Damage Assessment of Unreinforced Stone Masonry Buildings After the 2010–2011 Canterbury Earthquakes

The sequence of earthquakes that has affected Christchurch and Canterbury since September 2010 has caused damage to a great number of buildings of all construction types. Following post-event damage surveys performed between April 2011 and June 2011, an inventory of the stone masonry buildings in Christchurch and surrounding areas was carried out in order to assemble a database containing the characteristic features of the building stock, as a basis for studying the vulnerability factors that might have influenced the seismic performance of the stone masonry building stock during the Canterbury earthquake sequence. The damage suffered by unreinforced stone masonry buildings is reported and different types of observed failures are described using a specific survey procedure currently in use in Italy. The observed performance of seismic retrofit interventions applied to stone masonry buildings is also described, as an understanding of the seismic response of these interventions is of fundamental importance for assessing the utility of such strengthening techniques when applied to unreinforced stone masonry structures.     

Modeling the Seismic Response of Modern URM Buildings Retrofitted by Adding RC Walls

Modern unreinforced masonry buildings with reinforced concrete slabs are often retrofitted by inserting reinforced concrete walls. The main advantages of this technique are the increase in strength and displacement capacity with respect to masonry structures. This article presents two modeling approaches for evaluating such structures: a shell-element model and a macro-element one. The objective is to formulate practical recommendations for setting up a macro-element model using as input the geometry of the structure and results from standard material tests. Structural configurations of masonry buildings, in which the insertion of reinforced concrete walls is an efficient retrofit technique, are also investigated.     

砖石结构古建筑修缮中的规范应用问题

我国现存大量的砖石结构古建筑急需修缮保护,但文物行业目前还没有关于古建筑修缮质量控制的一套完整标准体系和规范。鉴于当前古建筑修缮工作的发展水平,本文针对砖石结构古建筑的特点,就现有相关其它行业规范在砖石结构古建筑修缮中的材料、设计和施工等方面的应用进行分析,同时针对砖石结构古建筑修缮的特性提出问题及相应建议。     

中央扶持和全国支援西藏

在中共中央关于帮助西藏建设的思想指导下,中央人民政府在西藏和平解放以来的各个历史阶段始终关心西藏,制定和实施了一系列优惠政策,不断推动中央关心西藏,全国支援西藏工作持续而深入地开展。全国支援西藏以经济援藏、干部援藏和教育援藏为主干,从多方面发展到全方位。中央扶持和全国支援,为西藏经济社会发展提供了必要的物质技术、财政资金和干部人才基础,有力地促进了西藏的民主改革、民族区域自治和新时期由加快发展到跨越式发展的实现。     

Assessment of Construction Techniques and Material Usage in İzmir Rural Houses

The domestic architecture in the rural villages of ?zmir comprises a unique built environment with their masonry wall textures, semi-open sofas, round tiled-hipped roofs, and chimneys, and represents an important part of the cultural and architectural heritage. This assessment is mainly based on field observations that focus on the architectural and structural layout of intact, damaged, and destroyed houses. During field observation and the analysis of data certain plan typologies and relationships between the geological formations of the region and choice of materials and construction techniques were observed. While load-bearing masonry and timber skeleton systems are common, extensive use of timber laces, stone, and fired or adobe brick masonry with mud mortar and timber frames infilled with masonry materials were frequently seen. Generally, round timber elements such as wall plates, laces, lintels, posts, and frames of flooring systems are used. Architectural degenerations in authentic houses, defective details and partially due to the earthquake-prone nature of the region seismicity have been evaluated. An overall approach for the preservation and sustainability of this heritage is suggested.     

Thermographic Survey at Hagia Sophia: Main Arches,Pendentives and Tympana

Hagia Sophia is one of the oldest and most complex existing monuments. Many unanswered questions are still open on the historical and constructive evolution of this monument. The boundaries between the different construction phases and the details of the masonry and materials used in the various phases are still not defined with precision.

The thermographic survey, carried out inside the monument, made ??it possible to answer some of these questions by specifying the exact location of the past interventions and the variability of the materials employed allowing a better understanding of the constructive history of the monument. The technique was applied at a great distance and in normal environmental conditions, taking advantage of the high thermal sensitivity of the instrumentation. The results achieved confirm the validity of the technique in the study of ancient buildings.     

In Situ Flat-Jack Testing of Traditional Masonry Walls: Case Study of the Old City Center of Coimbra,Portugal

Single and double flat-jack tests are presently used widely for assessing the mechanical characteristics of stone masonry. This technique remains as one of the most versatile in situ test procedure for the estimation of the main mechanical properties of masonry walls. Nevertheless their application is still controversial due to the difficulty of accepting in some cases the results as reliable. This article presents and discusses the results of an experimental campaign resorting to flat-jack technique carried out with the scope of the rehabilitation process of the historical city center of Coimbra.     

Experimental Study on Postponing the Deboning of FRP Sheets in Masonry Walls

ABSTRACT

A large number of buildings all around the world are constructed of unreinforced masonry. These structures do not act well during earthquakes because of their vulnerable behavior. In last two decades, fiber-reinforced polymers (FRPs) has been used widely in seismic rehabilitation and strengthening unreinforced concrete and masonry structures. One important issue in using FRP composites for strengthening masonry walls is the inopportune debonding of composites from the wall surface; thus, in this article new methods are proposed to further delay the mentioned debonding issue. For this purpose, 13 masonry panels with 100x870x870 mm dimension are strengthened by using carbon and glass FRPs (CFRPs and GFRPs). A variety of strengthening methods such as surface preparation, boring, grooving, nailing, and plaster are used to mount FRP composites to the walls. For each specimen subjected to diagonal compression test, the loading level along with tensile and compressive diagonal displacements are evaluated. In order to assess the effect of FRP composites, four unreinforced masonry walls are tested as well. The results show 110% increase in ductility index of reinforced specimens compared to the unreinforced ones.     

Seismic behavior of two Portuguese adobe buildings: part II —numerical modeling and fragility assessment

Considering the likely unfavorable behavior under seismic action of adobe construction, this article aims at providing a seismic fragility characterization of two adobe Portuguese traditional buildings, using numerical models calibrated over experimental results. The study of such two case-study buildings in the region of Aveiro contributes to the understanding of the seismic fragility of adobe construction in the region in general. The buildings were numerically modeled to estimate their structural behavior under seismic loading using adobe material properties that were calibrated based on the experimental results of a cyclic in-plane test of a full-scale double-Tshaped adobe wall. The method chosen to characterize adobe masonry and model its nonlinear behavior followed a total strain crack-based macro-modeling (TSCM) approach, whereas pushover analysis was carried out to reproduce the pseudo-static experimental test in order to enable a refined calibration of adobe masonry mechanical properties. Fragility functions were then derived, based on the above-mentioned numerical models, using nonlinear static analysis, bringing further insight on the seismic fragility of traditional Portuguese adobe construction.     

A Simplified Drift-Based Assessment Procedure for Regular Confined Masonry Buildings in Seismic Regions

This article presents a simplified procedure for assessing the seismic performance of existing low-to-medium rise confined masonry (CM) buildings, which are a typical construction type in Latin-America. The procedure consists of the estimation of the peak roof and first-story inelastic drift demand of CM buildings. The expected peak inelastic displacement demand is related to drift-based fragility curves, which express the probability of being or exceeding two key damage states in the masonry panels, developed from a relatively large experimental database. The proposed procedure could be very useful for obtaining rapid estimates of expected performance during future earthquake events and for assessing the seismic vulnerability of regular confined masonry structures.     

Restoration Techniques Applied to Tile Dome Conservation in the Western Mediterranean. Valencia,Spain

The domes studied, widespread in a large area of the Mediterranean, constitute an architectural heritage of great value to the history of architecture and construction. They were all built using brick masonry and ceramic tile roofs. Restoration work has made it possible to define their geometry, including the construction layouts of the buildings. In addition, on inspection it can be seen that common construction problems tend to be located at specific critical points. The restoration process of different cases sharing the same methodology, construction criteria, and solutions is accurately described. Following international charters, there is minimal intervention and maximum respect for the original solutions, but also a carefully considered incorporation of new materials and technologies to improve the critical points.     

Seismic vulnerability assessment methodology for slender masonry structures

ABSTRACT

Slender masonry structures such as towers, minarets, chimneys, and Pagoda temples can be characterized by their distinguished architectural characteristics, age of construction, and original function, but their comparable geometric and structural ratios yield to the definition of an autonomous structural type. These structures constitute a part of the architectural and cultural heritage. Their protection against earthquakes is of great importance. This concern arises from the strong damage or complete loss suffered by these structures during past earthquakes. Seismic vulnerability assessment is an issue of most importance at present time and is a concept widely used in works related to the protection of buildings. However, there is few research works carried out on developing the seismic vulnerability assessment tools for such structures.

This article presents a new method for assessing the seismic vulnerability of slender masonry structures based on vulnerability index evaluation method. The calculated vulnerability index can then be used to estimate structural damage after a specified intensity of a seismic event. Here, 12 parameters are defined to evaluate the vulnerability index for slender masonry structures. Implementation of this methodology is carried out in different types of slender masonry structures to develop vulnerability curves for these structure types.     

History and Characteristics of Construction Techniques Used in Traditional Timber Ottoman Houses

The aim of this article is to make a comprehensive review of the traditional timber house constructions in Turkey, which constitutes the majority of the existing Ottoman architectural legacy. After a short historical background focused on the Ottoman territory, the first section explores regional differences in the housing tradition, developed according to local features and defined by architectural features, material characteristics, and availability of materials. Derived from these regional differences, in the second section diversity in traditional timber construction systems in Turkey is described with special emphasis on the Ottoman h?m?? system. In this part, besides the discussion of the h?m?? technique which spread over Ottoman lands from the Balkans to Syria, the timber masonry and frame systems of the Eastern Black Sea Region and Thrace are presented in detail with visual support.     

中国古代砖砌体力学性能研究综述

古代砖砌体建筑由于材料劣化、环境影响,材料特性及力学性能均受到不同程度的影响和损伤,为了保护历史文化的载体,结合古建筑材料获取原始且必要的数据,系统总结了古砖、传统灰浆的制备工艺和材料性能,简要归纳了古砖、传统灰浆和古砖砌体基本力学性能及其测试方法,对比分析了单砖和砌体抗压强度的差异以及古建筑砌体材料力学性能研究现状。并对今后古砌体如弹性模量等力学性能、古砌体材料及结构的损伤机理等的研究提出了展望或建议,可为砖石古建筑的修缮保护提供参考依据。     

Review of Out-of-Plane Seismic Assessment Techniques Applied To Existing Masonry Buildings

ABSTRACT

Observations after strong earthquakes show that out-of-plane failure of unreinforced masonry elements probably constitutes the most serious life-safety hazard for this type of construction. Existing unreinforced masonry buildings tend to be more vulnerable than new buildings, not only because they have been designed to little or no seismic loading requirements, but also because connections among load-bearing walls and with horizontal structures are not always adequate. Consequently, several types of mechanisms can be activated due to separation from the rest of the construction. Even when connections are effective, out-of-plane failure can be induced by excessive vertical and/or horizontal slenderness of walls (length/thickness ratio). The awareness of such vulnerability has encouraged research in the field, which is summarized in this article. An outline of past research on force-based and displacement-based assessment is given and their translation into international codes is summarized. Strong and weak points of codified assessment procedures are presented through a comparison with parametric nonlinear dynamic analyses of three recurring out-of-plane mechanisms. The assessment strategies are marked by substantial scatter, which can be reduced through an energy-based assessment.     

Experimental analysis of rubble stone masonry walls strengthened by transverse confinement under compression and compression-shear loadings

Stone masonry walls of ancient buildings have reasonable resistance to vertical loads but lower resistance to shear forces and reduced tensile strength. However, to achieve such compressive strength the masonry must not disaggregate when subjected to loading. This can be achieved if during the construction of the walls larger stones, usually referred as “through stones”, are used, spanning the thickness of the wall, making it possible to improve the transverse confinement of the masonry. For rehabilitation projects and structural reinforcement of such buildings, the transverse confinement can be achieved by fixing steel elements perpendicular to the wall. This confinement technique is often part of a more comprehensive rehabilitation solution, which includes the application of mortar or concrete reinforced layers applied to the wall surface.

This article presents results of an experimental research on material properties and mechanical characterisation of stone masonry specimens strengthened by two transverse confinement solutions (independent steel reinforcing rods and continuous steel ribbons wrapping the specimen). Specimens were tested under compression and compression and shear loadings.

This experimental work is part of a major research project to study the mechanical behavior of URM and strengthened walls, and the characteristics of the building materials of such specimens.     

藏族传统生态文明与藏族聚居区的生态法治建设

我国藏族聚居区生态环境的特殊性导致了其生态法治不仅需要先进的立法技术支持,更需要发掘藏族传统生态文明的"本土资源",尤其是藏族传统生态文明中所蕴含的生态规律等理性因素,这对解决当代藏族聚居区生态法治中的"高原反应"与内在伦理支持的缺失有着重要的现实意义。只有形成藏族聚居区传统生态文明与生态法治建设的深层脉动,才能真正解决其生态法治问题的"病源",构建具有藏族聚居区特色的生态法治,进而维护藏族聚居区的生态安全。     

Long-term performance evaluation of an earthen grouting mortar: the Nuraghic complex of Genna Maria,Sardinia

Abstract

This paper presents a critical assessment of the long-term performance of an earth-based material employed nine years ago in conservation work on a building of massive, Cyclopean-style construction at the Genna Maria Nuraghic complex in central-southern Sardinia (Italy). The material was used for filling the large gaps between stones in the masonry walls to create a barrier to ingress of water into the masonry walls. In situ observations and laboratory analyses were conducted on samples of the grouting material to assess its condition after nine years.     

Sonic Tomography for Masonry Walls Characterization

ABSTRACT

Nowadays, Sonic Pulse Velocity tests (SPV tests) are widely applied for detecting the morphology, hidden defects, and voids within structural elements. This technique, largely applied because non invasive and easy to perform, reveals particularly adapt in the case of ancient buildings, where usually any damage is not tolerated due to the historical preservation requirements. Moreover, recently the SPV tests have been also applied with tomography technology to obtain images of sonic speeds from which it is possible to rapidly reconstruct the internal elements morphology.

In this article, the results of some SPV tomographies regarding masonry elements are presented. The tests are carried out with the aim of establishing consistency and accuracy of this technique in determining the morphology of the investigated elements. The influence of investigation points number and noise smoothing is taken into account, too. At first, the results of a tomography derived from synthetic data of an ideal section are shown. Then, the SPV tomographies of some masonry specimens and of elements sections of a real case study are illustrated and compared among them.