Tragfähigkeitsuntersuchungen der Natursteinmauerwerkstützen des Berliner Olympiastadions

Load‐carrying capacity investigations of the natural stone masonry columns of the olympic stadium in Berlin. During the modernization or repair of structural buildings the questions about the actual load‐carrying capacity of the existing construction units and the range of necessary reinforcement are important. For a meaningful and economic planning a realistic analysis can be very useful. The employment of conventional, simple engineering models can lead to uneconomic results with increasing complexity of the structure. This paper shows an effective way for a realistic determination of the load‐carrying capacity of an existing masonry structure with modern numerical and experimental methods on example of the olympic stadium of Berlin. It is shown that for the realistic computation of the failure load and the associated failure mechanisms the inclusion of the nonlinear deformation behavior of the masonry is necessary. An three‐dimensional nonlinear material model was implemented in the finite element code ANSYS. So it was possible to show the stress and strain state of the masonry structure very realistic and to verify the stability as well as the serviceability plausibly.     

The work of CIB W23

The joint co‐ordinators of the CIB working commission on ‘Wall structures’ review the main areas of present interest: the design and execution of masonry structures, including reinforced masonry; masonry construction in earthquake zones; the sizing of mechanical connections for large‐panel concrete buildings; and the renovation of existing structural walls.     

圬工拱桥承载能力评估方法研究

针对目前既有诸多圬工拱桥出现承载能力不足及病害等问题,总结了圬工拱桥承载能力的计算理论和评估方法,提出了外观检测、荷载试验,并根据有限元计算结果,结合相关评估规范等多种评定方法相结合的综合分析评定方法。以某大跨圬工拱桥为例,应用综合分析评定方法评定该桥现有状况,与实际情况较为吻合,表明该方法具有较好的工程实用使用价值和理论意义。     

Behaviour of a masonry arch bridge repaired using fibre-reinforced polymer composites

This paper describes a series of laboratory tests investigating the behaviour of a large model masonry arch bridge repaired with externally bonded fibre-reinforced polymer (FRP) on its intrados. Many similar masonry arch bridges form critical links in the world’s transport infrastructure, but they are often not suited to the increased demands of modern traffic loading, especially in ageing arch structures that have suffered structural deterioration. FRP plates, adhesively bonded to the intrados of the masonry arch are a convenient method for strengthening arch bridges. The tests described in this paper demonstrated that FRP strengthening is an effective technique for improving the structural performance of a masonry arch bridge.A two-span, single-ring semi-circular brick arch bridge was tested in this study, complete with fill material. Each of the spans was initially loaded to investigate their response and to establish a four-hinge collapse mechanism, simulating damage prior to strengthening. FRP strengthening was then applied to the two arches, and each of the spans was again tested separately until the failure of the strengthening system. The global (load and deflection) and local (crack width and FRP strain) response of the structure was recorded. The FRP strengthening resisted flexural crack opening in the masonry, and hence prevented a four-hinge mechanism collapse. Failure instead occurred when the FRP strengthening debonded from the masonry adjacent to an existing intrados hinge crack. As well as shear debonding adjacent to flexural cracks in the masonry, peel debonding occurred where shear deformation occurred across a masonry crack. Catastrophic collapse did not occur, as the FRP continued to contribute to the load capacity by acting as a tie after the ultimate load had been reached.     

Neues BAW‐Merkblatt zur Bewertung der Tragfähigkeit bestehender massiver Verkehrswasserbauten

New BAW Code of Practice for the assessment of the load bearing capacity of existing solid hydraulic structures Many of Germany's solid hydraulic structures, i. e. structures made from concrete, reinforced concrete or masonry, are of above‐average age. For example, about a third of all locks for which the Federal Waterways and Shipping Administration (WSV) is responsible is more than a hundred years old. In other words they have exceeded the design lifetime of 100 years that is nowadays the requirement for such structures. Not only existing locks, but also numerous weirs and canal bridges show static characteristics, such as construction methods or very large cross sections, that are no longer common practice today. If any alterations are made to these structures, or if they exhibit visible damage, it is essential to re‐assess the statics of the supporting structure and perform new calculations to verify its conformity with stability requirements. This re‐assessment can be done with a new BAW‐Code of Practice „TbW”. In contrast to bridges and buildings, no adapted regulations have been released until now for re‐assessing the statics of existing solid hydraulic structures.     

青海村镇砌体结构房屋抗震缺陷分析

青海玉树地震中砌体结构的严重震害表明,村镇砌体结构房屋存在着较大的抗震缺陷。依据《建筑抗震设计规范》(GB 50011-2010)的抗震设防标准,通过玉树地震中砌体结构房屋表现出的震害特征,从墙体、结构基础、结构体系及结构布置四方面对青海村镇砌体结构房屋存在的主要抗震缺陷进行了分析,并结合青海省现有村镇砌体结构房屋在抗震性能方面存在的主要问题,提出了相应的加固改造措施。     

Seismic assessment of masonry arch bridges

In this paper, the seismic performance of existing masonry arch bridges is evaluated by using nonlinear static analysis, as suggested by several modern standards such as UNI ENV 1998-1 2003, OPCM 3274 2004, and FEMA 440 2005. The use of inelastic pushover analysis and response spectrum approaches becomes more difficult when structures other than the framed ones are investigated. This paper delves into the application of this methodology to masonry arch bridges by presenting two particular case studies. The need for experimental tests in order to calibrate the materials and the dynamic properties of the bridge is highlighted, in order to correctly model the most critical regions of the structure. The choice of the control node in the pushover analysis of masonry arch bridges and its influence on seismic safety evaluation is investigated. The ensuing discussion emphasizes important results, such as the unsuitability of the typical top node of the structure for describing the bridge seismic capacity. Finally, the seismic safety of the two bridges under consideration is verified by presenting an in-depth vulnerability analysis.     

钢筋网聚合物砂浆面层加固砌体结构分析

多层砌体结构是现有校舍建筑最常用的结构形式之一,由于一些建筑建造年代较早,结构抗震性能较差或抗震构造措施不满足现行规范要求,需进行抗震加固。本文对钢筋网聚合物砂浆面层加固砌体墙的抗震承载能力进行了分析,结果显示这种加固方式可以显著提高结构的抗震性能,是一种较好的加固方法。     

石拱桥的加固与施工

介绍了一座3-11.6 m石拱桥的加固设计与施工技术,具体分析了设计施工要点、施工程序及应注意的关键点,从而为同类桥梁的加固积累经验,同时保证石拱桥的运营安全。     

盾构穿越浅埋石拱桥施工技术

盾构穿越既有建筑物或构筑物是地铁施工的主要难点,穿越浅埋石拱桥更为困难,以南昌地铁土建六标彭家桥-师大南路站区间穿越玉带河上的两孔浅埋石拱桥为背景,分析了工程难点以盾构施工及对既有桥的影响、介绍了施工过程中采取的相应对策与措施,以期为类似工程借鉴与参考。     

Experimental study and design of a new hybrid RC frame system with stiffened masonry wall subjected to cyclic loading

This paper experimentally investigates the hysteresis behavior of a hybrid reinforced concrete (RC) frame system with stiffened masonry wall to enhance the seismic performance of existing RC buildings subjected to cyclic loading. The influences of the depth of the columns section, the length of masonry walls, and the grouting ratio of reinforced masonry were evaluated by designing a series of orthogonal quasi‐static tests on a half‐scale specimen. Test results indicated that the grouting ratio played the most significant role on the maximum strength, energy dissipation capacity, and the relative stiffness degradation rate of the hybrid structural system, whereas the length of masonry walls tends to dominate the deformation capacity. A trilinear analytical model and design recommendations are proposed to estimate the cyclic behavior based on force‐displacement hysteresis law that takes account of the effects of the post‐peak strength and unloading stiffness degradation.     

石结构房屋抗震防灾关键技术研究与展望

我国东南沿海地区现存的大多数石结构房屋的整体性和抗震能力极差,存在＂小震成灾、小震大灾＂的隐患。本文分析了石结构房屋的构造特点和存在的主要抗震薄弱环节,评述了已有石结构研究的主要工作及存在问题,明确了现代石结构研究应围绕＂有效减轻区域重大灾害＂和＂利用创新科技保护并发扬传统石结构文化＂这两个中心任务开展。提出了石结构防灾及现代石结构的研究框架,并介绍了基于该研究框架下的石结构抗震防灾研究工作的最新进展。     

Decision support software approach to the assessment of stone masonry bridges

This paper identifies the need for a formalized approach to the assessment of the integrity of stone masonry bridges and develops the concept of the use of a computer database and suitable software to support the practising bridge engineer in the decision-making process (decision support software, DSS).

The different standard techniques of assessment of masonry bridges are outlined and their limitations described. The common faults associated with masonry structures are discussed and the problems of identifying these faults are described. The part played by the individual components of a masonry arch bridge is outlined and the significance of faults on the individual components of the structure is discussed.

Database development and operation of the DSS are detailed and their value to the bridge engineer is discussed. The system is illustrated with a demonstration run.     

Time-variant reliability profiles for steel girder bridges

Evaluation of existing steel bridges becomes more important due to natural aging, increasing load spectra, deterioration caused by corrosion, and other problems. In the result, bridge structures exposed to aggressive environmental conditions are subjected to time-variant changes of resistance. Therefore, there is a need for evaluation procedures for an accurate prediction of the load carrying capacity and reliability of bridge structures, in order to make rational decisions about repair, rehabilitation, and expected life-cycle costs. The objective of this paper is to develop time-variant reliability models for steel girder bridges. Traditional methods based on deterministic analysis do not reveal the actual load carrying capacity of the structure. The proposed approach is based on reliability analysis of components and structural systems. The study involves the selection of representative structures, formulation of limit state functions, development of load models, development of resistance models for corroded steel girders, development of the reliability analysis method, reliability analysis of selected bridges, and development of the time-dependant reliability profiles including deterioration due to corrosion. The results of the study can be used for a better prediction of the service life of deteriorating steel girder bridges, and development of optimal reliability-based maintenance strategies.     

川西藏羌石砌碉房民居抗震构造更新设计研究

川西藏羌石砌碉房民居,历经多次地震考验并沿用至今,其营造中必定蕴含科学合理的抗震设计技术。论文通过调研民居营建中的构造设计做法,揭示了石砌碉房民居多种地域抗震构造设计技术;同时为了解决现代建筑与石砌建筑之间风貌延续的矛盾,结合现代混凝土砌体抗震方法,通过创新的抗震构造设计,成功解决风貌保护与抗震设防的矛盾,从而为民居更新和民居修复提供技术支持。     

A review of experimental investigations and assessment methods for masonry arch bridges

Masonry arch bridges constitute a significant proportion of European road and rail infrastructures. Most of them are well over 100 years old and are supporting traffic loads many times above those originally envisaged. The inherent variation in their constituent materials, the traditional design criteria and methods used for their construction, their deterioration over time caused by weathering processes and the development of other defects, significantly influence the mechanical response of these historic structures. A deep understanding on the numerous factors that affect the structural behaviour of masonry arch bridges and on the analysis methods to assess the life expectancy of such bridges and inform maintenance and strengthening strategies is essential. This paper provides a critical review of the experimental studies that have been carried out and of the assessment approaches that have been developed in the last three decades to these aims. The current knowledge is established and areas of possible future research work are identified, with the aim of providing students and researchers, asset managers and bridge owners, and practitioners with a guidance for research activities and maintenace strategies.     

Seismic design in reinforced masonry

CIB working commission W23, which deals with structural walls, has published design Recommendations for both reinforced and unreinforced masonry. The procedures set out for seismic design in reinforced masonry have been tested in a research project in Italy, and the results are presented here by Professors Calvi and Macchi from the University of Pavia. They show that buildings of 4 storeys in high‐risk zones and of 5 storeys in moderate‐risk zones can safely be designed in reinforced masonry according to the Recommendations, using highly perforated blocks only 300 mm thick.     

Numerical investigation of historic masonry walls under normal and shear load

The behaviour of masonry under seismic loads has recently become of great interest. New methods for design and analysis, as well as for resistance, have been developed. The main focus has been on experimental and analytical research for the development of new brick material and mortar. With the introduction of Eurocode 8, the behaviour of old masonry structures under seismic load became an interesting topic for engineers. In particular, the available resistance capacity of existing masonry structures is highly relevant to the restructuring of existing buildings. Laboratory tests on masonry walls were performed in order to determine the mechanical behavioural characteristics of old brick material.     

既有砖混结构校舍隔震加固技术及其工程应用

结合我国抗震规范中的相关规定,分析校舍结构的结构特点和加固需求。针对其中多层砖混结构,介绍叠层橡胶基础隔震加固的计算分析方法、构造要求及相应的施工工艺。结合某7度抗震设防区一栋4层砖混结构教学楼的隔震加固实例,介绍其工程应用并分析技术经济指标。