Instituto de Ingeniería de la UNAM

En una investigación anterior realizada en mesa vibradora en el Instituto de Ingeniería de la UNAM, se efectuaron ensayes de un edificio miniatura de acero con base fija, sin aisladores, denominado EM2, con un registro de aceleraciones que llevó al espécimen a una respuesta del tipo no lineal. En la investigación que se describe en este artículo, se ensayó un segundo espécimen denominado EM2-I, en la misma mesa vibradora y con el mismo registro empleado en la investigación anterior. El espécimen EM2-I, tuvo la misma superestructura que el espécimen EM2, pero con aisladores de base del tipo doble péndulo de fricción. La máxima distorsión de entrepiso medida fue igual a 5.3% y 0.97% para los especímenes EM2 y EM2-I, respectivamente. La máxima distorsión global medida fue igual a 4% y 0.63% para los especímenes EM2 y EM2-I, respectivamente. El máximo coeficiente sísmico medido en la superestructura aislada fue igual al 26 % del máximo valor medido en el espécimen EM2. Los resultados encontrados en esta investigación muestran la importancia del uso de estructuras aisladas como una solución eficiente para que después de terremotos las estructuras puedan ser ocupadas de manera inmediata.
Shaking table tests were conducted in previous research at the National University of Mexico (UNAM) on a miniature steel building named EM2, using a strong ground motion record. This building represented a conventional building. This paper describes the results of a second test unit called EM2-I, tested in the same shaking table with the same ground motion used in the test of EM2. The test unit with isolators, EM2-I, had a superstructure identical to that of the test unit EM2 but with base isolators of double friction pendulum type. Measured maximum interstory drifts were equal to 5.3% and 0.97% for test units EM2 and EM2-I, respectively. Measured maximum global drift was equal to 4% and 0.63% for test units EM2 and EM2-I, respectively. The maximum seismic coefficient measured in the isolated superstructure was equal to 26 % of the maximum value for this parameter measured in test unit EM2. Implications of the results in this research are discussed in this paper, showing the importance of using isolated structures as an efficient solution for resisting strong earthquakes and capable of immediate occupancy.

En una investigación anterior realizada en mesa vibradora en el Instituto de Ingeniería de la UNAM, se efectuaron ensayes de un edificio miniatura de acero con base fija, sin aisladores, denominado EM2, con un registro de aceleraciones que llevó al espécimen a una respuesta del tipo no lineal. En la investigación que se describe en este artículo, se ensayó un segundo espécimen denominado EM2-I, en la misma mesa vibradora y con el mismo registro empleado en la investigación anterior. El espécimen EM2-I, tuvo la misma superestructura que el espécimen EM2, pero con aisladores de base del tipo doble péndulo de fricción. La máxima distorsión de entrepiso medida fue igual a 5.3% y 0.97% para los especímenes EM2 y EM2-I, respectivamente. La máxima distorsión global medida fue igual a 4% y 0.63% para los especímenes EM2 y EM2-I, respectivamente. El máximo coeficiente sísmico medido en la superestructura aislada fue igual al 26 % del máximo valor medido en el espécimen EM2. Los resultados en...

State-of-the-art numerical solvers in Earth Sciences produce multi terabyte datasets per execution. Operating on increasingly larger datasets becomes challenging due to insufficient data bandwidth. Queries result in difficult to handle I/O access patterns. BEMC is a new mechanism that allows querying and processing wavefields in the compressed representation. This approach combines well-known spatial-indexing techniques with novel compressed representations, thus reducing I/O bandwidth requirements. A new compression approach based on boundary integral representations exploits properties of the simulated domain. Frequency domain representation further compresses the data by eliminating temporal redundancy found in wave propagation data. This representation enables the transformation of a large I/O workload into a massively-parallel CPU-intensive computation. Queries to this representation result in largely sequential I/O accesses. Although, decompression places heavy demands on the CPU, it exhibits parallelism well-suited for many-core processors. We evaluate our approach in the context of data analysis for the Earth Sciences datasets.

We have developed a novel analytic capability for scientists and engineers to obtain insight from ongoing large-scale parallel unstructured mesh simulations running on thousands of processors. The breakthrough is made possible by a new approach that visualizes partial differential equation (PDE) solution data simultaneously while a parallel PDE solver executes. The solution field is pipelined directly to volume rendering, which is computed in parallel using the same processors that solve the PDE equations. Because our approach avoids the bottlenecks associated with transferring and storing large volumes of output data, it offers a promising approach to overcoming the challenges of visualization of petascale simulations. The submitted video demonstrates real-time on-the-fly monitoring, interpreting, and steering from a remote laptop computer of a 1024processor simulation of the 1994 Northridge earthquake in Southern California.

Parallel supercomputing has traditionally focused on the inner kernel of scientific simulations: the solver. The front and back ends of the simulation pipeline - problem description and interpretation of the output - have taken a back seat to the solver when it comes to attention paid to scalability and performance, and are often relegated to offline, sequential computation. As the largest simulations move beyond the realm of the terascale and into the petascale, this decomposition in tasks and platforms becomes increasingly untenable. We propose an end-to-end approach in which all simulation components - meshing, partitioning, solver, and visualization - are tightly coupled and execute in parallel with shared data structures and no intermediate I/O. We present our implementation of this new approach in the context of octree-based finite element simulation of earthquake ground motion. Performance evaluation on up to 2048 processors demonstrates the ability of the end-to-end approach to overcome the scalability bottlenecks of the traditional approach

This paper presents a verification of three simulations of the ShakeOut scenario, an Mw 7.8 earthquake on a portion of the San Andreas fault in southern California, conducted by three different groups at the Southern California Earthquake Center using the SCEC Community Velocity Model for this region. We conducted two simulations using the finite difference method, and one by the finite element method, and performed qualitative and quantitative comparisons between the corresponding results. The results are in good agreement with each other; only small differences occur both in amplitude and phase between the various synthetics at ten observation points located near and away from the fault—as far as 150 km away from the fault. Using an available goodness-of-fit criterion all the comparisons scored above 8, with most above 9.2. This score would be regarded as excellent if the measurements were between recorded and synthetic seismograms. We also report results of comparisons based on time–frequency misfit criteria. Results from these two criteria can be used for calibrating the two methods for comparing seismograms. In those cases in which noticeable discrepancies occurred between the seismograms generated by the three groups, we found that they were the product of inherent characteristics of the various numerical methods used and their implementations. In particular, we found that the major source of discrepancy lies in the difference between mesh and grid representations of the same material model. Overall, however, even the largest differences in the synthetic seismograms are small. Thus, given the complexity of the simulations used in this verification, it appears that the three schemes are consistent, reliable and sufficiently accurate and robust for use in future large-scale simulations.

We present a hybrid approach for solving the dynamic rupture problem in an anelastic medium. It combines the advantages of the boundary integral equation method (BIEM), which is capable of representing accurately the solution near a crack tip, with those of the domain finite element method (FEM), which can handle conveniently heterogeneous materials, as well as the traction-free condition on a free surface and the continuity of traction across interfaces. When applied jointly, the proposed BIEM and the FEM can be used to solve efficiently spontaneous rupture problems in heterogeneous media, provided the rupture surface is contained within a homogeneous portion of the domain. The proposed method, BIEM-FEM approach (BDM, for Boundary/Domain Method), is verified for several antiplane (SH) and in-plane (P-SV) 2-D cases, in which the slip is prescribed along the fault (kinematic rupture). For spontaneous rupture, we examine the performance of the BDM by computing its convergence rate for an example in a homogeneous half-space with a slip-weakening friction law on the fault. By including the boundary integral representation on the fault, without using any refinement near the crack tips, the solution converges with the same rate as problems that do not exhibit any stress concentrations; that is, for the piecewise linear elements used here, the rms of the slip-rate distribution and of the traction distribution on the fault converge as O(Δx), whereas the slip distribution converges as O(Δx2), in which Δx is the mesh size of the finite element mesh. Additional 2-D spontaneous rupture simulations are performed for an inclined fault in a half-space for different values of the dip angle and for a folded layer system in a half-space, focusing only the P-SV case. The results show that the waves generated at the free surface and within the layers contribute to the propagation of the fault rupture and have a visible and sometimes strong effect on the ensuing ground motion.

We demonstrate a new scalable approach to real-time monitoring, visualization, and steering of massively parallel simulations from a personal computer. The basis is an endto-end approach to parallel supercomputing in which all components -meshing, partitioning, solver, and visualization -are tightly coupled and execute in parallel on a supercomputer. This approach avoids bottlenecks associated with transfer and storage of massive simulation outputs, thereby enabling real-time visualization and steering on supercomputers with thousands of processors. We have incorporated this methodology into a framework named Hercules, which targets octree-based finite element simulations. The submitted video demonstrates real-time monitoring and steering from a laptop PC of a 1024-processor simulation of the 1994 Northridge earthquake in Southern California. Because this end-to-end approach does not require moving large data over the network and is completely scalable, our approach shows promise for overcoming the challenges of visualization of petascale simulations.

We have developed a novel analytic capability for scientists and engineers to obtain insight from ongoing large-scale parallel unstructured mesh simulations running on thousands of processors. The breakthrough is made possible by a new approach that visualizes partial differential equation (PDE) solution data simultaneously while a parallel PDE solver executes. The solution field is pipelined directly to volume rendering, which is computed in parallel using the same processors that solve the PDE equations. Because our approach avoids the bottlenecks associated with transferring and storing large volumes of output data, it offers a promising approach to overcoming the challenges of visualization of petascale simulations. The submitted video demonstrates real-time on-the-fly monitoring, interpreting, and steering from a remote laptop computer of a 1024processor simulation of the 1994 Northridge earthquake in Southern California.

This paper deals with the analysis of the generation of Construction and Demolition Waste (CDW) in Havana, Cuba, for the period 1999 to 2010 and its possible use in the manufacturing of recycled aggregates in mortar and concrete production. In order to define the possible applications of the CDW as aggregates in mortar and concrete production the characteristics of the waste as well as studying the existing technologies available in the province for their treatment were analysed. Based on the experimental results, it was determined that the recycled fine aggregates of a mixed composition achieved the minimum requirements defined by Cuban regulations. All the mortars produced with recycled fine aggregates achieved a compressive strength of 5.2 MPa after 28 days which is the minimum requirement for a Type III mortar, consequently they could be used in the manufacturing of masonry mortar. The recycled coarse aggregate originating from precast floor elements could possibly be used in the production of structural concrete for medium and low aggressive environments when concretes were made with 50% and 100% of recycled coarse aggregates in substitution of the natural aggregates, respectively.

Evaluación de morteros de albañilería elaborados con áridos reciclados mixtos con diferentes procesos de obtención INGENIERÍA CIVIL Resumen En La Habana se generan diariamente más de 1 000 m 3 de residuos de construcción y demolición (RCD). La mayoría de estos residuos son de composición mixta, pues provienen de derrumbes de edificaciones en mal estado o de demoliciones que no se realizan de forma selectiva. A partir de los RCD, por lo general se emplean dos formas para producir áridos reciclados, una es a través del tamizado de los escombros por el tamiz de 5mm, utilizando la fracción pasada por el mismo, que es una práctica muy utilizada por los pobladores de la ciudad y otra a partir de la trituración de las fracciones gruesas en máquinas productoras de áridos reciclados. En este trabajo se evalúan los áridos reciclados procedentes de un mismo RCD mixto, uno obtenido mediante la trituración de la parte gruesa del residuo y otro utilizando la parte fina. Con los dos áridos reciclados se elaboraron morteros de albañilería según las especificaciones de la norma cubana. A los morteros se les determinaron las siguientes propiedades: retención de agua, resistencia a flexión, resistencia a compresión, adherencia y absorción de agua por capilaridad. Las propiedades de los morteros se compararon con las de un mortero patrón fabricado con un árido natural y con los valores establecidos por la norma cubana. Los resultados muestran que los morteros elaborados a partir de la fracción gruesa de los residuos presentan mejores prestaciones mecánicas cumpliendo los estándares de la norma cubana. Palabras clave: morteros de albañilería, residuos de construcción y demolición, reciclaje

This paper details the research work carried out on masonry mortars produced employing recycled aggregates in 100% substitution for natural sand aggregates. The main objective of the work being the validation of the resulting recycled aggregate mortar for use as a new construction material in Cuba. The recycled aggregates were acquired from the crushing of demolition material obtained from four different houses of distinct construction types. The work was carried out in two experimental stages. In stage 1, mortars with different percentages of recycled aggregates were produced and analysed. The analysis was carried out in order to achieve the optimal mix dosage, while employing the largest usable volume of recycled aggregates and in compliance with the functional requirements established by Cuban regulations. In stage 2, all mortars were produced employing the defined optimal mix proportion The fresh state properties (water retentivity) and hardened state (flexural, compression and bond strengths and capillary absorption capacity) were evaluated in the mortars produced with the other three mixed recycled aggregates of different compositions. It was concluded that the mortars produced with recycled aggregates needed less filler than that of the control mortar in order to obtain adequate properties in their fresh state. However, these recycled aggregate mortars obtained lower mechanical properties and higher capillary absorption that those of the control mortar. Nevertheless they were in compliance with the minimum requirements established in the Cuban regulation. Keywords: construction and demolition waste, recycled fine aggregate, masonry mortars, properties in fresh and hardened state Resumen En el presente trabajo se detalla la investigación llevada a cabo sobre morteros de albañilería utilizando áridos reciclados en sustitución al 100% de la arena natural. El objetivo principal del trabajo es la validación del mortero fabricado con árido reciclado como nuevo material de construcción en Cuba. Los áridos reciclados fueron obtenidos de la trituración del material de demolición de cuatro tipos de viviendas de diferente tipología de construcción. El trabajo se llevó a cabo en dos etapas experimentales. En la etapa 1, se fabricaron y analizaron morteros fabricados con diferentes porcentajes de un tipo de árido reciclado. El análisis se llevó a cabo con el fin de obtener la dosificación óptima del mortero utilizando el mayor porcentaje de árido reciclado posible y en cumplimiento con los requerimientos establecidos por las normas cubanas. En la etapa 2, todos los morteros se fabricaron utilizando la óptima dosificación definida en la etapa anterior. En cada mortero fabricado con los otros tres tipos de áridos reciclados obtenidos, se determinó la retención de agua en estado fresco, y las propiedades de resistencia a flexión, compresión y adherencia así como la absorción capilar en estado endurecido. Se concluyó que los morteros producidos con árido reciclados necesitan menos filler que el de mortero de control para obtener adecuadas propiedades en estado fresco. Sin embargo, los morteros fabricados con árido reciclados obtuvieron menores propiedades mecánicas y mayor absorción capilar que el obtenido por el mortero de control. No obstante todos los morteros fabricados con árido reciclado alcanzaron los límites establecidos por la normativa cubana. Palabras clave: residuos de construcción y demolición, árido fino reciclado, Morteros de albañilería, propiedades en estado fresco y endurecido

This paper analyses the influence of the fine fraction of two types of construction and 5 demolition waste (CDW1 and CDW2) on the properties of recycled aggregates (RA) and 6 masonry mortars. The CDW1's main component was ceramic while the CDW2 were 7 concrete. Three different kinds of fine RA were produced from each source of CDW; the 8 first type was produced by only using the fraction finer than 4.76 mm, the second one by 9 employing only the coarser fraction than 4.76 mm, and the third type was a mix of both 10 fractions of CDW. The masonry mortars were produced employing the 100% substitution 11 of natural aggregates. The results show that all the recycled mortars achieved a higher 12 water retentivity capacity than that of the conventional mortars. However, the sole use of 13 the fine fraction of the CDW was found to have a deleterious effect over the hardened 14 mortar properties, thus making it only adequate for the rendering or bonding of interior 15 walls at or above ground level. In contrast a combination of both the fine fraction and 16 coarse fraction of the CDW in the production of the RA achieved all the minimum 17 requirements for rendering and bonding masonry mortar. 18 Highlights 20  Two sources of CDW, one with ceramic and other with concrete as main components, 21 were employed. 22  Three different RA were obtained from two different sources of CDW. 23  Masonry mortars employing 100% of recycled aggregate were validated. 24  Ceramic high content recycled aggregates mortars achieved the most adequate 25 properties. 26  The employment of the coarse fraction of the CDW guarantee high quality aggregates 27 for masonry mortar. 28