Advanced Materials Research Vols. 133-134

Abstract: Architectural heritage masonry buildings located in seismic areas are highly prone to suffer damage under seismic loading, due to their structural features. In this study, the Salares medieval tower, which is placed in the province of Malaga (Spain) - a zone with high seismic hazard in the Iberian Peninsula- is adopted as a case study. This is a precious heritage building which exhibits severe damages, such as depth cracks and inclination. Owing to those reasons detailed seismic and dynamic analyses are crucial for its preservation. The present work is arranged in three sections that deal with seismic hazard analysis, selection of real acceleration time-histories representative of the site, and dynamic response by means of numerical models. In order to obtain the design earthquake at the specific location, different parameters were analyzed, namely the region seismic activity, the geotechnical and geological conditions at the site and the acceptable risk level. Hazard analysis was performed following deterministic and probabilistic methods. As far as the seismic input is concerned, real accelerogram representative of the 1884 Andalusia earthquake were selected. It was a destructive earthquake that caused catastrophic damages near the analyzed structure. The accelerograms thus obtained were used as input for subsequent non-linear dynamic analyses on three-dimensional finite element models. Different cracking capable constitutive models were considered in order to predict local and global collapse mechanisms. Moreover, the suitability of each model was discussed when crushing, high plastic deformation or response under cyclic loading are concerned. The aforementioned studies yield significant results in order to perform a comprehensive safety assessment under ground motion effects. Thus, regarding the seismic input, the obtained accelerogram provides a relevant application aimed at revising the maximum acceleration and the response spectra of the Codes, as seismic code recommendations are limited in those issues. Furthermore, the dynamic structural response via numerical approach, allows determining damage propagation and collapse probability as a main step to select appropriate repair measures. The followed method could be used to assess and improve the structural strength of similar architectural heritage buildings located in active seismic areas.

Abstract: Based on strengthening project of a business architecture built during the period of the Republic of China in Nanjing, some key problems in strengthening design of reinforced concrete frame structures built during the period of the Republic of China are roundly discussed, including methods of testing and appraisement, computing and analyzing, foundation reinforcement, brick wall reinforcement, concrete members reinforcement and seismic reinforcement, etc. Some effective methods are introduced to solve the problems, which can be referenced for similar design.

Abstract: The paper presents calculated and experimentally determined dynamic characteristics of masonry arch bridges. Two bridges were considered: the road viaduct at Zaborow and the bridge at Kamienica Dolna (South Poland). Finite element models were built considering all parts of the structures: arch, spandrel walls, fill, soil-structure interaction. For verification of calculations in situ investigations of dynamic characteristics of bridges were conducted. As a basic ways of realization of dynamic loads impulse load (drop of a lorry wheels from a threshold) as well as kinematic excitation (train passage under the viaduct) were applied. For determination of natural frequencies power spectral density function and transfer function of measured signals were applied. Basing upon the recorded vibrations the value of logarithmic decrement of damping was evaluated. The results of measured and calculated natural frequencies were compared. With regard to the degree of complexity of structures the differences between experimental and computational results can be accepted.

Abstract: The Grand Bazaar is a historical trade centre more than 500 years in the historical peninsula of Istanbul, Turkey. It consists of almost 3,600 small shops from different sectors (such as jewellery, carpet, leather, souvenir, finance, restaurant, café, confection etc.), two Bedesten, 64 street and 16 Han (inn) buildings. The Bazaar has 21 main gates that open to different streets and have different relation with outside. More than 25000 staff work in the shops and 300-500 thousand users come to Bazaar daily depending on the season and day. The pedestrian density is changeable, depending on the place of the inner street and the type of the sector. The historical disaster records (earthquake, dated 1766 and 1894, the grand bazaar fire, dated 1954) show that there was evacuation vulnerability. The main gates (exit doors) and exit route need some rehabilitation for safety evacuation during any disaster. The aim of this study is to evaluate the Grand Bazaar’s emergency evacuation vulnerability. The evacuation vulnerability factors question the width, length and natural illumination of the evacuation route, maintenance of the roof, presence of hazardous materials, door specifications as size, material, opening direction, maintenance and difference in elevation on the route and exit area such as staircase and thresholds.

Abstract: This paper deals with the dynamic characterization and the evaluation of the seismic response of the medieval civic tower of Soncino (Cremona, Italy). The dynamic characteristics and the mechanical properties of the masonry tower are evaluated through ambient vibration tests, which provide results in a fast and non destructive way with respect to the traditional methods such as forced vibration tests. Nonlinear static and dynamic analyses are performed on a finite element model of the tower calibrated on the results of the dynamic identification. The damage levels and the seismic capacity of the structure are also evaluated. The obtained results allow to predict the seismic behaviour of the tower and to define possible strengthening and restoration interventions.

Abstract: A mechanical based method for the evaluation of the seismic capacity of masonry buildings’ classes in terms of damage limit states is presented: the purpose of the study is to achieve, in the framework of vulnerability analyses at territorial scale, reliable values for the damage level of vulnerability classes of masonry buildings, depending on the seismic input level. This approach is, in fact, designed as a “1st level” tool based on easily traceable information provided by expeditious surveys. Once identified a limited number of typological, physical and mechanical parameters that are necessary to define each vulnerability class, a significant number of simplified models of masonry buildings belonging to each class has been created. Non-linear static analysis of these models allowed the creation of bilinear elastic perfectly plastic capacity curves: the displacement capacity described by these curves is related with the actual displacement values required by seismic intensities associated to different return periods. It is so possible to identify, for different vulnerability classes and different seismic inputs, the loss of capacity in terms of damage level of each building. An application of the method to models representative of masonry buildings in the historical centre of Sulmona, in L’Aquila province, and a comparison of the results with others obtained with other methodologies of assessment are presented.

Abstract: In Turkey, as well as in Balkan countries, examples of an extant housing tradition namely hımış, which was formed during Ottoman period, can still be observed. In spite of minor local differences according to geographical locations, these Ottoman hımış houses are distinguished with a number of common architectural and technical peculiarities that is worth to preserve. They have similar timber frame construction system with different infill materials. There are numerous reports claiming that the hımış houses are seismically more resistant than other construction types such as reinforced concrete and/or masonry structures. However, nearly all such reports are based on observations made after historical or contemporary earthquakes and lack quantitative engineering approach. For these reasons, within the framework of an ongoing research project, supported by The Scientific and Technological Research Council of Turkey (TUBITAK), coded 106M499, the seismic resistance of traditional timber frame houses in Turkey was investigated. A number of timber frames were tested in the laboratory under cyclic and reverse lateral loading, with and without infill. The results were reproduced with pertinent analytical work. As a result, it was shown that connections that were traditionally made with the sole use of standard nails were always the location of failure. In this paper, the results obtained for one of these frames is presented together with its capacity curve analysis to see whether strengthening is needed or not from seismic design point of view.

Abstract: This paper presents a review of the methods for seismic vulnerability assessment, together with an experimental method based on shaking table testing. This method is applied to a Portuguese masonry building typology with stone walls and timber floors, subjected to increasing earthquake damage. Traditional-like materials and techniques are used in the building. The vulnerability curves are presented and the damage indicator is correlated with the crack patterns and EMS 98.

Abstract: The earthquake that hit the city of L’Aquila, in central Italy, on the 6th of April 2009 has severely damaged most of the heritage buildings of the area. Soon after the event, a first survey of damage to ancient churches and palaces has been carried out according to a predefined classification procedure. Subsequently, a more detailed damage analysis was started in order to facilitate decision on future interventions. For one of these churches, S. Biagio Amiterno, damage consisted in the collapse of the upper part of the façade, in the localized collapse of the main vault, and in an extended crack pattern in vaults, columns, and walls. This damage pattern is interpreted here as case study. In more general terms, the exam of specific case studies gives the possibility of shedding light on various issues related to the seismic behavior of the building typologies concerned.

Abstract: The influence of the natural hydraulic lime-based grout on the dynamic behaviour of injected multi-leaf stone masonry elements is discussed in the paper. Shaking table experiments on two stone masonry buildings, tested before and after grout injection, have been performed. The paper focuses on the analysis of both the recorded accelerations and related displacements, at the bottom and at each further storey. This leads to evaluate the stiffness of the unstrengthened and injected structures. The input at increasing PGA allowed the stiffness decay to be studied, simulating a gradual damaging of the structures. These results were also interpreted in the light of both computed frequencies and mode shapes. Finally, the comparison among these results, obtained from all the models, allows to deepen the knowledge concerning the effects induced by the lime-based grout injection and on its capability to modify the dynamic behaviour, when intervening on a damaged (repairing) or on an undamaged (strengthening) structure.