28; In a Latin American context, few studies exist regarding the construction of churches during the colonial period using adobe and rammed-earth techniques. Investigations of their spatial characteristics, systems of construction, and structural behavior, therefore, are also scarce. This lack of research has led to poor results in restoration attempts for these kinds of churches, which has caused the loss of important Colombian architectural and historical heritage. Additionally, Colombia is at a high seismic risk, and adobe and rammed-earth buildings are particularly vulnerable during earthquakes. This paper presents the results of an investigation of these kinds of structures, developed by the investigative groups investigation group on materials and structures (GRIME) and Estructuras & Construcción (at Pontificia Universidad Javeriana) during the period 2002–2013. The investigation focuses on churches in the geographical area within the central Colombian highlands built during the 16th and 17th centuries. The study takes an architectural and historical approach coupled with structural laboratory work (involving shake table tests on 1:50 models), where the authors applied a reinforcement alternative with confinement wood elements to improve the seismic performance of the structural system of rammed-earth churches. According to these results...
Current seismic design practice promotes inelastic response in order to reduce the design forces. By allowing the structure to yield while increasing the ductility of the structure, the global forces can be kept within the limited bounds dictated by the yield strength. However, during severe earthquakes, the structures undergo significant inelastic deformations leading to stiffness and strength degradation, increased interstory drifts, and damage with residual drift. The research presented in this thesis has three components that seek to address these challenges.
To prevent the inelastic effects observed in yielding systems, a new concept “apparent weakening” is proposed and verified through shake table studies in this thesis. “Apparent weakening” is introduced in the structural system using a complementary “adaptive negative stiffness device” (NSD) that mimics "yielding” of the global system thus attracting it away from the main structural system. Unlike the concept of weakening and damping, where the main structural system strength is reduced, the new system does not alter the original structural system, but produces effects compatible with an early yielding. Response reduction using NSD is achieved in a two step sequence. First the NSD...
Las consecuencias catastróficas de los sismos ocurridos en el mundo durante los últimos años han incentivado estudios experimentales para evaluar los efectos sísmicos sobre las estructuras. En este trabajo se presentan los resultados del diseño de una mesa vibratoria uniaxial neumática, para ensayos de estructuras a escala reducida. La mesa es capaz de simular los efectos sísmicos en estructuras con peso máximo de 10 kN. El informe está dividido en tres secciones principales. En la primera sección se presenta la evaluación del problema, una revisión de la literatura y la recolección de datos disponibles. En la segunda sección se evalúan diferentes propuestas de diseño con base al análisis de montaje, movimiento y cimentación, y se desarrolla el diseño correspondiente. En esta etapa se eligieron los elementos mecánicos que permiten el movimiento de la mesa, luego se validó el desempeño del sistema a partir de herramientas de simulación de elementos finitos (FEA), y finalmente, se realizó la automatización de la mesa por medio de la selección de componentes neumáticos y un control on-off con sistema de lazo abierto, realizando pruebas y simulaciones. En la tercera sección se presentan las conclusiones del proyecto y las recomendaciones para futuros trabajos. La utilidad de esta mesa vibratoria...
The origin of earthquake has long been recognized as resulting from
strike-slip instability of plate tectonics along the fault lines. Several
events of earthquake around the globe have happened which cannot be explained
by this theory. In this work we investigated the earthquake data along with
other observed facts like heat flow profiles etc... of the Indian subcontinent.
In our studies we found a high-quality correlation between the earthquake
events, seismic prone zones, heat flow regions and the geothermal hot springs.
As a consequence, we proposed a hypothesis which can adequately explain all the
earthquake events around the globe as well as the overall geo-dynamics. It is
basically the geothermal power, which makes the plates to stand still, strike
and slip over. The plates are merely a working solid while the driving force is
the geothermal energy. The violent flow and enormous pressure of this power
shake the earth along the plate boundaries and also triggers the intra-plate
seismicity. In the light of the results reported by the California Energy
Commission from the ongoing geothermal power project at the Big Geysers in
California, we further propounded that by harnessing the surplus geothermal
energy the intensity and risk of the impending earthquakes can be substantially
reduced.; Comment: 17 pages...
The FBA-11 is a feedback-controlled accelerometer widely used to measure and record accelerations arising from earthquakes. It has found application both for structural response and for ground motion studies. The design intent of the FBA-11 was to provide electronic control of the natural frequency, damping, and output voltage. Included in this paper are (1) a circuit analysis yielding the complete closed-loop transfer function, and (2) the corroborative test results from shake table evaluations. The transfer function can be used to correct recorded accelerations for instrument response.
Comerio, Mary C.; Stallmeyer, John C.; Smith, Ryan; Makris, Nicos; Konstantinidis, Dimitrios; Mosalam, Khalid; Lee, Tae-Hyung; Beck, James L.; Porter, Keith A.; Shaikhutdinov, Rustem; Hutchinson, Tara; Chaudhuri, Samit Ray; Chang, Stephanie E.; Falit-Baia
Fonte: Pacific Earthquake Engineering Research CenterPublicador: Pacific Earthquake Engineering Research Center
Tipo: Report or Paper; PeerReviewedFormato: application/pdf
Publicado em /11/2005Português
Relevância na Pesquisa
From 2002 to 2004 (years five and six of a ten-year funding cycle), the PEER Center organized
the majority of its research around six testbeds. Two buildings and two bridges, a campus, and a
transportation network were selected as case studies to “exercise” the PEER performance-based
earthquake engineering methodology. All projects involved interdisciplinary teams of
researchers, each producing data to be used by other colleagues in their research. The testbeds
demonstrated that it is possible to create the data necessary to populate the PEER performancebased framing equation, linking the hazard analysis, the structural analysis, the development of
damage measures, loss analysis, and decision variables.
This report describes one of the building testbeds—the UC Science Building. The project
was chosen to focus attention on the consequences of losses of laboratory contents, particularly
downtime. The UC Science testbed evaluated the earthquake hazard and the structural
performance of a well-designed recently built reinforced concrete laboratory building using the
OpenSees platform. Researchers conducted shake table tests on samples of critical laboratory
contents in order to develop fragility curves used to analyze the probability of losses based on
equipment failure. The UC Science testbed undertook an extreme case in performance
assessment—linking performance of contents to operational failure. The research shows the
interdependence of building structure...