Wing Walls Research Articles

Passive cooling and natural ventilation by the windcatcher (Badgir): An experimental and simulation study of indoor air quality, thermal comfort and passive cooling power

The upper wing wall can be integrated into the windcatcher to prevent direct solar and rain penetration. The impact of this combination was not considered in previous studies. Moreover, analyzing adaptive thermal comfort is another gap that was not addressed by preceding windcatcher studies, particularly for the tropical climate. Therefore, the current research aims to evaluate a two-sided windcatcher incorporated with the upper wing wall from two views: indoor air quality (IAQ) and adaptive thermal comfort. A small-scale model was tested in the wind tunnel. Next, CFD models were validated against experimental data with a good agreement between the two methods. Windcatchers with different upper wing wall lengths ranging between 10 cm and 50 cm were assessed. The results showed that the length increase led to a slight increase in the ventilation rate, and the best performance was seen in the 50 cm configuration. Subsequently, IAQ and adaptive thermal comfort were evaluated at different wind speeds of this climate. The results demonstrated that even in wind speeds below the annual average (2.5 m/s), the windcatcher performance can still satisfy IAQ parameters such as airflow rate and air change rate, recommend by CIBSE Guide A. In addition, based on the simulated conditions the results showed that wind speed from 2.5 m/s to 4 m/s could provide thermal comfort within 50%–80% of the ventilated space. Finally, the estimation of passive cooling power showed that windcatcher could provide a maximum (9.6 kW) cooling power if the wind speed is at 4 m/s and outdoor temperature at 23 °C.

Combined operation mode of sub-critical W-flame boiler and coal mill optimized numerical simulation

The flow, combustion, heat transfer and NOx emission characteristics of a 600 MW subcritical W-flame boiler were numerically simulated under different combined operation modes of coal mills, and compared with the measured results. The results show that the combustion, average residence time, burnout rate, NOx emission characteristics and temperature distribution near the side wall of pulverized coal particles in the furnace have different effects on the combined operation mode of pulverized coal. In the combustion efficiency of give attention to two or more things, screen superheater section of fly ash carbon content and flue gas temperature of entrance at the same time, compared with six coal mill run at the same time, 5 coal mill run, shut down near the side wall of the coal mill is beneficial to reduce NOx emission concentration, to achieve the emission reduction, at the same time under the wing wall and side wall area chamber of a stove or furnace slagging significantly reduce.

Effect of Counterforts and Buttresses on Retaining Wall using Finite Element Analysis

Retaining walls are used with tying with more than one wall at perpendicular joints to retain liquids, water storage and materials storages such as dyke walls and tanks. Retaining walls excessively used in culverts and as well as in the bridges i.e., construction of abutments, wing walls supposed to resist soil pressures, applied perpendicular to the axis of the walls. Due to in-sufficient land and based on the present construction scenario followed in the construction of retaining structures, the wall height is often increased, thereby increasing the cost of construction of sub structure. The values of the bending moment at the base increases due to the increase in the height of the wall resulting in higher sections which is uneconomical. The need of having safe and economical section shall be achieved by transforming the structural system of retaining wall i.e., by introducing supports to the vertical wall thus decreasing the thickness of stem. The design of rigid retaining wall either Cantilever or Counterfort or Buttress retaining wall is based on pressure exerted by the retaining material, wall slope, height, ease of construction and stability. When the retaining wall height is more than 8 m, the selection of extra supports i.e., either counterforts or buttresses is based upon the designer’s experience. By conducting comparative study on resisting forces for varying heights, the behaviour of these supports on retaining wall can be depicted. The depiction of forces can be achieved by running an analysis in STAAD.pro with preliminary dimensions and soil parameters respectively. Resisting forces from counterfort and buttress supports on retaining wall are equal when the height is in between 9 m to 24 m but buttress support has shown less resisting forces when the height is less than 9 m.

Energy dissipation in stepped spillways using baffled stilling basins

ABSTRACT Stepped spillways have become increasingly popular due to the low-cost of construction and high efficiency. A stepped spillway is a hydraulic structure that is an integral part of the dam that allows the safe passage of overtopping flows. In this paper, an experimental study was employed to investigate the stepped spillway with four steps of 32 cm height and 54 cm width contracted by wing wall width (C) = 0.2 from the width of the flume. Eighteen runs were carried out considering different positions, heights, and widths of the baffle to increase the energy dissipation resulting from this contraction stepped spillway. The results indicated that the best position of baffles was (a/y2 ) = 1.4, the relative baffles height was (hb/y1 ) = 0.95, and the best relative baffles widths (wb/W) = 0.68, compared with cases of contraction stepped spillway without baffles. The results showed that the baffles on the stilling basin downstream stepped spillway increase the energy dissipation. Simple formulae were also deduced to evaluate the energy parameters.

EXPERIMENTAL STUDY ON STRUCTURAL PERFORMANCE OF R/C COLUMN WITH CLT WING WALLS

EXPERIMENTAL STUDY ON STRUCTURAL PERFORMANCE OF R/C COLUMN WITH CLT WING WALLS

Effects of envelope features on wind flow and pollutant exposure in street canyons

Traffic pollution has posed a serious threat to the health of near-road city residents and pedestrians, especially in high-density cities. However, the influences of envelope features, including balconies, overhangs and wing walls, on pollutant exposure to near road residents and pedestrians have not been fully understood. This paper investigates the effects of three commonly-used envelope features on wind flow and pollutant exposure to residents in street canyon with three different aspect ratios. The evaluation metrics of personal intake fraction and daily pollutant exposure are used to quantitatively assess the influences caused by different envelope features on healthy risk of near-road residents and pedestrians, alongside with wind flow pattern and pollutant distribution. The results show that these envelope features have increased the risk of pollutant exposure for the leeward side residents, while the risk of pollutant exposure for the windward side residents is reduced for most cases, in particular for the first floor. This observation is especially prominent when the canyon has the highest aspect ratio among the tested ratios, with the increased ratio of personal intake fraction reaching up to 540%. Moreover, the pollutant concentration is overall higher on leeward side of upstream building than that of windward side of downstream building. These findings can help urban planners and architects to build healthy and sustainable urban environment.

Effects of wing wall at the balcony on the natural ventilation performance in medium-rise residential buildings

A deep plan layout and internal partitioning and resistances along the wind path in interior spaces make single-sided ventilation the only strategy possible for residential units. In this work, the potential of single-sided ventilation through the introduction of a balcony was investigated. The design of the wing wall at the balcony was investigated to determine its effect on the performance of single-sided indoor ventilation. The methodology used in was computer simulation (computational fluid dynamics or CFD) validated by data on an existing wind tunnel study and the measurements from a selected case study. CFD simulation was conducted on a simplified model of a medium-rise and low-cost residential building in Johor Bahru, Malaysia. Upon validation, the four wing wall depths and three wing wall angles were applied to the balcony, and each was evaluated numerically. Results showed that the provision of wing wall in the balcony could increase the indoor air velocity and airflow rate and improve the airflow distribution in the room if appropriately designed. The indoor ventilation performance was improved by increasing the wing wall size up to a certain depth and deviation of 22.5°. The provision of a balcony with wing walls can be a façade design alternative to improve indoor ventilation and possibly reduce energy consumption in buildings.

Optimal seismic retrofit method for reinforced concrete columns with wing walls

Seismic retrofit of reinforced concrete (RC) columns using wing walls can be used to improve the shear and flexural strength of the column through a relatively simple process. However, the feasibility and efficiency of the seismic retrofitting of RC frames with wing walls heavily depends on the selection of number of columns to be retrofitted, the cross-sectional dimensions of wing walls, and the quantity of re-bars of the wing wall. In this study, an optimal seismic retrofit design method is proposed to minimize not only the initial retrofit cost but also the earthquake-induced damage expected during the life cycle of the building. The seismic performance of structures before and after the application of the retrofit has been verified with the comparison of four response parameters: pushover curves, the inter-storey drift ratios, the energy dissipation capacities, and failure modes. The proposed retrofit method is applied to seismic retrofit of a six-storey RC building example and an actual RC building structure in use. For the retrofit of actual building structure, with an initial retrofit weight of 70.85 kN, which corresponds to 1.85% of the weight of the non-retrofitted building, the energy dissipation capacity was increase by 3.02 times and the life cycle cost (LCC) of the retrofit was reduced to 69.47% of the required LCC for the non-retrofitted building. In addition, it has been confirmed that no storey collapse occurred in collapse prevention level, which indicates the most severe failure mechanism of a structure due to an earthquake.

Six legged concrete (SLC) elements as scour countermeasures at wing wall bridge abutments

ABSTRACT Previous research studies have shown that abutment scour makes a major contribution to bridge failures. Protecting bridges against scour is, therefore, a priority need. For existing bridges, armouring methods, such as riprap, have a wide application. In the areas where providing stones is expensive, concrete blocks or similar techniques are often used. In the present study, the application of the Six Legged Concrete (SLC) elements was experimentally investigated. The SLC elements were placed in three different densities (open, medium and dense) at three different placement depths (h/l = 0, 0.5 and 1; where h is the element installation height above the bed and l is element height). Each alternative was tested under different flow conditions for a wing-wall abutment. In general, the results showed that the SLC elements can considerably reduce the scour under different flow conditions. In an optimal arrangement, the elements reduced the scour depth at abutment nose up to 100%. The maximum reduction of scour depth was obtained when the SLC elements were placed densely on the bed (h/l = 1).

The effect of bridge abutment shape variation toward flow velocity characteristic

Lots of bridge failure phenomenon caused by scour on pier foundation or abutment. One of the most important factors of the bridge is the abutment. Abutment is a structure, built at the edge of the bridge. Abutment is designed to hold the weight of the bridge and over the bridge. The structure of abutment usually planted in to the river. One of methods to minimize the scour impact is considering the shape and design of abutment. This research aims to find out the effect of abutment model or shape variation (semi-circular end abutment, wing wall abutment and spill through abutment) toward the change of velocity using Flow-3D for numerical modeling, the physical test to validation the flow condition and analyze the characteristic sediment transport pattern using Hjulstörm curve. The result of research state that the spill through abutment is the most effective model to keep the stability of flow velocity around the abutment. Correlation between Froude Number (Fr) with Relative Longitudinal Distance Ratio is discussed in this paper. Then, Hjulstörm curve shows that with bed material diameter (d 50) of 0,54 mm, sediment transport in the entire abutment model located at erosion zone.

Influence of Horizontal and Vertical Barriers on Fire Development for Ventilated Fa\xe7ades

Although using various innovative materials for ventilated facade systems positively contribute to the energy efficiency of buildings, the application of such materials can also pose a certain risk of fire propagation through the façade. In the last decade, medium and large-scale tests, as well as numerical analysis have been performed to assess the impact of fire barriers on fire propagation through ventilated façades. However, the number of fire barriers and their specific positions can also have an effect on the fire safety of facades, which has not been studied. Consequently, the question arises whether real fire exposure on a façade can be adequately simulated and analysed in sufficient detail, by using large-scale testing methods. This paper aims to conduct a parametric analysis on a broader range of large-scale samples by using the procedure given in the standard BS 8414-1:2015 + A1:2017. To understand better the impact of the number and position of cavity barriers for different types of insulation materials (stone wool/PIR/phenolic foam) used in modern façade systems with non-combustible cladding (ACM-A2). Seven tests were carried out in Croatia between October 2017 and April 2018. In the case of combustible insulation, two horizontal barriers were insufficient in preventing fire propagation. Temperatures accumulated above 600°C, reaching 840°C in PIR insulation and 979°C in phenolic foam insulation. For the same sample designed with non-combustible insulation, the maximum temperature measured was 133°C. Facades with combustible insulation passed the test only when four horizontal barriers were used. The existence of vertical barriers had a positive impact on preventing the fire propagation because the insulation on the left side of the chamber, behind the vertical barrier, remained undamaged. Vertical barriers on the right side of the chamber delayed the horizontal fire propagation from the main wall to the wing wall depending on the type of insulation. The results from these tests can serve as a basis for future research on the effects of fire barriers on fire propagation.

Improving integrity of RC beam‐column joints with deficient beam rebar anchorage

SummaryIn recent earthquakes in developing countries, severe damage was observed on reinforced concrete buildings. This study focuses on exterior beam‐column joints with substandard beam rebar anchorage and seismic strengthening by installing wing walls. First, a series of experiments was conducted to investigate the seismic behavior of exterior joints with substandard beam rebar anchorage representing typical Bangladeshi buildings. Two 0.7‐scaled exterior joint specimens were tested, and these specimens showed beam rebar anchorage failure and/or joint shear failure. Prior to strengthening of the joint, a series of pullout tests was conducted on postinstalled bonded anchors in low‐strength concrete for strengthening design. Then, an experiment was performed to apply the strengthening method by wing walls to one of the exterior joint specimens to improve the integrity, and this method was intended to prevent the failure of beam rebar anchorage. The strengthening method is proposed to extend the development length of beam longitudinal bars by considering the embedment length along the wing walls. The test results verified the effectiveness and applicability of the proposed strengthening method to upgrade exterior RC beam‐column joints with deficient beam rebar anchorage.

Risk analysis of seismic bridge damage: case study after Lombok and Palu earthquake

Indonesia is known as an earthquake-prone region, lies in the ring of fire zone. This potential hazard can impact several infrastructures, including bridges. Seismic bridge damages could possibly disrupt traffic flow furthermore cut off the regional connectivity. In this study, risk analysis is carried out on several bridges after Lombok and Palu earthquake. Visual inspection has been undertaken on 38 bridges on-site, and several damages identification are reported. Risk analysis was then carried out according to the severity of element damages and the frequency of occurrence. From the analysis, it is concluded that embankment settlement in the approach road is found to be the most potential element with the highest risk of damage due to earthquakes. Besides, the superstructure displacement and crack in the wing wall are at moderate risk. This finding makes the substructure become the most vulnerable element which needs more attention. Therefore, it is recommended to specify a higher design specification for substructure to mitigate seismic bridge damages, especially for bridges located in the high seismic zone area.

Effects of shape, inlet blockage and wing walls on local scour at the outlet of non-submerged culverts: undermining of the embankment

Drainage works using culverts are potentially affected by local scour risk. Local scour process is a complex phenomenon affected by many factors. Most of them have been analyzed in previous studies, either individually or in small groups. However, no fully joint analysis has been developed so far. Since the number of factors and interactions is high, the main objective of this work was to determine which of them best represents the dimensions of the scour hole and the embankment undermining. 80 experiments have been designed and developed and studied by ANOVA techniques. These results highlight the effect of wing walls with a floor slab at the outlet and the inlet blockage, showing them to be of major importance. The influence of the tailwater depth and the culvert shape on the scour hole are confirmed as relevant factors, as well as the presence of wing walls. Some interactions have been identified as relevant. The main outcome of this work is the set of factors and interactions that has significant impact on local scour process occurring beside a culvert. This selection is the basis for performing further experimental work in the future to obtain a general empirical law that quantifies this kind of local scour.

Prediction of scour pattern around hydraulic structures using geostatistical methods

Simulation of sediment movement, identification of scour pattern, and sediment variations play an important role in river rehabilitation and protection of hydraulic structures considering their stability and safety. In general, different shapes of abutments (circular, vertical, and wing wall) and also spur dikes were employed to protect against scouring. The main purpose of this paper is to investigate spatial variations of local scour depth around these hydraulic structures using deterministic spatial estimator known as InverseDistance Weighed (IDW), and two geostatistical approaches known as Ordinary Kriging (OK) and Bayesian Maximum Entropy (BME). To achieve this goal, experimental tests were conducted to measure scour pattern under three types of abutments and spur dikes. To evaluate the results of scour depth, leave-one-out cross-validation technique has been used. The comparison of the computed versus observed scour depth depicts that geostatistical methods (OK and BME) can estimate the maximum scour depth more reliably and accurately than IDW method. Experimental results show that the trend of scour depth for all abutment types does not significantly differ. Maximum scour depths at the wing wall abutment were lower than vertical abutment.

Effects of envelope features and upstream buildings on ventilation performance of naturally-ventilated building

In order to study the influence of building facade components (sunshade, wing wall and balcony, etc.) on indoor and outdoor air distribution and indoor natural ventilation in high-density cities being hot in summer and warm in winter, 18 different cases are established to stimulate the effect of natural ventilation frequency of different position in the room by using the computational fluid dynamics (CFD) numerical simulation method through changing the incoming wind direction (wind incidence angle <italic>α</italic>=0° and <italic>α</italic>=45°), the height width ratio of upstream turbulence buildings and vertical and horizontal facade components. The results show the target building generally has a better natural ventilation performance when the wind obliquely incidents on the building (45°). In addition, the effect on ventilation performance of wing walls is highly dependent on the environmental factors including the approaching wind directions, the orientation of the target building and height of the upstream building. The interaction of these parameters affects the flow field characteristics, and changes the effect of facade components on the natural ventilation efficiency of the target building. This study can provide reference for improving the indoor natural ventilation efficiency and air quality by the facade optimization design of the building.

Design of Free Cantilever, Counter fort and T-flanged Cantilever Type Retaining Wall

Retaining walls are widely used as permanent structures for retaining soils at different levels.Type of the wall depends on the soil pressure, such as active or passive earth pressure and earth pressure at rest and drainage conditions. Types of walls generally used are gravity walls, RCC walls, counterfort walls and buttress retaining walls. Retaining walls behavior depends on the wall height and retention heights of the soil at its backfill. Retaining walls are used with tying with more than one wall at perpendicular joints to retain liquids, water storage and materials storages such as dyke walls and tanks. Retaining walls excessively used in culverts and as well as in the bridges for construction of abutment wing walls supposed to resist soil pressures laterally applied perpendicular to the axis of the walls.Based on the present scenario used in retaining structures within the civil industries there requirements of height of walls are being increased due to lake of land and cost of sub structures being incurred in the project work, higher height of walls develops huge bending moment at the base because of the cantilever action of the walls, thus resulting in higher sections at the base which deploys into a uneconomical zone so different wall systems are required in different arrangements so as to transfer the loads with limited sections. In the present study retaining walls of height 6m, 9m and 12m are considered for study and the length of the walls considered as 30m and the material properties considered are M20 and Fe415 steel bars and the supports considered to be fixed at the base.

Numerical modeling of the seismic out-of-plane response of a plain and TRM-strengthened rammed earth subassembly

The importance of raw earth is highlighted by the millions of persons living in earthen buildings around the World and by numerous historical monuments made of this material. Its widely availability led to the development of a variety of building techniques, including rammed earth, which is the main focus of this study. Similarly to unreinforced masonry structures, rammed earth buildings acceptably withstand gravity loads, but are significantly vulnerable to earthquakes. In this regard, great attention has been put on the proposal of efficient, compatible, affordable and reversible strengthening solutions. However, very limited studies address either the experimental testing or modeling of the seismic response of such buildings. The current study investigates the seismic out-of-plane performance of a plain and subsequently strengthened rammed earth subassembly (U-shape) using an advanced finite element modeling approach calibrated based on previously conducted small-scale experiments. Here, failure mechanisms, corresponding capacity and efficiency of the adopted strengthening solution (low-cost textile-reinforced mortar) are evaluated by means of pushover analyses. Then, the reliability of the pushover analyses is assessed by comparing its outcomes with that of the incremental dynamic analyses. In general, the failure was found to be governed by overturning of the web wall due to its detachment from the wing walls, while the strengthening was found to increase the capacity and delay the damage development.

Seismic strengthening and rehabilitation of RC frame structures with weak beam-column joints by installing wing walls

A substantial number of reinforced concrete (RC) buildings with seismically substandard beam-column joints have suffered severe damage in past earthquakes. This paper focuses on the installation of RC wing walls to upgrade weak beam-column joints and to rehabilitate those moderately damaged by earthquakes. Cyclic load tests were conducted using four specimens representing an exterior 1.5-story frame with a beam-column joint. The first specimen was for a benchmark specimen, the second and third were strengthened by installing wing walls to the interior or exterior of the columns, and the fourth was rehabilitated after the existing frame was moderately damaged. Consequently, the benchmark specimen suffered severe damage to the beam-column joint. The two strengthened specimens showed different damage behaviour: the second one was ductile with beam yielding, and the third one prevented the column-sway mechanism. For the rehabilitated specimen, the beam yielded and the maximum strength was nearly equivalent to that of the second specimen in which wing walls were installed to the interior side of the columns, but damage to the joint was more severe. The test results indicated that the developed wing wall installation method is practical not only for strengthening poorly detailed beam-column joints but also for rehabilitating such joints moderately damaged by earthquakes.

OPTIMASI BUKAAN DENGAN MEMANFAATKAN EFEK WIND TUNNEL PADA RUMAH DERET Studi kasus : KAMPUNG DERET PETOGOGAN, JAKARTA

Energyconsumptionon domestic uses in Indonesia provokes designers to implement passive design concept as an effort to reduce the use of mechanical and electrical solution for household comfort. This research observed KampungDeretPetogoganwhich a wind tunneleffect could not accurately provide natural comfort inside the row houses. Openings design was a key element to determineoptimization of air movement indoors, including its positions, types, and dimensions. Thegoals wereto identify the causes and determine ideal openings design to optimize air circulation indoors. First assessmentinvolvedrelevantdesign theories that conducted as guidelines. Then the existed design openings were examined and compared with guidelines, thus the ideal design openings were generated. The final results concluded multiple solutions for optimizing air movement control. Anaddition of wing wall, to help control the air movement. Repositioning the openings, both on walls and roofs. The selection of opening types which would be suitable basedonairmovement pattern. Lastly, redesign the dimension of the openings to fit the needs of natural comfort inside the houses.