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。     

English Peasant Buildings in the Later Middle Ages (1200–1500)

FROM A SYNTHESIS OF evidence for late medieval peasant buildings this article argues that their size, quality and complexity have frequently been underestimated. Documentary evidence from the West Midlands is used to define the main features of peasant buildings—agricultural buildings as well as houses—in the period 1350–1500. Similar characteristics are found in the same period in other regions, in the context of their own building traditions. The origins of durable vernacular houses must be sought in the 13th century with the move away from earth fast construction. A series of changes began long before the ‘Great Rebuilding’ of the 16th and 17th centuries, and connected with that process in an evolutionary pattern.     

Experimental Characterization of Ancient Metal Tie-Rods in Historic Masonry Buildings

Metal tie-rods play a decisive role in the control of horizontal thrusts in historic masonry buildings. The main goal of the present study is to investigate the relationship between metallurgical and mechanical properties of original tie-rods in order to contribute to a wider study on ancient building stability and their restoration protocols. This article presents the results of an experimental test campaign carried out on 14 historic tie-rods (dating back from 16^th–19^th century) recovered from restoration works or building demolitions. Stress-strain mechanical tests showed that the elastic modulus of the material is comparable to that of modern structural steel, while the strength and the elongation capability are significantly lower, with a large scatter. Further analyses based on metallography allowed us to assess that this mechanical behavior depends on the heterogeneous nature of the material, which can eventually be compared to a composite with vitreous elongated particles in a ferritic or ferrito-pearlitic matrix. The origin of such metallurgical condition is related to the iron making based on direct smelting from ores.     

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.     

LOCALIZING HISTORICAL CLUES USING IRT AND PETROGRAPHIC ANALYSES AT VILLA MIRABELLO,MONZA (ITALY)*

The rebuilding of Villa Mirabello started in 1666. Built on designs of Gerolamo Quadrio, the project refurbished and enlarged a smaller 16th century country house (‘casa da nobile e da massaro’). Archival documents report on the remodelling, which consisted of selective demolition of portions of the structure, re‐using most of the masonry as the core of the new building, and the reinforcement of retained masonry by insertion of ‘ceppo’ stone quoins to update new exteriors. The aim of Quadrio was to create an elegant and sumptuous mansion, suitable for noble owners such as Giuseppe Durini and his family. The plan and a small part of original finishing (‘marmorino’ plaster decoration) are recognizable nowadays. Nevertheless, there are many questions in interpretation when one compares the documents and the building. That is, Cardinal Angelo Durini made a major modification in the 18th century, and further minor changes were made in the 19th century. Although these latter modifications did not alter the plan, they changed the distribution of rooms and masked both decoration and finishing. After over 20 years of neglect, Villa Mirabello is now close to being restored. Architects in charge ordered a preliminary set of diagnostics to assess damage and study the historical evolution of the building. Integration of IR thermography (IRT) and endoscopy allowed restorers to detect the structure's texture underneath the plaster, and to detect openings filled with masonry. Moreover, archive documents confirmed these results and, above all, defined a date for the use of specific building techniques. This research constitutes a reference for buildings set in the same time and location that do not have significant archival documentation. Active IRT provided useful information for structural assessment (such as location of arches, chimney stacks, different thickness of wall, wooden elements, voids, beams etc.) and for crack pattern evaluation. This information directs design professionals working on this conservation project, and helps define the costs of intervention.     

CHARACTERIZATION OF ARCHAEOLOGICAL AND IN SITU SCOTTISH WINDOW GLASS

Scottish window glass from both archaeological sites and historic buildings was examined using portable X‐ray fluorescence (pXRF) and scanning electron microscopy – energy‐dispersive X‐ray micro‐analysis (SEM–EDX). The elemental composition of the glass provides information regarding the materials used and, subsequently, an approximate range of dates of manufacture. pXRF is shown to be more vulnerable than SEM–EDX to the effects of surface corrosion and matrix effects in archaeological samples. The study showed that the production of window glass in Scotland from the 17th century onwards appears to closely parallel that in England. It also demonstrated the potential of pXRF for in situ studies of window glass in historic buildings. pXRF was used to assess two Scottish buildings; one in state care and one in private ownership. The building in state care, the Abbot's House at Arbroath Abbey, showed a uniform glass type, suggesting that the building was re‐glazed completely at some point during the late 19th or early 20th century. The building in private ownership, Traquair House, had a range of glass types and ages, demonstrating a different maintenance and repair regime. This type of data can be useful in understanding historic buildings in the future, particularly if re‐glazing is being considered.     

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.     

Dynamic One-Sided Out-Of-Plane Behavior of Unreinforced-Masonry Wall Restrained by Elasto-Plastic Tie-Rods

Past earthquakes have shown the high vulnerability of existing masonry buildings, particularly to out-of-plane local collapse mechanisms. Such mechanisms can be prevented if façades are restrained by tie rods improving the connections to perpendiculars walls. Whereas in the past only static models have been proposed, herein the nonlinear equation of motion of a monolithic wall restrained by a tie rod is presented. The façade, resting on a foundation and adjacent to transverse walls, rotates only around one base pivot and has one degree of freedom. Its thickness is explicitly accounted for and the tie rod is modeled as a linear elastic—perfectly plastic spring, with limited displacement capacity. The model is used to investigate the response to variations of wall geometry (height/thickness ratio, thickness), tie rod features (vertical position, length, prestress level), and material characteristics (elastic modulus, ultimate elongation, yield strength) typical of historical iron. The most relevant parameter is the steel strength, whereas other characteristics play minor roles allowing to recommend reduced values for pre-tensioning forces. The force-based procedure customary in Italy for tie design is reasonably safe and involves protection also against collapse, although probably not enough as desirable.     

Pompeii’s Stabian Baths. Mechanical behavior assessment of selected masonry structures during the 1st century seismic events

The eruption of Mount Vesuvius in 79 AD buried and preserved the Stabian Baths building in the exact configuration which the archaeological excavations carried out in the second half of the 19th century recovered. By combining archeologists’ studies with the analysis of deformations and cracking pattern due to the 1st century seismic events, in this article numerical models have been formulated which allowed the formation of some hypotheses coherent on the timeline of the events, the damage to as well as the change of the shape and stylistic language of the thermal building. Specifically, through global seismic analyses and kinematic analyses of masonry portions of the “destrictarium” block, it is proven that during the 1st century not only a sole catastrophic earthquake occurred but, at least, two important seismic events took place.

The purpose of this article is to identify and parameterize the responsible earthquake by the analysis of seismic effects detectable in the damages and archaeological remains of the masonry walls of the Stabian Baths. The identification of the earthquake and the grading of provoked damages represent a useful knowledge tool that provides information about the vulnerability of ancient buildings and can be suitably used also to safeguard architectural heritage from seismic risk.     

A Hybrid Masonry and Steel Mirror-Type Vault with Lunettes: Survey and Structural Analysis

ABSTRACT

The structural analysis of a mirror-type vault, consisting of a single- or double-curvature perimeter and a nearly flat part, is carried out. The vault is similar to a number of hybrid iron (or steel) and masonry vaults built between the late 19th century and the early 20th century to span large halls. The numerical analyses were preceded by an accurate geometrical survey and mechanical tests aimed at evaluating the properties of the materials. Thermography allowed the complex brick pattern of the vault to be detected. The influence of rib-walls (frenelli) and the material anisotropy on the stress and deformation of the vault is discussed. Eventually, attention is focused on one of the segmental vaults in the central part of the structure: it is found that the stress can be safely estimated by assuming its boundary to be fixed.     

Timber-framed Houses Built for the Court Members after the 1894 Earthquake in Istanbul: Rationalization of Construction Techniques

During the second half of the 19th century, Western European industrial achievements affected construction techniques in Istanbul. Ottoman archival documents reveal the usage of industrial materials and machine shaped timber elements, which brought the rationalization of traditional timber construction techniques. After the 1894 Istanbul earthquake, many post-earthquake timber-framed houses constructed as temporary shelters in the precincts of masonry mansions were rapidly built due to the rationalization in building techniques. Since there is not any inventory for the industrial materials and techniques used in the second half of the 19th century in Istanbul, their determination is of crucial importance in the process of conservation.     

Notice of the Cross-Legged Sepulchral Effigies,Existing at Cashel

Evidence recovered on the site known from late ninth-century charters as Æthelred’s hithe illustrates successive phases in the early development of London as an international port. While two middle Anglo-Saxon female skeletons were found in foreshore deposits, coins and other metalwork, along with the remains of gangplank trestles, suggest the site was a trading shore from at least the later ninth century. Riverside construction followed by the late tenth century: several low waterfront embankments date to the late tenth and early eleventh century, the waterfront was divided into regular plots and timber buildings erected. Reused nautical and building timbers include fragments of a Frisian ship and an arcaded building.     

Assessing Seismic Behavior of a Masonry Historic Building considering Soil-Foundation-Structure Interaction (Case Study of Arge-Tabriz)

ABSTRACT

Historic heritage buildings are a part of historic basis of each society and an economic resource. Therefore, preserving and maintenance of these buildings are cultural, economic and social demand. This research investigates the seismic performance of a historical building named Arg of Tabriz (Arge Alishah) that dates back to 14th century and is located at the city center of Tabriz (NW of Iran). Static, modal, and finally nonlinear dynamic (time history) analysis were performed by both “Considering Soil-Structure Interaction (SSI)” and “fixed base (ignoring SSI)” Cases.

It is found from the results that, SSI extremely affects mode shapes and their frequencies and depending on the frequency content of the records, can has an incremental or decremental effect on structural responses. As expected, the building of Arg could carry gravity loads easily and despite its stability against earthquake loading in fixed base case, showed a weakness (especially in eastern and western walls direction) and overturned when it was analyzed in SSI case because of yielding of the surrounding soil.     

Characterization and Joining of an Historical Ferrous Tie-Rod

A ferrous tie rod, which was retrieved from a 17^th century masonry building, has been examined. The chemical composition and the microstructure of the tie-rod are consistent with the technology of the time.

The tie-rod was successfully welded to modern steel profiles, by means of gas metal arc welding, in order to verify if this method could be applied for restoration works. Threading tests were also successfully performed, for the same purpose.

Both the original tie-rod, and the welded specimens were thoroughly characterized with both metallurgical and mechanical methods; moreover, full-scale tensile tests were performed on both welded and threaded samples.     

Performance of Wall to Diaphragm Anchors for Use in Seismic Upgrade of Heritage Masonry Buildings

Performance of wall to diaphragm (WD) anchors in heritage unreinforced masonry (URM) buildings during the recent New Zealand earthquake series is commented on, detailing typical failure modes. Current building code provisions for the design of masonry anchors are discussed and overview of an associated experimental program investigating the effectiveness of a relatively new type of retrofit WD anchors is presented. A total of 40 anchors were tested for pull out capacity (POC), of which 30 were installed in salvaged heritage material assemblages and 10 were tested in-situ at a heritage URM building. The POC of anchors ranged from 13.01 kN to 23.12 kN when installed in a heritage URM wall and between 9.54 kN and 12.16 kN when driven from side into two consecutive floor joists of a heritage timber diaphragm. Investigated also were the effects of embedment length, installation quality, anchor location, condition of masonry, and condition of substrate materials on anchor performance.     

ON THE SEISMIC VULNERABILITY OF EXISTING UNREINFORCED MASONRY BUILDINGS

A large part of the building population in Switzerland is made of unreinforced masonry. For the assessment of the seismic risk the evaluation of the seismic vulnerability of existing unreinforced masonry buildings is therefore crucial. In this paper a method to evaluate existing buildings, which was developed for the earthquake scenario project for Switzerland, is briefly introduced and discussed in more detail for unreinforced masonry buildings. The method is based on a non-linear static approach where the seismic demand on the building is compared with the capacity of the building. In-plane and out-of-plane behaviour are considered. Comparisons with test results from model buildings show that the proposed method suitably forecasts the capacity of a building. Finally, a numerical example of the application of the method to a building in the city of Basel is given.     

Masonry Italian Code-Conforming Buildings. Part 2: Nonlinear Modelling and Time-History Analysis

ABSTRACT

The unreinforced masonry (URM) buildings designed to be conforming with the Italian building code, as illustrated in the companion paper, were analyzed by performing time-history analyses on models realized using an equivalent frame approach and by adopting two different constitutive laws. Both the effect of record-to-record variability and of epistemic and aleatory uncertainties in modelling were explored. The achieved results constitute the basis for the evaluation of the risk level implicit in Italian code-conforming buildings. Two main performance conditions are considered, namely usability-preventing damage and global collapse limit states.     

EVALUATION OF THE SEISMIC PERFORMANCE OF EXISTING RC BUILDINGS: II. A CASE STUDY FOR REGULAR AND IRREGULAR BUILDINGS

The results of a parametric study are presented, concerned with the evaluation of the structural overstrength, the global ductility and the available behaviour factor of existing reinforced concrete (RC) buildings designed and constructed according to past generations of earthquake resistant design codes in Greece. For the estimation of these parameters, various failure criteria are incorporated in a methodology established to predict the failure mode of such buildings under planar response, as described in detail in a companion publication. A collection of 85 typical building forms is considered. The influence of various parameters is examined, such as the geometry of the structure (number of storeys, bay width etc.), the vertical irregularity, the contribution of the perimeter frame masonry infill walls, the period of construction, the design code and the seismic zone coefficient. The results from inelastic pushover analyses indicate that existing RC buildings exhibit higher overstrength than their contemporary counterparts, but with much reduced ductility capacity. The presence of perimeter infill walls increases considerably their stiffness and lateral resistance, while further reducing their ductility. Fully infilled frames exhibit generally good behaviour, while structures with an open floor exhibit the worst performance by creating a soft storey. Shear failure becomes critical in the buildings with partial height infills. It is also critical for buildings with isolated shear wall cores at the elevator shaft. Out of five different forms of irregularity considered in this study, buildings with column discontinuities in the ground storey exhibit the worst performance. Furthermore, buildings located in the higher seismicity zone are more vulnerable, since the increase of their lateral resistance and ductility capacity is disproportional to the increase in seismic demand.     

The Changing Vernacular: archaeological excavations at Temple End,High Wycombe,Buckinghamshire

Abstract

Excavations beneath and around the late Georgian Glinester House at Temple End, in High Wycombe, Buckinghamshire, revealed the presence of at least three major phases of building. Dating from the 16th century these structures appear to be a succession of farmhouses lying at the centre of wider farm complexes. While these buildings are located within the former lands of Temple Manor, from which the area and farm name derives, no evidence of a medieval manor complex was located within the excavation area. Rather the pattern of development is more indicative of wider transformations in vernacular housing and domestic life between the 16th and 19th centuries.     

Three Deserted Medieval Settlements on Dartmoor: A Report on the late E. Marie Minter's Excavations

HOUNDTOR, HUTHOLES AND DINNA CLERKS are three deserted medieval settlements on the granite uplands towards the eastern side of Dartmoor Forest, Devon. Houndtor and Hutholes were small villages comprising eleven and six buildings respectively; Dinna Clerks was an isolated homestead. Extensive excavation at these sites by the late Mrs E. Marie Minter revealed a long sequence o f superimposed houses, divisible into two periods. Those of the first were built of turf. Although their remains were few, and in some places confusing, they provided much information on the construction of this type of building in the South- West of England. During the second period commencing in the middle of the 11th century, the houses of turf were gradually replaced by those of stone. The excavation of the well-preserved remains of the long-houses and their associated barns and corn-driers and the recording of the gardens and some of the open fields have given a clear insight into the ecology of a community dependent upon mixed farming at altitudes between 1100 and 1300 ft above sea level. The excavation of these settlements has also demonstrated how the deterioration of the climate in the late 14th and early 14th centuries led to their eventual desertion.