Shaking table tests of a one-quarter scale model of concrete hollow block masonry houses retrofitted with fiber-reinforced paint.

Unreinforced masonry (URM) buildings are prone to significant damage when subjected to ground motion. Some strengthening methods have been proposed to increase the seismic capacity. However, the widespread adoption of these methods faces various challenges, including economic constraints experienced by common people in developing countries, the complexity of implementation, efficiency, and seismic safety of each technique. This paper introduces a new retrofitting method of fiber-reinforced paint using fiberglass as the primary reinforcing material. The advantage of this technique lies in its simplicity and ease of application, with the added benefit of using the paint to improve the appearance of the house. Two 1:4 scale concrete hollow block (CHB) masonry houses were constructed to represent unreinforced masonry and retrofitted masonry structures using fiber-reinforced paint (FR-Paint). The shaking table test results indicate that the retrofitted house model showed improvements of up to 18 times in deformation capacity and up to 13 times in energy dissipation compared to the non-retrofitted house model. FR-Paint has a robust performance even in high input motion at a seismic intensity JMA of 7 (Japan Meteorological Agency). This confirms that this retrofitting method has a high earthquake-resistant performance.

Simplified engineering geomorphic unit-based seismic site characterization of the detailed area plan of Dhaka city, Bangladesh.

Severe failure of improperly designed and poorly constructed structures may occur due to the amplified and prolonged ground motion during an earthquake, and hence prediction of the ground motion characteristics at the soil surface is crucial. In this study, based on the prepared simplified engineering geomorphic map, we performed a one-dimensional (1D) nonlinear site response analysis for seismic site characterization of the recently proposed Detailed Area Plan (DAP) area of Dhaka City, the Capital of Bangladesh. The engineering geomorphic unit-based map was prepared from image analysis and verified with the collected borehole data and surface geology map. The study area was classified into three major geomorphic units and seven sub-units subject to the subsurface soil profiles. Nine earthquake time histories, seven from the PEER NGA WEST2 data set and two synthetics, and seven identified subsurface soil profiles were used for nonlinear site response analysis, along with the BNBC 2020 uniform hazard spectrum as the target spectrum. For the selected earthquake ground motions, the near-surface soil response of the DAP area showed de-amplification of acceleration in the short period and amplification of acceleration in the long period. The amplified long-period acceleration could cause severe damage in inappropriately designed and poorly constructed long-period structures. The outcome of this study could be used to prepare a seismic risk-sensitive land use plan for the future development of the DAP of Dhaka City.

3-=Tres Dimensional istinct element simulation of liquefaction phenoma

The mechanism of liquefaction pehnomenon at microscopic level is studied using 3-Dimensional Distinct Element Model (3D-DEM) in which the effects of pore-water are directly considered using a simple algorithm. In this method, the region of DE simulation model, which is composed of many particle elements, is considered as an assembly of cubic shaped blocks having virtual boundary. Behavoir of pore-water is calculated usign each block as a unit volume in order to make the calculation algorithm simple. We applied the method to the hollow cylindrical torsion test and san boiling due to liquefaction. The simulation results obtained showed that the proposed 3-Dimensional Distinct Element Method can simulate the mechanism of liquefaction and its associated phenomena. (AU)

Simulation of collapse process of elevated expressway bridges due to the 1995 Kobe eathquake

At 5:46 a.m.(local time) on January 17, 1995, the Great Hanhin(Hyogoken-nambu or Kobe) earthquake hit the Hanshin-Awaji area, Japan. The damage due to this eartquake was the worst eartquake disaster in Japan since the 1923 Great Kanto earthquake. Over 100.000 houses and buildings collapsed and many modern civil infraestructures such as elevated bridges of highways and railways and port facilities, etc. were also heavily damaged. In addition, fires broke out razing many houses after the quake. The death toll was more then 6.400 including deaths due to various problems followint the earthquake. Unfortunately, mos deaths were caused due to collapse of structures. To mitigate casualties due to earthquakes, it is important to study the mechanism of collapse of structures during earthquakes. In this study, using the Extended Distinct Element Method(EDEM) wich is applicable to both a composite and continuous medium, and a perfect discrete one, the collapse mechanism of structures during the 1995 Great Hanshin earthquake is studied. Although the phenomena treated in this study were difficult to be simulated by the conventional methods such as the finite element method, the numerical results obtained agree well with the actual earthquake damage. (AU)

Applied element simulation for collapse analysis of structures

A new extension for the Applied Element Method (AEM) for structural analysis is introduced. This paper introduces a numerical approach to deal with detailed structural collapse process. Contact and collision forces are considered in the analysis through collision springs, which are added at the locations where collision or recontact between elements occurs. The effects of separation, recontact and collision can be considered easily with high accuracy and without large increase of the CPU time. The main advantage of the proposed technique compared to the Extended Distinct Element Method (EDEM) is that the time increment can be much larger than the EDEM.(AU)

Simulation of buckling and post-buckling behavior of structures using applied element method

A new wxtension for the Applied Element Method (AEM) for structural analysis is introduced. This paper deals with the large deformation of elastic structures under static loading condition. In the formulation used, no geometric stiffness matrix is adopted. The formulation used is simple and general and it can be applied for any structural configuration or material type. This technique is based on determination of the residual forces due to geometrical changes of the structure during simulation. The accuracy of the proposed technique is checked by comparing with the theoretical results and, in all cases, the buckling loads, mode and post-buckling behavior of structures can be followed accurately.(AU)

Urban space design and safety evaluation from viewpoint of evacuation behavior of users

To build safe city spaces and structures, it is very important to ensure the safety of the users in both normal and emergency situations as well as to secure structural strength. As a first step, we have developed a new evacuation model in which individual personality of the users, effect of disaster such as smoke and fire, and also the effects of evacuation guidance, can be considered. Using the model, safety of the spaces and efficiency of evacuation guidance are studied.(AU)

Simulation of collapse process of elevated expressway bridges due to the 1995 Kobe earthquake

At 5:46 a.m. (local time) on january 17, 1995, the Great Hanshin (Hyogo-Ken Nambu or Kobe) earthquake hit the Hanshin-Awaji area Japan. The damage due to this earthquake was the worst earthquake disaster in Japan since the 1923 Great Kanto earthquake. Over 100,000 houses and buildings collanssed and many modern civil infrastructures such as elevated bridges of highways and railways, and port facilities, etc. werre more than 6,300 including deaths due to various problems following the earthquake.In this study, using the Extended Distinct Element Method (EDEM), which is applicable to both a composite and continuous medium and perfect discrete one, the collapse mechanism of structures during the 1995 Great Hanshin earthquake is studied. Although the phenomena treated in this study were difficult to be simulated by the conventional methods such as the finite element method, the numerical results obtained agree well with the actual earthquake damage. (AU)

Development and application of a new model for fracture behavior analysis of structures

A new method for fracture analysis of reinforced concrete structures is proposed. The concrete is modeled as an assembly of distinct elements made by dividing the concrete virtually. These elements are connected by distributed springs in both normal and tangential directions. The reinforcement bars are modeled as continuos springs conneting elements together. Local failure of concrete is modeled by failure of springs connecting elements when the stress calculated from forces acting on springs exceed the critical stress. The element formulation and the computer code were developed and the accuracy of the method were verified by comparing many experimental results. In these experiments the results showed good agreement in determining the failure load, the load-deflection relations, the prediction of crack initiation, crack location and crack propagation. The formulations used to ddevelop this method are simple and efficient in modeling the mechanical behavior of RC structures. (AU)

Developments of earthquake monitoring and early damage assessment systems

This paper highlights recent developments of earthquake monitoring systems and early damage assessment systems in Japan. Recently, several earthquake monitoring networks have been established in order to use earthquake information for early warning or damage assessment of urban systems. UrEDAS of Japan Railway (JR) group and SIGNAL of Tokyo Gas Company are the pioneers of such systems. A few other early damage assessment systems were also developed bu local governments as well as utility companies in Japan boomed. Although some networks and systems are still under construction, this paper provides an overview of recent vintage ans future directions of real-time earthquake hazard assesssment are discussed (AU)

A new efficient technique for fracture analysis of structures

A new method for fracture analysis of reinforced concrete structures in proposed. The concrete is modeled as an assembly of distinct elements made by dividing the concrete virtually. These elements are connected by distributed springs in both normal and tangential directions. The reinforcement bars are modeled as continuos springs connecting elements together. Local failure of concrete is modeled by failure stress. In element formulation and the computer code were developed and the accuracy of the method were verified by comparing many experimental results. In these experiments, the results showed good agreement in determining the failure load-deflection relations the prediction od crack initiation, crack location and crack propagation. The formulation used to develop this method are simple and efficient in modeling the mechanical behavior of RC structures (AU)

Effects of power outage in urban area considering regional characteristics

Modern societies heavily rely on electric power. These societies suffer functional damage due to power outage when natural disasters such as earthquakes and typhoons strike. As the first step for developing a new methodology for estimating the effects of power outage on cityu functions considering the characteristics of the area, and time and duration of outage, a database is made which consists of regional characteristics and electric power demand in the Tokyo Metropolis using geographic information systen (GIS). Power demand is examined as a function of time, season and region. Through the analysis, it is found there are several typical curves and that classification of the areas by such typicalload curves might be possible.With a statistical technique, four elemental load curves of residential, office, industrial and entertainment components are calculated. Assuming that every load curve is a combination of the four elemental curves, the contribution rate of the four elements in each area is calculated. Using the contribution rate, the areas could be classified considering the characteristics of the effects of power outage on various city functions considering the time and duration of outage, and the characteristics of the area.(AU)

Power outage caused by typhoon 9119 and its effects on the lifeline systems in Hiroshima

Typhoon 9119, the 19th typhoon in 1991, significantly affected critical lifeliens throughout a large portion of western Japan, Kyushu Island, and the Chugoku region of the main island. This paper reviews the perfomance of utilities and lifelines during Typhoon 9119 in Hiroshima City with a population of 1,080,000. Widespread power outage took place and adversely affected the operations of other critical lifelines. A cross section of damages to power supply, water and wastewater, communications, transportation, city gas, and broadcasting systems is presented and some recommendations for improving the perfomance of these lifelines are made.(AU)