System interactions of stormwater management using sustainable urban drainage systems and green infrastructure

This study explores system interactions of stormwater management solutions using Sustainable Urban Drainage System (SuDS) and Green Infrastructure (GI) within the wider urban landscape. A series of interdependencies between urban components relating to stormwater management are identified. These include physical interdependency, geographical interdependency, cyber interdependency and logical interdependency, as defined by Peerenboom (2001). Stormwater management using SuDS/GI are viewed according to their Hydrological, Ecological and the Built Environment functions during events up to the design rain (non-flood condition) and during controlled exceedance and uncontrolled inundation (flood condition). The inclusion of SuDS/GI into the urban fabric is shown to modify urban functional and relational interdependencies under both these conditions. Within the context of the UK, there are fragmented responsibilities across planning scales created by SuDS/GI solutions which have not addressed the relational complexities that exist between agencies and competent authorities. The paper identifies the key barriers towards effective adoption of SuDS/GI within the context of the UK as physical barriers, perception/information barriers and organisational barriers.     

城市暴雨处理及分析集成模型系统(SUSTAIN)介绍

暴雨的管理与控制已经成为制约城市可持续发展的重要议题之一,最佳管理实践(BMP)和低影响开发(LID)策略的提出,对于改变传统观念、建立新型的城市暴雨管理体系具有积极意义,但缺乏有效的设计与评估工具,制约了该理念的工程推广与应用。美国国家环保局(USEPA)支持开发的城市暴雨处理及分析集成模型系统(SUSTAIN),以ArcGIS为基础平台,综合应用了水文、水力和水质分析模型,可以对BMP和LID的措施类型、安置地点和实施效果进行科学有效的设计与评估,对于在我国开展暴雨管理措施的模型分析与设计评估具有很好的借鉴意义。     

Analysis and predictive models of stormwater runoff volumes,loads, and pollutant concentrations from watersheds in the Twin Cities metropolitan area,Minnesota, USA

Urban nonpoint source pollution is a significant contributor to water quality degradation. Watershed planners need to be able to estimate nonpoint source loads to lakes and streams if they are to plan effective management strategies. To meet this need for the twin cities metropolitan area, a large database of urban and suburban runoff data was compiled. Stormwater runoff loads and concentrations of 10 common constituents (six N and P forms, TSS, VSS, COD, Pb) were characterized, and effects of season and land use were analyzed. Relationships between runoff variables and storm and watershed characteristics were examined. The best regression equation to predict runoff volume for rain events was based on rainfall amount, drainage area, and percent impervious area (R2 = 0.78). Median event-mean concentrations (EMCs) tended to be higher in snowmelt runoff than in rainfall runoff, and significant seasonal differences were found in yields (kg/ha) and EMCs for most constituents. Simple correlations between explanatory variables and stormwater loads and EMCs were weak. Rainfall amount and intensity and drainage area were the most important variables in multiple linear regression models to predict event loads, but uncertainty was high in models developed with the pooled data set. The most accurate models for EMCs generally were found when sites were grouped according to common land use and size.     

Aerodynamic characteristics of a tube train

Recently, full-scale research about a passenger tube train system is being progressed as a next-generation transportation system in Korea in light of global green technology. The Korea Railroad Research Institute (KRRI) has commenced official research on the construction of a tube train system. In this paper, we studied various parameters of the tube train system such as the internal tube pressure, blockage ratio, and operating speed through computational analysis with a symmetric and elongated vehicle. This study was about the aerodynamic characteristics of a tube train that operated under standard atmospheric pressure (open field system, viz., ground) and in various internal tube environments (varying internal tube pressure, blockage ratio, and operating speed) with the same shape and operating speed. Under these conditions, the internal tube pressure was calculated when the energy efficiency had the same value as that of the open field train depending on various combinations of the operating speed and blockage ratio (the P-D relation). In addition, the dependence of the relation between the internal tube pressure and the blockage ratio (the P-β relation) was shown. Besides, the dependence of the relation between the total drag and the operating speed depending on various combinations of the blockage ratio and internal tube pressure (the D-V relation) was shown. Also, we compared the total (aerodynamic) drag of a train in the open field with the total drag of a train inside a tube. Then, we calculated the limit speed of the tube train, i.e., the maximum speed, for various internal tube pressures (the V-P relation) and the critical speed that leads to shock waves under various blockage ratios, which is related to the efficiency of the tube train (the critical V-β relation). Those results provide guidelines for the initial design and construction of a tube train system.     

Dynamic characterisation of wind turbine towers account for a monopile foundation and different soil conditions

The response of wind turbines is induced by dynamic loads such as wind, transient and cyclic loads, and also extreme loads such as earthquakes. Thus, the structural design requires an accurate evaluation of the modal parameters of the system because it is strongly required that no resonances are excited. Moreover, it has been concluded from previous research works that soil–structure interaction (SSI) should be accounted for the analysis. In the present paper, the structural dynamic response of wind turbine towers is investigated considering different soil conditions using a numerical model. This research is focused on SSI effects. Firstly, changes in the modal parameters of three different wind turbines considering the effect of three soils are evaluated. The results show that the evaluation of the natural frequency and the resulting classification of the wind turbine design type can be affected by SSI. The obtained results could be used to evaluate the decrement of the natural frequency of the wind turbine account for the soil and the foundation in relation to the frequency computed without soil interaction. Next, the seismic response of the wind tower is analysed considering two seismic events: a horizontally polarised shear incident wave and El Centro earthquake.     

Operational deformations in long-span bridges

Long-span bridges deform quasi-statically and dynamically under a range of operational conditions including wind, traffic and thermal loads, in varying patterns, at different timescales and with different amplitudes. While external loads and internal forces can only rarely be measured, there are well-developed technologies for measuring deformations and their time and space derivatives. Performance data can be checked against design limits and used for validating conceptual and numerical models which can in turn be used to estimate the external loads and internal forces. Changes in performance patterns and load–response relationships can also be used directly as a diagnostic tool, but excessive deformations themselves are also a concern in terms of serviceability. This paper describes application of a range of measurement technologies, focusing on response to extreme loads, for suspension bridges over the River Tamar (with 335 m main span) and Humber (with 1410 m man span). The effects of vehicular, thermal and wind loads on these very different structures are compared, showing that apart from rare extreme traffic and wind loads, temporal and spatial temperature variations dominate quasi-static response. Observations of deformation data and sensor performance for the two bridges are used to highlight limitations and redundancies in the instrumentation.     

弯矩调幅对钢筋混凝土连续梁使用阶段裂缝和挠度影响的试验研究

本文通过五根低配筋两跨连续梁的静力试验,研究了连续梁弯矩调幅后的内力重分布规律,详细分析了弯矩调幅对低配筋连续梁使用荷载阶段裂缝宽度和挠度的影响,其结论可供编制内力重分布设计规程参考。     

Thermo-hygro-mechanical modelling of self-induced stresses during the service life of RC structures

Current practices of structural design in reinforced concrete (RC) structures usually account for stresses caused by phenomena such as heat of hydration and drying shrinkage in a quite simplified manner. The present paper aims to evaluate the consequences of explicitly considering self-induced stresses, which actually vary significantly within structural cross-sections, combined with stresses caused by external loads. The used numerical framework involves the explicit calculation of the temperature field in concrete, with proper account for the heat of hydration of cement. Simultaneously, the moisture field in concrete is computed in order to ascertain the relative humidity changes in the pore structure caused by drying, and the inherent shrinkage strains. Stress calculations are made with due consideration of the evolution of mechanical properties of concrete as a function of the equivalent age, as well as relevant phenomena like creep, concrete cracking and influence of reinforcement. Two separate groups of numerical applications are presented, checking influence of the self-induced stresses: a unrestrained concrete prism usually used for shrinkage measurement, and concrete slabs subjected to external loads. Particularly for the second set of applications, the obtained results (with explicit consideration of the differential effects of self-induced stresses) are compared, in terms of cracking loads and crack propagation, to those that would be obtained by using the simplified design approach based on considering uniform shrinkage fields in concrete. It is found that the behaviour of both formulations is quite similar after crack stabilization, but may be quite distinct in the crack propagation phase.     

金刚宝座塔的现代演绎——天津和记黄埔营口道项目之解析

文章系统地分析了天津和记黄埔营口道项目的建筑背景,总体布局,人流物流的组织,分析了作为城市综合体的各个组成部分的设计逻辑和设计策略,解读项目外部造型和内部空间设计之间的逻辑关系。     

Contribution of trace metals from atmospheric deposition to stormwater runoff in a small impervious urban catchment

The contribution of atmospheric deposition to emissions of trace metals in stormwater runoff was investigated by quantifying wet and dry deposition fluxes and stormwater discharges within a small, highly impervious urban catchment in Los Angeles. At the beginning of the dry season in spring 2003, dry deposition measurements of chromium, copper, lead, nickel, and zinc were made monthly for 1 year. Stormwater runoff and wet deposition samples also were collected, and loading estimates of total annual deposition (wet+dry) were compared with annual stormwater loads. Wet deposition contributed 1-10% of the total deposition inside the catchment, indicating the dominance of dry deposition in semi-arid regions such as Los Angeles. Based on the ratio of total deposition to stormwater, atmospheric deposition potentially accounted for as much as 57-100% of the total trace metal loads in stormwater within the study area. Despite potential bias attributable to processes that were not quantified in this study (e.g., resuspension out of the catchment or sequestration within the catchment), these results demonstrate atmospheric deposition represents an important source of trace metals in stormwater to waterbodies near urban centers.     

重大事件对城市规划学科发展的意义及启示

作为2008年新热点问题的城市重大事件需要有一个可操作的定义和范畴,狭义上的城市重大事件具有长远性、全局性、稀缺性、主动性和活动性的特征.城市的发展过程是由内部经常性动力构成的底线增长和由外部突发性动力构成的跨越提升组成的.作为一种特殊的外部突发性动力,城市重大事件与城市发展有着密切的关系,如果合理利用,将在短时间实现城市的跨越提升.立足于国民生命财产安全和公共设施管理,城市规划师的任务在于把短期的事件引导到城市长远的可持续发展的生态环境、经济环境和社会环境框架中,将具体的为重大事件所建设的基础设施与城市未来发展战略相结合,使之成为城市全面可持续发展的催化剂.     

某图书馆圆形楼盖设计

本文介绍了黑龙江省铁力市第一中学图书馆圆形预应力井式梁板楼(屋)盖应用SAP2 0 0 0软件及有关规范的设计过程。给出了该预应力井式梁板结构的材料选择、预应力工艺选择、预应力筋的线型选择、荷载取值与内力计算、预应力筋与非预应力筋的选配等设计计算的思路和方法,可供建造同类工程时参考。     

城市发展战略规划研究中的空间拓展方向分析方法

通过对沈阳市铁西新区发展战略规划的实践,提出一种从外部环境拉动、内部需求推动、自身现有基础三个视角,分别考察产业发展、空间结构、城市形象、行政效率等相关要素,来确定城市空间拓展方向的系统分析方法.     

Wind‐induced internal pressure effect within a novel super‐large cylindrical–conical steel cooling tower

A cylindrical–conical steel cooling tower (SCT) is a new type of very large thin‐walled, flexible structure. This study focused on the wind loads on the internal and outer surfaces of this structure and its wind‐induced responses. First, using the computational fluid dynamics method, the numerical wind tunnel was conducted to simulate a 189‐m‐high cylindrical–conical SCT, Asia's highest cooling tower that is still under construction. This numerical method was validated by comparing the wind pressures across typical cross sections of the tower model's cylindrical and conical segments with known standard curves. Based on this, the features of the airflow around the typical cross sections and its wake were extracted, and the distribution of mean wind loads along the internal and outer surfaces of the cylindrical and conical sections was obtained. Then functions for estimating the internal and outer surfaces shape factors of the cylindrical and conical segments were obtained by fitting to the simulated data. Furthermore, finite element method was used to analyze the static wind‐induced response of the cylindrical–conical SCT under internal pressure, external pressure, or both internal and external pressure. The effect patterns of internal pressures on the wind‐induced responses of the main tube, stiffening trusses, and auxiliary trusses of the tower were derived from the analysis results. Main findings of the research can provide a reference for design of very large cylindrical–conical SCTs for wind resistance in the future.     

Form Follows Water: A Study on Stormwater Resilient Urban Design

Rapid urbanization and global warming cause a sharp increase of frequency and intensity of stormwater disaster. Urban design, depending on the methodology of urban form and the creation of the spatial environment to promote stormwater resilience, has broken through the traditional design mode and become an efficient path leading to addressing urban stormwater disaster. Firstly, this paper discusses the concept and connotation of stormwater resilient urban design based on the resilient city theory in order to set up the theoretical framework of the design method. Then combining with the specific cases and focusing on four key problems of urban design, the practical urban design methods in favor of stormwater resilience are analyzed, including the optimization of land use, the organization of urban structure, the creation of multi-functional space, and the integration of urban systems. In the end, the paper further analyzes the challenges in practical application. Stormwater resilient urban design expands the boundary of traditional urban design and provides a new choice for performance-based e co-city design.     

城市群新认知:一种中间体组织

城市群是城镇化发展到一定阶段的客观产物,具有地理接近性与关系接近性两大核心特征。作为一种介于市场经济组织和行政科层组织之间的中间体组织,城市群的出现与成长为解决城市间分工演进与交易费用之间的两难选择提供了一种有效率的交易体系、市场结构与制度安排。在中国,城市群具有双重战略角色:对内是区域空间演变与联系深化的有机整体;对外是接轨全球经济和参与全球竞争的重要单元。     

呼伦贝尔城市规划展览馆钢结构屋顶结构设计

呼伦贝尔城市规划展览馆屋顶造型为"白云屋面",呈现出"草原上一片云"的建筑设计方案,结构形式采用双向正交桁架式网架。根据当地严寒气候条件以及屋顶独特造型,对结构各项荷载进行逐一分析,通过设置双向、单向球形铰支座释放内力,调节钢结构屋盖对下部混凝土结构的不利影响,利用SAP 2000有限元结构软件进行设计及计算,使结构经济合理,既能满足建筑造型要求,又能实现预定的性能目标。     

Synergistic use of ultra-high-performance fiber-reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP) for improving the impact resistance of concrete-filled steel tubes

Concrete-filled steel tubes (CFSTs) have received growing attention, owing to their rapid construction, reduced labor requirement, and reasonable material cost. While in service, the CFSTs can be subjected to unexpected impact loads, originating from vehicle and vessel collision, as well as water- and wind-borne debris impact. Such extreme loading events often cause a partial or complete failure of conventional CFSTs, risking the safety and performance of the entire structural systems that rely on them. To address this issue, the current study explores how two advanced composite materials, including ultra-high-performance fiber-reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP), can be utilized to provide superior mechanical properties and minimize the vulnerability of CFSTs to impact loads. The composite materials under consideration are appropriate for both new and existing structures, in which normal-strength concrete can be replaced with UHPFRC, while CFRP sheets can further strengthen the CFSTs. For obtaining in-depth insights, a computational framework validated with the experimental tests was developed in the current study. Using a set of representative impact scenarios, various response measures, such as internal forces and deflections, as well as the energy absorbed by the CFSTs, were recorded during impact simulations. The investigations were then further extended to capture the influence of the main design parameters related to concrete, CFRP, and steel tube. From the conducted investigations, an energy absorption index was introduced, as a measure to evaluate the performance of CFSTs under impact loads.     

人防工程结构设计中的等价等效静载法

人防工程设计时采用等效静载形式,由于动、静荷载计算特征性质不同,相互之间难于直观的比较,从而给设计及研究工作带来很多不便。等价等效静载是将有关动我特征内容(如构件强度设计安全系数不同,材料强度提高系数等)全部反应到拟研究的等价等效静载的数值内,从而可直接应用钢筋混凝土结构设计规范(TJ10-74)及有关图表进行人防结构设计而不必再考虑动载特征之影响。可使民用结构设计人员也能准确的完成上述两规范要求的防护工程设计。