Un sistema de construcción para climas tropicales basado en pórticos arriostrados de bambú

A low-cost housing system was developed for use in tropical countries, specifically Haiti, with the aims of minimizing environmental impact (including carbon emissions), maximizing use of local and preferably recycled materials, and using local labor. The housing system integrates low-strength concrete blocks (made using recycled concrete aggregate), an innovative seismically-resistant bamboo frame, earthen plasters, bamboo trusses, and metal deck roofs. The bamboo frame relies on flexural yielding of a short rebar dowel to provide ductile performance at a controlled strength level. The plinth walls below the frame and short rebar dowel protects the bamboo from moisture. The top of a plastic soda bottle is used to protect the rebar from moisture and to seal the base of the bamboo culm, allowing mortar to be introduced into the culm above. This paper focuses on the experimental and analytical results of the flexural yielding of the rebar dowel to establish the structural design of this critical component of the system for resisting wind and seismic loads.En este artículo se presenta un sistema de construcción de viviendas de bajo coste para países tropicales en los cuales existe riesgo sísmico. Los objetivos de este trabajo son generar bajo impacto medioambiental (incluyendo las emisiones de carbono), empleo de materiales locales, preferiblemente reciclados, y mano de obra local. Para esta construcción se han empleado bloques de hormigón de baja resistencia (con agregado reciclado) junto con un innovador sistema de pórticos de bambú, botellas de plástico, vigas de bambú y cubiertas de chapa. El comportamiento dúctil de la estructura se garantiza introduciendo una barra de acero en la base del pórtico de bambú. Para proteger el bambú de la humedad, el pórtico se monta sobre un zócalo. Los resultados experimentales y analíticos obtenidos se utilizan para el diseño estructural del sistema frente a cargas de viento y sísmicas

Using Pulse R-Factors to Estimate Structural Response to Earthquake Ground Motions

National Science Foundation EEC-970178

Seismic Design and Evaluation of Multistory Buildings using Yield Point Spectra

Constant ductility response spectra are presented for 15 recorded earthquakes ground motions using the Yield Point Spectra (YPS) representation. Yield Point Spectra are used for analysis and design of SDOF structures. The spectra were computed for bilinear and stiffness degrading load-deformation models, for displacement ductilities equal to 1, 2, 4 and 8. A methodology for the performance-based seismic design of regular multistory buildings using Yield Point Spectra is described. The methodology is formulated to make use of current code approaches as much as possible while allowing the design engineer to limit the peak displacement response and, to some extent, the peak interstory drift to user-specified values. To achieve this objective, the design methodology makes use of an equivalent SDOF model of the building. A method to estimate peak displacement response and interstory drift indices of multistory buildings using YPS and establish SDOF formulations is also presented. The method may be considered a new nonlinear static procedure (NSP). Interstory drift indices (IDIs) are estimated using deformed shapes of the building based on the first mode shape and combinations of the first and second mode shapes.National Science Foundation EEC-970178

Modeling the Transverse Response of Short Bridges Subjected to Earthquakes

The transverse response of short bridges is often critical to their seismic performance. When transverse displacements are large, damage to substructure columns may occur, often in the form of plastic hinges, shear failures, or lap splice failures. A significant component of the transverse response is due to the dynamic response of the embankment. Current design provisions (ATC-32 1996, Caltrans 1999) neglect this contribution entirely, and other researchers have only investigated linear models of embankment contribution (Wilson and Tan 1990; Werner et al. 1993; Goel 1997). This report focuses on the modeling of short bridges to improve estimates of column displacement demands. In particular, improved approach-embankment models are developed based on seismic response data recorded at two short bridges in California. The models are nonlinear and can be used in conjunction with software programs such as DRAIN-2DX and DRAIN-3DX. One model explicitly considers the piles and embankment soils, while a second, simpler, model considers only the embankment soils. Both models are calibrated to the recorded California bridge data. The more complex model is used to generate response data for representative Illinois bridges, and this data is used to calibrate the simpler model for Illinois bridges. Furthermore, when transverse demands are excessive, one mitigation technique is the use of conventional elastomeric bearings to seismically isolate the superstructure. Nonlinear models for Illinois Type I, II and III elastomeric bearings are developed. The effectiveness of the bearings for reducing column displacement demands is addressed by analytical studies. These studies consider potential effects of cold temperatures on bearing stiffness.National Science Foundation EEC-970178

USEE 2001: Utility Software for Earthquake Engineering Report and User's Manual

National Science Foundation EEC-970178

Lateral force-resisting capacities of reduced web-section beams: FEM simulations

Avoiding fracture in the beam-column connections of steel moment frames is critical to their seismic performance. In the RWS approach, large openings are introduced into the web of the beam, so that the arrangement and configuration of the openings determine the mode of inelastic mechanism that develops within the beam. In this paper, numerical simulation results are discussed for nine RWS specimens that were subjected to lateral loading