Papers by Keyword: Masonry Building

Abstract: After the recent earthquakes occurred in some cities in Iran, such as Bam and Kermanshah, the engineering community was forced to pay special attention to the seismic vulnerability of traditional structures. Unreinforced masonry walls exhibit poor seismic performance under moderate and high seismic demand, due to the rapid degradation of stiffness. The development of effective techniques for the strengthening of these walls is an urgent need. The Base Isolation System (BIS) provides solutions to mitigate seismic hazard [1]. In this work, the seismic vulnerability of heritage masonry walls is assessed by conducting extensive numerical studies on both unreinforced (fixed-base) and reinforced (Base Isolation System) masonry walls. In this manner, modeling and analysis are conducted using standard finite element software, ABAQUS 6.13, and results of fixed-base masonry wall and similar base-isolated walls retrofitted with laminated rubber bearings are compared. Nonlinear time history analyses (using the actual Bam earthquake), which enable description of the pre-peak and post-peak behavior of walls, have been used to describe the behavior of structures.Finally, comparison of the failure modes between unreinforced and reinforced masonry walls reveals efficiency of using the rubber bearing isolation (passive control vibration devices) for a reduction in acceleration and an increase in the structural resistance to earthquake excitations [2].

Abstract: Performance-based seismic design is the basis of most new seismic design standards and specifications worldwide. In a performance-based seismic design, a performance objective consists of the specification of a performance level and a corresponding probability that this performance level may be exceeded. This study explored some probability information for seismic performance for reinforced concrete buildings and masonry buildings. The exceeding probabilities of various performance levels for reinforced concrete buildings and masonry buildings during their 50-year useful lives were investigated. Then, a probabilistic evaluation was performed for these buildings to examine the achievement of desired performance design objectives.

Abstract: A building context as complex as that of many historical centers in Europe is the typical scenario where more and more technicians found themselves at work. In addition to the usual difficulty of dealing with the complexity of masonry building clusters, they particularly feel the lack of the essential support of dedicated computational tools. In fact, the calculation codes currently available do not address modeling and analysis of building clusters in a personalized manner. VENUS, Italian acronym for Nonlinear Assessment of Structural Units, is a software developed in C++, which deals with the seismic assessment of building clusters in an integrated manner, accompanying the practitioner from the early stages of defining the level of knowledge, to the management of the design quantities, until the graphic elaboration of the results. Finally, it allows to test the effectiveness of a local intervention with traditional and innovative strengthening techniques and to evaluate its effects on the global response. Finally, a brief description of a stochastic approach foreseen in a future version of the software is discussed.

Abstract: Aghjots Monastery was built in IX - XIII centuries within the Khosrov State Reserve in Armenia. It takes a vantage point in the slope and is featured with beauty and unique carvings. Aghjots Monastery consists of the Saint Stephan church, which is the cruciform inscribed in a rectangle externally rectangular church with a cruciform interior, a single apse and four corner - chambers (two-story side-chapels in each corner), the church of Saints Peter and Paul, is the single naved hall-type church with no freestanding pillars and no dome and a gavit adjacent [1,2]. Aghjots Monastery experienced some strong earthquakes which resulted in its almost complete destruction. This article presents a description of the existing state of the Aghjots monastery and importance of the detailing geometrical survey, decay and material mapping. Stress-strain state of main church at seismic action including dynamic behavior of Saint Stephan church is considered in the article. The bearing system is modeled by using shell finite elements by software based on finite element methods. This proves to be an important feature to understand the damage mechanisms, solve the conservation and reconstruction problems.

Abstract: Performance levels in performance-based seismic design are affected by many factors. In this paper, based on the unclear division of the performance levels, finite element models of masonry buildings with windows of different sizes and different structural measures, according to damage constitutive equation of masonry in strain space and damage evolution equation [1], are built, which are analysed by the pushover analysis method. Stiffness change and damage evolution of masonry buildings under earthquake action are quantitatively described by the basic damage index and holistic damage index. In order to show their joint action on seismic performance of masonry buildings, the comprehensive evaluation coefficient is suggested to divide and evaluate performance levels of masonry buildings, which can evaluate overall seismic behavior of masonry buildings.

Abstract: In the present work some characteristical features of autoclaved aerated concrete structures are illustrated in the seismic and nonseismic design for residential and industrial buildings. Besides the properties of this material with regards to fire resistance and thermal and acoustical insulation, the use of autoclaved aerated concrete for engineering structures may have the advantage of a confined structure with reinforced concrete bond elements that are disposed horizontally and vertically. In the present work the dynamical behavior of a building prototype realized with autoclaved aerated concrete is analyzed, a finite element modelling of the structure has been calibrated according to an experimental modal analysis carried by loading the structure with a vibrodyne located on top of the building and by monitoring the building outputs due to horizontal harmonic forces. The finite element modelling of the dynamical behavior of the autoclaved aerated concrete structure has been compared with a similar tuff masonry building whose characteristical behavior has already been the object of experimental and numerical analysis in a previous work.

Abstract: A finite element modelling of a masonry building prototype is illustrated in this paper. A computational analysis describing the dynamic behavior of the structure is presented in order to characterize some dynamical features of the system under the effect of harmonic forces of different intensity. The structure is represented by a two-story masonry building characterized by a regular floor plan. The finite element modelling of the structure intends to reproduce an experimental test of the masonry building subject to a harmonic force input supplied by a vibrodyne. Frequency response functions corresponding to the frequency load inputs are reported for different monitored nodal points of the finite element mesh. In this way by comparison with the experimental results obtained in a parallel study it is possible to suitably assess the calibration of the parameters for characterizing the dynamical behaviour of the masonry structure.

Abstract: In the present paper an experimental study has been performed on a masonry building prototype and some preliminary experimental results are illustrated for analyzing the structural behavior of a masonry building prototype subject to harmonic forces of different intensity. The physical model used for the laboratory test is a two-story masonry building characterized by a regular floor plan. The structure test is subjected to a harmonic force input supplied by a vibrodyne. The experimental results are aimed at characterizing the dynamic response of the masonry building subject to harmonic forces in order to describe the bahaviour of the masonry building under the predominant actions of a seismic input.

Abstract: Collapse safety is the most important objective of performance-based seismic design. Buildings should have enough safety margin to avoid collapse during severe or mega earthquake. However, current Chinese seismic design code does not have explicit design specification or quantitative evaluation for collapse-resistant capacity. Take a two-story masonry building as an example, an equivalent frame model for pushover and incremental dynamic analysis are established, and the comparison are also studied. In addition, the fragility curves can also be obtained. The analysis results show that the results of plastic hinge mainly appear in ground floor wall between windows and doors. Moreover, the analysis result has good uniformity with seismic damage. Judging from the failure mechanism, pushover and incremental dynamic analysis have very good similarity. In addition , they show elastic deformation is very small and brittleness is very apparent of the masonry building.Seismic vulnerability analysis shows that the significant damage and the near collapse curves are very close to each other .This mean that , once the significant damage limit state is reached ,only small PGA increments are need for reaching the near collapse limit state.

Abstract: Wall and tie column shear strength of every floor in masonry buildings as indicators of earthquake-resistant capacity, the evaluation criteria of the indicators was obtained based on the earthquake damage analysis on the 72 multi-storey masonry buildings in Dujiangyan and Hanwang areas. Based on these tests, a rapid seismic evaluation method of masonry buildings was proposed, this method can assess the degree of earthquake damage for the masonry structure under the level of seismic intensity directly. The application of the method is introduced by analyzing the earthquake damage of a masonry building in Wenchuan earthquake. The results show that the method can evaluate the aseismic performance for masonry buildings, and can assess the degree of earthquake damage additionally.