Health Assessment of Large Two Dimensional Structures Using Limited Information: Recent Advances

Some recent advances of a recently developed structural health assessment procedure proposed by the research team at the University of Arizona, commonly known as generalized iterative least-squares extended Kalman filter with unknown input (GILS-EKF-UI) are presented. The procedure is a finite elements-based time-domain system-identification technique. It can assess structural health at the element level using only limited number of noise-contaminated responses. With the help of examples, it is demonstrated that the structure can be excited by multiple loadings simultaneously. The method can identify defects in various stages of degradation in single or multiple members and also relatively less severe defect. The defective element(s) need not be in the substructure, but the defect detection capability increases if the defect spot is close to the substructure. Two alternatives are suggested to locate defect spot more accurately within a defective element. The paper advances several areas of GILS-EKF-UI to assess health of large structural systems

Effect of Damping and Yielding on the Seismic Response of 3D Steel Buildings with PMRF

The effect of viscous damping and yielding, on the reduction of the seismic responses of steel buildings modeled as three-dimensional (3D) complex multidegree of freedom (MDOF) systems, is studied. The reduction produced by damping may be larger or smaller than that of yielding. This reduction can significantly vary from one structural idealization to another and is smaller for global than for local response parameters, which in turn depends on the particular local response parameter. The uncertainty in the estimation is significantly larger for local response parameter and decreases as damping increases. The results show the limitations of the commonly used static equivalent lateral force procedure where local and global response parameters are reduced in the same proportion. It is concluded that estimating the effect of damping and yielding on the seismic response of steel buildings by using simplified models may be a very crude approximation. Moreover, the effect of yielding should be explicitly calculated by using complex 3D MDOF models instead of estimating it in terms of equivalent viscous damping. The findings of this paper are for the particular models used in the study. Much more research is needed to reach more general conclusions

Probabilistic evaluation of damage potential in earthquake-induced liquefaction in a 3-D soil deposit

Issued as Final report, Project no. E-20-64

Research initiation - probabilistic evaluation of damage potential in earthquake-induced liquidification in a 3-D soil deposit

Issued as Technical report and Final project report, Project no. E-20-62

Probabilistic Evaluation of Liquefaction of Sand Under Earthquake Motions

250 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1976.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Probabilistic evaluation of damage in liquefaction

Issued as Abstracts [nos. 1-2], Reports [nos. 1-6], Annual progress report, and Technical reports [nos. 1-2], Project no. E-20-60

Mathematical Modelling Of A Post-Northridge Steel Connection

A robust mathematical model to capture the behaviour of an attractive post-Northridge type, Partially Restrained (PR) steel connection is proposed. The proposed procedure captures the loading behaviour for this type of connection reasonably well. It is suggested that the unloading and reloading parts of M - θ curves required for seismic analysis can be theoretically generated by using the Masing Rule. This study confirms some of the important desirable features of the connection. Although it is a PR connection, its initial stiffness is similar to that of bolted, a single web angle with top and seat connection, generally considered to be a Fully Restrained (FR) connection. Thus, a steel frame with the connection studied is not expected to show weakness in satisfying serviceability requirements. Furthermore, the beam develops full plastic moment and the ductility of the connection and its seismic energy dissipation characteristics are expected to be significantly improved. Copyright © 2007 Inderscience Enterprises Ltd

Structural Engineering In The New Millennium: Opportunities And Challenges

Purpose Structural engineering as a part of civil engineering has over 5,000 years of distinguished history, as documented in this paper. An attempt is made in this paper to define structural engineering as it exists at present, then some historical structures are identified. Design/methodology/approach The advances of structural engineering are discussed in chronological order, encompassing the development of the concept, analysis, the use of innovative construction materials, and construction. The developments which necessitated the change of design philosophies are presented, and the current status of structural engineering is discussed in terms of several specific topics. Opportunities and challenges in the new millennium in structural engineering are then presented in terms of education, service to society, and research. Findings In the past, structural engineering always met the challenges it faced. It helped to improve our quality of life, and its role in society is not expected to change in the near future. Originality/value The paper has provided an over-view of this important profession – from ancient history to the present day. Based on research over several decades it offers a prediction of the direction in which this profession and the academic research that underpins it is likely to take in the future. © 2008, Emerald Group Publishing Limite