抗震性能试验结果,探讨相应高精度有限元模型建立方法,并进行多参数结构抗震性能影响分析.最后,基于有限元分析结果和新型装配式剪力墙工作原理,确定最优起滑荷载.研究结果表明:所提出的新型装配式剪力墙具有良好的滞回耗能能力;螺栓预紧力、钢材摩擦因数、螺栓总距等对结构抗震性能影响显著,应作为相应结构设计的主要参数,竖向荷载、钢板厚度、钢材弹性模量影响较小,可以忽略不计;当起滑荷载设定为墙体屈服荷载时,结构模型耗能达到峰值,同时耗能系数开始明显降低,因而将结构的最优起滑荷载确定为屈服荷载.

The mechanical properties of the connection joints/horizontal joints of the fabricated shear wall structure play a vital role in the fabricated structure. In order to improve the seismic performance of the fabricated shear wall structure, a new type of assembled shear wall horizontal connection device is designed and developed based on the principle of energy dissipation in this study. Two horizontal connection devices with different bolt number are designed and manufactured. The device comprises of high-strength bolts and Q345 steel. The dynamic mechanical behaviors are tested for the horizontal connection device under different sinusoidal loading frequencies. The influence laws of different bolt preload, loading frequencies and bolt numbers are explored on the mechanical properties of the device. The effect of friction temperature rise on the mechanical properties of the device is investigated. The experimental results indicate that the device can not only ensure the reliable connection of the structure, but also dissipate significant seismic energy by the internal friction of the device, so as to effectively reduce the seismic response of the structure and protect the main structure. Additionally, the energy dissipation capacity and secant stiffness of the device is proportional to the bolt preload, but the equivalent damping ratio is independent of the preload; the mechanical properties of the horizontal connection device hardly depend on the loading frequency; the increase of the bolt number can considerably enhance the energy dissipation of the device; Both the preload and loading frequency are important factors affecting the temperature rise of the device, but the temperature change has little effect on its mechanical behaviors.

Considering the failure mechanism and weaknesses of traditional fabricated shear wall structures under strong earthquakes, a new type of fabricated shear wall with functions of energy dissipation and shock absorption was proposed. On the basis of model test and numerical simulation, seismic performance tests were carried out on four specimens with scale ratio of 1∶1.54 and shear span ratio of 1.52. Further analysis was conducted to investigate the effects of bolt number, axial compression ratio, and reinforcement ratio of edge members on the seismic performance of the new fabricated shear wall, including failure modes, hysteretic performance, bearing capacity, displacement ductility, stiffness degradation, and energy dissipation capacity. Test results show that the four specimens experienced shear compression failure, which was the same as the cast-in-place shear wall with the same shear span ratio. However, the proposed shear wall had better hysteretic performance and energy dissipation capacity, and the energy dissipation capacity was higher than that of the cast-in-place shear wall at the failure point. When the number of bolts decreased, the hysteretic performance of the new fabricated shear wall decreased, the wall deformation increased, while the bearing capacity remained almost unchanged. When the axial compression ratio or reinforcement ratio of edge members decreased, the bearing capacity decreased, and the ultimate displacement increased. Finally, the finite element model of the specimens was established by ABAQUS program. Comparisons of numerical results and test results showed a good agreement, verifying the correctness of the model, which can be applied to the analysis of the new fabricated shear wall.

为精准、高效改善城市老旧小区居住环境品质,提高其防灾、减灾能力,提出一种基于云模型的老旧小区韧性评价体系.基于韧性理论,对所选老旧小区按照不同年代进行分组,通过实地调研,获得陕西省西安市 30 组具有代表性的老旧小区特征数据,参考相关文献及相关专家建议,确定建筑韧性、设施韧性、环境韧性、人员韧性共计 4 个一级指标、9 个二级指标、30 个三级指标,构成老旧小区的评价指标体系.采用层次分析法(analytic hierarchy process,AHP)确定各指标的主观权重,采用熵权法(entropy weight method,EWN)和准则去除效果法(method based on the removal effects of criteria,MEREC)确定客观权重,采用组合赋权法确定最终权重,运用MATLAB构建了基于云模型的老旧小区韧性评价体系.基于此评价体系,选取西安市一老旧小区——万庆巷小区进行韧性评价,所得结果能够较准确地反映该小区韧性薄弱环节,表明所建评价体系具有一定的适用性与有效性.

Based on high-strength bolts, steel plates and other components to achieve the advantages of prefabricated shear wall assembly connection "dry connection" operation advantages, a new type of assembled shear wall with friction energy consumption function was proposed. Using a combination of model tests and numerical simulations, three shear wall specimens with a scaling ratio of 1:1.54 were designed and the corresponding seismic performance tests were carried out. The effects of axial compression ratio and longitudinal reinforcement rate of edge members on the damage mode, hysteresis performance, load carrying capacity, deformation performance, stiffness degradation and energy dissipation capacity of specimens are systematically analyzed. The test results showed that the final failure modes of the three specimens were similar, which was the bending-shear failure from the development of the oblique cracks in the wall to the concrete spalling in the compression zone; The reduction of the axial compression ratio or the reinforcement rate of the longitudinal reinforcement of the edge members will lead to the reduction of the bearing capacity of the shear wall and the increase of the ultimate displacement has a negative impact on the seismic performance of the new assembled shear wall, which is manifested by the weakening of the hysteresis performance and the reduction of the ultimate bearing capacity. Combined with the finite element simulation results, the five-fold skeleton model and restoring force model of the new assembled shear wall were established, and then the calculation formulae of unloading stiffness and loading stiffness of the hysteresis curve were obtained by regression fitting. The restoring force model proposed in this paper is in good agreement with the test results, which can provide a reference for the elastic–plastic seismic response analysis of the new fabricated shear wall structure.

装配式剪力墙结构连接节点/水平接缝的力学性能对装配式结构起着至关重要的作用,为了提高装配式剪力墙结构的抗震性能,本文结合消能减震技术设计研发了一种新型装配式剪力墙水平连接装置.通过该设计,制作了2种不同螺栓数量的水平连接装置,并对其进行了不同正弦加载频率下的动态力学性能试验,探究了不同螺栓预紧力、加载频率及螺栓数量对装置力学性能的影响规律;探究了装置摩擦升温对其力学性能的影响规律.结果表明:该装置在保证结构可靠连接的同时,又能依靠装置的内部摩擦消耗大量地震能量,从而有效减小结构地震响应,保护主体结构.此外,螺栓预紧力与装置的耗能能力和割线刚度基本呈线性关系,但对等效阻尼比影响不大;水平连接装置的力学性能几乎不受加载频率的影响;增加螺栓数量可大幅提高装置耗能能力;螺栓预紧力与加载频率均是装置温度升高的重要影响因素,但装置温度变化对其力学性能影响不大.

In this paper, the varying laws of stress-strain curve, feature point stress, energy dissipation capacity, and equivalent damping ratio of shape memory alloy wires were studied with the variation of diameter of wires, strain amplitude and cyclic loading times. The results show that the mechanical properties of SMA wire tend to deteriorate with the increase of wire diameter. When the strain amplitude reached 6% and the loading cycles reached 15, SMA wire could be formed with good hysteretic performance and working stability. Based on the superelastic property of the trained SMA wire and the basic working principle of tuned mass damper (TMD), a kind of detachable SMA suspension pendulum damping system convenient for disassembly was designed and fabricated. For this kind of damping system, the corresponding performance tests were completed, and the natural frequency of the system, the phase relationship between the mass vibrator and the controlled structure, and the variation of the equivalent damping force with the mass of the vibrator and the length of the pendulum rod were analyzed. The results show that the phase relationship between the mass vibrator and the controlled structure maintains between 150 degrees similar to 180 degrees under sine wave and real earthquake excitation, meanwhile the control effect increases with the rise of equivalent damping force. Above all, the system can be easily applied to the control of structural vibration, and provide stable and efficient damping force, so that the structure can be protected from strong dynamic disasters.

Through the low cycle loading test of three full-scale enhanced-performance recycled aggregate concrete frame joints, the damage evolution and accumulation are analyzed according to the traditional ductile damage model (single parameter) and the improved Park-Ang damage model (double parameters): when the characteristic displacement of each specimen equals 20 mm, the specimen has been damaged, but the calculated results are negative according to ductile damage model; when the characteristic displacement exceeds 100 mm, the calculated results of the improved Park-Ang damage model show that all the specimens have been completely destroyed and cannot continue to bear load, but the actual results of the specimens still show certain bearing capacity and energy dissipation capacity. Therefore, it is necessary to modify the aforementioned damage model to make it suitable for enhanced-performance recycled aggregate concrete structures. Based on the foregoing test results, the fiber coefficient a, displacement coefficient alpha, and correction coefficient of energy coefficient k were proposed and fitted for the improved Park-Ang damage model. In addition, a corresponding modified Park-Ang damage model was established. Finally, using the proposed damage model, the error analysis of damage index was carried out with the example of HF-RAC2. The results show that the average error is within 6%, so the proposed two-parameter damage model can be applied to the analysis of seismic damage assessment of EC-RAC frame joints.

By means of the low cycle loading tests on six recycled aggregate concrete (RAC) columns with different proportions, in combination with the Park-Ang two-parameter damage model suitable for ordinary concrete columns and the damage degree Dc of actual structures, the calculated value of cyclic loading coefficient β of recycled aggregate concrete columns was determined. It would be achieved by analyzing the calculated β that the impact of the replacement ratio of recycled aggregate and the content of mixed fibers on β was significantly different. Considering the reinforcement ratio mentioned in paper. Matlab was further employed to fit multivariable linear equation regarding recycled aggregate replacement ratio, mixed fibers contents and reinforcement rate as the basis, so that the computation formula of the cyclic loading coefficient β suitable for recycled aggregate concrete columns was revealed.

通过对3个足尺性能增强再生混凝土(EC-RAC)框架中节点进行低周反复加载试验,分析其结构模型地震损伤演化过程,确定其震后实际损伤状态与损伤指标.同时,针对传统钢筋混凝土Park-Ang双参数损伤模型无法准确描述加载位移大于100mm后EC-RAC框架节点模型的损伤演化与累积行为的缺点,本文提出了一种修正的Park-Ang双参数损伤模型,并基于前述试验结果,拟合了纤维项系数、位移项系数、能量项系数.最后,利用所提出的损伤模型,以HF-RAC2为例进行损伤指标误差分析,结果表明:平均误差在6％以内,即所提出的双参数损伤模型能够适用于EC-RAC框架节点地震损伤与评估分析.

Based on ANSYS finite element software and combined with the physical properties of piezoelectric materials, the actuating properties of the new piezoelectric ceramic tubular actuator was simulated. In addition, the maximum displacement, output and response frequency characteristics of the actuator were obtained. The results shown that the actuator was suitable for the development of structural vibration control device. The intelligent damper for adjusting friction in real-time was proposed by using the above-mentioned new actuator. In addition, the dynamic mechanical properties of the intelligent damper were analyzed, the constitutive relationship under the sinusoidal simple harmonic action and the calculation formula of the energy consumed in one cycle were obtained.

In this study, the vibration mixing technology is researched, and the effect of the vibration on the performance of recycled concrete is investigated. Through the analysis of the strengthened mechanism on the recycled concrete adopting vibration mixing, the vibration could increase of collision numbers between aggregates so as to purify the surface of recycled aggregates, and improve the interface between the recycled aggregates and cement pastes, and realize the macroscopic and microscopic uniformity of recycled concrete to improve the performance of recycled concrete. The performance of recycled concrete mixed by ordinary forced mixing and vibration mixing respectively, was compared experimentally. And the results indicate that the vibration could increase the air contents of recycled concrete, improve the mechanical performance of the recycled concrete, provide a favorable environment in order to enhance the microscopic structure and strengthen the recycled concrete.

通过对3个足尺性能增强再生混凝土框架中节点进行低周反复加载试验,按照传统延性损伤模型(单参数)、改进的Park-Ang损伤模型(双参数)对其损伤演化与累积进行分析:各试件特征位移等于20 mm时,试件已经出现损伤,但按照延性损伤模型计算结果为负;当特征位移超过100 mm时,改进的Park-Ang损伤模型计算结果表明各试件已经完全破坏,无法继续承载,但试件实际结果却仍表现出一定的承载能力与耗能能力.因而有必要对前述损伤模型进行修正,使其能够适用于性能增强再生混凝土结构之中.基于前述试验结果,针对改进的Park-Ang损伤模型,提出并拟合了纤维项系数、位移项系数和能量项系数3种修正系数,并建立了相应的修正的Park-Ang损伤模型.最后,利用所提出的损伤模型,以HF-RAC2为例进行了损伤指标误差分析,结果表明:平均误差在6％以内,即:所提出双参数损伤模型能够应用于性能增强再生混凝土框架节点地震损伤与评估分析之中.

This paper systematically studies the change law of the SMA (Shape Memory Alloy) stress-strain curve, stress at feature points, energy dissipation capacity and equivalent damping ratio with SMA diameter, strain amplitude, loading rate and the number of cyclic loading. As SMA’s dynamic mechanical property cannot be described in Brinson's SMA phenomenological constitutive model, an SMA simplified constitutive model, in which the influence of loading and unloading rate is considered, is introduced combined with the above test results. Then, this model is used to simulate SMA wires, and the obtained average error of all feature points at the stress-strain curve is only 3%. The results show that the established rate-dependent SMA simplified constitutive model can not only accurately describe the hyperelastic behavior of SMA during the phase change process induced by stress, but also reflect the influence of loading and unloading rate and strain amplitude on SMA’s dynamic constitutive model. This model has a simple structure and broad prospect in engineering application.