• Earthquakes and Structures
• /
• v.10 no.6
• /
• pp.1331-1346
• /
• 2016

Historical masonry structures have an important value for cultures and it is essential for every society to strengthen them and confidently transfer to the future. For this reason, determination of the seismic earthquake response, which is the most affecting factor to cause the damage at these structures, gain more importance. In this paper, the seismic earthquake behaviour of Kaya Çelebi Mosque, which is located in Turkey and the restoration process has still continued after 2011 Van earthquake, is determined. Firstly the dynamic modal analysis and subsequently the seismic spectral analysis are performed using the finite element model of the mosque constructed with restoration drawings in SAP2000 program. Maximum displacements, tensile, compressive and shear stresses are obtained and presented with contours diagrams. Turkish Earthquake Code and its general technical specifications are considered to evaluate the structural responses. After the analyses, it is seen that the displacements and compressive/shear stresses within the code limits. However, tension stresses exceeded the maximum values at some local regions. For this mosque, this is in tolerance limits considering the whole structure. But, it can be said that the tension stresses is very important for this type of the structures, especially between the stone and mortar. So, some additional strengthening solutions considering the originality of historical structures may be applicable on maximum tensile regions.

• Structural Engineering and Mechanics
• /
• v.62 no.5
• /
• pp.643-649
• /
• 2017

Masonry walls are amongst the oldest building systems. A large portion of the research on these structures focuses on the load-bearing walls. Numerical methods have been generally used in modelling load-bearing walls during recent years. In this context, macro and micro modelling techniques emerge as widely accepted techniques. Micro modelling is used to investigate the local behaviour of load-bearing walls in detail whereas macro modelling is used to investigate the general behaviour of masonry buildings. The main objective of this study is to investigate the elastic behaviour of the load- bearing walls in masonry buildings by using micro modelling technique. In order to do this the brick and mortar units of the masonry walls are modelled by the combination of plane truss elements and plane frame elements with no shear deformations. The model used in this study has fewer unknowns then the models encountered in the references. In this study the vertical frame elements have equivalent elasticity modulus and moment of inertia which are calculated by the developed software. Under in-plane static loads the elastic displacements of the masonry walls, which are encountered in literature, are calculated by the developed software, where brick units are modelled by plane frame elements, horizontal joints are modelled by vertical frame elements and vertical joints are modelled by horizontal plane truss elements. The calculated results are compatible with those given in the references.

• Structural Engineering and Mechanics
• /
• v.59 no.3
• /
• pp.539-558
• /
• 2016

Minarets are almost the inevitable part of Mosques in Islam and according to some, from a philosophical point of view, today they symbolize the spiritual elevation of man towards God. Due to slenderness, minarets are susceptible to earthquakes and wind loads. They are mostly built in a masonry style by using cut limestone blocks or occasionally by using bricks. In this study, one minaret (M1 Minaret) of one of the charmest mosques of Turkey, Sultan Ahmed Mosque, popularly known as Blue Mosque, built between 1609 and 1616 on the order of Sultan Ahmed by the architect Mehmet Agha is investigated under some registered earthquake loads. According to historical records, a great earthquake hit Istanbul and/or its close proximity approximately every 250 years. Ottomans tackled with the problem of building earthquake resistant, slender minarets by starting to use forged iron connectors with lead as a filler to fix them to the upper and lower and to adjacent stones instead of using traditional mortar only. Thus, the discrete stones are able to transfer tensile forces in some sense. This study investigates the contribution of lead to the energy absorption capacity of the minaret under extensive earthquakes occurred in the region. By using the software ANSYS/LS-DYNA in modelling and investigating the minaret nonlinearly, it is found out that under very big recorded earthquakes, the connectors of vertical cast iron-lead mechanism play very important role and help to keep the structure safe.

• Earthquakes and Structures
• /
• v.5 no.2
• /
• pp.207-223
• /
• 2013

Practical seismic assessment and design of retrofit for the multitude of small ecclesiastical monuments that abound in the Balkans is the subject of this work. Application of the proposed procedures and methodologies are illustrated in an example case study, a small byzantine church located in Western Greece, which is the region with the highest seismicity in Europe. The church, known as the Fragavilla Monastery, had remained almost undamaged for 800 years, until 1993 when the Pyrgos earthquake caused critical damage mainly in the vaults. Linear elastic analysis to the recorded ground motion, capped by a biaxial failure criterion reproduced the developed damage. The same modelling and analysis procedure was subsequently used for assessment of the intended retrofitting measures. Proposed retrofitting measures included mitigation of the undesirable implications of past interventions along with a combination of strengthening schemes with externally bonded AFRPs strategically placed in the structure. The effectiveness of the proposed solutions is gauged by successful reduction of stress intensity in the critical regions and mitigation of stress localization throughout the structure.

• Smart Structures and Systems
• /
• v.14 no.3
• /
• pp.367-376
• /
• 2014

Ambient vibration techniques are nowadays a very popular tool to assess dynamic properties of buildings. Due to its non destructive character, this method is particularly valuable, especially for health monitoring of historical monuments. The present ambient vibration experiment consists on the evaluation of vibration modes of a Medieval tower. Situated in Soncino (close to Cremona, in the Northern Italian region named Lombardia), the tower of 41.5 meters height has been monitored by seismometers located at different points inside the structure. Spectral ratios of the recorded ambient vibrations clearly identify a fundamental mode at about 1 Hz, with a slight difference in the two horizontal components. A second mode is also evidenced at approx 4-5 Hz, with a moderate degree of uncertainty. The records of a ML 4.4 earthquake, occurred during the monitoring period, confirm the information obtained by microtremor analysis. Daily variations of both 1st and 2nd mode were detected: these variations, of an amount up to 2%, seem to be well related with the temperature.

• Earthquakes and Structures
• /
• v.18 no.3
• /
• pp.321-335
• /
• 2020

The aim of the present contribution is to consider and underline the essential interactions among the historical knowledge, the seismic vulnerability assessment, the investigation experimental tools, the preservation of the architectural quality and the strengthening design in regard to architectural heritage conservation. These topics are argued in relation to Palazzo Murena in Perugia, designed in the eighteenth century by the famous Architect Luigi Vanvitelli, and currently headquarters of the city's University. Based on the surveys and the visual inspections, a preliminary a priori global analysis has been performed by means of the FME method. The obtained results permitted to plan an experimental tests campaign inclusive of structural health monitoring. The new achieved "knowledge" of the building allowed to refine the seismic safety assessment. In particular it was highlighted that the "mezzanine floor" can be a vulnerable element of the building with the collapse of its masonry walls. Preserving the architectural characteristics, a local reinforcement intervention is proposed for the above-mentioned level; this consists of the application of plaster with FRCM, assuring an adequate strength, without burden the masonry structure with additional weight, and therefore a decreasing of the seismic vulnerability. The necessity to consider, in this ongoing research, other local mechanisms is highlighted in the unfolding of the last part of work.

• Earthquakes and Structures
• /
• v.1 no.4
• /
• pp.371-390
• /
• 2010

Historical buildings in seismically active regions are severely damaged by earthquakes, since they certainly were not designed by the original builders to withstand seismic effects. In particular the reports after major ground motions indicate that earthquake-induced pounding between buildings may lead to substantial damage or even collapse of colliding structures. The research on structural pounding during earthquakes has been recently much advanced, although most of the studies are conducted on simplified single degree of freedom systems. In this paper a detailed pounding-involved response analysis of three adjacent structures is performed, concerning the main bodies of the "Quinto Orazio Flacco" school. The construction includes a main masonry building, with an M-shaped plan, and a reinforced concrete building, separated from the masonry one and realized along its free perimeter. By the analysis of the capacity curves obtained by suitable pushover procedures performed separately for each building, it emerges that masonry and reinforced concrete buildings are vulnerable to earthquake-induced structural pounding in the longitudinal direction. In particular, due to the geometric configuration of the school, a special case of impact between the reinforced concrete structure and two parts of the masonry building occurs. In order to evaluate the pounding-involved response of three adjacent structures, in this paper a numerical procedure is proposed, programmed using MATLAB software. Both a non-linear viscoelastic model to simulate impact and an elastic-perfectly plastic approximation of the storey shear force-drift relation are assumed, differently from many commercial softwares which admit just one non-linearity.

• Smart Structures and Systems
• /
• v.4 no.2
• /
• pp.183-194
• /
• 2008

An important historical monument of Cyprus is an aqueduct that was built in 1747 to provide water to the city of Larnaca and to its port. Because of its importance to the cultural heritage of Cyprus, the aqueduct has been selected as one of the case-study monuments in the project Wide-Range Non-Intrusive devices toward Conservation of Historical Monuments in the Mediterranean Area (WIND-CHIME). Detailed drawings of the aqueduct obtained from the Department of Antiquities of Cyprus have been used for the development of a computational model. The model was fine-tuned through the measurement of the dynamic characteristics of the aqueduct using forced and ambient vibrations. It should be noted that measurement of the dynamic characteristics of the structure were performed twice in a period of three years (June of 2004 and May of 2007). Significant differences were noted and they are attributed to soil structure interaction effects due to seasonal variations of the water-level in a nearby salt-lake. The system identification results for both cases are presented here. This monument was used to test the effectiveness of shape memory alloy (SMA) pre-stressed devices, which were developed during the course of the project, in protecting it without spoiling its monumental value.

• Journal of the Korea Concrete Institute
• /
• v.24 no.3
• /
• pp.305-313
• /
• 2012

Unreinforced masonry buildings represent a significant portion of the existing and historical buildings around the world. Recent earthquakes have shown the need for seismic retrofitting for these types of buildings. Various types of retrofitting materials (i.e., shotcrete, ECC and Fiber Reinforced Polymer sheets (FRPs)) for unreinforced masonry buildings (URM) have been developed. Engineers prefer to use FRPs, because these materials enhance the shear strength of the wall without expansion of wall sectional area and adding weight to the total structure. However, the complexity of the mechanical behavior of the masonry wall and the lack of experimental data from walls retrofitted by FRPs may cause problems for engineers to determine an appropriate retrofitting level. This paper investigate in-plane behavior of URM and retrofitted masonry walls using two different types of FRP materials to determine and provide information for the retrofitting effect of FRPs on masonry shear walls. Specimens were designed to idealize the wall of a low-rise apartment which was built in 1970s in Korea with no seismic reinforcements with an aspect ratio of 1. Retrofitting materials were carbon FRP and Hybrid sheets which have different elastic modulus and ultimate strain capacities. Consequently, this study evaluated the structural capacity of masonry shear walls and the retrofitting effect of an FRP sheet for in-plane behavior. Also, the results were compared to the results obtained from the evaluation method for a reinforced concrete beam retrofitted with FRPs.

• Journal of Korean Association for Spatial Structures
• /
• v.15 no.3
• /
• pp.69-76
• /
• 2015

Cheomseongdae is the masonry stone structure with the cultural and historical values. But, this structure has the various damages such as cracks, gaps, slope variations and ground subsidence. So, the interests for the safety security in the structural parts have been increased. Therefore, this study performs the structural modelling which considers the several damage cases, and then evaluates the structural behavior characteristics through the discrete element analysis. Especially, this study checks the swelling and displacement gap of the whole structure and the separation between the neighboring members.