Most of the old rural houses in Beijing are single-layer buildings with double-sloping roofs. Under an earthquake, the gable is prone to an outward tilt, and the structure is prone to collapse as a whole. In view of the structural characteristics of the existing rural houses in Beijing, a reinforcement technology is proposed, in which the embedded steel frame reinforcement is mainly used, supplemented by a steel plate strip reinforcement. A 1/4 masonry structure model is designed for a shaking table test. A full-scale model is established in a finite element simulation analysis. The results show that the longitudinal wall is seriously damaged, and the gable has a considerable outward inclination under earthquakes. However, owing to the reinforcement effect of the steel frame, the overall collapse of the structure is avoided. The steel strip can effectively restrain the outward inclination of the gable and ensure safety of personnel.

为解决既有老旧农宅的修补与加固问题,以两开间的北京某单层砌体结构为原型,根据内框架加固思路提出了一种以内嵌式轻型钢框架加固为主,钢板带加固为辅的加固方法,并设计了1/4的砌体结构振动台模型进行振动台试验.试验结果表明:模型结构在小震作用下即出现明显损伤,在中震与大震作用下结构横墙出现明显的外倾,但由于钢框架与钢板带的加固约束作用,并未发生倒塌,外闪程度控制在安全范围内,加固后的结构达到了"大震不倒"的设防目标;随着地震荷载的逐次加载,结构自振频率逐渐衰减;试验模型的加速度放大系数随着地震强度的增加,在整体上呈现减小的趋势,当采用内钢框架与钢板带进行加固后,结构加速度放大系数有微小的增大趋势;结构的位移随着震级的增大而增大,且前檐口的位移大于后檐口的位移,出现了扭转效应;内钢框架在大震后仍保持未损坏的状态,避免了结构发生整体倒塌,保证了结构的安全性.

发电厂中新型脱硫排烟一体式钢塔属于复杂的高耸薄壁结构,由于顶部截面突然变细,风荷载作用下极易产生较大振动,为了减小风致振动,提出了适用于脱硫排烟一体式钢塔的调谐质量阻尼器(tuned mass damper,TMD)减振方案.基于流固耦合理论,建立了结构场与流场计算模型,成功利用数值风洞方法计算了有无TMD结构的风振响应,并通过现场风振监测对数值方法的可靠性进行了验证.结果 表明,该脱硫排烟一体式钢塔振型以局部或整体的平动、转动、屈曲与扭转为主,通过在塔体顶部设置TMD,位移动力响应最大值降低41％,均方根值降低75％.频谱分析表明,结构安装TMD后部分低频振型被激起,同时主频率对应的动力响应大大降低,TMD对于该脱硫排烟一体式钢塔可以起到较好的减振效果,为类似高耸薄壁结构的风振控制提供了参考.

Creep is an important characteristic of bamboo and wood materials under long-term loading. This paper aims to study the long-term bending behaviour of prestressed glulam bamboo-wood beam (GBWB). For this, 14 pre-stressed GB... | Find, read and cite all the research you need on Tech Science Press

In order to detect the grouting defects of the assembled building joints, this study uses ultrasonic testing methods to detect the grouting sleeves in six different defect conditions in the laboratory and the two-sided grouting and unfilled shear wall joints. The main ultrasonic sound velocity value detection index, research shows that: through the grouting sleeve ultrasonic detection sound velocity value analysis, ultrasonic testing can effectively detect the position of the grouting defect in the sleeve, there is a clear boundary line between the defect and the non-defect; And the eccentricity has an influence on the sound velocity value of the unfilled part, and the influence on the sound velocity value of the grouting part is not obvious; the ultrasonic sound velocity value and the amplitude detection result of the grouting sleeve of the field assembled shear wall joint are analyzed, and the unfilled sleeve shear wall test component is analyzed. The acoustic wave test results are around 1.0km/s-1.3km/s, and the acoustic wave test results of the grouting sleeve shear wall test members are around 2.0km/s-2.3km/s. The ultrasonic test wave of the ungrouted sleeve shear wall test component is tested. The amplitude result is about 24.3 dB - 30.0 dB, and the ultrasonic test wave amplitude value of the grouting sleeve shear wall test component is 40.3 dB - 44.5 dB. Around dB, the position of the grouting sleeve and the unfilled sleeve can be effectively discriminated by ultrasonically detecting the sound velocity value and the amplitude value.

The earthquake resistant behaviors and damage characteristics of the lightweight composite panel (space board) fabricated structure model were studied through shaking table tests on the full-scale model.According to the joint connection characteristics and force distribution characteristics,33 working conditions based on the 8 degree of seismic precautionary intensity in Beijing were designed,and test analyses were carried out for corresponding working conditions.Results show that there is certain damage in the structure under frequent earthquake,fortification earthquake and rare earthquake of 8 degree of seismic precautionary intensity,but there is no obvious torsion.The maximum interlayer displacement angle of the overall structure can meet code requirements,and the overall structure can meet performance-based seismic design objectives of "not damaged under frequent earthquake,repairable under fortification earthquake and not collapsing under rare earthquake".Analysis results can provide technical basis for widely application of low-rise lightweight composite structure.

In order to know the economic indicators of the aseismic strengthening measures on rural residential building in Beijing, in this paper, the aseismic strengthening measures of four pilot projects in Beijing Daxing District and Shunyi District are analyzed in economic indicators. A comparative analysis of the unit area construction cost of the reinforcement measures under different structure types, different masonry materials, different apartment layout rural buildings are comparatively analyzed, and the proportion of the construction cost of reinforcement measures on different structural parts in total aseismic reinforcement cost are analyzed. At same time, the reinforcement cost of aseismic weak parts including gable wall and front longitudinal wall are comparatively analyzed, and the cost of main reinforcement measures are comparatively analyzed. The construction cost of the pointed reinforcement measures are comprehensively obtained by the paper analyzing. Moreover, the cost analyzing results of the four typical rural pilot projects have provided economic reference for rural strengthening design and construction in Beijing.

Comparision of resistant behavior was made between two kinds of seismic strengthening methods for the single-story brick-wood structure with brick columns representative of existing rural buildings in Beijing, through shaking table tests on large-scale models. According to the seismic damages of unreinforced model test,the seismic strengthening measures were proposed,which included:(1)addition of a concrete window frame to increase the lateral stiffness of front longitudinal wall,(2)strengthening the walls,brick columns and under-window walls by using cement mortar to increase the carrying and deformation capacity,(3)addition steel ring beam to enhance the robustness of the structure.The results of testing damage and the dynamic characteristics parameters,such as,dynamic frequency,structural damping,acceleration dynamic coefficient,hysteresis curve etc.,showed that the reinforcement measures significantly increased the seismic resistance of this kind of brick-wood structure.At same time,the reinforcement measures could achieve the seismic design target of “operational under minor earthquakes, repairable damage under design basis earthquakes,and collapse prevention under rare earthquakes.”

砌体墙开设门窗洞口会导致其平面内的刚度及抗剪承载力降低,而开洞砌体墙的分布不均衡又使得地震作用下整体结构出现扭转变形,从而加大地震震害.以3片开洞砌体墙的拟静力试验为原型,采用ABAQUS有限元程序对3个模型(未加固的开洞砌体墙A-1、单面钢筋网加固的开洞砌体墙A-2、单面钢筋网和钢窗框同时加固的开洞砌体墙A-3)进行建模和非线性计算,得出了在低周反复水平荷载作用下砌体墙的荷载-位移滞回曲线,并通过对滞回曲线的处理,对比分析了应力云图、应变云图、滞回特性、砌体墙耗能、骨架曲线和刚度退化曲线,验证了有限元模型的合理性和有效性,同时也验证了加固措施的有效性.

根据北京地区既有农村住宅典型砖木结构(木柱支撑,木屋盖,外砖墙)的抗震性能特点以及农宅砖木结构未抗震加固模型的振动台试验损伤特征,结合北京地区8度抗震设防的要求,提出以下加固结构方案:①配筋砂浆带圈梁、②前檐加设钢门窗框、③房屋四角钢丝网砂浆加固,并设计2/3大比例缩尺模型,进行了8个工况振动台试验,研究了北京地区既有农村住宅单层砖木结构房屋上述抗震加固方法的有效性.通过与未加固模型的振动台试验损伤结果、动力特性、动力反应和频谱分析比较,验证了提出的加固方案的抗震性能和可行性.振动台试验结果表明:加固后模型达到了“小震不坏、中震可修、大震不倒”的抗震设防目标,为制定这类结构的抗震加固方案提供了依据.

A rural building in Beijing is a typical single-story brick-timber structure built in 1980 's.There aren't any aseismic measure in the building. The building by aseismic strengthening could achieve the design target of operational after minor earthquake,repairable damage under middle earthquake,and collapse prevention under rare earthquake. The structural aseismic key strengthening technologies against seismic fortification intensity in Beijing are introduced.

In order to investigate the seismic resistant capacity of typical brick structures in Beijing rural area,a 2 /3 scaled typical brick-timber structure model with brick columns,wood roof and brick peripheral walls was designed and tested on a shaking table,which is a single story brick-timber structure with three bays.According to the national seismic design code GB50011,seismic fortification intensity is 8 for most rural areas in Beijing.Different dynamic base excitation levels,such as design small earthquake with PGA = 0.072g,design moderate earthquake with PGA = 0.2g and great earthquake with PGA = 0.4g respectively,were input to the model.By analyzing the dynamic responses and cracking characteristics on the brick walls after testing.the seismic resistant capacity of the model was obtained.Some key technologies on how to strengthen and retrofit the existing rural brick-timber structures in Beijing were pointed out.

Considering the front longitudinal wall of rural housing built by mud masonry as an object of study,three windowed walls reinforced by different methods are designed through the quasi-static test of windowed brick masonry.These three walls are analyzed from the aspects which include destruction,ultimate load and cracking displacement,and the weaknesses of windowed walls are summarized in the earthquake.At the same time,the reinforcement effects and damage characteristics are analyzed for the steel mesh and cement mortar reinforcement and the steel sash reinforcement.In addition,reinforcement recommendations about two reinforcement methods are proposed.

The investigation and seismic reinforcements of typical rural dwellings in Beijing have been sped up since Wenchuan earthquake in 2008.Based on the investigations of the seismic performances of typical rural dwellings in 13 districts of Beijing,the information of structure system,construction time and construction materials were summarized.Based on seismic damage characteristics of similar rural dwellings in Wenchuan earthquake,the actual seismic performances of rural dwellings in Beijing were analyzed and security risks as well as countermeasures were proposed.The research provides reference for design,construction and research of seismic reinforcements of rural dwellings in Beijing.

This paper presents seismic retrofit for the single-story brick-wood structure representative of existing rural buildings in Beijing.The retrofitting effectiveness was examined through large-scale shaking table tests on the unretrofitted and retrofitted specimens.The test results indicate that,for the unretrofitted specimen,the front brick columns deform and damage severely when subjected to the longitudinal motions,because large of lateral stiffnesses difference exists between the front and back longitudinal walls.The brick gables experience significant out-of-plane deformation,resulting in diagonal cracks.The unretrofitted specimen is cracked under minor earthquakes,significantly damaged under design basis earthquakes,and approaches to collapse under rare earthquakes.The method of seismic retrofit was proposed based on the test results of the unretrofitted specimen,including the addition of a steel doorframe,steel window frames and steel plate collar beams,and the strengthening of the brick gables and columns by cement mortar reinforced with steel mesh.Shaking table test results show that the retrofit method significantly improves the earthquake-resistant capacity of the brick-wood building structure,and the retrofitted specimen can achieve the design objective of 'operational under minor earthquakes,repairable damage under design basis earthquakes,and collapse prevention under rare earthquakes'.

Based on the mechanism understanding of the buoyancy effect of the regional groundwater,on the base study about the static features of the interaction between a layered foundation soil and the structural basis on an abnormally high water level conditions of a particular region,the study of the destruction properties of the upper structure were established due to the elevated underground water level,by the above study the interaction mechanism among the layered subsoil,the foundation and the upper structure;the simplified calculation method of the groundwater buoyancy and the characteristics of the destruction of the upper structure has been gotten.This conclusion can provide the basis for the design of the foundation and upper structure of the building,the understanding of the damage elevation of the upper structure of the existing building which due to the abnormal in-crease of ground water buoyancy and the research of the reinforcement technology.

In order to investigate the seismic resistant capacity of typical brick-timber structures in rural areas of Beijing,a 2/3 scaled typical brick-timber structure model with timber columns,wood roof and brick peripheral walls was designed and tested on a shaking table,which is a single-story brick-timber structure with three bays.According to the national seismic design code GB50011,the seismic precautionary intensity is 8 for most rural areas in Beijing.Different dynamic base excitation levels,such as design small earthquake with PGA=0.072g,design middle earthquake with PGA=0.2g and great earthquake with PGA=0.4g respectively,were input to the model.Dynamic responses and cracking characteristics on the brick walls were recorded.Based on the test results,the seismic resistant capacity of the model was obtained and analyzed.It was found that due to different lateral resisting stiffness of the front wall and the back wall for different door or window openings,the response of the front wall was far greater than that of the back wall in the longitudinal direction.This leads to out plan flexure of the end brick wall,some key technologies for how to strengthen and retrofit the existing rural brick-timber structure in Beijing are pointed out.

The reinforced method of steel mesh mortar is used in the reinforced tests of Beijing rural masonry structures.In order to establish the nonlinear theoretical model of brick wall reinforced with steel mesh mortar,in this paper,the three-linear deteriorating restoring force curve of reinforced brick wall is discussed,the computational formulas of resistance to lateral stiffness under the different states of shear failure or flexure-shear failure are respectively summarized,and then the computational formulas of load at first crack and the ultimate load are respectively provided according to the existing quasi-static testing data of brick wall reinforced with steel mesh mortar.The above computational formulas are verified by comparing calculated results with testing data,and the comparing result demonstrated that these formulas are feasibility.The nonlinear theoretical model will also being used in the nonlinear seismic analysis of Beijing rural reinforced brick structures.

Taking some sandwich system as an example, the authors analyze and calculate global mechanical status under surrounding temperature and sunshine condition in winter and summer in Beijing area and mainly think about influence of deadweight stress and temperature stress on global mechanical status. By analyzing,it is found out that the key factor,which can influence on stability and durability of this system,is temperature stress on interface and mortar layer,which horizontally parallels to wall. Also the current standards are lack of the mechanical properties indexes of tension and compression stress on external wall external insulation system,which need to be paid attention for the relevant departments.