受火后钢筋混凝土吊车梁加固方法的试验研究

为研究受火后钢筋混凝土吊车梁的维修加固方法,开展了粘贴CFRP布和粘贴钢板加固受火后足尺吊车梁受力性能的试验研究、理论分析和有限元分析。结果表明：未受火对比试件发生受拉区钢筋屈服、受压区混凝土压碎破坏;粘贴CFRP布加固试件的主要破坏模式为受拉区钢筋屈服和CFRP布拉断;粘贴钢板加固试件的主要破坏模式为受拉区钢筋和加固钢板受拉屈服以及受压区混凝土压碎。对于ISO 834等效受火60min后钢筋混凝土吊车梁,粘贴钢板加固效果优于粘贴CFRP布;ISO 834等效受火60min和90min后的钢筋混凝土吊车梁采用CFRP布加固后,极限荷载接近。加固后钢筋混凝土吊车梁试件跨中截面混凝土应变发展规律在混凝土腹板垂直裂缝完全发展前基本符合平截面假定。受火后加固试件的位移延性系数较未加固对比试件有所降低,粘贴钢板加固试件降低稍大。加固的受火后钢筋混凝土吊车梁极限荷载计算结果和有限元结果与试验结果误差绝对值为0.4%~7.8%,满足工程精度要求。     

受火后钢筋混凝土吊车梁加固方法的试验研究

为研究受火后钢筋混凝土吊车梁的维修加固方法,开展了粘贴CFRP布和粘贴钢板加固受火后足尺吊车梁受力性能的试验研究、理论分析和有限元分析。结果表明:未受火对比试件发生受拉区钢筋屈服、受压区混凝土压碎破坏;粘贴CFRP布加固试件的主要破坏模式为受拉区钢筋屈服和CFRP布拉断;粘贴钢板加固试件的主要破坏模式为受拉区钢筋和加固钢板受拉屈服以及受压区混凝土压碎。对于ISO 834等效受火60 min后钢筋混凝土吊车梁,粘贴钢板加固效果优于粘贴CFRP布;ISO 834等效受火60 min和90 min后的钢筋混凝土吊车梁采用CFRP布加固后,极限荷载接近。加固后钢筋混凝土吊车梁试件跨中截面混凝土应变发展规律在混凝土腹板垂直裂缝完全发展前基本符合平截面假定。受火后加固试件的位移延性系数较未加固对比试件有所降低,粘贴钢板加固试件降低稍大。加固的受火后钢筋混凝土吊车梁极限荷载计算结果和有限元结果与试验结果误差绝对值为0.4%～7.8%,满足工程精度要求。     

采用碳纤维布加固预应力混凝土吊车梁的设计方法

分析了预应力混凝土吊车梁存在的问题,并结合实际情况,对其提出了初步可行的处理方案。通过对初选方案的对比与优选,结合使用要求,确定采用黏贴碳纤维布(CFRP)方案对吊车梁实施加固。详细介绍了用碳纤维布加固鱼腹式T形截面预应力混凝土吊车梁的设计方案,给出了正截面受弯和斜截面受剪补强加固的计算方法,并提出了相应的施工方法及具体的构造措施。研究结果表明,加固处理后吊车梁的各项技术指标均达到了设计要求,效果良好。     

碳纤维布加固预应力混凝土吊车梁的设计方法

针对预应力混凝土吊车梁存在的问题,结合实际工作条件和结构所处的环境,对其提出初步处理方案。通过对初选方案对比和优选,并结合使用要求,确定采用粘贴碳纤维布方案对吊车梁实施加固。在详细介绍用碳纤维布加固鱼腹式T形截面预应力混凝土吊车梁的设计要点和方案的基础上,给出正截面受弯和斜截面受剪补强加固的计算方法,并提出相应的施工方法以及具体构造措施。加固处理后吊车梁的各项技术指标均达到了设计要求,效果良好。研究成果可为类似工程的应用提供理论和方法上的参考。     

钢吊车梁加固前后受力性能试验研究

以某厂工字形带裂缝的钢吊车梁为研究对象,在对国内外开裂钢吊车梁疲劳损伤进行广泛调查研究的基础上,提出了以提高吊车梁上部区域有效面积和刚度为目的的加固方案.通过吊车梁加固前后200万次疲劳试验,对加固前后裂缝尖端主应力的大小及方向的变化规律进行了研究.研究结果表明:通过增大截面有效面积及刚度可以延长开裂钢吊车梁的疲劳剩余使用寿命,对实际工业厂房中存在开裂的钢吊车梁的加固及维护有很好的指导意义.     

某钢结构厂房加固改造设计工程实践北大核心CSCD

结合某钢结构厂房加固改造的工程设计实践,探讨了因吊车吨位增大,对吊车梁系统以及门式刚架轻钢房屋结构进行复核验算、加固改造设计的方法,采用增大截面法加固了钢吊车梁以及钢牛腿,采用围套法加固了柱下独立基础,提出了加固改造设计中一些需要注意的问题。     

某钢结构厂房加固改造设计工程实践

结合某钢结构厂房加固改造的工程设计实践,探讨了因吊车吨位增大,对吊车梁系统以及门式刚架轻钢房屋结构进行复核验算、加固改造设计的方法,采用增大截面法加固了钢吊车梁以及钢牛腿,采用围套法加固了柱下独立基础,提出了加固改造设计中一些需要注意的问题。     

吊车梁升级后强度加固的探讨

以某金工车间吊车梁升级后强度加固工程为例，从体外加扁钢、增加截面主筋、增加梁截面高度三方面，介绍了经济、方便的混凝土梁强度加固施工方法，以满足设计规范要求。     

南京仙人桥碎矿厂房结构加固设计

文章结合工程实例,介绍了碎矿厂房结构中柱子和吊车梁的加固方法 ,厂房柱采用增大截面法加固,吊车梁采用碳纤维片材加固,并对其它构件进行了必要的修复、防腐处理。实践结果表明,加固达到了预期的效果,为类似改造加固工程提供了经验。     

钢吊车梁的改造校算及预应力加固分析

针对承载力不足的吊车梁 ,提出了预应力加固法的截面验算公式 ,并给出了吊车梁校算及预应力加固的工程算例。算例分析表明 ,本文所提出的设计方法计算简单、精确度高 ,可供类似工程设计参考     

Development of a shrouded wind turbine with a flanged diffuser

We have developed a wind turbine system that consists of a diffuser shroud with a broad-ring flange at the exit periphery and a wind turbine inside it. The flanged-diffuser shroud plays a role of a device for collecting and accelerating the approaching wind. Emphasis is placed on positioning the flange at the exit of a diffuser shroud. Namely, the flange generates a low-pressure region in the exit neighborhood of the diffuser by vortex formation and draws more mass flow to the wind turbine inside the diffuser shroud. To obtain a higher power output of the shrouded wind turbine, we have examined the optimal form of the flanged diffuser, such as the diffuser open angle, flange height, hub ratio, centerbody length, inlet shroud shape and so on. As a result, a shrouded wind turbine equipped with a flanged diffuser has been developed, and demonstrated power augmentation for a given turbine diameter and wind speed by a factor of about 4-5 compared to a standard (bare) wind turbine. In a field experiment using a prototype wind turbine with a flanged diffuser shroud, the output performance was as expected and equalled that of the wind tunnel experiment.     

开孔板连接件相对滑移机理试验研究

为研究组合结构桥梁中开孔板连接件的相对滑移机理,以开孔板厚度、孔中钢筋直径、开孔板孔径为变化参数,进行了21个开孔板连接件抗剪性能模型试验。通过理论分析与试验结果比较,揭示了开孔板连接件相对滑移量主要由孔中钢筋剪切变形量、孔中混凝土压缩变形量和剪切变形量三部分组成,以及抗剪承载力对应相对滑移量随板厚增加而减小,随孔径、孔中钢筋直径增加而增大的滑移机理。     

Temperature distribution within a ceiling jet propagating in an inclined flat-ceilinged tunnel with natural ventilation

In this study, we conducted detailed measurements of the temperature distribution within a steady fire-driven ceiling jet, formed in a tunnel with a rectangular cross-section. We then compared the measured temperature distributions with those for an unconfined smooth-ceiling jet flow, and estimated the relative errors between them. The results showed that the temperature distribution in a horizontal tunnel exhibits a greater bulge than that of a ceiling jet under an unconfined ceiling and varied from a bulging shape to an exponential shape as the tunnel inclination increased. We propose a new correlation for representing the temperature distribution, which takes the tunnel inclination into account, and which consists of an exponential function and a cubic function with a coordinated transformation.     

Equivalent representations of beams with periodically variable cross-sections

This paper examines representations of a beam with periodically variable cross-sections. First, the rotational equivalence of a beam with two periodical steps to a uniform beam is considered when a constant bending moment is applied along the lengths of the two beams. The representation is then extended to a beam with several different steps and then to a beam with a variable cross-section. Variable bending moments are also taken into account in the equivalent representation. Equivalent representations based upon the same maximum deflection and fundamental natural frequency are derived. If a beam consists of several periodically variable units and the bending moment in each unit is considered to be constant, the various equivalent criteria can be unified. Detailed finite element analysis (FEA) shows that the plane-deformation assumptions no longer hold in the transition regions between adjacent steps. The transition area is defined using a straight line with an angle determined by curve-fitting and the results are provided in a tabular form considering all related parameters. A comparison of the maximum displacement and fundamental natural frequency shows good agreement for a number of beams with periodically variable cross-sections and their equivalent uniform beams. The study demonstrates that the equivalent representation of a beam with periodical variable cross-sections is accurate and simple to apply to engineering practice.     

Shear strength of the connection between a steel coupling beam and a reinforced concrete shear wall in a hybrid wall system

No specific guidelines are available for computing the shear strength of the connection between a steel coupling beam and a reinforced concrete shear wall in a hybrid wall system. There were carried out analytical and experimental studies on the connection between a steel coupling beam and a concrete shear wall in a hybrid wall system. The bearing stress at failure in the concrete below the embedded steel coupling beam section is related to the concrete compressive strength and the ratio of the width of the embedded steel coupling beam section to the thickness of the shear walls. Experiments were carried out to determine the factors influencing the shear strength of the connection between a steel coupling beam and a reinforced concrete shear wall. The test variables included the reinforcement details that confer a ductile behaviour in the connection between a steel coupling beam and a shear wall, i.e., the auxiliary stud bolts attached to the steel beam flanges and the transverse ties at the top and the bottom steel beam flanges. In addition, additional test were conducted to verify the strength equations of the connection between a steel coupling beam and a reinforced concrete shear wall. The proposed equations in this study were in good agreement with both our test results and other test data from the literature.     

Time to build options in construction processes

Time to build is a very important factor in a real estate development venture. Delay in completion of a project not only affects the financing costs and the rental revenue but also it may, on a more strategic note, determine the success or failure of a project. A time to build option model consisting of a stochastic rate of completion and a stochastic net project payoff is applied to the sequential construction process of a large scale construction project. The results of the sensitivity analysis show that the optimal payoff value, that triggers the exercise of the option to invest at a maximum rate, increases positively with the increases in cash flow volatility, input cost uncertainty, excess asset return per unit risk and maximum rate of investment. However, it has a negative relationship with the rental yield. In a case study involving a commercial project, the premium for hedging the payoff risks by pre-leasing a project was estimated at 11.29%, whereas the additional cost incurred for shielding a project against input cost risks in a design and build contract was estimated at 7.80%, where each is given as a percentage of the total construction costs.     

Data collection and analysis of the building stock and its energy performance—An example for Hellenic buildings

The process of building labeling and certification in accordance to the provisions of the European Directive on the Energy Performance of Buildings (EPBD) constitutes a unique opportunity for collecting information on the characteristics of the building stock and its energy performance on a national and European level. Thus, there is a need to handle data from a large stock of buildings and to be able to analyse information and extract practical trends and benchmarks. Stakeholders and technical managers who oversee a number of buildings experience similar needs in order to collect, organize and monitor the energy performance of a large pool of buildings. To facilitate these efforts, a common evaluation database and complimentary software for its exploitation have been developed in the frame of a European project.This paper presents an overview of the database and its available tools, and the main results from a case study on Hellenic buildings that reveals relevant characteristics. The Hellenic database included a sample of 250 buildings from different regions in Greece, with a breakdown that is representative of the national building stock. The main results focus on the buildings’ energy performance, thermal envelope characteristics and the exploitation of solar thermal energy.     

香港新世纪桥梁建设的发展和前景

昂船洲大桥位处于香港港口一个显的位置，落成后将成香港一个主要标志。大桥的主跨为1018m，这般大跨度的斜拉桥将是一项世界纪录，亦将是斜拉桥科技上的一大突破。设计和兴建昂船洲大桥将是一项极大的挑战。对此项艰巨而且复杂的工作，引入国际性竞争机制是明智决定。本工程如按常规在本地招标设计，     

Development of a smart city planning support tool using the cooperative method

A reduction of environmental burdens is currently required. In particular, proposing a new approach for the construction of a smart city using renewable energy is important. The technological development of a smart city is founded building equipment and infrastructure. However, planning methods and their techniques using the collaboration approach with residents are only just developing. This study aimed to develop a support tool for the construction of a smart city using renewable energy while facilitating consensus-building efforts among residents using the method for a cooperative housing development. We organized the supporting methods for the construction of residential area using the cooperative method. Then, we developed supporting tools that interface the computer with these methods. We examined the support techniques for the construction of a residential area using renewable energy technology by analyzing Japanese cases of a smart city. Moreover, we developed a support tool for the construction of a smart city on a trial basis. We integrated the smart city construction tools and the cooperative housing construction support tool. This tool has a 3D modeling system that helps residents to easily understand the space image as a result of the examination. We also developed a professional supporting tool that residents can consider for cost-effectiveness in renewable energy and its environmental load reduction rate for the planning of a smart city.     

Improvement of registration accuracy of a handheld augmented reality system for urban landscape simulation

The need for visual landscape assessment in large-scale projects for the evaluation of the effects of a particular project on the surrounding landscape has grown in recent years. Augmented reality (AR) has been considered for use as a landscape simulation system in which a landscape assessment object created by 3D models is included in the present surroundings. With the use of this system, the time and the cost needed to perform a 3DCG modeling of present surroundings, which is a major issue in virtual reality, are drastically reduced. This research presents the development of a 3D map-oriented handheld AR system that achieves geometric consistency using a 3D map to obtain position data instead of GPS, which has low position information accuracy, particularly in urban areas. The new system also features a gyroscope sensor to obtain posture data and a video camera to capture live video of the present surroundings. All these components are mounted in a smartphone and can be used for urban landscape assessment. Registration accuracy is evaluated to simulate an urban landscape from a short- to a long-range scale. The latter involves a distance of approximately 2000 m. The developed AR system enables users to simulate a landscape from multiple and long-distance viewpoints simultaneously and to walk around the viewpoint fields using only a smartphone. This result is the tolerance level of landscape assessment. In conclusion, the proposed method is evaluated as feasible and effective.