<p>У овом раду анализирани су утицају интеракције конструкција-темељ-<br />тло током сеизмичких дејстава. Примењене су нелинеарне анализе<br />временске историје (TH) и пушовер метода. Анализирани су модели<br />гредних мостова, на каркатеристичним локацијама и са оптерећењима и<br />материјалима према БАБ&#39;87. Интеракција је третирана преко<br />еластичних опруга и као нелинеарнa преко линк елемената p-y кривама.<br />Криве су моделоване вишелинијским Тaкеда хистерезисним моделом.<br />Проучено је стање конструкција у току и након земљотреса, укључиво и<br />други удар земљотреса. У мањем обиму су анлизиране конструкције<br />зграда према ЕЦ2 и ЕЦ8.</p> / <p>U ovom radu analizirani su uticaju interakcije konstrukcija-temelj-<br />tlo tokom seizmičkih dejstava. Primenjene su nelinearne analize<br />vremenske istorije (TH) i pušover metoda. Analizirani su modeli<br />grednih mostova, na karkaterističnim lokacijama i sa opterećenjima i<br />materijalima prema BAB&#39;87. Interakcija je tretirana preko<br />elastičnih opruga i kao nelinearna preko link elemenata p-y krivama.<br />Krive su modelovane višelinijskim Takeda histerezisnim modelom.<br />Proučeno je stanje konstrukcija u toku i nakon zemljotresa, uključivo i<br />drugi udar zemljotresa. U manjem obimu su anlizirane konstrukcije<br />zgrada prema EC2 i EC8.</p> / <p>The thesis studies the effects of the structure-foundation- soil interaction<br />during seismic action using non-linear analysis methods Time History and<br />PushOver. Analysis is made of beam bridges, in their typical locations and<br />with loads and construction materials based on BAB&rsquo;87/-Yu Code. The<br />interaction is treated as linear using elastic spring model, and non-linear as<br />link element on p-y curves which are modeled using the multi-linear Takeda<br />hystheresis model. Studies are made on the performance of the<br />constructions during and after an earthqake including aftershocks. The work,<br />to a lesser extent, also includes similar analyses and studies for buildings,<br />based on EC2 and EC8 codes.</p>

Genetic Expression Programming (GEP) is used to create Ground Motion Predicting Equations (GMPEs) for the average peak ground acceleration using 12,854 ground motion records obtained from the NGA-WEST2 project. The predictor set considered in this research consists of the moment magnitude, dip angle, rake angle, depth to the top of fault rupture, Joyner Boore distance, closest distance to the ruptured fault area, and the shear wave velocity in the top 30 m of the site. Four out of 23 candidate models were able to fairly predict the PGA for magnitudes larger than 4.5 and compared well with existing GMPEs in literature. GEP was capable of reasonably predicting the physical importance of the magnitude and distance parameters. However, other parameters often were either not fitted, or fitted as regression coefficients. The results illustrate GEP’s potential as a viable alternative to regression methods currently used in developing GMPEs.

This research examines the seismic energy dissipation potential of steel structures by focusing on new types of specially engineered cladding-to-frame connections. Traditional connection details consist of rigid restraints of cladding panels, resulting in seismic design that only considers the panel self-weight with connection design left up to the precast fabricators and typical details. It is postulated that by considering these elements to actively participate in building response a more efficient and resilient structure could be designed which accurately captures the effects of non-structural cladding elements on building behavior. In this preliminary research, two mechanisms to dissipate seismic energy using engineered cladding systems are presented. Analysis results on a reference steel building indicate that demands on structural elements may be significantly reduced.

Natural hazards are a growing risk across the globe. As regions have urbanized, single events impact greater proportions of the population, and the populations within those regions have become more dependent on infrastructure systems. Regional resilience has become closely tied to the performance of infrastructure. For a comprehensive risk assessment losses caused by lifeline outage must be considered alongside structural and nonstructural risks. Many well developed techniques quantify structural and nonstructural risk; however, there are insufficient procedures to determine the likelihood of lifeline outages. Including lifelines in seismic assessments will provide a comprehensive risk, improving a decision maker’s capacity to efficiently balance mitigation against the full spectrum of risks. An ideal lifeline risk assessment is infeasible due to the large geographic scale of lifeline systems and their system structure; these same characteristics also make them vulnerable to disruption in hazard events. Probabilistic methods provide solutions for their analysis, but many of the necessary analysis variables remain unknown. Continued research and increased collection of infrastructure data may improve the ability of advanced probabilistic methods to study and forecast performance of lifelines, but many inputs for a complete probabilistic model are likely to remain unknown. This thesis recognizes these barriers to assessment and proposes a methodology that uses consequences to simplify analysis of lifeline systems. Risk is often defined as the product of probability of failure and consequence. Many assessments study the probability of failure and then consider the consequence. This thesis proposes the opposite, studying consequence first. In a theoretical model where all information is available the difference in approach is irrelevant; the results are the same regardless of order. In the real world however, studying consequence first provides an opportunity to simplify the system assessment. The proposed methodology starts with stakeholders defining consequences that constitute ruin, and then the lifeline system is examined and simplified to components that can produce such consequences. Previously large and expansive systems can be greatly simplified and made more approachable systems to study. The simplified methodology does not result in a comprehensive risk assessment, rather it provides an abbreviated risk profile of catastrophic risk; risk that constitutes ruin. By providing an assessment of only catastrophic lifeline risk, the risk of greatest importance is measured, while smaller recoverable risk remains unknown. This methodology aligns itself with the principle of resilience, the ability to withstand shocks and rebound. Assessments can be used directly to consider mitigation options that directly address stakeholder resilience. Many of the same probabilistic issues remain, but by simplifying the process, abbreviated lifelines assessments are more feasible providing stakeholders with information to make decisions in an environment that currently is largely unknown.

This thesis presents the results of an investigation of a multiple degree of freedom (MDOF) structure with hyperelastic bracing using nonlinear and incremental dynamic analysis. New analytical software is implemented in the investigation of the structure, and the study seeks to investigate the effectiveness of hyperelastic bracing as a seismic protection device. Hyperelastic braces incorporate a new idea of a nonlinear elastic material that gains stiffness as the brace deforms. Structural behaviors of particular concern for an MDOF frame are stability, residual displacement, base shear, and dispersion. The structure is analyzed under two ground motion records of varying content, and for two separate P-Delta cases of varying severity. Two sets of hyperelastic braces are investigated for their influence under the two ground motions and two P-Delta cases. Each scenario is analyzed using nonlinear dynamic analyses to investigate the response histories, and Incremental Dynamic Analysis (IDA) to investigate dispersion and the behavior of specific response measures as ground motion intensity increases. IDA curves are created for interstory drift and base shear for comparison between the two response measures. The research shows that the inclusion of hyperelastic braces in the MDOF frame improves the overall stability of the structure and reduces the amount of dispersion and residual displacement. The hyperelastic braces are shown to give positive performance characteristics while not detrimentally increasing system forces under regular service loads. The results highlight the benefit of the unique stiffening properties of hyperelastic braces as a seismic protection device. / Master of Science

No description available.

We extend the application of the substructure synthesis method to more complex structures, and establish a design methodology for base isolation and active control in a distributed model of a building under seismic excitation. Our objective is to show that passive and active control complement each other in such an advantageous manner for the case at hand, that simple devices for both types of control are sufficient to achieve excellent response characteristics with very low control forces. The Rayleigh-Ritz based substructure synthesis method proved to be highly successful in analyzing a structure more complex than the ones previously analyzed with it. Comparing the responses of the hybridly controlled building and the conventional fixed building under El Centro excitation, we conclude that the stresses are reduced by 99.6 %, the base displacement is reduced by 91.7 % and the required control force to achieve this is 1.1 % of the building weight. / Ph. D.

No description available.

University of Macau / Faculty of Science and Technology / Department of Civil and Environmental Engineering

Shape memory alloys (SMAs) are unique metallic alloys which can undergo large deformations while reverting back to their undeformed shape through either the application of heat (shape memory effect) or the removal of the load (superelastic effect). A multi-scale and multi-disciplinary approach is taken to explore the use of large diameter NiTi SMAs for applications in earthquake engineering. First, a materials characterization study is performed by studying precipitate formation, grain size and orientation, thermal transformation behavior, and strength. Cyclic tensile tests on coupon specimens and full-scale large diameter bars are then used to correlate the microstructural properties to the macroscopic behavior. Further experimental studies using NiTi wire are performed in order to optimize their properties for seismic applications. The ability of mechanical training to stabilize NiTi cyclic properties, the ability of pre-straining to increase damping levels, and the influence of different types of earthquake loadings are considered. Phenomenological mechanical models are then developed based on these results. An analytical study is then used to evaluate the performance of structural systems incorporating SMAs. One type of system evaluated includes an SMA bracing system used to modify the response of a structure during a seismic event. Overall, the results of this study have shown the ability to optimize the properties of NiTi SMAs for seismic applications through material processing. The analytical results show potential for the use of SMAs in seismic applications and provide areas for continued research.