Drift Concentration Research Articles

Seismic Simulation of U.S. and Japanese Type Steel Moment-Resisting Frame Structures Using Practical FEM Macro Models

Building structures around the world have been designed using various framing methods. In Japan, the two-way moment-resisting frame structure, which is designed as a 3D seismic frame with beams connected to the columns, with moment connections in both directions, is traditionally constructed. In contrast, in the United States and many other countries in high seismic regions, the one-way moment-resisting frame structure, which is designed as separate seismic and gravity frame structure with only a few expensive moment connections in seismic frames, is typically constructed. Structures with these different framing systems are likely to exhibit different seismic response and collapse mechanism when subjected to large earthquake excitation. However, the simulation up to complete collapse has almost not been conducted and safety margin to complete collapse of these different framing systems has not been sufficiently understood. In this study, seismic simulation of U.S. and Japanese type three-story steel moment-resisting frame structures is conducted using general-purpose finite element analysis program. Practical macro models used for the simulation are based on beam and shell elements. It is found that composite effects of floor slab accelerate column yielding in both U.S. and Japanese type steel frame structures and drift concentration may occur at relatively small ground motion level and eventually result in complete collapse.

Seismic Stability of Buckling-Restrained Braced Frames

Buckling Restrained Braced Frames (BRBFs) are widely used as seismic force resisting systems due to their ductility and energy dissipation. However, because of the modest overstrength and relatively low post-yielding stiffness, BRBFs subjected to seismic loading may be susceptible to concentrations of story drift and global instability triggered by P-∆ effects. Due to the use of simplistic methods that are based on elastic stability, current code design provisions do not address seismic stability rigorously and do not consider the particular inelastic response of a system. Design strategies are needed to prevent undesirable seismic response in BRBFs, such as drift concentration and large residual drift. This study used the FEMA P-695 Methodology to evaluate the response of current U.S. code-based BRBF designs and to study the effect on seismic stability of three potential enhancements: strong-axis orientation for BRBF columns, gravity column contribution, and a BRBF-SMRF dual system. Results from nonlinear static and dynamic analyses allowed assessment of seismic behavior. Results from collapse performance evaluation quantify the improvement that is achieved with each alternative and provide a means of comparison.

Modeling of Behavior of Continuous Energy-Dissipative Steel Columns Under Cyclic Loads

ABSTRACTThis paper presents analytical and numerical models of cyclic behavior of a novel continuous energy-dissipative column (CEDC) system. It consists of two steel columns connected by replaceable steel strip dampers (RSSDs). The CEDC system is designed to realize the function of energy dissipation, lateral resistance, and mitigating inter-story drift concentration. The formulas to determine the elastic stiffness, yield, and ultimate capacity of the CEDC system are derived based on continuous medium method. A simplified model of hysteretic behavior of the CEDC system is proposed and validated with experimental results.

Research on residual drift response of steel frames under strong earthquakes

Steel frames designed to the current codes will undergo an unrecoverable plastic deformation under strong earthquakes. The structures subjected to excessive deformations after earthquakes cannot be desirably repaired to their serviceable state, and can only be demolished, which brings about a serious direct and indirect economic loss. Thus, it is of great significance to predict the residual drift for the performance evaluation and control of structures after earthquakes. In order to investigate the residual drift response of steel frames under strong earthquakes, steel frames between 2 and 10 stories in height are designed according to Code for seismic design of buildings (GB50011-2010) and Code for design of steel structures (GB50017-2003) in this study. The designed structures are investigated numerically by pushover analysis and elasto-plastic time history analysis. Furthermore, the peak drifts, residual drifts and drift concentration factors are reasonably obtained under the action of moderate earthquakes and major earthquakes. The results indicate that the scatter in the residual drift results is a bit large. On the basis of analysis results, the calculation formulae are proposed to estimate the residual drifts of steel frames as a function of the expected peak drift, the initial recoverable elastic drift, and the drift concentration factor of steel frames.

11.16: Seismic performance evaluation of MRFS with dissipative continuous columns

ABSTRACTThe Dissipative Continuous Column (DCC) concept is proposed as a gravity load and seismic energy dissipating dual‐functional structural component. The proposed DCC is made up of two closely spaced continuous columns which are interconnected with replaceable steel strip dampers (RSSDs) over the height. It works in a way similar to pin supported coupled shear walls, but minimizes the construction invasive and ensure rapid return to occupancy after severe earthquakes. The innovative moment resisting frame (MRF) system with DCCs can also mitigate the inter‐storey drift concentration and reduce the soft storey failure risk significantly due to the contribution of large flexure stiffness of the DCCs. Based on the experimental test results, a simplified analysis model of the DCCs is developed for the design and seismic performance evaluation of the MRFs system with DCCs. The simplified analysis model consists of dual column and multiple zerolength equivalent elasto‐plastic springs with rigid end. Numerical models of a 4‐story conventional steel MRF and a 4‐story steel MRF with DCCs were set up using the proposed simplified model. Nonlinear Dynamic Time History Analysis were undertaken, and the results showed that the MRFs with DCCs can reduce the economic loss by limiting the structural damage in the replaceable steel strip dampers and mitigating both the maximum inter‐story drift ratio and drift concentrations.

11.43: Seismic performance of staggered steel plate shear wall systems in high rise buildings

ABSTRACTUnstiffened Steel Plate Shear Walls (SPSWs) are used as the lateral load‐resisting systems in building structures. The energy dissipation mechanism of SPSWs is consisted of the tension yielding of web plates and the formation of plastic hinges at the ends of horizontal boundary elements (HBEs). High‐rise buildings experience the high overturning moments leading to the high axial demands in the vertical boundary elements (VBEs) of SPSWs. The presence of high axial forces in VBEs can cause a reduction in their flexural capacity resulting in the drift concentration or even soft‐story mechanisms in the lower storey levels during an earthquake event. Past studies have shown that a staggered arrangement of steel plates may help in reducing the force demand in VBEs. Two simple methods are investigated in this study to r b educe the VBE forces are (i) by increasing the width of the web plates and (ii) by staggering the web plates over the frame height. A 20‐story steel frame building has been considered as the study frame. Three types of systems are designed to study the effect of aspect ratio and staggering on the seismic behaviour of SPSW. Force‐displacement characteristic of SPSW used in the numerical model is validated with the test results. Both nonlinear static and dynamic analyses are carried out in this study. Axial and shear force demands in the VBEs are reduced for the study frame, while achieving the desired hinge mechanisms. Nonlinear dynamic analyses under twenty spectrum‐compatible design‐level ground motions exhibited that staggered steel plate shear wall systems reduced the inter‐story drift by about 50% with respect to their conventional counterpart.

Modeling on collapse behaviour of high-rise concrete-filled steel composite frames under over-design seismic excitations

This paper presents a numerical study on seismic collapse capacity of high-rise concrete-filled steel tubular moment resisting frames (CFT-MRFs) under extreme ground motions that are beyond the design levels. The ground motions characterised as flat velocity spectral shape were selected to neglect record-to-record uncertainty induced by the changing of the natural periods of structures. A simple numerical approach was developed using fibre element with stiffness and strength degradation accounted in stress–strain models. Then, incremental dynamic analyses with various parameters were performed to evaluate the P-Delta and degradation effects on local and global collapse mechanisms. Results have shown that a drift concentration at the lower stories triggered the side-sway collapse mode that was dominated by the post-buckling strength degradation of CFT columns. The height of drift concentration indicates the range where the collapse mechanism was formed, and a drift concentration factor was proposed to estimate the extent of drift concentration. Last, a factor indicating the safety margin under collapse was computed based on the probability of earthquake occurrence.

Interactions of baseflow habitat constraints: Macroinvertebrate drift, stream temperature, and physical habitat for anadromous salmon in the Calapooia River, Oregon

Abstract The Calapooia River in western Oregon supports a small winter steelhead trout (Oncorhynchus mykiss) population and historically supported spring Chinook salmon (Oncorhynchus tshawytscha). Early timber harvesting removed the riparian forest, and log transportation practices simplified the channel. Those disturbance legacies continue to affect fish habitat by limiting shade and channel complexity, complicating conservation efforts. To evaluate juvenile salmonid rearing potential, macroinvertebrate drift, thermal regime and physical habitat were measured at eight sites in 24 km of the upper river during late summer baseflow. Overall physical habitat was simple, with few functioning instream structures or pools. During the 22‐day drift study, flows declined and maximum site stream temperatures ranged from 23.1°C at the lower end to 16.4°C 24 km upstream. Macroinvertebrate drift concentrations ranged from 0.7–13.7 ind. m−3 with biomasses from 0.02–1.23 mg m−3. Drift concentration biomass was higher upstream (P = 0.006) than downstream and declined overall (P < 0.001) during the study. Drift biomass was dominated by five taxon groups – Baetis tricaudatus, Calineuria californica, Hesperoperla pacifica, Simulium spp., and Chironomidae, which were 65% of total biomass. During twilight, total biomass and biomass of B. tricaudatus, Simulium spp., and Chironomidae (both larvae and adults) were higher. Total drift declined dramatically over the study period owing to decreases in drift concentration and a 58% decline in discharge, greatly reducing overall drift and available food resources for juvenile‐rearing salmonids. The upper catchment, both with cooler temperatures and higher food availability, provided the best conditions for juvenile anadromous salmonids to survive late summer conditions. Conservation consequences of climate change‐induced alterations in flow and temperature may further affect habitat quality for juvenile salmonids in this catchment in the coming decades.

Drift Concentration of a Three-Story Special Concentrically Braced Frame with Strongback under Earthquake Loading

In conventional special concentrically braced frame (SCBF) structures, the buckling of the braces leads to severe reduction in system strength and stiffness. Therefore soft story mechanisms followed by large permanent deformation are commonly observed in SCBF structures. The strongback system using additional structural components along the height of the building to resist local deformation is able to improve the distribution of the drift. This research conducted case studies to investigate the effects of strength and stiffness of the strongback system on the behavior of typical three-story SCBF system. The primary variables to be investigated are stiffness factor α (strongback stiffness/SCBF stiffness) and strength factor β (strongback strength/SCBF strength). We conducted nonlinear dynamic analyses to evaluate the effectiveness of α and β on structural demand parameters including maximum drift ratio and drift concentration factor (DCF). Analyses results show that although strongback system with excessively high α and β will reduce maximum drift ratio and DCF of SCBF systems, it is noneconomic. On the other hand, strongback systems with low α and β (α<0.0048 and β<0.054) have only little effects on improving structural behavior. The case studies suggested that 0.0096≤α≤0.0168 and 0.081≤β≤0.134 accounting for both efficiency and economics can be used in the design of the selected SCBF systems.

Species traits and channel architecture mediate flow disturbance impacts on invertebrate drift

Summary Pulsed flow disturbances strongly influence invertebrate drift in lotic ecosystems. However, drift‐flow relationships are often context dependent and non‐intuitive, suggesting that local abiotic and biotic conditions mediate the impacts of flow on the physical and behavioural drivers of drift entry. Two factors may be particularly important: physical channel architecture, which modulates how flow influences velocity and habitat area; and species traits, which determine behavioural responses to flow and susceptibility to passive entrainment. We examined how channel architecture and species traits (e.g. mobility, body size, and dislodgement susceptibility) mediated the effects of flow on bulk drift abundance and taxa‐specific per capita drift rates (the rate of emigration from the benthos). In complementary experiments, we reduced and increased flows in stream mesocosms with contrasting cross‐sectional channel profiles: concave channels, where habitat area contracted and expanded with altered flow but velocity remained relatively constant; and flat channels, which maintained constant habitat area but experienced greater changes in velocity. Total drift concentration increased following flow reductions and decreased following flow increases whereas drift flux (the total number drifting) showed the opposite pattern. Channel architecture did not influence drift during flow reductions, but during flow increases drift flux and concentration were amplified in flat channels that experienced larger increases in velocity and shear stress. Contrasting responses among individual taxa to flow manipulation were explained by variation in mobility (swimming and crawling ability) and body shape (susceptibility to drag). Per capita drift rates for the most mobile taxa increased c. 10% under flow reduction, indicating a behavioural response, whereas drift of other taxa declined. Per capita drift increased for all taxa following elevated flow but by the largest magnitude in taxa with body shapes that experience more drag, suggesting passive dislodgement. Our results imply that: (i) stream channel architecture can modify the impacts of flow increases on stream invertebrates; and (ii) invertebrate taxa vary in their vulnerability and behavioural responses to flow disturbance. Together these inferences clarify some of the previously unexplained context‐dependent responses of drift to flow disturbances.

Improving inter-story drift distribution of steel moment resisting frames through stiff rocking cores

This investigation assesses adequacy of the Stiff Rocking Core (SRC) technology for rehabilitating steel Moment Resisting Frames (MRFs) vulnerable to drift concentrations and soft-story failures. The technology installs a single or multiple SRCs pinned to the foundation and connected to a deficient multi-story steel MRF to re-distribute seismic forces along its height and create more uniform inter-story drift and ductility demand distributions. This research team implemented the SRC technology in two archetype steel MRFs including one three-story and one nine-story. Results from nonlinear static analyses show that the SRC technology can reduce inter-story drift concentration in both steel MRFs regardless of the seismic force distributions and drift limits considered in design. Additionally, the SRC extending along the entire height of a steel MRF is more preferable than the one extending over the bottom portion of the system, although these two SRC options can be both valid in many cases.

Can Weighted Useable Area Predict Flow Requirements of Drift‐Feeding Salmonids? Comparison with a Net Rate of Energy Intake Model Incorporating Drift–Flow Processes

AbstractWe compared a process‐based invertebrate drift and drift‐feeding net rate of energy intake (NREI) model and a traditional hydraulic‐habitat model (using the RHYHABSIM [River Hydraulics and Habitat Simulation] software program) for predicting the flow requirements of 52‐cm Brown Trout Salmo trutta in a New Zealand river. Brown Trout abundance predicted by the NREI model for the constant drift concentration–flow scenarios were asymptotic or linear, depending on drift concentration, increasing through the mean annual low flow (MALF; 17 m3/s). However, drift concentration increased with flow, consistent with passive entrainment. The predicted fish abundance–flow relationship based on flow‐varying drift concentration increased logistically, and more steeply, with flow through the MALF and beyond. Predictions for the relationship between weighted useable area (WUA) and flow were made for three sets of drift‐feeding habitat suitability criteria (HSC) developed on three midsized and one large New Zealand river (flow at sampling was 2.8–4.6 m3/s and ~100 m3/s, respectively) and the South Platte River, Colorado (flow at sampling, 7–18 m3/s). The midsized‐river HSC ascribe lower suitability to water velocities > 0.6 m/s. They predicted WUA peaking at 10–11 m3/s, well below the MALF. The WUA–flow relationships for the two large‐river HSC were asymptotic at about 22 m3/s. Overall, WUA appears to underestimate the flow needs of drift‐feeding salmonids. The NREI model showed that assessing flow needs of drift‐feeding fish is more complex than interpreting a WUA–flow relationship based only on physical habitat suitability. The relationship between predicted fish abundance and flow is an emergent property of flow‐dependent drift‐foraging dynamics interacting with flow‐dependent drift concentration and drift flux, local depletion of drift by feeding fish, and flow‐related replenishment of drift from the bed and dispersion. It is time that the principles and predictions of drift–NREI models influence assessments of habitat capacity and instream flow needs of drift‐feeding fish.Received April 10, 2015; accepted November 10, 2015 Published online April 27, 2016

Impact of season-long water abstraction on invertebrate drift composition and concentration

Surface water abstraction from rivers for irrigated agriculture is one of the largest uses of freshwater resources in the world. Water abstraction has important impacts on the structure of riverine assemblages. However, little work has examined the chronic, season-long impacts on ecosystem functions. Invertebrate drift is an important ecosystem function of river systems influencing nutrient cycling, food webs, and invertebrate population dynamics. We examined the season-long impact of reduced discharge resulting from multiple points of abstraction on drift assemblage composition, concentration, and total drift load. Early in the season, water abstraction had little impact on drift assemblage composition. However, later in the irrigation season, the drift assemblage at sites impacted by water abstraction diverged from upstream, control sites. The degree of change in assemblage composition at impacted sites was related to the amount of water abstracted such that sites with the lowest discharge also had assemblages that differed most strongly from control sites. Drift assemblages at impacted sites became dominated by tolerant microcrustaceans. In addition, water abstraction resulted in an increase in drift concentration (ind./m3). However, despite this increase in concentration at impacted sites, total drift load (# of invertebrates drifting in the river) decreased with decreasing discharge.

Seismic response estimation method for earthquake‐damaged RC buildings

SummaryThis study proposes a procedure for identifying spectral response curves for earthquake‐damaged areas in developing countries without seismic records. An earthquake‐damaged reinforced concrete building located in Padang, Indonesia was selected to illustrate the identification of the maximum seismic response during the 2009 West Sumatra earthquake. This paper summarizes the damage incurred by the building; the majority of the damage was observed in the third story in the span direction. The damage was quantitatively evaluated using the damage index R according to the Japanese guidelines for post‐earthquake damage evaluation. The damage index was also applied to the proposed spectral response identification method. The seismic performance of the building was evaluated by a nonlinear static analysis. The analytical results reproduced a drift concentration in the third story. The R‐index decreased with an increase in the story drift, which provided an estimation of the maximum response of the building during the earthquake. The estimation was verified via an earthquake response analysis of the building using ground acceleration data, which were simulated based on acceleration records of engineering bedrock that considered site amplification. The maximum response estimated by the R‐index was consistent with the maximum response obtained from the earthquake response analysis. Therefore, the proposed method enables the construction of spectral response curves by integrating the identification results for the maximum responses in a number of earthquake‐damaged buildings despite a lack of seismic records. Copyright © 2016 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.

Performance Control and Efficient Design of Rocking-Wall Moment Frames

AbstractRocking-wall moment frames (RWMFs) are unique, lateral resisting structures in which the shear wall pivots about its pinned base rather than act as a fixed base, upright cantilever. The function of the wall is to prevent soft-story failure, reduce drift concentration, and provide suitable supports for energy-dissipating devices. However, despite their favorable seismic performance, their practical design aspects have not been fully addressed in the literature. This paper proposes a new approach based on the principles of design-led analysis. It provides a lucid study of the analytic components and inner workings of RWMFs as efficient lateral resisting systems. While complementing existing literature on the subject, this study presents several interesting findings and useful design conclusions. For instance, it points out that under certain circumstances, neither the rocking wall nor its appendages can influence the ultimate carrying capacity of the frame. The proposed solutions are entirely suitab...

A distributed parameter model of a frame pin‐supported wall structure

SummaryMany reinforced‐concrete frames collapse via a soft‐story mechanism during severe earthquakes. Such collapses are mainly attributed to concentrated deformation in a soft story. Deformation control is thus important in preventing collapse. The frame pin‐supported wall structure is a type of rocking structure that releases constraints at the bottom of the wall. Previous research has obtained good results for the deformation control of this type of structure. However, the interior forces and strength demands of the pin‐supported wall have not been systematically explored. In this paper, a distributed parameter model is developed to investigate the strength demand of the wall in a frame pin‐supported wall structure. In the model, the pin‐supported wall is simplified as a bending beam and the frame is simplified as a shear beam. The two beams are joined by distributed shear connectors, so that the shear force can be transferred at any location on the interface. The model can be solved using differential equations based on equilibrium and compatibility. The accuracy of the model is verified using SAP2000 (Computers and Structures Inc., Berkeley, CA, USA). Displacement distribution of the structure and distributions of the moment and shear force within the pin‐supported wall are obtained for two typical external force profiles. It is found that the pin‐supported wall can effectively reduce the drift concentration factor. Distributions of the displacement, moment, and shear force are closely correlated with the relative stiffness of the wall and frame. Finally, recommendations on the stiffness and strength of a pin‐supported wall are made. Copyright © 2015 John Wiley & Sons, Ltd.

Mitigation of inter-story drift concentration in multi-story steel Concentrically Braced Frames through implementation of Rocking Cores

Abstract This paper investigates a new seismic rehabilitation technology for low-rise and mid-rise steel Concentrically Braced Frames (CBFs) vulnerable to inter-story drift concentration and soft-story failures. The technology consists of installation of a single or multiple sufficient Rocking Cores (RCs) pinned to the foundation and connected to an existing deficient multi-story CBF building to re-distribute seismic forces along its height and create more uniform inter-story drift and ductility demand distributions. Two benchmark steel CBF buildings including one three-story and one six-story are rehabilitated using the RC technology. Nonlinear static pushover analyses are conducted to demonstrate the beneficial contribution of the RC in mitigating non-uniform inter-story drift distributions in the benchmark buildings. The RC stiffness is varied and the Monte-Carlo simulation technique is adopted to generate random lateral force distributions in the nonlinear static pushover analyses. It is shown that the RC is effective in reducing inter-story drift concentration in both benchmark buildings when they reach the inter-story drift limits associated with collapse prevention, lift safety and immediate occupancy per FEMA 356. This paper also presents the strength demands on RC and the links connecting RC to existing frame from the nonlinear static pushover analyses, which are essentially caused by the first mode responses of the rehabilitated systems.

Food and space revisited: The role of drift-feeding theory in predicting the distribution, growth, and abundance of stream salmonids

In this paper we review drift-feeding models for stream salmonids. We assess their historical development and current state, and we propose areas for future research. Drift-feeding models serve as the critical input for energetics-based habitat selection and habitat quality models, which have recently begun to see widespread use for predicting salmonid distribution, growth and abundance. We use a bibliometric approach to find drift-feeding model publications, especially those citing three landmark papers that began the quantification of drift feeding by stream fish (Fausch 1984; Hughes and Dill 1990; Hill and Grossman 1993). Subsequent drift-feeding models have largely been built upon these models. Research effort has focused on model development and applications but model testing has been neglected. To date, the only rigorous test of a drift-feeding model (Hughes et al. 2003) identified several limitations and violations of model assumptions. The most important limitation was that prey capture- and gross energy intake rates were overestimated by a factor of two, due largely to poor predictions of prey detection probabilities. Consequences of error in drift-feeding models, and consequently in the habitat selection/quality models that employ them, are greater for applications aimed at predicting growth and abundance than they are for predicting distribution. Research effort on a broad front is needed to advance both drift-feeding models and habitat selection/quality models, including: further development of drift-foraging theory, revision and testing of drift-feeding models (specifically new, functional prey detection and interception sub-models), and revision of habitat selection/quality models to incorporate spatial, temporal, and flow-dependent variation in drift concentration.

The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river

Summary Invertebrate drift is a fundamental process in streams and rivers. Studies from laboratory experiments and small streams have identified numerous extrinsic (e.g. discharge, light intensity, water quality) and intrinsic factors (invertebrate life stage, benthic density, behaviour) that govern invertebrate drift concentrations (# m−3), but the factors that govern invertebrate drift in larger rivers remain poorly understood. For example, while large increases or decreases in discharge can lead to large increases in invertebrate drift, the role of smaller, incremental changes in discharge is poorly described. In addition, while we might expect invertebrate drift concentrations to be proportional to benthic densities (# m−2), the benthic–drift relation has not been rigorously evaluated. Here, we develop a framework for modelling invertebrate drift that is derived from sediment transport studies. We use this framework to guide the analysis of high‐resolution data sets of benthic density and drift concentration for four important invertebrate taxa from the Colorado River downstream of Glen Canyon Dam (mean daily discharge 325 m3 s−1) that were collected over 18 months and include multiple observations within days. Ramping of regulated flows on this river segment provides an experimental treatment that is repeated daily and allowed us to describe the functional relations between invertebrate drift and two primary controls, discharge and benthic densities. Twofold daily variation in discharge resulted in a >10‐fold increase in drift concentrations of benthic invertebrates associated with pools and detritus (i.e. Gammarus lacustris and Potamopyrgus antipodarum). In contrast, drift concentrations of sessile blackfly larvae (Simuliium arcticum), which are associated with high‐velocity cobble microhabitats, decreased by over 80% as discharge doubled. Drift concentrations of Chironomidae increased proportional to discharge. Drift of all four taxa was positively related to benthic density. Drift concentrations of Gammarus, Potamopyrgus and Chironomidae were proportional to benthic density. Drift concentrations of Simulium were positively related to benthic density, but the benthic–drift relation was less than proportional (i.e. a doubling of benthic density only led to a 40% increase in drift concentrations). Our study demonstrates that invertebrate drift concentrations in the Colorado River are jointly controlled by discharge and benthic densities, but these controls operate at different timescales. Twofold daily variation in discharge associated with hydropeaking was the primary control on within‐day variation in invertebrate drift concentrations. In contrast, benthic density, which varied 10‐ to 1000‐fold among sampling dates, depending on the taxa, was the primary control on invertebrate drift concentrations over longer timescales (weeks to months).

풍속 및 수중확산에 따른 방역용 Deltamethrin의 수중 잔류변화

The objectives of this study were to provide the basic data of the residue of deltamethrin in the stream water. Deltamethrin was treated on side of Ban-Suk stream and Juk-Dong ditch for hygienic purpose by air spray. The drift concentration of deltamethrin was investigated with different wind speed condition on Ban-Suk stream (A), and the change of residue with time course on Juck-dong ford (B). Also we found the residual change of deltamethrin until 48 hour in Yu-Seong stream confluence (C) where two streams join. Maximum residues of A were (5 min, 200 m) at strong wind speed and (0 min, 25 m) at moderate wind speed according to different wind velocity. Residues of B were (0~480 min) after spraying, and decreased to a non-detected level after 720 min. Residues of C were (0 min), (1 min) and (12 hr) after spraying, and no residues were detected in any other samples. From these results, it is concluded that deltamethrin residues in water should be rapidly diluted into stream water and affected negligible toxic effect to stream ecosystem.