3. Producción
Browse
6 results
Search Results
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental investigation of a spherical rubber isolator for use in low income countries(Elsevier, 2021-11-03)This paper presents an experimental study of a low-cost seismic isolator that can be used for the protection of low-rise houses in low-income countries. The isolator is based on rolling of a rubber sphere on flat or spherical concrete surfaces. Using a closely spaced grid of such spheres may allow for avoiding of the diaphragm slab at the isolation level, or of reducing its thickness. Avoiding the cost of this extra slab is crucial for building seismically isolated low-rise dwellings economically feasible in low-income regions of the globe. The effects of the geometry of the rolling surface (i.e., flat or concave), of the diameter of the rolling sphere (i.e., 25, 50 or 100 mm), and of the applied compressive load on the seismic behavior of such isolation bearings were investigated. Initially, the rubber isolators were subjected to monotonic uniaxial compression to examine their behavior under vertical loading. Subsequently, cyclic tests were performed to obtain the lateral force–displacement diagram of the isolation system. Finally, a slab supported by 4 isolators was subjected to a group of 61 ground motions. Eight different configurations were tested, leading to a total of 488 dynamic tests. It was found that the restoring force of such systems can originate not only from the curvature of the concrete surface, but also from the vertical motion induced by the drastic change of the shape of the rubber spheres, as well. In fact, for the configurations tested, the vertical motion sourcing from shape of the deformed sphere was much larger than the vertical motion sourcing from the curvature of the concrete surfaces. Moreover, equations offering the coefficient of friction as a function of the vertical load, the size and the deformation of the sphere were derived. This is crucial for design, as the governing parameter for the design of the rubber spheres is not material failure, but excessive compressive deformation that leads to undesirably high rolling friction. Dynamic tests proved that the proposed low-cost rolling rubber isolators can substantially reduce the accelerations transmitted to the superstructure The cost of the tested 25 mm, 50 mm and 100 mm diameter natural rubber spheres is 0.6 $, 3 $ and 17$, respectively. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Seismic strengthening techniques for adobe construction(Springer Nature, 2021-01-01)Heavy damage to adobe constructions observed after earthquakes, experimental programmes and numerical simulations have demonstrated high vulnerability levels that require appropriate strengthening measures. Given that a large fraction of adobe constructions are located in less developed countries, there is a need for effective strengthening techniques that are low-cost and easy to install at the same time. In this chapter, a comprehensive selection of research studies is critically reviewed to provide useful information to researchers and professionals involved in the conservation and retrofit of adobe constructions. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Shaking table testing of adobe masonry structures(Springer Nature, 2021-01-01)This chapter presents the seismic simulation systems (shaking tables) as essential resources for experimental research on adobe masonry structures. An overview of selected relevant shaking tables existing in laboratories around the world gives an idea of the broad testing scope possible with this type of equipment. Its use in testing of adobe masonry structures goes back to 1986 at the University of California at Berkeley and to 1988 at the Pontifical Catholic University of Peru (PUCP). Shaking table testing has been considered the experimental technique that may closest reproduce the real behaviour of an adobe structure during earthquakes. After the description of a typical shaking table test procedure, based on more than thirty years of PUCP experience, some seismic simulation tests on adobe masonry structures performed in different countries are briefly described. Each case presents the basic characteristics of the shaking table and some qualitative results obtained to understand the seismic behaviour of adobe masonry structures. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Quasi-static in-plane testing of adobe masonry walls and structures(Springer Nature, 2021-01-01)The lateral seismic capacity and the in-plane failure pattern of adobe masonry may be understood by performing quasi-static experimental tests on full-scale adobe walls. Information regarding the maximum lateral capacity and the displacement ductility are normally obtained during these tests. Also, information about limit states could be obtained. Along the years, universities in Europe, Asia and Latin America have performed this type of tests and the results of some of these works are summarized in this chapter. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Rope mesh as a seismic reinforcement for two-storey adobe buildings(Springer Science and Business Media B.V., 2022-06-01)Throughout the world, millions of people are at risk because they live in unreinforced earthen dwellings, which have consistently shown extremely poor structural behaviour during earthquakes. Every single earthquake occurring in these areas has caused unacceptable loss of life, injuries, and property damage. Earthquakes are recurrent and construction damage is cumulative. It is urgent, therefore, to devise low-cost, easy-to-implement seismic reinforcement systems and to make them available to the actual dwellers. A group of researchers at the Pontificia Universidad Católica del Perú has been working towards that goal, especially on improving the seismic capacity of one-storey adobe dwellings. They have proposed construction methodologies for a seismic reinforcement system consisting of a mesh of nylon ropes that confines all earthen walls. This reinforcement system would control the wall displacements and prevent the overturning of wall portions that may occur due to seismic shaking. To validate the effectiveness of the nylon rope mesh reinforcement on two-storey adobe dwellings, shaking table tests were conducted on unreinforced and half-scale reinforced adobe models, simulating the actions of slight, moderate and strong seismic ground shaking. These models were designed to include the main construction features of typical adobe dwellings in the Peruvian Andes. The results of the experimental tests showed that the rope mesh reinforcement system was able to preserve the structural stability of the tested reduced-scale adobe models under strong motions, thus preventing collapse. It is expected that the proposed reinforced system would also improve the seismic performance of one and two-storey adobe dwellings, reducing in this way their inherent high seismic risk. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimental in-plane behaviour and drift-based fragility assessment of typical Peruvian confined masonry walls(Elsevier Ltd, 2022-07-25)Around 56% of dwellings in Lima are constructed with confined masonry walls, and over 70% are built without engineering design and supervision. This building stock is exposed to the seismic activity of the Peruvian coastline. Then, in case of a severe earthquake, many of these buildings may suffer significant damage and eventually collapse, causing high economic losses and fatalities. Thus, it is essential to investigate the seismic behaviour of these constructions to understand their seismic vulnerability. This work studied the seismic performance of typically confined masonry walls built with hollow bricks based on cyclic in-plane tests. The imposed boundary conditions allowed the walls to behave as a cantilever. The influence of vertical pre-compression was also explored by performing separate tests with and without such load. Outcomes suggest that these walls may collapse after 0.5% drift. Also, mechanical features like stiffness degradation and damping values were calculated for different displacement limit states. Finally, fragility curves of confined masonry walls considering different unit types (i.e. solid, hollows, tubular), axial load ratio, and horizontal reinforcement are computed. The results demonstrate that tubular units should be forbidden as bearing walls, and horizontal reinforcement inside the walls improves their displacement ductility.