Thrust network analysis of masonry helical staircases

We exploit a recent generalization of the Thrust Network Analysis (TNA) to analyse masonry structures of extremely complicated and audacious geometry such as helicoidal staircases. Actually, differently from available methods, based on ad-hoc solutions holding for each particular structure, the TNA allows for studying the equilibrium of structures of arbitrary shape by invoking the principles of limit analysis of masonry structures dictated by Heyman. Four paradigmatic monumental staircases, with increased degree of complexity, have been selected as case studies in order to show the versatility and accuracy of the proposed approach. The results entailed from the generalized TNA are also successfully compared, for the first time in the literature, with those related to the adoption of available analytical methods for the analysis of no-tension membranes.     

Evaluation of Structural Intervention in the Quartel das Esquadras,Almeida (Portugal)

ABSTRACT

The “Quartel das Esquadras” is an 18th century infantry barrack located within the limits of the bulwarked fortress of Almeida, in Portugal. An ongoing adaptive reuse project of the building aims to recover its full capacity and also its importance, by implementing a variety of new uses. The architectural intervention results in the need of the structure to withstand new and diverse imposed loads. As the current configuration of the structure will be altered, the main objective of this article is to evaluate the suitability of some of the proposed structural interventions. The current condition has been characterized following a multidisciplinary approach comprising historical research, visual inspection, non-destructive testing, and structural analysis to identify the possible sources of major structural problems. A portion of the building particularly affected by the alterations has been selected to carry out structural analysis. A comparative safety assessment of the selected area in both current and altered condition has been done through finite element modelling and nonlinear static analysis, resulting in an identification of the weaker points against the new implemented loads and alterations. Finally, proposals for the implementation of the studied intervention, as well as recommendations for future research and analyses, have been given.     

Updating Numerical Models of Masonry Arch Bridges by Operational Modal Analysis

This article aims at presenting and discussing the strategies for updating the finite element numerical modeling of stone masonry arch bridges using operational modal analysis. The study comprehended three bridges: two old ones, the St. Lázaro and the Lagoncinha bridges, and a recently constructed bridge in Vila Fria, Portugal. Updating of the bridge models is performed by comparing the numerical and experimental modal parameters. Three-dimensional detailed numerical models are used to perform modal analysis of the bridges. Experimental modal identification of the bridges is based on the measurement of their acceleration responses during normal operation. The assigned material properties are also based on available results obtained from in situ and laboratory tests and on the results of visual inspection and historical research carried out for both old bridges.     

Petrochemical Identification and Insights on Chronological Employment of the Volcanic Aggregates Used in Ancient Roman Mortars

Through the assistance of trace element and petrographic analyses on 14 samples of mortar aggregates from Roman monuments, including the Porticus Aemilia, the Temple of Concordia, the Temple of the Dioscuri, Temple B and other structures of the Area Sacra di Largo Argentina, and the Villa di Livia, we establish the source area and we investigate the chronological employment of the volcanic materials used in ancient Rome's masonry. In contrast to previous inferences, the petrochemical data presented here show that systematic exploitation of the local ‘Pozzolane Rosse’ pyroclastic deposit has occurred since the early development of concrete masonry, at the beginning of the second century bc , through the early Imperial age. Subsequently, exploitation was extended to the overlying Pozzolane Nere and Pozzolanelle deposits. Only during the early phase of development of the concrete masonry in Rome, volcaniclastic sediments outcropping near the construction sites were mixed with the sieved remains of the tuff employed as the coarse aggregate, to produce the fine aggregate. The results of the study on the investigated monuments suggest the possibility of establishing the chronological identification of three different types of mortars, as a function of the composition of the volcanic material employed in the fine aggregate, which, when implemented by future studies, may contribute to the dating of monuments and archaeological structures.     

Seismic vulnerability assessment and fragility analysis of stone masonry monastic temples in Sikkim Himalayas

Buddhist monasteries in Sikkim Himalayas constitute important religious and architectural heritage. These random rubble (RR) stone masonry structures located in high seismically active regions of the Himalayas have suffered varied degrees of damages in the past earthquakes. The study presents seismic vulnerability assessment of four archetypal monastic temples using finite element (FE) analyses. Linear and nonlinear analyses of these structures were conducted in Abaqus FE environment. These analyses identified the damage prone areas of the structures and provided load-deformation behavior under lateral loads. Fragility analyses indicate a high probability of collapse for the specified design level earthquake of the region. The study shows that performance of the structure can be enhanced by improving the strength and stiffness of the stone masonry walls.     

Dynamical Assessment of the Work Conditions of Reinforcement Tie-Rods in Historical Masonry Structures

Tie-rods are essential structural elements, which have been employed for centuries in masonry historical buildings, either during the construction or in successive strengthening interventions, with the aim of containing dangerous horizontal actions. The actual work conditions of these tie-rods, which are strongly influenced by their load history, are difficult to be quantified theoretically, and an effective method for their measure is of great importance in order to ensure the efficiency of these elements during the time and the stability of the entire building. Common measurements are often carried out adopting models based upon significant simplifications, like, for example, hinges at the extremities. These assumptions, rarely represent the real work conditions for anchorages. In this work, a non-destructive testing method is presented, based upon sophisticated dynamical models that can take into consideration many of the circumstances neglected by the simplified models. Four case studies are extensively described, trying to embrace the most common situations in term of peculiar features of the building, structural configuration, and load history. The discussion of the results yields the safety margin of the rod with respect to the material failure and provides important indications about the overall stability of the whole building.     

峡江地区汉晋南朝花纹砖上的车轮纹饰

文章对峡江地区汉晋南朝花纹砖上的车轮纹饰进行全面检讨。首先将车轮纹饰分为若干种类,其后以发掘报告为依据讨论各类车轮花纹砖的年代,最终归纳出峡江地区车轮纹饰的演变线索。文章以为,峡江地区的车轮花纹砖大约出现在新莽至东汉初期,东汉中晚期至东晋最为流行,南朝仍有发现。文章同时分析了各阶段车轮纹饰的时代特征,并且简要讨论了与车轮花纹砖相关的若干问题。     

江苏淮安财富广场南北朝墓群发掘报告

江苏淮安财富广场南北朝家族墓是一处典型的家族墓地,墓葬排列有序,随葬器物较为丰富精美,时代特征明显,文化因素较为复杂,对研究南北朝时期丧葬礼俗及淮安地方历史文化具有重要的价值。     

基于磁化率测量平遥古城古砖的烧制温度

古砖的烧制温度决定了其物理力学性质。本研究提出基于磁化率来确定古砖烧制温度的方法。通过对古砖重新加温,测量不同温度下古砖的磁化率,得到磁化率差值的平方-温度曲线图。图中第一个较大的偏差对应的横坐标即为古砖的烧制温度。利用上述方法测得实际烧制温度为700℃、800℃和900℃的黏土砖的烧制温度分别为690℃、810℃和870℃。二者误差较小,认为利用该方法确定砖的烧制温度可行。本研究利用该方法确定了平遥古城10块古砖的烧制温度,发现其烧制温度在650～690℃和850～870℃两个区间范围内。据此推测平遥古城古砖是以秸秆和木柴为燃料烧制而成。本研究实验结果可为古建筑修复和保护提供理论参考。