The reconstruction of the Cathedral of Noto

The Cathedral of Noto, one of the most important baroque monuments that has given notoriety to the town of Noto, collapsed in the 13th of March 1996, approximately 5 years after the earthquake of ‘Santa Lucia’ that took place in December 13th 1990. The collapse has pointed out serious deficiencies in constructive materials of pilasters, even in their capacity to support vertical loads. That is why the earthquake of 1990 has acted as ‘the last blow’, coming after a long period of fatigue. Instead, the geometry of the church results to be ‘good’, and for this reason the reconstruction design consists merely in new pilasters, well made with local material, the well known ‘pietra di Noto’ and the replacement is going to take place both on the right, in the place of the collapsed pilasters, and on the left, in substitution of the old pilasters, really not adaptive for restoration. In this way, and with few other interventions, the ‘new’ church should result capable to resist to earthquakes similar to the one that occurred in 1693.     

Noto Cathedral: soil and foundation investigation

On 13th March 1996 the dome of the St. Nicolò Cathedral of Noto fell due to a post-seismic structural collapse. In order to study the soil–structure interaction a comprehensive laboratory and in situ investigation has been carried out to obtain a soil profile. In this paper the dynamic characterisation results and normalised laws are proposed to consider shear modulus decay and damping ratio increase with strain level. The existing foundations of the cathedral were investigated by means of excavations and tests on the stones and the mortar. In this way the foundations were subjected to visual inspections to detect their size and their embedment level. Now, the soil–foundation interaction has been analysed by means of the finite element code SOFIA, considering at this stage the superstructure weight through the influence area approach. In particular, the effects of the designed remedial work of the foundation have been studied, comparing the two configurations before and after the foundation improvement.     

Characterisation of the materials used in the construction of the Noto Cathedral

After the partial collapse of the Cathedral of Noto, the authors were required to carry out an extensive on site and laboratory investigation in order to support the designers of the Cathedral reconstruction to check the possibility of preserving the parts which are still standing and to choose the right solutions and the most compatible materials for the reconstruction. The tests carried out in laboratory in order to characterise the chemical, physical and mechanical properties of the original materials are described and their results discussed.     

Application of sonic and radar tests on the piers and walls of the Cathedral of Noto

The authors applied systematically sonic tests, radar tests and other diagnostic techniques on the remaining walls and piers of the Cathedral of Noto. The experimental survey was carried out by the Laboratory of the DIS, Politecnico of Milan (Person in Charge: Prof. Binda, Prof. Baronio) in collaboration with the designers (Ing. R. De Benedictis, Arch. S. Tringali) and the experts working on the reconstruction. The Prefettura of Siracusa founded the research. The right aisle and most of the dome of the Cathedral collapsed in 1996. The aim of the research was to verify the state of damage and the possibility of conservation of the walls and piers in view of the reconstruction of the damaged part of the Cathedral. Furthermore, the sonic tests were used to control the effect of grout injection used as a possible technique for repair of the damaged masonry (Proceedings of the Conference on Nondestructive Evaluation of Civil Structures and Materials, Boulder, Colorado; (1992) 329; Proceedings of the Sixth Conference on Structural Faults and Repair, 3 (1995) 195). In the following the results will be reported and the reliability of the tests will be discussed as it was confirmed by the use of other complementary diagnosis techniques (Proceedings of the Sixth International Conference on Structural Studies, Repairs and Maintenance of Historical Buildings, STREMAH 99, Dresden, Germany, (1999) 323).     

Experimental research for the choice of adequate materials for the reconstruction of the Cathedral of Noto

Following the experimental and structural investigation the design for reconstruction was proposed. The authors were requested to test new materials, stones, mortars, grouts for injection in order to choose and proposed the material to be used for the reconstruction of the pillar and for the repair of damaged elements.     

On-site investigation on the remains of the Cathedral of Noto

The Cathedral of Noto was damaged after the earthquake that hit Sicily in 1990. Soon after the event, cracks appeared on the domes of the lateral naves, and also on the pillars. In 1992 some provisional work had been carried out in view of confining the pillars of the central nave that were damaged. Some pictures made after the earthquake also show clearly the presence of moisture rise on the pillars and walls. A sudden collapse due to the damages was probably not expected, so that no other measures were taken to better strengthen and repair the structures. Only after the collapse of the Civic Tower in Pavia (1989) and the following research (Masonry Int J 6 (1992) 11, Second International Conference RILEM on Rehabilitation of Structures, Highett, Australia (1998) 542), it was clearly shown that in case of high stresses on low-strength masonry an existing damage can slowly lead to partial or total collapse of the structure over a long time. It seems a confirmation of this long-term behaviour of the structures that the Cathedral collapse took place in 1996, 6 years after the earthquake, which had certainly caused high damages to the structure.     

Building the Cathedral of Noto; earthquakes,reconstruction and building practice in 18th-century Sicily

The collapse of the nave and dome of the Cathedral of Noto, S. Nicolò, in a rainstorm in 1996 brought to light 18th century construction errors unique to this building. S. Nicolò is the most prominent church in the city of Noto, a rich Baroque center in southeastern Sicily completely reconstructed after an earthquake in 1693. During the course of its construction and reconstruction between 1696 and 1950, S. Nicolò was plagued by multiple earthquake failures and construction errors. This paper attempts to assemble the unwritten construction history of the church for the first time in English, and to address the question of how architects, engineers and builders responded to the problem of creating a seismically resistant building.     

断裂力学和损伤力学在混凝土中的应用

叙述了断裂力学和损伤力学的形成、应用及发展过程，并将断裂力学和损伤力学引入到混凝土的研究中，探讨了断裂力学和损伤力学在混凝土中的应用。     

中华门城堡重建闸楼后城门结构的模拟计算分析

本文采用有限元分析方法 ,对中华门城堡券门结构进行了模拟计算 ,计算了拱券门在重建闸门楼后的应力状况。计算结果表明 ,重建后拱形券门中以压力为主 ,局部微小区域出现拉应力。     

Mode I fracture toughness determination with straight notched disk bending method

A new method called the straight notched disk bending method is developed for mode I fracture toughness determination using rock cores. Disk specimens of andesite and marble having a single straight edge notch were subjected to three-point bending loads. Dimensionless stress intensity factor estimations and fracture toughness tests were conducted for different notch lengths, span lengths, thicknesses and diameters of the cylindrical rock specimens. Stress intensity factors were computed by three-dimensional finite element modeling and the results were presented for a wide range of specimen geometrical parameters. Results of experiments were compared to the results of well-known mode I fracture toughness testing methods. For specimens having thickness equal to the radius, mode I fracture toughness was lower and close to the results obtained by semi-circular bending method. When thickness was increased and doubled, mode I fracture toughness increased and approached to the value found by the suggested cracked chevron notched Brazilian disk method. Advantages of the new method included easy specimen preparation and testing procedure, stiffer specimen geometry, smaller fracture process zone, and flexibility of the specimen geometry for the investigation of the size effect behavior.     

高强混凝土砌块填芯砌体性能分析与研究

对三种不同试件类型的高强混凝土砌块填芯砌体受压性能进行了试验研究。分析了三类试件不同影响因素下的破坏特征、抗压强度、弹性模量及泊松比,提出了较为合理的确定高强混凝土砌块砌体力学性能指标的试件类型及计算公式,计算结果与试验值符合较好。     

Buckling of cracked functionally graded plates under tension

Buckling of functionally graded cracked plates under tension has not been investigated so far. In this paper critical buckling load of functionally graded plates containing a crack has been obtained using classical plate theory through the finite element method. Displacement in vicinity of crack tips has been approximated using previous solutions related to bending of cracked plates. Effect on buckling of plate under uni-axial and bi-axial tension of different parameters, such as plate dimensions and material properties, are studied. Results show that the critical load decreases as material gradient index increases, while bi-axial loading leads to higher critical loads compared to uni-axial case.     

土力学课程有限元软件的优化与应用

为了弥补当前土力学课程实践教学环节的不足,在前期开发的土力学教学有限元仿真软件基础上,新增了三个计算模块,使得该软件涵盖了平板载荷试验、三轴试验、恒定渗流、简单边坡稳定性和挡墙土压力分析等土力学课程中所有重要问题的分析。另外,在每个仿真模块中添加了关于该模块的土力学原理、有限元基本理论和实现方法,以及模型计算参数的含义与经验取值范围的介绍,提高了软件的易用性。优化后的软件涵盖内容全面,具有更好的容错性和易用性,能够服务于土力学课程的本科教学,达到以"虚"补"实",激发学生学习兴趣和提高学生学习能力的目的。     

The reconstruction of the sandstone dome of the Frauenkirche

The entire original cupola of the Frauenkirche (Church of Our Lady) was built in Saxon sandstone with iron anchor rings. In the early stages of planning the reconstruction of this unique dome, the engineers analysed the original structure. It was concluded that it would be possible to reconstruct in sandstone masonry because it would produce the obvious strength. To master the problem of cracking, prestressed anchor rings of steel bandages are to be provided under the faced stone layer of the outer wall of the dome.     

Prediction of the fatigue life of slender web plates using fracture mechanics concepts

The results of a series of fatigue tests, on slender plate girders subjected to repeated shear loading, are summarised and used to establish a lower bound fatigue strength curve for the welded web boundary, based on geometric or principal surface stress ranges. The propagation of a semi-elliptical surface crack, through the thickness of a plate, is studied using fracture mechanics concepts. An extensive parametric study indicates that the initial crack size and aspect ratio, the geometric stress concentration at the weld toe, and the plate thickness, all have a significant influence on fatigue strength. It is concluded that the fracture mechanics approach requires specification of a number of parameters which are difficult to determine in practice. However, having specified a realistic crack size and aspect ratio and an approximate stress concentration at the weld toe, the solution can be calibrated against available experimental fatigue strength curves.     

文化遗产的“突围”——德国科隆大教堂周边文化环境的保护与步行区的营造

德国科隆在二战中遭受了毁灭性的破坏,而科隆大教堂得以幸存。但是在近年来的发展中,作为世界遗产的科隆大教堂,其保护也同样面临着与城市建设之间的矛盾,并一度被列入“濒危遗产名单”。后来经过设置合理的缓冲区和营造多样化的步行环境,不仅通过商业、旅游业的振兴推动了当地经济的发展,同时也使大教堂获得了良性的保护环境,为该市提供了一条经济振兴与文化遗产保存的双赢道路。这为我国协调城市文化遗产及文化环境保护与经济发展的关系提供了很好的借鉴。     

超高龙门吊安装塔架结构系统的非线性静力分析

大型龙门吊安装塔架系统是应用于重型龙门吊安装过程中的一种索杆混合结构体系。在水平力作用下 ,体系非线性效应显著。为了比较全面的解决大型龙门吊安装塔架的非线性静力问题 ,文中给出了龙门吊安装塔架静力分析的经典力学法和非线性有限元法。前者首先建立了轴压悬臂柱的平衡微分方程 ,再联立纤绳方程 ,求解了柱顶位移和纤绳内力 ;后者通过一种非线性直线单元 ,建立了混合体系的增量平衡方程。最后分别用两种分析方法验算了体系横风、纵向顺风 ,两种工况 ,并比较了二者的柱顶位移和纤绳张力。结果表明 ,两种方法都是可靠的