共查询到20条相似文献，搜索用时 718 毫秒
1.
根据基础隔震理论,在钢筋沥青隔震礅的基础上,提出一种新型钢结构隔震礅,设计和制作了缩尺房屋模型,并对其进行振动台试验。通过对隔震结构模型的动力特性、地震响应及能量平衡分析,绘制试验过程中的加速度及能量时程曲线,研究钢隔震礅应用于低层框架结构的减震耗能能力。大量工程实例可以看出该隔震礅隔震效果显著,制作简单、价格低廉、耐久性好,适于在广大村镇地区低层框架结构中推广使用。试验表明:隔震结构模型在不同的地震作用下,加速度折减系数处在0.24~0.51之间,且结构的阻尼耗能在振动台试验中占总输入能量的60%~70%,对结构耗能起主导作用,说明该基础隔震装置不仅具有较好的减震耗能特性能,对于控制隔震层的位移也有好的效果。 相似文献
2.
文中在新型水泥基压电传感器的基础上开发了一套水泥基压电传感系统,该系统由水泥基压电传感器、专门开发的小型电荷放大器、多通道数据采集仪和监测软件组成.该水泥基压电传感系统具有与混凝土的兼容性好,耐久性好,成本低廉等优点.将该系统应用到短柱模型和框架结构模型的动态响应测试中.试验结果表明:水泥基压电传感器在埋入混凝土构件后其频响特性和输入输出的线性关系不变,而且由其构成的传感系统还能够准确获得结构在简谐及地震地面运动下的内力.水泥基压电传感系统可用于混凝土结构的动态监测. 相似文献
3.
预应力混凝土连续梁桥振动特性变异及舒适度评价 总被引：2，自引：1，他引：1
由于预应力损失、混凝土收缩徐变、超载等原因,预应力混凝土桥梁出现了较强的振动。本文通过对福建省福州市闽江三桥全桥环境振动试验和正常运营条件下24小时的监测,研究预应力混凝土连续梁桥的动力特性及其变异和振动舒适度,结果表明:在较为稳定的风和温湿度环境下,固有频率在一天内的最大变化为3.06%,模态阻尼比的最大变化为37.93%,舒适度的狄克曼指标降到“能忍受短时间振动”的区域。 相似文献
4.
纤维增强材料对于改善水泥基材料的韧性和抗冲击性、大幅度提高混凝土的断裂能、防止混凝土发生脆性破坏具有重要意义;而"绿色"纤维在提高混凝土结构安全性的同时,具有环保、节能、利废、可降解再生等特性。本文介绍了"绿色"纤维的分类,分析了"绿色"纤维增强水泥基材料的特点,总结了"绿色"纤维在水泥基材料中应用、研究的进展。指出:"绿色"纤维与水泥基材料复合,适应循环经济和建材行业可持续发展的要求,是未来纤维增强水泥基复合材料发展的主要方向。 相似文献
5.
介绍了一套基于耐久性好、价格低廉及全天候运行的水泥基压电传感器的交通量监测系统。首先将两个水泥基压电传感器埋入一段混凝土梁的两端,以此梁作为埋入路面下的传感单元。再将4根测试好的混凝土梁埋入一条车道的两道沟槽内,每道槽内放入两根。系统运行时通过传感器数据分析来计算交通流量,即以测试信号中的峰值个数计算车辆数,以传感器的响应之和计算车重,并以两道沟内传感器响应的时间差及距离计算车速。其后通过已知重量的卡车进行传感系统现场标定。目前,该套系统已经成功安装到一座高速公路桥梁中,且运行顺利。通过与视频监测结果的对比表明,该系统能够准确的获得车流量、车辆速度以及近似重量。进而可见,该水泥基压电传感器在交通量监测中是有效的。 相似文献
6.
在细观层次上,混凝土可以被看作由水泥基、分散粒子和界面过渡层组成的三相复合材料。首先,基于骨料分布和形态的随机特性,将瓦拉文公式推广应用于确定二维混凝土试件截面凸多边形骨料分布,提出圆形骨料模型中以圆骨料的面积为控制参数,以圆内接多边形为基架的凸多边形随机骨料算法。进而以C80高强高性能混凝土为例,对数值试样进行单轴受压的数值模拟,得到相应的应力-应变曲线和损伤演化图。数值模拟结果与物理试验结果对比表明本文提出的数值模型合理可行。 相似文献
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8.
交通量监测在公路管理养护系统中有着重要的作用。为此,一种用于监测交通量的新型水泥基压电传感器得以开发研制。该传感器能够响应由于车辆所引起的冲击荷载,而且具有耐久性好、价格低廉及全天候运行等优点。本文介绍了该传感器的制作及其基本性质。并将两个水泥基压电传感器埋置于一段混凝土梁中,以该梁作为埋入路面以下的传感单元。对该梁的测试实验表明,埋入混凝土梁的水泥基压电传感的性能没有发生变化,仍可以正确地反应各类冲击荷载。由此可见,该水泥基压电传感器对交通量的监测应用中是行之有效的。 相似文献
9.
为了研究不同跨高比多层钢框架内填混凝土深梁结构的抗震性能,在钢框架内填混凝土深梁滞回性能试验的基础上,利用ABAQUS对六层纯钢框架（结构一）、钢框架内填跨高比为2混凝土深梁结构（结构二）和钢框架内填跨高比为0.75混凝土深梁结构（结构三）进行弹塑性时程分析。结果表明:内填混凝土深梁使结构整体刚度明显增大;在地震波的作用下,结构二的最大顶点位移降低可达58.3%,结构三的最大顶点位移降低可达89.3%,内填混凝土深梁,结构的抗侧移性能得到了极大改善,且随着深梁跨高比的减小而大幅度提升;结构二滞回曲线饱满,呈现纺锤形,混凝土深梁充分起到了第一道防线作用。经济合理的钢框架内填混凝土深梁结构具有一定的工程应用价值。 相似文献
10.
对既有受损混凝土结构的加固维修是地震灾后重建的重点之一。应用喷射超高韧性水泥基复合材料（UHTCC）的拉伸应变硬化特性,研究了带裂缝混凝土梁底部喷射20mm薄层UHTCC的加固作用。结果表明:薄层喷射UHTCC对混凝土梁的弯曲强度和弯曲刚度有明显的加固作用,可将带预制裂缝的混凝土梁极限承载力提高117.5%,使受损混凝土梁的承载能力恢复到相同尺寸无损混凝土梁承载能力相当的水平;此外混凝土梁底部薄层喷射UHTCC能将裂缝宽度控制在0.1mm以下的微裂缝,有利于提高混凝土梁的耐久性。 相似文献
11.
根据模型试验相似比尺和桩土间应力协调要求,用机制砂、河砂、水泥、石粉等配置了40组（每组6个）低强度、低弹性模量的圆柱形微混凝土相似材料试件。测试结果表明：微混凝土具有和原型混凝土大致相同的应力应变阶段和破坏模式,可以模拟原型结构的力学行为和变形、破坏特征。砂率和石粉取代率不同时,微混凝土试件的轴压强度和弹性模量在较大范围内变化;砂率较合适时,同一配合比微混凝土6个试件的强度和弹性模量一致性较好。微混凝土可以满足不同比尺模型试验对相似材料力学性质稳定、力学参数可以在较大范围内调整的要求。 相似文献
12.
Building sandstone surface modification by biofilm and iron precipitation: emerging block‐scale heterogeneity and system response 
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下载免费PDF全文 Stephen McCabe Daniel McAllister Patricia A. Warke Miguel Gomez‐Heras 《地球表面变化过程与地形》2015,40(1):112-122
Stone surfaces are sensitive to their environment. This means that they will often respond to exposure conditions by manifesting a change in surface characteristics. Such changes can be more than simply aesthetic, creating surface/subsurface heterogeneity in stone at the block scale, promoting stress gradients to be set up as surface response to, for example, temperature fluctuations, can diverge from subsurface response. This paper reports preliminary experiments investigating the potential of biofilms and iron precipitation as surface‐modifiers on stone, exploring the idea of block‐scale surface‐to‐depth heterogeneity, and investigating how physical alteration in the surface and near‐surface zone can have implications for subsurface response and potentially for long‐term decay patterns. Salt weathering simulations on fresh and surface‐modified stone suggest that even subtle surface modification can have significant implications for moisture uptake and retention, salt concentration and distribution from surface to depth, over the period of the experimental run. The accumulation of salt may increase the retention of moisture, by modifying vapour pressure differentials and the rate of evaporation. Temperature fluctuation experiments suggest that the presence of a biofilm can have an impact on energy transfer processes that occur at the stone surface (for example, buffering against temperature fluctuation), affecting surface‐to‐depth stress gradients. Ultimately, fresh and surface‐modified blocks mask different kinds of system, which respond to inputs differently because of different storage mechanisms, encouraging divergent behaviour between fresh and surface‐modified stone over time. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
13.
大开间小型混凝土砌块10层模型房屋抗震性能试验研究(Ⅰ) 总被引：8，自引：3，他引：8
我国抗震设计规范（GB50011－2001）规定在6、7、8度区，混凝土小砌块结构分别可以建七、六、五层。由于混凝土小砌块结构的最大优势在于10－20层（与混凝土框架或框架剪力墙结构比）。本文按1／4比例制作了10层混凝土小砌块结构模型，按7度设防要求实施构造措施，通过振动台试验研究模型结构的抗震性能。结果表明，模型结构完全能够满足在7度区“小震不坏，大震不倒”的要求。圈梁、构造柱以及水平拉结筋构成的约束体系抗震作用是明显的。试验利用砌块的非注芯孔灌注铁砂来模拟墙体出平面动力效应。在本模型的构造措施下，平出面反应不对结构破坏起控制作用。 相似文献
14.
A freestanding rigid block subjected to base excitation can exhibit complicated motion described by five response modes: rest, pure rocking, pure sliding, combined sliding-rocking, and free flight. Previous studies on the dynamics of a rocking block have assumed that the block does not interact with neighboring objects. However, there are many applications in which the block may start or come in contact with an adjacent boundary during its motion, for example, a bookcase or cabinet colliding with a partition wall in an earthquake. This paper investigates the dynamics of a sliding-rocking block considering impact with an adjacent wall. A model is developed in which the base and wall are assumed rigid, and impact is treated using the classical impulse and momentum principle. The model is verified by comparing its predictions in numerical simulations against those of an existing general-purpose rigid-body model in which impact is treated using a viscoelastic impact model. The developed model is used to investigate the effects of different parameters on the stability of a block subjected to analytical pulse excitations. It is found that wall placement (left or right) has a dominant effect on the shape of the overturning acceleration spectra for pulse excitations. In general, decreasing the gap distance, base friction coefficient, and wall coefficient of restitution enhance the stability of the block. Similar observations are made when evaluating the overturning probability of a block using earthquake floor motions. 相似文献
15.
J. Moeyersons 《地球表面变化过程与地形》1978,3(2):115-128
This study reveals that the Quaternary mantle of reworked Kalahari Sands undergoes a post-sedimentary composite process at the archaeological site of Gombe (Kinshasa, Zaïre). There is a biological activity which consists of an upworking of soil particles, mainly by termites and worms. This causes a diminishing dry volume weight of the sediment. In response, the mantle reconsolidates. When the soil surface is horizontal, the particles which are not brought up will sink down in the soil profile as a result of the reconsolidation. When the soil surface is inclined, it is only the resettlement of the sediment which can give rise to creep, caused by wetting and drying. Creep of the dead mineralogical material alone seems to be very improbable once the structure and settlement of the sediment are in equilibrium with a given slope. Only a new phase of bioturbation can induce further creep movements. The experiments have shown that stone implements in reconsolidating Kalahari Sands do not exactly accompany the compaction movement of the sediment. Depending on their form, their size, their orientation and the water content of the sediment around them, stone implements can undergo differential movements during the reconsolidation process. This can result in a dispersion of the implements over levels of different ages. As creep is a phenomenon, going hand in hand with the resettlement of the sediment after biogenic upworking, partially analogous movements of stone implements can be expected in a creeping Kalahari Sands mantle. Partial or total reconcentration of the stone implements at the base of affective biogenic activity can be expected. This can lead to typical stone-line profiles which must be interpreted very carefully. 相似文献
16.
A shaking table testing program was undertaken with the main objective of providing basic information for the calibration of analytical models, and procedures for determining seismic response of typical stone masonry temples of the 16–18th centuries stone masonry construction in Mexico. A typical colonial temple was chosen as a prototype. A model at a 1:8 geometric scale was built with the same materials and techniques as the prototype, and was subjected to horizontal and vertical motions of increasing intensities. The maximum applied intensity corresponded to a base shear force of about 58 of the total building weight. Vertical component of the base motion significantly affected the response and increased the damage of the model. Damage patterns were similar to those observed in actual temples. Damping coefficients of the response ranged from 7 for undamaged state, reached about 14 for severe damage. The main features of the measured response were compared with those computed using a nonlinear, finite element model; for the latter, a constitutive law developed for plain concrete was adopted for reproducing cracking and crushing of the irregular stone masonry. Observed damage patterns as well as measured response could be reproduced with reasonable accuracy by the analytical simulation, except for some local vibrations, as those at the top of the bell towers. It can be concluded that the simple constitutive law adopted for the simulation was able to reproduce the experimental response with reasonable level of accuracy. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
17.
新型节能复合混凝土空心砌块砌体抗震性能的试验研究 总被引：2，自引：0，他引：2
本文通过2片开窗洞加窗台梁节能复合混凝土小型空心砌块墙体和2片不开窗洞墙体的水平低周反复荷载试验,研究了节能复合混凝土小型空心砌块砌体墙的受力全过程、开裂部位、裂缝发展情况以及破坏形态,分析了墙体的滞回特性、延性、耗能能力,刚度退化曲线等抗震性能,同时,考察了墙体外叶保护层的受力性能、破坏程度以及与墙体的共同工作机理,探讨了不同构造措施以及开窗洞对墙体抗震性能的影响。研究结果表明:复合混凝土小型砌块砌体从开始加载到最终破坏,砌块保护层都没有明显的鼓凸和脱落现象,说明聚苯层及横向拉结筋能够提供可靠的连接,保证外叶保护层在水平剪力和竖向荷载共同作用下和墙体整体工作,此外,开窗洞对墙体的抗震性能削弱较大。 相似文献
18.
Ugo Andreaus 《地震工程与结构动力学》1990,19(8):1181-1196
In the present paper a two-degree-of-freedom system is considered which allows the simulation of rigid blocks uplifting and sliding on frictional foundations; the monolateral constraint between block and base is schematized by means of a joint model, which allows the contact problem to be discretized. The joint model is governed by normal and shear constitutive laws, which have been derived by the phenomenological behaviour of stone blocks and rock joints, as given by rock mechanics. Furthermore, a numerical procedure has been developed in order to solve the non-linear equations governing the motion of the block-base system, and to analyse the dynamic response of this system under seismic excitation; particular attention has been paid to the influence of the vertical displacement on the slip response. 相似文献
19.
宽频带强震仪与地震仪同一台基上记录仿真对比研究 总被引：6，自引：0，他引：6
本文依据作者提出的由加速度记录实时仿真速度、位移时程和由速度记录实时仿真加速度时程及位移时程时域实时方法,对福建省和黑龙江省在同一台基上记录到的宽频带加速度记录与速度记录分别进行了仿真,并与仪器记录进行了比较分析。结果表明,可由宽频带加速度记录仿真得到真实的速度与位移时程;由宽频带速度记录也可得到加速度时程和位移时程,但对加速度时程高频成分会有一定的损失;应用此方法也可以仿真得到某一型号地震仪或者强震仪记录。 相似文献
20.
The aseismic design of concrete faced rock-fill dams (CFRDs) has become vitally important in recent years. A series of 1-g large-scale shaking table model tests were conducted, applying similitude laws to evaluate the effectiveness of various aseismic measures. The following four reinforcing measures are discussed in this study: reinforcing the top zone with geogrid, protecting the downstream slope surface using stone block, replacing the top zone of the dam with cemented rock-fill material or concrete layers. The failure developments were visualised using the particle image velocimetry (PIV) technique. The mechanisms of these reinforcement measures were analysed in detail. The effectiveness of these measures was evaluated by comparing the crest settlement rates and key accelerations corresponding to surface grain yield, slab fracture and slab dislocation. Based on the model test results, a combination of reinforcement measures was proposed for the prototype CFRDs. 相似文献