A Statistical Study of the Maximum Ground Motion in Strong Earthquakes

This paper presents the results of a theoretical analysis of the statistical properties of the maximum ground motions in strong earthquakes. The statistical model of earthquakes is proposed so as to be consistent with the past records of occurrence of earthquakes and with strong motion accelerograms, on the basis of which the methods are discussed to find the probability distribution of the maximum ground motion in a single earthquake and that for a certain future period. Numerical results are given in the form of charts and seismic maps

Analysis of Flexural Behavior and Lateral Buckling of Inelastic Steel Beams under Cyclic Loads

Inelastic steel beams are analyzed with emphasis on their transient flexural behavior and lateral buckling under cyclic loads. The constraint and load conditions are chosen so that they simulate inelastic beams, of a frame structure subjected to a horizontal seismic motion. An analytical model of inelastic beams is proposed that accounts for basic transient behaviors of mild steel. On this basis, a detailed discussion is made on the mechanism of transient behaviors including those of the plasic hinge, loaddeflection relation, lateral buckling load, etc. A physical interpretation is given as regards the transient flexural behavior and the deformation capacity for the lateral buckling of steel beams under monotonic and cyclic loadings

Random Fatigue Analysis of Structural Steel Bars Subjected to Plastic Bending

Low-cycle fatigue life of structural steel bars subjected to random plastic flexural deformation is analyzed. Fatigue tests are performed on 100×100 SS41 H bars under constant-amplitude and randomly varying repeated loads. Fatigue life for random loads is estimated by using the linear cumulative damage law. Damage per unit time (or cycle) is predicted by (1) the equivalent amplitude factor and (2) peak-trough and plastic deformation criteria. Estimated results are compared with test results

Seismic Response Analysis of Joint-Connected Buried Pipelines Including Bent Sections

Response analysis of joint-connected buried pipelines including bent sections has been carried out using analytical models, types of which are commonly used in the actual underground lifeline systems. The details of the structures and materials along the trunk routes of the Kyoto City Water Supply Districts have been intensively examined to establish these analytical models. Response analysis for four representative models of buried pipelines has been performed with some analytical parameters of pipe-structures, input ground motions, and soil springs, etc., focusing on the effects of the structural and input ground motion parameters on the response behavior of pipelines

Effects of symmetry on Braess-like paradoxes in distributed computer systems - A numerical study

Abstract Numerical examples of a Braess-like paradox in which adding capacity to a distributed computer system may degrade the performance of all users in the system have already been reported. Unlike the original Braess paradox, this behavior occurs only in the case of finitely many users and not in the case of infinite number of users in the models examined. This study examines a number of numerical examples around the Braess-like paradox such as above. The numerical examples suggest that the Braess-like paradox is stronger, i.e., the performance degradation of all users in the Brass-like paradox is larger when the system has a higher degree of symmetry and, in particular, is strongest in the completely symmetrical system whereby the parameter values describing each user are identical, which is against our previous intuition

Revisiting Collusion in Routing Games: a Load Balancing Problem

International audienceIs it profitable for players to unite and merge to a single player? Obviously, the sum of utilities at an equilibrium cannot exceed the sum obtained if all players join together. But what happens if only a subset of players join together? Previous work on collusion have already shown that the society may either gain or loose from collusion of a subset of players. In this paper we show for a simple load balancing example that not only the society may loose, but also the subset of players that collude may end up with a worse performance than without collusion. In doing so, we introduce new concepts that measure the price of collusion

Anomalous Relations among Various Performance Objectives

Abstract Distributed computer systems consist of a set of heterogeneous host computers (i.e., nodes) connected by a communication network. A job that arrives at a node may either be processed locally or transferred to another node for remote processing, which we call load balancing. One possible performance objective of load balancing in distributed computer systems is to minimize the overall mean response time. We can characterize analytically the static load balancing policy whereby the mean overall response time is minimized, which we call the overall optimal policy. This policy, however, lacks fairness in the sense that, for example, two jobs arriving at the same node but being forwarded to different nodes may not have the same expected response time. To satisfy fairness among jobs we can consider an individually optimal load balancing policy whereby jobs arriving at the same node have the same (minimum) expected response time regardless of the nodes which process them. Furthermore, we can think of a node optimal load balancing policy whereby the mean response time of jobs arriving at each node is minimum given the decision by the other nodes of which jobs arriving at those nodes are forwarded. We report the existence of some seemingly anomalous phenomena in the mutual relation among the above policies

Fairness in non-convex systems

In general, the set of users utilities is boundedbecause of the limitation of resources. There may existmany Pareto optimal points in the set of users utilities.For selecting a Pareto optimum point, a family of fairnesscriteria, that contains the max-min fairness and aparameterized family of fairness (by Mo andWalrand), hasbeen proposed and examined in some concrete networkingcontexts that result in specific convex utility sets. We newlyexamine general compact (closed and bounded) utility setswhich include the specific utility sets as special cases. Wefirst prove that each of the family of fairness criteria givesa unique fair (Pareto optimum) point if the utility set isconvex. We find, however, counter-examples where each ofthe family of fairness criteria gives multiple fair points ifthe utility set is not convex. We propose an extention of thefamily of fairness criteria such that each of them gives onlya unique fair point regardless of whether the utility set isconvex or not, to which we give proofs. By using a specificload balancing model, we illustrate the counter-examplesand how each criterion of our extended fair family givesa unique fair point

Load Balancing Congestion Games and Their Asymptotic Behavior

International audienc