Caselles, J. O., J. Clapes, P. Roca, and A. Elyamani, "Approach to Seismic Behavior of Mallorca Cathedral", 15th World Conference of Earthquake Engineering, Lisbon, Portugal, 24-28 September , 2012. Abstractapproach_to_seismic_behavior_of_mallorca_cathedral.pdf

The paper presents the current state of an on-going research aimed at characterizing the seismic response of Mallorca cathedral. Mallorca cathedral is an audacious Gothic structure built in the island of Mallorca during 14th-16th centuries, characterized for its large dimensions and slender structural members. So far, experimental and numerical modal analysis, in addition to tentative model updating and seismic analysis, have been performed. The dynamic identification tests have been carried out by ambient vibration testing, while the frequency domain decomposition (FDD) technique has been used to obtain the modal parameters. A 3D Finite Element (FE) model has been used to determine the vibration modes. The model has been updated by modifying some structural parameters to improve the matching between experimental and numerical modal parameters. Once updated, the model has been utilized to study the seismic response of the cathedral using non-linear static pushover analysis. Conclusions on the possible collapse mechanisms and the seismic performance of the structure are presented.

Elyamani, A., P. Roca, O. Caselles, and J. Clapes, "Seismic safety assessment of historical structures using updated numerical models: The case of Mallorca cathedral in Spain", Engineering Failure Analysis, issue 74, pp. 54-79, 2017. AbstractWebsite

The paper presents an integrated approach aimed at assessing the seismic safety of Mallorca cathedral. This cathedral is an extraordinary historical construction dating back to the middle ages. The experimental modal parameters of the cathedral were identified using Ambient Vibration Testing (AVT). The cathedral numerical model was updated using the identified modal parameters. This updated model was then used to study the seismic response of the cathedral using non-linear static (pushover) analysis. A sensitively analysis was carried out to reveal the dependency of the seismic capacity on the input materials properties. To assess the seismic performance and the safety of the cathedral, the N2 method was employed. It was found that the cathedral is safe when subjected to the earthquakes expected in Mallorca Island.

Elyamani, A., "Conservation-Oriented Structural Analysis of the Spire of Barcelona Cathedral", International Journal of Materials Science and Applications , vol. 5, issue 6-2, pp. 1-9, 2016. AbstractWebsite

The spire of Barcelona cathedral suffered from severe problems due to the corrosion of the steel ties used in reinforcing its stone masonry beams. Wide visible cracks were noticed in the stone beams and large parts were detached. Therefore, the full spire was dismantled and reconstructed using titanium ties to eliminate the corrosion problem. A finite element model of the spire was created and analyzed using DIANA software to support this decision. This analysis helped in understanding the role and strength contributions of these ties in resisting the applied loads on the spire, specifically, the lateral loads of earthquakes and wind. A nonlinear static (pushover) analysis was carried out to assess the spire capacity under the lateral loads. A number of constitutive models for modeling the masonry behavior were tried. Also, a number of seismic actions patterns were considered. As a main conclusion of this study, the ties were highly needed to carry the tensile stresses caused by earthquakes and wind loads. Therefore, in the reconstruction of the spire, such ties must be kept in the masonry beams.

Elyamani, A., Integrated monitoring and structural analysis strategies for the study of large historical construction. Application to Mallorca cathedral, , Barcelona, Technical University of Catalonia, 2015. Abstract

Historical structures are vital to the realization of how the technical, artistic, and scientific skills of the human kind have developed over time. These structures are one of the motors of the tourism industry, and therefore, the studies related to their conservation do not only have social benefits but as well economical ones. It is unfortunately that many countries rich with valuable architectural heritage are characterized by high seismic activity, Italy and Turkey are obvious examples. Due to earthquakes, many invaluable historical structures have been lost forever. Consequently, there is an increasing need for more research on the topic of seismic assessment and protection of this class of buildings. This work contributes to the methodological approaches adopted for the seismic assessment of historical structures. In many cases, due to the lack of knowledge about the assessed historical structure, it is essential to combine many investigation activities in such approaches. The aim is to minimize any possibly required seismic strengthening interventions (minimum intervention concept) by increasing the level of knowledge about the structure. In the current research, the employed experimental investigation activities are the dynamic identification tests and the dynamic monitoring. Most approaches for dynamic monitoring are based on the use of a threshold limit which is used to trigger the system when the parameters measured surpass the limit. Here, an alternative is considered that consists of a continuous monitoring system based on the permanent measurement of the ambient vibration. A thermography monitoring is used as a complementary system for the measurement of temperature. The integration between the dynamic investigation and the numerical modeling is essential and it includes two main features. On one hand, tentative structural analyses are carried out to identify important aspects of the dynamic tests and monitoring strategies such as critical points of the structure where to place the sensors. On the other hand, the results of the dynamic investigation are used to perform model updating until obtaining a satisfactory structural model adequately matching the measured dynamic properties of the structure. Once the structural model is validated, it is used to carry out the seismic assessment of the structure. This assessment is performed using different methods, to cross check the results, including the pushover analysis, the kinematic limit analysis and the nonlinear dynamic analysis. It is then possible with these assessments to identify the seismic behavior of the structure. Using the N2 method, the evaluation of the structural performance and its safety are carried out. Hence, the needs for any possible seismic strengthening are revealed, keeping in mind, the respect to the "minimum intervention" concept. As an application, the cathedral of Mallorca (Spain) is taken as a case study. This structure is one of the largest cathedrals built during the Middle Age. For each of the previously mentioned research steps, the followed criteria and the experience gained are transferred into recommended methodological approaches to be applied to other historical structures. Finally, the integration of these partial steps into one integrated methodology is discussed.

Elyamani, A., Wind and earthquake analysis of spire of cimborio of Barcelona cathedral, , Barcelona, Spain, Technical university of Catalonia, 2009. Abstract

Barcelona Cathedral is one of the most important monuments not only in Spain but also all over the world. The construction of the Gothic cathedral started in 1298 under King Jaume II and in 1460 the main building was completed. The two architects Josep Oriol Mestres and August Font i Carreras completed the construction of the gothic façade in 1889 and the central spire in 1913, following the same design previously proposed by the French architect Charles Galters in 1408. The central spire reaches a height of 90 m over ground level which makes it very vulnerable when subjected to lateral loads like wind and earthquakes. Being finished at the beginning of the 20th century (when the concept of reinforced concrete was being widely spread) gave the builders the chance to centrally reinforce all masonry beams of the spire with steel ties and nowadays these steel ties are facing very severe problems due to corrosion. A complete project for restoration of the spire is being executed nowadays in which a complete dismantling and reconstruction will be carried out. The steel ties will be replaced with titanium ones in order to eliminate the corrosion problem. In order to understand wind and seismic performance of the spire and the role and strength contributions of the steel ties, the different applied loads on the spire which are self weight, wind loads and earthquake loads have been estimated ,then a numerical model of the spire has been created and analyzed using the finite element program DIANA. First a linear elastic analysis under the effect of spire self weight then a combination of spire self weight and wind loads and finally a combination of spire self weight and earthquake loads. The high tensile stresses in masonry beams under the effect of the combination of spire self weight and wind loads and the combination of spire self weight and earthquake loads meant that linear elastic analysis wasn't enough to describe the structure behavior and a nonlinear analysis was essential. A nonlinear analysis under the effect of spire self weight (using three different constitutive models to describe masonry nonlinear behavior) was investigated and it revealed an elevated safety margin as the spire can carry more than ten times its self weight. Then to investigate the seismic performance of the spire a nonlinear static pushover analysis (using two different constitutive models) has been carried out.As a conclusion of this study the steel ties are highly needed to carry the tensile stresses resulted from seismic actions and the spire would be able to resist a maximum base shear of 420 KN (16% of the spire self weight).

El-Derby, A. A. O. D., and A. Elyamani, "The adobe barrel vaulted structures in ancient Egypt: a study of two case studies for conservation purposes", Mediterranean Archaeology and Archaeometry, vol. 16, issue No. 1(2016), pp. 295-315, 2016. AbstractWebsite

This research aims at throwing the light on one of the few survived examples of Ancient Egyptian vaulted structures; those are the storerooms of the temples of the Ramesseum and Sety I built in the 13th century BC. In the first case, only some of the adobe vaults and walls are still standing; whereas in the second case all the vaults collapsed and only the walls exist. Due to lack of maintenance and also scientific research on this topic, the survival remains may be lost forever. The research started with tracking the chronological development, the architecture and the construction of the adobe barrel vault in Ancient Egypt. The two case studies of the research were visually inspected and the existing damage symptoms and causes were reported and investigated. A structural analysis were carried out to understand the structural behavior and the causes of damage. Finally, a number of interventions were proposed that may help the existing ruins to survive.

Elyamani, A., J. O. Caselles, J. Clapes, and P. Roca, "Assessment of Dynamic Behavior of Mallorca Cathedral", 8th International Conference of Structural Analysis of Historical Construction, Wroclaw, Poland, 15-17 Oct. 2012. Abstractassessment_of_dynamic_behavior_of_mallorca_cathedral.pdf

The paper presents the application of continuous dynamic monitoring and thermographic monitoring to the study of Mallorca Cathedral, one of the largest medieval structures built in Europe. The dynamic monitoring has been carried out by means of a network of three strong motion tri-axial accelerometers installed in December 2010. This network has allowed the capture of seven seismic events characterized by different epicenter locations and frequency contents. The post-processing of the information recorded during these events has provided significant insight on the cathedral dynamic response. The paper also presents the post processing of raw data of nine months of continuous dynamic monitoring, allowing the characterization of the effect of temperature changes on the natural frequencies of different mode shapes. A complementary study undertaken by thermographic monitoring, in which a part of the cathedral has been monitored for at least two weeks in summer and also in winter using an IR camera, is also presented. The relation between the stone masonry temperature of different structural elements (columns, vaults, arches, walls) and natural frequencies has been investigated. This study is part of a more detailed research, still in progress, aimed at investigating the seismic behavior and vulnerability of Mallorca Cathedral.

Moustafa, S., S. Anwar, D. Ashraf, S. Ramadan, and A. Elyamani, "The tomb of the High Priest of Aton in the regime of King Akhenaten: description, damage and restoration works", 4th Int. Conf. of Faculty of Archaeology, Cairo Univ. “Egypt and Mediterranean Countries Through Ages”, Cairo, Egypt, 15-19 Oct., 2015. Abstractthe_tomb_of_the_high_priest_of_aton_in_the_regime_of_king_akhenaten_description_damage_and_restoration_works.pdf

The discovery of the tomb of Meryneith is one of the recent and important discoveries in
Saqqara. The tomb was discovered in the period from 2001 to 2003 by the archaeological
mission of Leiden University (the Netherlands). The importance of the discovery goes back to
the positions held by the tomb owner Meryneith. He was the High Priest of Aton in the reign
of King Akhenaten and also was the Minister of Finance in the reign of King Tutankhamun.
The tomb was subjected to a complete restoration project. It was afterwards open for visit in
2011. The authors of this paper visited the tomb many times during late 2014 and October
2015. They conducted many times a detailed visual inspection of the tomb during those visits.
This paper discusses the tomb description and the signs of damage currently noticed and the
possible reasons behind. As well, it comments on the restorations carried out by the Holland
mission and comparing it with the tomb status at the time of the discovery. The paper aims at
comparing the restorations done with the basics and the common scientific rules in
architectural and fine restoration of monumental structures. The objective is to contribute in
improving the current situation of the tomb and to give recommendations for possible future
restorations of similar tombs.

Elyamani, A., O. Caselles, P. Roca, and J. Clapes, "Dynamic Investigation of a Large Historical Cathedral", Structural Control and Health Monitoring, vol. 24, issue 3, 2017. AbstractWebsite

The presented research aimed at studying the dynamic behavior of Mallorca cathedral (Mallorca Island, Spain) under ambient sources of vibration and seismic events. The cathedral is one of the greatest built masonry structures worldwide. It is characterized for its audacious dimensions and slender structural members. Because of it, the study of its dynamic behavior is a clear concern. The cathedral dynamic properties were firstly identified using ambient vibration testing. Afterwards, a dynamic monitoring system was implemented to continuously measure, record, and wirelessly transfer the acceleration records without having to set up an activating threshold. This monitoring type was implemented because of the low seismic intensity of Mallorca Island with a basic ground acceleration of only 0.04 g according to the Spanish seismic standard. The continuous monitoring allowed for capturing some seismic events and some drops in the natural frequencies were noticed because of a breathing crack effect. Using both ambient vibration testing and continuous monitoring system, global modes could be more accurately identified than more local ones. The identification of the global modes was more attainable than in the case of more local ones. The temperature was a more influential environmental parameter than humidity and wind for all of the identified modes except for one more directly depended on wind.