Distributed object‐based software environment for urban system integrated simulation under urban‐scale hazard—Part I: Infrastructure

In this paper, a distributed object‐based software environment (DOSE) has been developed to facilitate the integrated simulation of an urban system under the risk of urban‐scale hazards such as earthquakes. It is understood that individual simulation participants perform their simulation services in separate environments, bartering service exchange relationships to get what they need to resolve their part of the problem. This is the communication gap between the scientists on one side and the end users who need to understand knowledge and employ it on the other side. The authors envision a distributed simulation service software environment running in parallel with the activities of simulation participants. DOSE has lent itself to integrate interdisciplinary participants through an infrastructure that has three basic building blocks, namely: modularity, scalability, and interoperability. The modular, object‐based, design of DOSE architecture is described in terms of key functionalities of four distinct layers, namely: resource, core, domain, and interface layers. DOSE scalability in terms of urban system size and participant third‐party application complexity is enabled through the interface layer. A message passing model is developed using the Message Passing Interface standard and a control room is provided to schedule the interaction/communication among model processes. DOSE interoperability with the vulnerability analysis third‐party applications is enabled through the Industry Foundation Classes (IFC) standard. An adopted analogy between DOSE and construction industry is employed to provide interpretation and implementation for DOSE interoperability. While interfacing IFC object model to solve DOSE interoperability questions, an extension model for the structural view of IFC is proposed and accepted by the International Alliance for Interoperability. The DOSE application for real‐world urban systems is beyond the scope of this paper and is presented in an accompanying paper work. Copyright © 2007 John Wiley & Sons, Ltd.     

System identification applied to long‐span cable‐supported bridges using seismic records

This paper presents the application of system identification (SI) to long‐span cable‐supported bridges using seismic records. The SI method is based on the System Realization using Information Matrix (SRIM) that utilizes correlations between base motions and bridge accelerations to identify coefficient matrices of a state‐space model. Numerical simulations using a benchmark cable‐stayed bridge demonstrate the advantages of this method in dealing with multiple‐input multiple‐output (MIMO) data from relatively short seismic records. Important issues related to the effects of sensor arrangement, measurement noise, input inclusion, and the types of input with respect to identification results are also investigated. The method is applied to identify modal parameters of the Yokohama Bay Bridge, Rainbow Bridge, and Tsurumi Fairway Bridge using the records from the 2004 Chuetsu‐Niigata earthquake. Comparison of modal parameters with the results of ambient vibration tests, forced vibration tests, and analytical models are presented together with discussions regarding the effects of earthquake excitation amplitude on global and local structural modes. Copyright © 2007 John Wiley & Sons, Ltd.     

Application of an earthquake early warning system and a real-time strong motion monitoring system in emergency response in a high-rise building

We apply a combination of earthquake early warning system (EEWS) and real-time strong motion monitoring system (RSMS) to emergency response for a high-rise building; The Kogakuin University has a 29-story high-rise building in Shinjuku Ward, Tokyo. The proposed strategy is based on the Plan, Do, Check, Action (PDCA) Cycle to brush up the systems and the users: in the “Plan” stage, we apply EEWS and RSMS to the building, where EEWS predicts not only short-period strong ground motions but also long-period ground motions [1]. The system is built into a building announcement system, an emergency elevator control system, and an email message system, which quickly send emails to the emergency response team. Meanwhile, RSMS provides information on seismic intensities at each floor of the building via the web browser in real time using the existing network in the building. In addition, the building response and structural damage can be estimated based on this information. The network system is impervious to the earthquake damage, because the network cable has extra length, there is, however, possible that a network system does not work due to power outage. Thus, we develop the network system that has uninterruptible power-supply system (UPS) and apply it to EEWS and RSMS. The high-rise building has the emergency call units to the security control center in the building on every floor. The emergency call line, however, will be busy promptly, because it is able to use only one line. Therefore, we installed IP telephone which uses the network system on main floors. UPS will work about 30 min after a major earthquake, it is supposed to be enough time for gathering the damage information about the building during initial response. In the “Do” stage, we prepare emergency response instruction manuals and educate the faculty members and students to carry out promptly emergency response. In the “Check” stage, the validity of the proposed systems are verified by carrying out an earthquake drill in an actual high-rise building. The earthquake drill confirmed that our proposed approach is valid. In the final “Action” stage, we improve these systems and emergency response manual and educate people in the building how to use effectively these systems.     

Trench triple junction off Central Japan—preliminary results of French-Japanese 1984 Kaiko cruise, Leg 2

Leg 2 of the French-Japanese 1984 Kaiko cruise has surveyed the trench triple junction off central Japan, where the Japan, Izu-Bonin and Sagami Trenches intersect. The Izu-Bonin Trench is deeper than the Japan Trench and filled by a thick turbiditic series. Its anomalous depth is explained by the westward retreat of the edge of the northwestward moving Philippine Sea plate. On the contrary to what happens in the Japan Trench, horst and graben structures of the Pacific plate obliquely enters the Izu-Bonin Trench, suggesting that the actual boundary between these two trenches is located to the north of the triple junction. The inner wall of the Izu-Bonin Trench is characterized in the triple junction area by a series of slope basins whose occurrence is related to the dynamics of this area. The northernmost basin is overthrust by the edge of the fore-arc area of the Northeast Japan plate. The plate boundary is hardly discernible further east, which makes it impossible to locate precisely the triple junction itself. These features suggest that large intra-plate deformation occurs there due to the interaction of the plates involved in the triple junction and the weak mechanical strength of the wedge-shaped margin of the overriding plates.     

Relation of fracture resistance to fabric for granitic rocks

Double-torsion specimens of two granitic rocks were prepared in several directions with reference to microcracks fabric. Even for the same rock and at the same stress levels, the observed crack velocities in two granitic rocks were dependent on both the propagation direction and the opening direction. The maximum difference by several orders of magnitude was found for both rocks. The highest crack velocity was observed when the subcritical crack was parallel to most of the preexisting cracks. The maximum critical stress intensity factor was about twice as high as the minimum one in different directions. An analysis for a thin plate having anisotropic elasticity under torsional load showed that the observed difference in the crack velocity and the critical stress intensity factor was not an error due to conventional equations derived on the assumption of isotropic elasticity but the true material's property. As the preferred orientation of microcracks has been pointed out for many granitic rocks, we can conclude that the anisotropic nature of the fracture resistance of the two granitic rocks used in this study was not exceptional. A region of a transport-limited velocity was not found for rocks, even at the velocity of 10^–2 m/s, that is almost equal to the theoretical limit of the stress corrosion cracking.     

Evaluation of pounding countermeasures and serviceability of elevated bridges during seismic excitation using 3D modeling

This paper conducts elaborate analyses to evaluate the effectiveness of pounding countermeasures and the serviceability of elevated bridges subject to severe ground motions using detailed 3‐dimensional non‐linear modeling of an entire bridge structure system. A three‐span elevated steel bridge is selected for a case study. The peak and residual magnitude of gaps between girders and the maximum shear deformations of bearings are computed and used in the serviceability evaluation. The results show that under proper configurations the mitigation devices work effectively in reducing pounding actions in both the longitudinal and rotational directions. Copyright © 2004 John Wiley & Sons, Ltd.     

Pounding of superstructure segments in isolated elevated bridge during earthquakes

Past severe earthquakes indicate that pounding may cause considerable damage or even lead to collapse of colliding structures. The aim of this paper is to present an analysis of pounding between superstructure segments of an isolated elevated bridge induced by the propagating seismic wave. High-damping rubber bearings (HDRBs), used as isolation devices, are modelled by proposed non-linear formulation and the significance of the bearings model for pounding is indicated. The results of the study show that pounding leads to the increase or decrease of the forces acting on piers, depending on the gap size between superstructure segments. © 1998 John Wiley & Sons, Ltd.