某住宅楼梁板裂缝的分析与修补处理

某框架-剪力墙住宅楼现浇钢筋混凝土梁板局部开裂,在现场调查与检测的基础上,对局部结构建模计算复核,全面分析论证粱板裂缝产生的原因．结果表明：梁板承载力满足要求,楼板裂缝为非荷载原因的收缩裂缝,T形交叉梁端竖向裂缝为集中荷载作用点局部协调变形裂缝。在此基础上,提出了相应裂缝的处理与修补措施,并对此类问题在施工和设计上提出了合理可行的建议。     

Bending performance of composite bridge deck with T-shaped ribs

This paper proposes a new type of steel-concrete composite deck, which is composed of orthotropic steel deck (OSD) with T-shaped ribs, concrete plate and studs connecting OSD and concrete plate. The OSD can act as framework for concrete plate and contribute to load bearing capacity at the same time, which could save construction time. Compared with conventional OSD system, this new type of composite bridge deck can also improve fatigue performance.ƒConsidering that this type of composite deck is not yet applied in practical engineering and its mechanical performance is not revealed in previous literatures, two full-scale specimens were designed and manufactured in this research. The mechanical performance, particularly, bending capacity in positive and negative region was carefully tested and analyzed. The load-deflection curve, load-slip relation, strain distribution in concrete and steel were obtained. The test results showed that the plastic performance of this kind of composite bridge deck was satisfying and the bending capacity was high.     

Broadband circularly polarized Fabry‐Perot antenna utilizing Archimedean spiral radiator and multi‐layer partially reflecting surface

This article presents a method to design broadband circularly polarized (CP) Fabry‐Perot Resonator (FPR) antenna. The proposed antenna is based on multi‐layer thin dielectric slabs arranged in close proximity as a partially reflecting surface (PRS) and an Archimedean spiral as a CP radiating source. Experimental results show a broadband operation from 6 to 13 GHz, in which the reflection coefficient is less than ?10 dB and the axial ratio (AR) is lower than 3 dB. In addition, good radiation patterns and high broadside gain of better than 10.8 dBic are achieved over the operating bandwidth. The proposed antenna can be used for C‐ and X‐band satellite communications.     

有无信号灯控制的T形交叉口元胞自动机模型比较

利用元胞自动机方法建立了一个具有三个进车道的信号灯控制的T形交叉口模型。在以前的无信号灯控制的模型中,一些进车道的车辆在交叉口只有一个行驶方向,而在本文模型中采用更为实际的两个行驶方向,并采用具有固定周期的三相信号灯来控制交叉口的车辆冲突。通过数值模拟给出了本文模型的相图和系统的总流量,并与无信号灯模型结果进行了比较。     

CFRP布加固混凝土梁板防火涂料层厚度取值

为改善CFRP布加固混凝土梁板的抗火性能,选用厚涂型防火涂料作为CFRP布加固混凝土梁板的防火保护层的措施.以常温下正截面抗力标准值与频遇组合效应标准值的比值K、常温加固后抗力提高幅度β和防火涂料层厚度c0为参数,通过ANSYS有限元程序和matlab程序对火灾下CFRP布加固的混凝土梁板进行了大量的计算.提出了考虑K、β和耐火极限tu要求的CFRP布加固混凝土梁板厚涂防火涂料层厚度c0的取值建议.     

New variance expressions for systematic sampling: the filtering approach

We present a collection of variance models for estimators obtained by geometric systematic sampling with test points, quadrats, and n‐boxes in general, on a bounded domain in n‐dimensional Euclidean space ?ⁿ, n = 1, 2, ... , and for systematic rays and sectors on the circle. The approach adopted ? termed the filtering approach ? is new and different from the current transitive approach. This report is only preliminary, however, because it includes only variance models in terms of the covariogram of the measurement function. The estimation step is in preparation.     

Microstrip bandpass filters using coupled feed lines for third and fourth generation communications

In this paper, two compact tuneable bandpass filters (BPFs) based on the coupled feed lines are introduced. To approach a compact size, the coupled feed lines are bended. To design a high performance single-band bandpass filter (BPF), coupled feed lines are loaded by T-shaped stubs (as main resonators) and rectangular stubs (as suppressor stubs). Also, the mechanism of coupled feed lines combining with T-shaped open stubs is analyzed to show a tunable passband. The dual-band BPF includes two big radial-stubs, two small radial-stubs, two T-shaped structures and spiral coupled feed lines. The LC model of big radial-stubs is analyzed to compute the equation of transmission zero using its transfer function. The passband frequency of single-band BPF resonates at 2.12 GHz (3G) with corresponded insertion loss of 0.83 dB. Also, for dual-band BPF, the measured insertion-losses of first and second passbands are close to 0.8 and 1.1 dB, respectively. The frequency responses of BPFs are easily adjusted by altering the physical dimensions, demonstrating a adjustable performance. To verify the correct operation of circuits, the proffered filters are implemented and tested.     

T型微混合器合成Cu2O纳米颗粒

采用T型微混合器通过沉淀法,以氯化铜为铜源,氢氧化钠为沉淀剂,抗坏血酸为还原剂制备出了立方体氧化亚铜纳米颗粒。考察了进料流量、氢氧化钠浓度、抗坏血酸浓度和温度对产物氧化亚铜的形貌、粒度及其分布的影响。采用X射线衍射、场发射扫描电子显微镜和紫外可见分光光度计对其进行表征。结果表明,随着进料流量的增大、氢氧化钠浓度的减小、抗坏血酸浓度的增加和温度的提高,所制备的氧化亚铜颗粒的平均粒径减小、粒度分布变窄。     

预应力轻骨料混凝土空心板结构试验研究

通过预应力轻骨料混凝土空心板结构试验 ,按照《轻骨料混凝土结构设计规程》JGJ1 2 - 99进行分析研究 ,提出有关预应力轻骨料混凝土空心板标准图的几点设计经验 ,以供推广应用新型建材参考     

浅析25 m预应力空心板施工技术

针对25m预应力空心板在施工中容易出现的问题，结合大运高速平遥惠济河大桥施工实践，从预应力锚具、锚板、夹片、钢绞线等材料的选用和生产工序的控制，预应力张拉等几方面介绍了施工中采取的措施、方法，并进行了探讨，使生产的产品能量大可能地满足设计要求。