T. Aoki

• Dr. Eng.
• Professor (Full) at Nagoya City University

The Kashima Lighthouse, one of the lighthouses that suffered damage in the 2011 Great East Japan Earthquake, required a careful investigation to estimate its long-term behavior and seismic vulnerability. This study, therefore, undertook a meticulous process of the dynamic testing, dynamic identification, and long-term structural health monitoring o...

In recent years, the use and preservation of historic brick buildings have attracted attention. However, little technical data exists regarding the material properties of brick buildings, and a method of estimating the corresponding compressive strength for seismic evaluation has not been established. Therefore, technical data was collected in this...

Ensuring the seismic resilience of traditional rammed earth and stone masonry buildings in the Kingdom of Bhutan is essential for their preservation. This study aims to clarify the vibration characteristics of traditional masonry buildings during an earthquake, based on shaking table tests and seismic response analyses. Shaking table tests were con...

Bhutanese vernacular stone masonry architecture proved highly vulnerable to the recent seismic events affecting Bhutan since 2009. The isolation of rural communities, due to the site geomorphology, the precarious roads networks condition, the local labour limited skills, and the scarce resources availability, largely influence the applicability of...

The seismic analysis of historical and monumental masonry buildings, especially churches and cathedrals, is challenging and expensive. These difficulties are mainly related to complex geometry and the mechanical modelling of historic masonry structures. This paper aims to show the methodological approach to evaluate the seismic vulnerability of Mas...

Many lighthouses in East Japan suffered extensive damage in the 2011 Great East Japan Earthquake. The lighthouse dealt with in this paper is one of these damaged lighthouses. A careful investigation is required to estimate the long-term behaviour as well as the seismic vulnerability. The present study deals with the dynamic test, dynamic identifica...

This paper reports the experimental campaign for static tests performed on unreinforced (URE) and mesh retrofitted (RRE) full scale rammed earth building. Amongst varying building patterns of traditional rammed earth houses found in Bhutan, a two-storied building with a full solid wall (small openings) on the first floor and larger opening in the f...

The paper reports an experimental campaign to study the effectiveness of strengthening measures proposed for rammed earth (RE) wall in an out-of-plane direction. Two simple and feasible strengthening techniques were explored, namely, mesh-wrapped and timber-framed strengthening techniques. The test involved testing three full-scale U-shaped RE wall...

This paper reports on the series of element tests conducted on rammed earth (RE) wallettes to understand their behavior under compression and shear loading while exploring the mesh-wrap strengthening technique to strengthen the RE wallete. Compressive strength and shear strength of RE wallettes are evaluated with varying parameters, namely RE layer...

Present-Day Bhutan as a nation still practices and actively promotes the nation's indigenous construction practices involving rammed earth and stone masonry houses, which constitute almost 70% of the household in the country. However, the past seismic activities in the Bhutan Himalayan region highlighted that these structures show vulnerabilities a...

The rural houses in the western region of Bhutan are predominantly constructed using rammed earth material, which constitute more than 70% of present residential houses and are also preserved as traditional buildings. Unfortunately, these buildings suffered significant destruction by the 2011 Sikkim earthquake with a magnitude of 6.9. This work pro...

Rammed earth architecture is still widespread and alive in Bhutan, especially in rural villages, where dwellings are built by the local community. The country recently suffered two intense earthquakes that put traditional architecture at risk. Rammed earth building techniques show high seismic vulnerability by nature, whose degree strongly depends...

This paper reports an experimental campaign to assess effectiveness of strengthening interventions on the out–of–plane performance of rammed earth (RE) structures in Bhutan. An innovative strengthening technique is proposed for strength enhancement of RE walls. The tests involved two types of specimens, an unreinforced RE structure and an identical...

An economic performance evaluation scheme of historic buildings that consider the effect of structural renovation is proposed to provide information facilitating to the selection of reasonable renovation methods for preserving historic buildings. Ground motion scenarios, herein referred to as “lifecycle earthquake scenarios” in accordance with the...

The paper presents experimental and numerical works to assess the in-plane shear characteristics of rammed earth (RE) structures in Bhutan. The material characterization works involve compressive and tensile splitting strength tests on extracted cylindrical core samples. The effects of the RE layer thickness and drying period in the strength charac...

System identification is the key technique for damage detection in application of structural health monitoring. In contrast to modal parameters, changes in structural parameters (stiffness and damping) are more sensitive and straightforward for damage detection of a building under severe environments such as earthquakes. In this study, we first pre...

The airship hangar in Augusta, Sicily, Italy is the oldest airship hangar still now in existence in the world. Unfortunately, it has been damaged by frequent hooligan actions and now due to aging, human stupidity and indifference. The risk to lose the unique reinforced concrete airship hangar in the world become higher. This building undergoes subs...

The paper presents structural health monitoring (SHM) activities performed on some representative cultural heritage (CH) buildings in the city of l’Aquila after the strong earthquake (Mw = 6.3) that struck the Abruzzo region (central Italy) on April 6, 2009. The severity and the extent of damages caused by the earthquake to historical buildings and...

In Japan, to prevent the collapse of and power loss in lighthouses due to natural disasters such as earthquakes and typhoons and to ensure safe maritime traffic movement in disaster areas even after a disaster strikes, disaster-related measures including the reinforcement of lighthouses against earthquakes are implemented (Reference 5)). In the Bui...

This article reports pull-down tests performed on rammed earth construction in Bhutan. The pull–down specimens involved an old rammed earth building component as well as a newly prepared rammed earth wall. Both the wall specimens were tested in out-of-plane direction. Theoretical rigid body formulation and finite element (FE) models were developed...

Structural health monitoring is a method of estimating the presence of the damage of the structure, and its position and degree by the change of static and dynamic characteristics before and after the secular change or the action of external force. However, the static and dynamic characteristics of the actual structural fluctuate on daily, seasonal...

In this paper, we present the experimental results of a series of microtremor measurements of a RC building during demolition work (reduction process) in order to clarify their properties in dynamics. The RC building was reduced from 5 stories + 1 story penthouse to 4 stories. We conducted microtremor measurements before, during and after reduction...

A small-diameter drilling tester developed by the authors is one of the slight-destructive testers, with which the damage of materials tested can be very small. To apply the tester for checking the strength of compound materials e.g. Portland cement mortars, concretes etc., a series of experiments was carried out 1) to avoid the ill effect of cemen...

Various types of brick masonry are used in the handling and treatment of hot materials in steelmaking processes. Although trouble related to damage of the bricks and joints is an important issue, it is difficult to predict and prevent damage of brick masonry because masonry is characterized by heterogeneity, nonlinearity and nonequilibrium. In this...

In this paper, we present a novel model updating method for damage detection of multi-story shear buildings during severe earthquakes. The story stiffnesses are explicitly presented in an incremental manner; this enables a simple and robust algorithm for the purpose of identification of the story stiffnesses. The estimated modal data, including nat...

Various types of brick masonry are used in the handling and treatment of hot materials in steelmaking processes. Although trouble related to damage of the bricks and joints is an important issue, it is difficult to predict and prevent damage of brick masonry because masonry is characterized by heterogeneity, nonlinearity and nonequilibrium. In this...

The present paper describes a solution to a problem of identifying damage in a building based on experimentally measured vibrational eigenvalue and eigenmode pairs. The healthy rate, which is defined as the stiffness rate with respect to a perfect material, is chosen as the design target to be identified. The range of the healthy rate is restricted...

Seismic evaluation of the Handa Akarenga Building, which was constructed more than 100 years ago, was carried out. Based on the SSI (Subspace Identification) method, dy-namic identification of the structure was performed using the results of Microtremor measure-ments; thus fundamental frequencies and damping factors of the structure were estimated...

It is extremely important to obtain reliable information about actual structural and dynamic properties to evaluate the earthquake-resistance performance of a structure. However, examples of vibration experiments performed for a lighthouse are scarce. This study focuses on estimating the dynamic parameters of the Ujina Lighthouse by performing micr...

Historical masonry towers survive at an alarming angle of inclination and may be in danger of leaning instability due to the lack of stiffness of the supporting soil. Therefore, careful investigation is required to estimate the seismic vulnerability as well as its long-term behavior. These problems require a multidisciplinary approach to properly m...

The paper is focused on the post-earthquake assessment of the Civic Tower, an emblematic historic structure, part of ‘Palazzo Margherita’, the City Hall of l’Aquila, Italy, severely damaged by the strong earthquake occurred on the 6th of April 2009. The Civic Tower (6.5m x 7m base and 43m high) is a structural element particularly vulnerable due to...

In order to evaluate safety assessment of the Sanctuary of Vicoforte, Italy, a series of non-destructive tests were carried out for diagnostic inspection of its deterioration. Delamination of stone finishing and fresco painting were detected. Dynamic ambient vibration test was carried out and the relevant modes of vibration were identified resortin...

This is a reconnaissance report on the damage to buildings, bridges, and other structures caused by the 2009 L'Aquila, Italy earthquake. The authors conducted site investigation during the period of April 18–21, 2009. A detailed discussion on the damage of buildings, bridges, and other facilities, as well as possible damage mechanisms, is presented...

This is a reconnaissance report on the damage to buildings, bridges, and other structures caused by the 2009 L’Aquila, Italy earthquake. The authors conducted site investigation during the period of April 18–21, 2009. A detailed discussion on the damage of buildings, bridges, and other facilities, as well as possible damage mechanisms, is presented...

The present study deals with dynamic identification and model updating of the Howa brick chimney to preserve brick chimneys. From the results of dynamic tests, the fundamental frequencies of the Howa brick chimney are estimated to be about 3.06Hz and 2.69Hz in north–south and east–west directions, respectively. The natural modes and damping factors...

The Rakanji stone arch bridge has three spans of approximately 26 m, and the total length of the bridge is approximately 89.3 m. The rise:span ratio is approximately 0.19; hence, the arches are very shallow. To clarify the structural characterization of the Rakanji stone arch bridge, a series of dynamic, non-destructive and destructive tests are co...

When a 33-year-old schoolhouse of a university was dismantled, a beam that had been used as a structural member was removed, and its flexural crack properties and flexural load capacity were examined. It was found that the maximum flexural crack width at the main reinforcement position before flexural load was applied had become smaller than the du...

This paper presents the results of deterioration investigation of the ancient airship military Hangar in Augusta, Italy, which construction began in 1917. The stability of the airship hangar is now threatened by the differential settlements of its spread footings and a research project is currently underway to strengthen the hangar. In this paper,...

Dynamic and static analyses of existing structures are very important to obtain reliable information relating to actual structural properties. For this purpose a series of material test, dynamic test and static collapse test of the existing two brick chimneys, in Tokoname, are carried out. From the material tests, Young's modulus and compressive st...

This study deals with dynamic identification and model updating of the Howa brick chimney to preserve brick chimneys in Tokoname. From the results of dynamic tests, the fundamental frequencies of the Howa brick chimney are estimated to be about 3.06 Hz and 2.69 Hz in north-south and east-west directions respectively. The natural modes and damping f...

Rakanji stone arch bridge built in 1920 over Yamakuni River, Honyabakei, Oita, has three spans of about 26m and total length of the bridge is about 89.3m. For the purpose of obtaining the data concerning dynamic structural properties of Rakanji stone arch bridge, both microtremor measurement by ambient vibrations and acceleration by traffic vibrati...

The Sanctuary of Vicoforte, near Mondovì (Cuneo, Italy), is a building of great historical- architectural significance. It began to be constructed in 1594 by architect Ascanio Vittozzi from Orvieto. Declared a national monument in 1918, the Sanctuary owes it fame primarily to its great elliptical dome (figs. 1-2), erected in 1732, which is the four...

The present study deals with the collapse analysis of masonry arch bridges by means of Finite Element Method. Many experimental results on masonry arch bridges show importance of tensile resistance of joints as well as the prole and boundary condi- tion of bridges. In order to analyze and calculate masonry structures, there are several models such...

The present study deals with the Finite Element Analysis (FEA) of ma- sonry structures by means of Bott Dun inverse. There are various kinds of structural problem about static and dynamic behaviors under the sub- sidiary condition of displacement such as contact problem, unilateral stress problem, homology design problem, etc. In masonry structures...

A chemical industrial plant represents a sensitive presence in a region and, in case of severe damage due to earthquake actions, its impact on social life and environment can be devastating. From the structural point of view, chemical plants count a number of recurrent elements, which are classifiable in a discrete set of typological families (towe...

This paper deals with a series of material test of mortar used for historical masonry structures such as Hagia Sophia, Istanbul. According to the historical documents, the mixing ratio by volume for the mortar is estimated as follows ; sand : slaked lime : brick=2 : 1 : 2/3. Mechanical characteristics of mortar such as compressive, bending and tens...

The purpose of this paper is to formulate a two-dimensional elastic-plastic joint element through three truss elements. The joint element consists of three members forming a truss structure : one vertical and two diagonal elements with different stress strain relations. The yielding condition of the joint element is determined by two factors : one...

A series of non-destructive tests such as Radiation Thermometer, Electromagnetic Radar, Impact Echo Scanner, Concrete Test Hammer, Scratch Tester, Windsor Pin System, and Electromagnetic Induction Scanner are carried out for diagnostic inspection of deterioration on the Sanctuary of Vicoforte. In this paper, 1) Delamination of stone finishing and f...

The present study deals with the limit analysis of masonry walls with rect- angular openings by an equivalent shear panel model. Many experimental results on masonry walls with rectangular openings subject to both vertical and horizontal loads show importance of shear resistance of wall panels. Based upon these experimental results, in-plane failur...

For the purpose of obtaining the data concerning static and dynamic structural properties of brick chimneys in Tokoname, a series of material test, dynamic test and static collapse test of the existing two brick chimneys are carried out. From the material tests, Young's modulus and compressive strength of the brick used for these chimneys are estim...

Structural health monitoring (SHM) has been recently more and more utilized in the study of Cultural Heritage (CH) buildings, as a key activity to increase the knowledge on their structural behavior and to have a deeper insight into their conditions. This knowledge allows engineers to carry out with more confidence and only if necessary a strengthe...