Estimation of drift limits for different seismic damage states of RC frame staging in elevated water tanks using Park and Ang damage index

Damage to elevated water tanks in past earthquakes can be attributed to the poor performance of their supporting frame staging. In order to ascertain the performance of these elevated water tanks, it is crucial to categorize the damage in quantifiable damage states. Among various parameters to quantify the damage states, the top drift of frame staging can be conveniently correlated to the different damage levels. In literature, drift limits corresponding to different damage states of the frame staging of the elevated water tank are not available. In the present study, drift limits for RC frame staging in elevated water tanks corresponding to different seismic damage states have been proposed. Various damage states of the elevated water tank have been determined using the Park and Ang damage index. The Park and Ang damage index utilizes results of both pushover analysis and incremental dynamic analysis. Twelve models of elevated water tanks have been developed considering variation in staging height and tank capacity. Incremental dynamic analysis has been performed using the suite of twelve actual earthquake ground motions. Based on the regression analysis between damage indexes and drift, limiting drift values for each damage state are proposed.

Life Cycle Assessment of Household Water Tanks—A Study of LLDPE, Mild Steel and RCC Tanks

A case of household water tanks, 1000 L capacity, made of RCC, LLDPE and mild steel (stainless steel) was evaluated for life cycle analysis. The scope of the research comprised of the raw materials, energy inputs and corresponding emissions during all phases of product making such as extraction of raw material, it’s processing, followed by manufacturing and transport, as well as use and reuse of the product. Simapro 8 (System for Integrated environMental Assessment of PROducts), a modelling software, from Dutch PRé Consultants was used to conduct the life cycle analysis. Simapro 8 enables systematic and transparent modelling and analysis of complex life cycles based on the recommendations of the ISO 14040 series of standards. In the present study the most common method which is acceptable worldwide “Recipe Endpoint method” (ReCiPe) was employed. ReCiPe computes the impact categories and classifies them into two classes based on relevant arrays of characterization factors. Simapro addresses impact categories viz. ozone depletion, human toxicity, ionizing radiation, photochemical oxidant formation, particulate matter formation, terrestrial acidification, climate change, terrestrial ecotoxicity, agricultural land occupation, urban land occupation, natural land transformation, marine ecotoxicity, marine eutrophication, fresh water eutrophication, fresh water ecotoxicity, fossil fuel depletion, minerals depletion, fresh water depletion at the midpoint level. While at the Endpoint level, the impact categories are multiplied by corresponding damage factors and integrated to be represented as three Endpoint level categories, viz. human health, ecosystems and resource depletion. The three endpoint categories are normalized, weighted, and aggregated into a single score. LCA studies indicate that household water tanks of LLDPE have least environmental implications considering impacts on human health, ecosystems and resource depletion as compared to its counterparts viz. Household water tanks made up of mild steel and RCC. The sequence of the material with decreasing impacts is concrete tanks > mild steel tank > LLDPE tanks. The overall assessment is centred on the elements such as material inputs, energy inputs and environmental emissions.

Seismic Response Improvement of Existing Prototype School Buildings Using Water Tanks, Port Said City, Egypt

There is a global trend for seismic response improvement of new buildings to reduce cost and future damage. It is also important to improve existing structures that are designed without consideration of seismic load or using old provisions that cannot meet the new one. The objective of this paper is to draw attention to evaluate existing reinforced concrete school buildings, then to present a proposed methodology to improve the behaviour of such schools with low cost especially in a developing country. The proposed method uses overhead water tanks as a tuned mass damper. A pushover analysis has been performed to evaluate the existing schools and perform a feasibility study to select the best solution to achieve seismic response improvement of the existing structure. Of course, the proposed methodology can be applied easily to other existing structures.

Operation Performance of Central Solar Heating System with Seasonal Storage Water Tank in Harbin

This paper presented a preliminary research on the central solar heating system with seasonal storage(CSHSSS)used in cold climate in China.A mathematical model of the solar energy seasonal storage water tank used in the central solar heating system was firstly developed based on energy conservation.This was followed by the simulation of the CSHSSS used in a two-floor villa in Harbin,and analysis of the impacts on storage water temperature of tank volume,solar collector area,tank burial depth,insulation thickness around the tank,etc.The results show there is a relatively economical tank volume to optimize the system efficiency,which decreases with increasing tank volume at the constant collector area,and increases with increasing collector area at the constant tank volume.Furthermore,the insulation thickness has obvious effect on avoiding heat loss,while the tank burial depth doesn't.In addition,the relationship between the solar collector efficiency and storage water temperature is also obtained,it decreases quickly with increasing storing water temperature,and then increases slowly after starting space heating system.These may be helpful for relevant design and optimization in cold climates in China and all over the world.

Water-Tank Experiment on the Thermal Circulation Induced by the Bottom Heating in an Asymmetric Valley

Water tank experiments were carried out to investigate the thermal convection due to the bottom heating in an asymmetrical valley under neutral and stably stratified approach flows with the Particle Image Velometry (PIV) visualization technique. In the neutral stratification approach flow, the ascending draft induced by bottom heating is mainly located in the center of the valley in calm ambient wind. However, with ambient wind flow, the thermal convection is shifted leeward, and the descending draft is located on the leeward side of the valley, while the ascending draft is located on the windward side. The descending draft is minorly turbulent and organized, while the ascending draft is highly turbulent. With the increase of the towing speed, the descending and ascending drafts induced by the mechanical elevation begin to play a more dominant role in the valley flow, while the role of the thermal convection in the valley airflow becomes limited. In the stable stratification approach flow, the thermal convection is limited by the stable stratification and no distinct circulation is formed in calm ambient wind. With ambient wind, agravity wave appears in the upper layer in the valley. With the increase of the ambient wind speed, a gravity wave plays an important role in the valley flow, and the location and intensity of the thermal convection are also modulated by the gravity internal waves. The thermal convection has difficulty penetrating the upper stable layer. Its exchange is limited between the air in the upper layer and that in the lower layer in the valley, and it is adverse to the diffusion of pollutants in the valley.

Impact of Untreated Sedimentation Tank Sludge Water Recycle on Water Quality During Treatment of Low Turbidity Water

The overall purpose of this research is to examine the impact of untreated sedimentation tank sludge water( USTSW) recycle on water quality during treatment of low turbidity water in coagulation—sedimentation processes. 950 m L of raw water and different concentrations of 50 m L USTSW are injected into six 1 000 m L beakers without coagulant.The results indicate that USTSW characterized as accumulated suspended solids and organic matter has active ingredients,which possess the equivalent function of coagulant. The optimal blended water turbidity is in the range of 10-20 NTU,within which USTSW recycle achieves the highest save coagulant rate. The mechanism of strengthening coagulation effect when USTSW recycle mainly depends on the chemical effect and physical effect. What is more,through scanning electron microscopy( SEM),it is found that the floc structures with USTSW recycle are more compact than those without USTSW recycle. Besides,the water quality parameters of color,NH3-N,CODMn,UV254,total aluminum,total manganese when USTSW recycle is better than the raw water without recycle,indicating that USTSW recycle can improve water quality with strengthening coagulation effect.

Attenuating water hammer pressure by means of gas storage tank

The basic equations for computing the volume of gas storage tank were derived from the principles of attenuating water hammer pressure. Verifications using experiments indicate that the proposed equation can provide a fare precision in the predictions. By using the model of solid liquid two phase flow, the gas storage tank, pressure relief valves and slow closure reverse control valves were compared with practical engineering problems, and the functions of gas storage tank in attenuating water hammer pressure were further investigated. [

Optimal operation of water supply systems with tanks based on genetic algorithm

In view of the poor water supply system’s network properties, the system’s complicated network hydraulic equations were replaced by macroscopic nodal pressure model and the model of relationship between supply flow and water source head. By using pump-station pressure head and initial tank water levels as decision variables, the model of optimal allocation of water supply between pump-sources was developed. Genetic algorithm was introduced to deal with the model of optimal allocation of water supply. Methods for handling each constraint condition were put forward, and overcome the shortcoming such as premature convergence of genetic algorithm; a solving method was brought forward in which genetic algorithm was combined with simulated annealing technology and self-adaptive crossover and mutation probabilities were adopted. An application example showed the feasibility of this algorithm.

THE FREE BENDING VIBRATION OF CYLINDRICAL TANK PARTIALLY FILLED WITH-LIQUID AND SUBMERGED IN WATER

This paper studies the free bending vibration of cylindrical tank partially filled with liquid and submerged in water. The depths of liquid and water may be completely arbitrary. The exact calculating formulae of mode shape functions and inherent frequencies are deduced. The results can be gained by means of computer. The analysis shows that the effect of liquid and water on vibration of cylindrical tank is respectively equivalent to a generalized distributive mass attached to the tank.

Water Quality Variation of Malagane Tank:Lessons Learnt from Sustainable Ancient Hydraulic System,Sri Lanka

Tank Cascade Systems(TCS)are the back bone of the dry zone prosperity in Sri Lanka and supply water throughout the year to agricultural lands since the 2nd century BC.The main aim of this study was to understand the nutrient dynamics of small TCS and find out evidence for the sustainability of the system for thousands of years.Malagane tank cascade in the Deduru Oya Basin(the 5th largest river basin

Survey on Storage of Water for Domestic Use in Underground Reinforced Concrete Tanks: The Case of Brazzaville (Republic of Congo)

The problem of water supply from the public distribution network still poses very serious problems in many cities in developing countries. Intermittent water supply pushes some households to build underground reinforced concrete tanks for water storage to cope with unwanted water breaks. This study that relies on the results of a survey of households in some areas of the city of Brazzaville (Republic of Congo) aims to verify the importance that users attach to the quality of the works constructed. Indeed, the reliability of the tanks resulting in their impermeability to the external environment has a direct impact on the quality of stored water and therefore the use that is made of water daily. Five areas were selected because of their soil moisture. By 256 tanks identified, 143 are made of reinforced concrete and 113 in masonry. The coating materials used to seal the walls are preferably the earthenware tiles (64% of tanks), then the Sika cement (31%). Food painting (5%) is only rarely used. However, 66% of households are not assured of the potability of the water stored. A significant number of households (46%) think that the stored water could be contaminated with noxious substances seeping from the outside through the walls of the tanks. The issue of sealing of underground water tanks, especially in areas where the water table is shallow, seems concerned users.

核电工程异形水箱流固耦合分布式参数模型与效用研究

在流固耦合动力分析领域,传统的Housner模型在工程设计中发挥重要作用。但其理论推导仅适用于规则水箱,采用集中质量总体模型描述液体晃动的整体效应,难以有效模拟异形水箱储液结构的局部精细响应,亟须建立适用于不规则水体晃荡的分布式附加质量模型。基于势流理论推导了一种模态综合法模型,实现了分布质量与储液器壁激振加速度的解耦。该模型能够有效剥离分布式的脉冲质量与对流质量;同时,实体网格的振型分析适用于任意形状水体的动力分析。通过算例的形式将该模型与精细声学-结构耦合(Acoustic-Structural coupling,CAS)模拟法进行了比较,验证了模型的精确性与可靠性。最后,基于本文的模型研究了核电异形的安全水箱在不同水位和减晃格栅分布下的动力响应规律,并检验了其在工程中的适用性。

水下声学超表面异常折射方向调控研究

针对波束调控的问题,本文提出了一种控制波前相位的声学超表面。本文依据广义斯奈尔定律,利用不同声速的均匀介质构建了水中多频声学超表面模型,给出声学超表面产生异常声折射的基本原理,验证了声学超表面在多个频点下可以实现异常声折射现象,揭示了频率以及声波入射角对声学超表面异常折射现象的影响规律,制备了声学超表面实物在水箱中对理论结果进行验证。结果表明:在入射波频率为基频的整数倍时,超表面模型可以实现折射角相同的异常折射现象,并且入射角在一定范围内可以实现负折射现象。实验测量了水中钢板和超表面的折射情况,相较于均匀介质,在不同入射角度下设计的超表面均可以实现异常折射,并且测量值与理论值吻合较好。

Mobetron 2000型术中放疗设备的性能调试

目的探索新型术中放疗设备现场检测方法,为该类设备检测标准研制提供实验支撑数据。方法以某医院1台Mobetron 2000型术中移动式加速器为研究对象,参照标准,使用MP3-XS小型三维水箱和Dose2剂量仪等检测设备,检测电子线照射野均整度、对称性、最大吸收剂量比等指标。结果该术中移动式加速器均整度为2.5~3.7 mm,对称性为100.4%~101.1%,最大吸收剂量比为102.8%~105.3%,剂量偏差为-2.4%~-0.5%,重复性均为0.4%,线性为0.6%~1.0%,日稳定性为-0.4%~0.28%,6、9、12 MeV能量点杂散辐射分别为0.3%、0.4%、0.5%。结论在非标情况下,现有放疗检测设备测量术中移动式加速器结果可为标准研制提供参考。

基于高分子材质的L型城市应急防洪屏受力分析

国内关于高分子材质城市内涝应急防御装备的研究较为少见。采用水槽试验与流固耦合数值仿真相结合的方法,对城市应急防洪屏(以下简称“防洪屏”)的结构受力特性展开研究。结果表明,数值仿真模拟与试验结果吻合较好。随着水深和流速的增大,防洪屏的应力和变形逐渐增大,最大应力位于防洪屏的踵部,最大变形位于挡水面顶部两侧。防洪屏的结构受力系数随着来流弗劳德数的增大快速衰减,当弗劳德数大于0.15后,结构受力系数趋于定值;相对于惯性力,防洪屏承受最大应力的影响因素主要是重力。研究结果可为防洪屏的进一步优化设计提供参考。

多分水口长距离输水工程停泵水锤防护措施

为了能够有效避免多泵且多分水口输水系统在无防护抽水断电时可能出现较为严重的负水锤带来的危害,建立了全长106.46 km的大型供水工程的数学模型进行系统过渡过程计算,选择空气阀与两阶段液控蝶阀联合防护与单向塔防护2种方案消除其负水锤,在前者远不达理想防护效果后针对后者进行优化.结合工程实际在确定了单向塔的数量、位置以及塔高后,对不同位置单向塔的底面积进行多种方案的对比选取,最终选用塔1#的底面积为28.26 m^(2),塔2#的底面积为176.63 m^(2);为了防止单向塔漏空需要分水口以及供水终端调流阀配合关闭,在确保管道最大压力不超出其承压能力的前提下,创新性地对各分水口调流阀与供水终端调流阀的关闭时间规律进行了效果比较,使输水系统能够更加经济安全地稳定运行,为此类长距离多分水口多泵供水工程的水锤防护提供了优化方向.

长距离输水泵站中空气罐参数敏感度分析及正交优化设计

为了探讨长距离输水泵站中空气罐的优化设计方法,以西北某长距离输水工程为例,以泵站水击最大正压水头和最小负压水头作为优化目标,以初始气体压力、高度直径比、连接管直径、进口阻力系数和出口阻力系数为优化变量,基于正交优化设计方法和KYPipe软件,采用极差分析法获得空气罐各参数对于水击最大正压水头和最小负压水头的影响,同时对得到的结果进行排序,比较并找到最优参数组合.结果表明:初始气体压力、连接管直径和出口阻力系数等因素对于水击最大正压水头和最小负压水头的影响程度较大,其中初始气体压力是最敏感的参数,对于最大正压水头和最小负压水头的影响程度最大;经过比较发现最优方案的参数组合为初始气体压力水头50 m、高度直径比4、连接管直径250 mm、进口阻力系数10、出口阻力系数5;相比原始方案,优化方案使泵站的水击最大正压水头降低4.98%、最小负压水头升高64.00%.

深圳沙河水质净化厂及3#调蓄池工艺设计要点及特点

沙河水质净化厂设计规模为旱季10万m^(3)/d,雨季额外处理10万m^(3)/d初期雨水,3#调蓄池设计规模为15.3万m^(3)。污水及初期雨水处理采用预处理+多段厌氧-好氧(AO)+二沉池+磁混凝高效沉淀池+精密过滤+紫外消毒的工艺,出水水质执行深圳市地方标准《水质净化厂出水水质规范》(DB 4403/T 64—2020)B级标准,其中总氮(TN)≤8 mg/L。污泥处理采用离心浓缩+低温热干化工艺,处理后含水率≤40%。作为国内首个将水质净化厂与初期雨水调蓄池深度融合的全地下式水污染治理综合体,项目采用多段AO耦合“3W法”(Wet-Weather-Wastewater法),并以此为核心提出了一种实现大规模污水及初期雨水高标准协同处理的系统解决方案,且无需大幅度增加污水处理设施体量、投资和运行成本。

水击补气式压力罐及水力瞬变仿真

空气阀常常安装在输水管检修孔侧壁,进气后部分气体就会存留在检修孔上部产生气垫式压力罐的水击防护作用。据此,提出了水击补气式压力罐装置的设计方法,即利用泵站事故断电产生的水击负压现象,通过真空破坏阀或空气阀给压力罐补气,以防止输水管发生液体汽化现象并削减水击最大压力。然后,建立了水击补气式压力罐水力瞬变数值仿真数学模型。最后,以一个实际输水工程为例,计算比较了分别设置空气阀、空气阀调压室及真空破坏阀补气式压力罐时的水击防护效果,结果表明,补气式压力罐水击防护效果最好。