GFRP肋式剪力连接件受力性能对比试验研究

剪力连接件是保证GFRP混凝土组合梁/板中两种不同材料共同工作的重要构造,设计了矩形肋和T形肋两类GFRP肋式剪力连接件,进行了3组共8个GFRP肋式剪力连接件的推出试验,包括：矩形肋开孔、T形肋开孔、T形肋不开孔3组GFRP肋式剪力连接件,得到了其破坏形态、极限承载力、荷载滑移曲线及荷载应变变化规律,重点研究肋内开孔及肋的截面形式对GFRP肋式剪力连接件受力性能的影响。试验结果表明：GFRP肋式剪力连接件的破坏形态均为混凝土劈裂破坏;对比矩形肋开孔试件,T形肋开孔试件强度高、延性好;对比T形肋不开孔试件,T形肋开孔试件强度与延性均能提高。基于试验结果,建立了考虑肋内开孔及肋截面形式影响的GFRP肋式剪力连接件极限承载力计算公式,拟合得到了GFRP肋式剪力连接件的荷载滑移曲线上升段的理论模型,建立了其抗剪刚度计算公式。     

软岩地质条件下浅埋隧道锚缩尺模型试验

为研究隧道锚的受力变形和锚碇承载特性等问题,在重庆几江长江大桥工程北岸现场开展1∶30缩尺模型试验。试验结果表明：从相似设计荷载240 kN到1 680 kN,双锚碇前锚面沿拉拔方向的最大位移平均值为0.020~0.808 mm,双锚碇前端上部地表岩体铅直方向的最大位移值为0.028~0.749 mm,双锚碇后端上部地表岩体铅直方向的最大位移值为0.014~0.645 mm;锚碇围岩破裂类型是拉剪复合型破坏;锚碇上方地表横桥方向参与抗拔作用的岩体范围约2~3 m,而沿锚碇轴向参与拉拔作用的岩体破坏区类似一个倒塞体形状;通过试验得到模型锚的可靠抗拉拔承载能力为1 344 kN;模型锚在840 kN下的流变趋于稳定,其长期安全系数为3.5。模型试验结果表明软岩地质条件下浅埋隧道锚具有较高的抗拉拔承载能力,证明此设计方案是可行的。     

间作条件下玉米根系固土力原位测定

农作物的根系对土壤的固持作用可以减少坡耕地的水土流失。本研究以云南主要农作物玉米为例,通过采用剪切箱和锚杆拉力计,在玉米的成熟期对单作和与大豆间作2 种种植方式下的玉米根系在10 cm 深度上的固土能力进行了原位测定。结果表明,当施加载荷为1.5 kN 时单作玉米根系位移为5.9 mm,与大豆间作下的玉米根系位移是3.15 mm,裸地的位移是7.26 mm。单作玉米根系滑动距离要明显高于间作玉米根系,说明间作种植模式下的玉米的固持土壤能力要强于单作玉米。     

约束再生混凝土足尺试件受压应力应变全曲线试验研究

为研究箍筋约束再生混凝土的单轴受压应力应变全曲线,对9个直径为500 mm、高度为1 500 mm的再生混凝土圆形柱进行试验,采用20 000 kN伺服液压试验机进行位移控制加载。试验参数主要为纵筋率、箍筋间距与直径、加载应变速率。试验结果表明,箍筋间距、配箍率对试件延性影响较大。当加载应变速率由0.000 003/s增大到0.003 3/s时,试件的峰值应力增大1.14倍。分析表明,再生混凝土应力应变全曲线与普通混凝土类似,但下降段较普通混凝土陡峭,脆性更为明显。     

HDPF加固钢筋混凝土柱抗震性能试验研究

为了研究高延性聚酯纤维加固钢筋混凝土柱的抗震性能，共进行了7根柱的低周反复试验，其中，3根在未加固状态下进行试验，4根柱粘贴高延性聚酯纤维加固后进行试验，针对位移延性系数、等效粘滞阻尼系数、总耗能、承载力和纤维带的应变进行了研究与分析。研究结果表明：未加固柱的承载力、耗能能力和延性都比较低，采用高延性聚酯纤维加固后的试件裂缝发展缓慢，加固后柱的承载能力、耗能能力、延性均有不同程度地提高；在塑性铰区域内增加局部配筋，能够提高纤维布的约束效果。     

异位发酵床垫料的直剪切及压缩试验研究

为研究不同含水率的条件下异位发酵床垫料：抗剪强度、黏聚力、内摩擦系数、压缩载荷的变化规律。本研究采用土壤力学试验方法,测定垫料五种不同含水率的相关参数。结果表明：当垫料含水率为29.22%~36.13%时,抗剪强度、内摩擦角系数会随着含水率的增大而增大;当含水率为45.55%~61.11%时,抗剪强度、内摩擦角系数会随着含水率的增大而减小。黏聚力不会因含水率的改变而出现明显变化;垫料的压缩载荷随加载时间增大而增大,递增幅度逐渐增大。     

配置HRB500钢筋小跨高比带板开缝连梁的抗震性能试验研究

为了防止联肢剪力墙中小跨高比连梁发生低延性剪切破坏,在单连梁中部设置一条通缝,形成开缝连梁改善其抗震性能。试验完成了3个小跨高比带板开缝连梁的低周反复加载,通过与其他配筋形式连梁对比,分析了开缝连梁的破坏形态、滞回特征、承载力退化、刚度退化、延性、耗能等一系列抗震性能。利用软件ABAQUS对试件滞回曲线的骨架曲线进行模拟,并将模拟结果和试验结果相对比。结果表明,小跨高比开缝连梁具有良好的承载能力及变形能力,施工较为方便且经济,能有效防止小跨高比连梁延性较差的剪切破坏,具有较好的抗震性能,可在实际工程中推广。     

高强钢绞线网加固混凝土粘结性能试验研究

通过高强钢绞线网聚合物砂浆加固层与混凝土结构的剥离破坏试验，对加固层与混凝土界面的剥离破坏特征进行了研究。探讨了单侧加固、植筋加固及U型加固等不同的加固方式对加固层抗剪承载力及抗剪强度的影响。试验结果表明，采用U型加固等增加粘结面积的方式能有效提高加固层粘结面抗剪承载力，但同时会削弱加固层的抗剪强度，而在界面上植入抗剪钢筋后，能同时提高聚合物砂浆加固层的抗剪承载力及抗剪强度。根据试验结果，提出了最小植筋率的建议值。     

夯土-水硬石灰与石英砂浆液-木锚杆锚固系统性能

运用室内物理模型试验和原位试验,对基于水硬石灰与石英砂浆液的木锚杆锚固系统在夯土介质中进行了拉拔测试与杆体-浆体界面应变监测,研究了该锚固系统的锚固性能与破坏模式、杆体-浆体界面剪应变分布与传递特征。试验结果表明,该锚固系统50 cm锚固长度可以提供30~45 kN(室内)与16.2~19 kN(现场)的极限锚固力;锚固系统具有较强的延性;在加载进程中杆体-浆体界面的应力分布与传递特征具有单峰值或双峰值分布、界面应力向锚固末端传递、压应力出现在锚固段中末端等特征,表现出复杂的受力特性。研究结果表明,该锚固系统在结构形式和力学性能上适合于夯筑土遗址加固,并与遗址体具有较好的兼容性。     

水平荷载作用下斜坡刚性桩非线性分析

在综合分析现有水平荷载作用下桩基分析方法的基础上,建立了考虑桩侧土体受力状态的斜坡刚性桩力学模型;根据极限平衡原理,建立横向荷载作用下斜坡刚性桩弯矩和应力平衡方程;引入考虑斜坡影响的p-y曲线方法,提出了综合考虑桩侧土体极限承载力与水平抗力系数沿深度呈线性增加的侧向极限承载力与土体抗力承载力系数计算方法,同时,将该方法应用于计算实例,通过与已有有限元和理论计算方法对比分析,计算结果验证了本文方法的合理性与可行性;并利用该方法,分析了斜坡坡角、桩土接触面系数以及地基水平抗力系数对斜坡刚性桩承载特性的影响因素。分析表明:斜坡的坡角、桩土接触面系数对侧向荷载作用下斜坡刚性桩的荷载位移曲线影响明显,而桩侧土的抗力系数对侧向荷载作用下斜坡刚性桩的荷载位移曲线影响不明显。     

Experimental Analysis on Axial Compressive Behavior of R- CFTStub Columns with Prestressed Binding Bars

In order to investigate the effect of prestressed binding bars on axial compressive behavior of rectangular concrete-filled tubular (CFT) short columns, five rectangular CFT short columns, three with prestressed binding bars, one with ordinary binding bars, the other with no binding bars, were constructed and tested under axial compressive loads. The binding bars were made up with high-strength bolts. As used for ordinary binding bars, the high-strength bolts were welded to the steel tube before the column was loaded to axial compressive force. As used for prestressed binding bars, the high-strength bolts were first tensed by screwed screw cap down to bring force to prestress the steel tube and its core concrete, then welded to the steel tube before the column was loaded to axial compressive force. Test results indicate that the bearing capacity and ductility of rectangular CFT short columns are increased by setting binding bars. Compared to ordinary binding bars, the prestressed binding bars can decrease the longitudinal displacements corresponding to ultimate strength, but have little effect on the ultimate strength and displacement capacity after ultimate strength of the columns. The longitudinal displacements corresponding to ultimate strength of the columns decrease with the decreasing of space between binding bars. With the same section width and amount of binding bars, the bearing capacity of the columns improves with the increase of section long-broad-ratio, while displacement capacity after ultimate strength decreases with the increase of section long-broad-ratio.     

Experimental Analysis on Bending Capacity of Unbonded Prestressed Concrete Beams with HRBF500 Steel Bars

The bending capacity tests on ten simple supported beams were conducted to investigate the damage characteristics, prestress increment, beading capacity and displacement ductility of unbounded prestressed concrete beams with HRBF500 steel bars. The results show that the HRBF500 steel bars has yielded before the limit state. The concrete in compression zone crushes upon the broken of the beams, which shows a sudden damage mode. The measured ultimate stress increments of unbounded tendons are in linear relationship with the comprehensive reinforcement ratio index, while the values of the ultimate stress increments are obviously higher than those values specified in the code GB50010-2010, and the average ratio of predicted values to testing values is about 0.35. The mid span deflection upon yielding of the beams is large, while the displacement ductility is bad and the average value of the displacement ductility ratio is 1.67. The displacement ductility ratio decreases with the increases of the comprehensive reinforcement ratio index. Based on the experimental results, the proposed calculation formula of ultimate stress increments of unbounded tendons was established, and it is in good agreement with the experimental results when the testing value is less than 450 MPa.     

EXPERIMNTAL RESEARCH ON THE CRACK RESISTANCE AND BEARING CAPACITY OF PRESTRESSED BRICK MASONRY WALLS UNDER CYCLIC LOADING

By comparing the tests of prestressed and nonprestressed brick masonry walls with peripheral beams and Constructional columns, under cyclic lateral loading,the apperaence and development of Cracks,failure mechanism,hysteretic behavior,strength,stiffness,ductility and ener-gy dissipation of the brick rnasonry walls arc studied.Only the crack resistance and bearing capacity of walls are discussed in this paper.It is shown that prestressing on brick masonry wall can obviotisly improve its seismic behavior.Morcover,calculating methods for the crack resistance and the ultimate bearing capacity are presented,and the caculating results are identical with the tests.     

CFRP加固冷弯薄壁C型钢长构件的轴压承载力

为了研究CFRP加固冷弯薄壁C型钢长构件的承载能力，对腹板和翼缘均粘贴CFRP的试件进行了轴心受压加载试验。7根长度均为1 400 mm的试件，其中1根为未加固的控制试件，其余6根封闭缠绕外贴50 mm宽CFRP间距为50、100、150 mm 3种情况，层数为1层和2层。试验结果表明，在轴心荷载作用下的破坏模式为整体弯扭失稳，与控制试件相比，加固后试件的稳定极限承载力均有不同程度的提高；当CFRP间距与腹板高度的比值小于1时，加固效果较理想，且2层CFRP的加固效果好于1层。最后，采用有限元对模型进行数值模拟，对比试验数据和数值模拟结果，二者吻合较好。     

X形配筋增强高强钢筋异形柱边节点抗震性能试验研究

通过对核心区应用X形配筋增强的高强钢筋异形柱边节点和同等条件下未被增强的高强钢筋异形柱边节点进行拟静力试验研究，对比分析异形柱边节点的破坏特征、滞回曲线、承载能力、位移及延性、刚度退化、耗能能力等抗震性能指标。研究结果表明，配置HRB500高强钢筋异形柱边节点比配置600 MPa级的边节点承载能低，但滞回性能好，变形能力强，刚度退化推迟，耗能能力强；在核心区加入X形配筋，均可以改善高强钢筋异形柱边节点的破坏特征，使边节点抗剪能力、变形能力、耗能能力增强，刚度退化推迟，提高异形柱边节点抗震性能，配置HRB500高强钢筋的试件核心区应用X形配筋加强后抗震性能提高效果更好。     

Lateral Bearing Capacity and Simplified Equations of Dry Stack In filled Reinforcement Concrete Frame Structure

The mechanism and lateral bearing capacity of reinforcement concrete (RC) frame with dry stack in filled panel (DSIP) were investigated using quasi static experiments and finite element models. According to the parallel model and equivalent strut model, the lateral bearing capacity of RC frame and DSIP were researched separately. Results show that: 1) The plain stress element and interface element are applicable in finite element (FE) model analysis. According to the FE model, the failure of RC frame with DSIP is caused by the damage of frame; 2) Lateral bearing capacity of DSIP is mainly from the friction between bricks in the panel, which can be divided into 3 stages: constant stage, increasing stage and ultimate stage; 3) Equations for lateral bearing capacity of DSIP were proposed and verified by FE model results.     

城市模型反射率测量方法与运用

介绍了一种测试城市模型反射率的试验方法。制作10个条形和十字形的城市模型进行测试,观测路面不同反射率对城市反射率的影响,并将实测模型反射率与ASTM E1918-06规范计算结果进行对比。研究发现:瞬时太阳辐射强度变化值在规范允许范围内,模型计算的反射率与ASTM E1918-06测量值的误差在0~0.1之间。当峡谷纵横比(建筑物高度与路面宽度之比)为1.0时,路面反射率从0.15提高到0.65,城市峡谷反射率增幅在0~0.30之间;提高路面反射率并不能有效提高城市峡谷反射率,尤其是纵横比较大的深峡谷。城市峡谷中的多重反射抑制城市反射率的提高。同时,反射路面将给行人增加额外的辐射通量,可能带来热不适感和眩光刺眼等问题。因此,应谨慎看待反射路面作为一个缓解城市热岛效应策略。     

焊接加固热作用对工形截面压弯钢构件承载性能的影响

为研究焊接加固热作用及不同初始负载对工字形压弯钢柱承载性能的影响,基于考虑热影响的热结构耦合分析方法进行了热源模型热输入改进,并考虑初始几何缺陷、初始残余应力及摩擦等,完成了不同负载下焊接加固的3个工字形压弯钢柱的模拟分析。研究了焊接位移时程、腹板应力应变重分布及荷载位移关系,通过有限元分析与相应试验结果对比验证,进而获得了试验无法获得的焊接温度场、翼缘与加固板间的焊接应力应变重分布以及翼缘边缘屈服承载力等结果,并将承载力结果与规范计算结果对比,考察了现有设计方法。结果表明,焊接顺序决定焊接变形的发展过程,焊接热输入和初始负载共同决定持载焊接的位移变化范围和焊接残余变形的大小;初始负载越大,应力应变重分布往偏心受力方向发展更多,承载力越低,而初始残余应力不影响极限承载力;采用考虑热影响的有限元方法具有一定可行性和总体安全性,规范设计方法仍有可提升空间。