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141.
Analysis of the weightiness of site effects on reinforced concrete (RC) building seismic behaviour: The Adra town example (SE Spain) 总被引:1,自引:0,他引:1
Manuel Navarro Francisco Vidal Takahisa Enomoto Francisco J. Alcalá Antonio García‐Jerez Francisco J. Sánchez Norio Abeki 《地震工程与结构动力学》2007,36(10):1363-1383
The damage distribution in Adra town (south‐eastern Spain) during the 1993 and 1994 Adra earthquakes (5.0 magnitude), that reached a maximum intensity degree of VII (European Macroseismic Scale (EMS scale)), was concentrated mainly in the south‐east zone of the town and the most relevant damage occurred in reinforced concrete (RC) buildings with four or five storeys. In order to evaluate the influence of ground condition on RC building behaviour, geological, geomorphological and geophysical surveys were carried out, and a detailed map of ground surface structure was obtained. Short‐period microtremor observations were performed in 160 sites on a 100m × 100m dimension grid and Nakamura's method was applied in order to determine a distribution map of soil predominant periods. Shorter predominant periods (0.1–0.3 s) were found in mountainous and neighbouring zones and larger periods (greater than 0.5 s) in thicker Holocene alluvial fans. A relationship T = (0.049 ± 0.001)N, where T is the natural period of swaying motion and N is the number of storeys, has been empirically obtained by using microtremor measurements at the top of 38 RC buildings (ranging from 2 to 9 storeys). 1‐D simulation of strong motion on different soil conditions and for several typical RC buildings were computed, using the acceleration record in Adra town of the 1993 earthquake. It is noteworthy that all the aforementioned results show the influence of site effects in the degree and distribution of observed building damage. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
142.
High-frequency (HF) radar observations of surface currents were conducted for 3 months during summer 2002 in the Keum River estuary. A comparison between HF radar-derived currents and directly measured ones form a buoy showed that the regression slope is close to 1 and the correlation coefficient greater than 0.86, with an RMS difference less than 13 cm/s which is less than 17% of the tidal current. This fairly good agreement allows us to use HF radar observation in investigating the surface flow and circulation in this tidal-current-dominant coastal-plume area. To examine the spatial variation in tidal current characteristics, as well as currents associated with non-tidal forcing, the HF radar-derived currents were separated into tidal and sub-tidal frequency currents. The overall pattern of M2-current ellipse distribution in the study area showed a counterclockwise rotation, with the offshore maximum current direction to the northeast. Eccentricity, the direction of maximum current, and the phase of net motion of the ellipse changed near the estuary mouth and near the gap of the Saemangeum reclamation tide dyke due to the complex coastal geometry and the out-flowing jet during the ebb period. 相似文献
143.
The response of the Chesapeake Bay to river discharge under the influence and absence of tide is simulated with a numerical model. Four numerical experiments are examined: (1) response to river discharge only; (2) response to river discharge plus an ambient coastal current along the shelf outside the bay; (3) response to river discharge and tidal forcing; and (4) response to river discharge, tidal forcing, and ambient coastal current. The general salinity distribution in the four cases is similar to observations inside the bay. Observed features, such as low salinity in the western side of the bay, are consistent in model results. Also, a typical estuarine circulation with seaward current in the upper layer and landward current in the lower layer is obtained in the four cases. The two cases without tide produce stronger subtidal currents than the cases with tide owing to greater frictional effects in the cases with tide. Differences in salinity distributions among the four cases appear mostly outside the bay in terms of the outflow plume structure. The two cases without tide produce an upstream (as in a Kelvin wave sense) or northward branch of the outflow plume, while the cases with tide produce an expected downstream or southward plume. Increased friction in the cases with tide changes the vertical structure of outflow at the entrance to the bay and induces large horizontal variations in the exchange flow. Consequently, the outflow from the bay is more influenced by the bottom than in the cases without tide. Therefore, a tendency for a bottom-advected plume appears in the cases with tide, rather than a surface-advected plume, which develops in the cases without tide. Further analysis shows that the tidal current favors a salt balance between the horizontal and vertical advection of salinity around the plume and hinders the upstream expansion of the plume outside the bay. 相似文献
144.
145.
Sven HARTMANN Institute for Hydrosciences German Armed Forces University Munich Neubiberg Germany. 《国际泥沙研究》2001,16(2)
1 BASIC PROBLEMFlood protecton, sPreaing of settlements and occuPatin Of river valleys were maor reasons to damand lindt rivers throughout Europe in the ndd 19th century. Engineers of those days often knew very wellabout the effects of their plannings: shortening the river length would accelerat the now and thusencourage the erosion into the river's sedAnents. Two vital advanages could be obtalned from that kindof constrUction, landuse of the fOrmer flood plains on the one and increasin… 相似文献
146.
Thomas ELSNERand Sven HARTMANN Institute for Hydrosciences German Armed Forces University Munich Neubiberg Germany. Institute for Hydrosciences German Armed Forces University Munich Neubiberg Germany. 《国际泥沙研究》2001,16(2)
1 THE LOWhR unR INNThe Inn river has its source in the alPine region of the GraubUnden canton of Switzerand. ThecatChment area of about 260(X} kIn2 includes mountains of the central Alpes up to 40(X) m. The river runs5l7 km thrOugh the countries of SwitZerand, Austria and Germany on itS way into the Danube mver. Thedischarge of the river at its mouth in the city of Passau is mainly infiuenced by the snow melt in themountainous catchment area and vches between apProx. 200 m3ls durin… 相似文献
147.
区域发展限制性因素的探讨—以湛江市为例 总被引:1,自引:2,他引:1
几十年的研究与实践表明,区域发展要“扬长避短”,即要重视区域优势的发挥,也要注重区域发展的限制因素。在实地调查的基础上,以湛江市为例,强调了区域发展限制性因素研究的重要性。认为湛江市的区域发展在区域政策、区域组织、区际联系和区域管理等方面都存在着问题,这些问题在很大程度上阻碍了湛江市的区域发展。湛江市经济实力不强、区域发展水平低,产业结构不合理、工业发展长期滞后,主导产业的产业关联度不强,经济次益欠佳,限制性因素的负面效应非常明显。必须从限制性因素的弱化与克服方面入手,立足资源优势、合理确定经济发展政策,适当调整行政管理体制、提高行政效率,深化现代企业制度的改革、提高企业经济效益,重视城市形象工程建设,改善投资环境,才能改善湛江市区域发展的不利局面。 相似文献
148.
In order to realize sustainable development of the arid area of Northwest China, rational water resources exploitation and optimization are primary prerequisites. Based on the essential principle of sustainable development, this paper puts forward a general idea on water resources optimization and eco-environmental protection in Qaidam Basin, and identifies the competitive multiple targets of water resources optimization. By some qualitative methods such as Input-output Model & AHP Model and some quantitative methods such as System Dynamics Model & Produce Function Model, some standard plans of water resources optimization come into being. According to the Multiple Targets Decision by the Closest Value Model, the best plan of water resources optimization, eco-environmental protection and sustainable development in Qaidam Basin is finally decided. 相似文献
149.
150.
During the development of Qaidam Basin, which is an arid area in Northwest China, rational water resources utilization and optimization are primal prerequisites, and the main restrictive factors include the following facts: scarcy water resources are non-substitutional and uneven distributed in time and space. Based on the essential principle of sustainable development, this paper adopts Multiple Targets Decision by the Closest Value Model, and succeeds in getting the best plan, which can o… 相似文献