Low Roof Research Articles

Protecting occupants during passenger vehicle rollover crashes

Protecting occupants during passenger vehicle rollover crashes

Rock Deformation Behavior Near Excavations Under the Influence of High Tectonic Stress in Coal Seam V-12, “Severnaya” Mine, JSC “Urgalugol”

The article is devoted to determination of roof bolt parameters in coal mine excavations when there is rather high tectonic stress. The work was complicated by the presence of considerable number of fractures in the adjacent rock of seam V-12 in “Severnaya” mine (JSC “Urgalugol”) as well as variable stress field, low roof rock strength and heterogeneity, considerable rock shift during excavations development and maintenance. The article presents the results of horizontal and vertical stress measurements in the rock mass, physical and mechanical properties, roof rock structure and fracturing. According to the results of boreholes study by means of borehole endoscope the authors fully confirmed the forecasted parameters of areas with roof rock discontinuity, the boundaries of unstable rock. The article presents the measurement results of roof rock shift during development face advance. Based on the research, recommendations on excavations development and proper support using were given under conditions of seam V-12 in “Severnaya” mine (JSC “Urgalugol”).

Morfoscopia e Morfologia da Cobertura Pedológica às Margens do Rio Uruguai no Oeste de Santa Catarina

Knowledge and interpretation of the sedimentary record of surface coverage and landscape soil is a valuable tool for understanding the paleoenvironment and its changes Pleistocene/Holocene why this happened during the last few thousand years of the Quaternary period. In this sense, from the pedostratigraphy and morfoestratigraphy point of view, this work intends to contribute to the understanding of the genesis of soil cover on the banks of the Uruguay River and its paleoenvironmental context that contains evidence of pre-Columbian populations along this pedogenizado stuff in Aguas de Chapeco. Through morphological description and analysis morphoscopic of sands of three representative pedological profiles of low slope roofs, it is concluded that the morphoscopic analysis provided evidence of fluvial participation in both the banks of the Uruguay River where the study area is located. But the morphoscopic analysis was inefficient to distinguish the genetic origin of soil horizons in terms of allochthonous or autochthonous them.

A Field Study to Evaluate Runoff Quantity from Blue Roof and Green Blue Roof in an Urban Area

This study evaluated performance for runoff management of the Blue roof and Green blue roof comparing monitoring data measured at two low impact development (LID) facilities and control roof in Seoul metropolitan area. From the results these two roofs proved as suitable stormwater management practices in urban areas. For this purposes, Blue roof and Green-blue roof were installed at Seoul City Hall Annex Seosomun and Cheong-un middle school respectively. The data used for this study were collected during the actual storm events of more than 30 mm/hr and 60 mm/hr rainfall intensity in July and September 2014 at green blue roof and blue roof. During different actual storm events, rainfall runoff outflow was measured from blue roof was 0.45 l/s as compared to common roof where outflow was 1.55 l/s. While on the other hand, the outflow from green blue roof was 0.1 l/s to as compared to control roof where the runoff outflow was 0.3 l/s. Results also indicated the peak flow reduction in both types of roofs. From the results, it was found that Green blue roof is capable of handling effectively long duration rain events than blue roof. However, the blue roof is inexpensive than green blue roof and suitable option for retrofitting in urban areas. These results also revealed that Blue roof and Green blue roof could be applied to urban buildings as the suitable management practices for rainfall runoff management in urban areas. At the end, from theoretical analysis some suggestions are also made which could be apply for the more safe sustainable drainage system of an urban area.

In situ measurements of wind pressures on low slope membrane roofs

Pressure distributions created by wind flow on low slope roofs is an issue addressed by many wind tunnel studies and selective field experimental studies. Building codes and standards specify pressure coefficient data to determine the wind loads for commercial roofing claddings. Field measurements can provide valuable data to validate the current code provisions for wind loads, as well provide supporting data for existing wind uplift test methods for roof claddings. Thus the Special Interest Group on Dynamic Evaluation of Roofing Systems (SIGDERS) selected four locations (Ottawa, Vancouver, Mt. Pleasant and Rialto) across North America and collected wind speed, wind direction and wind pressure data for extended time periods to understand the wind interaction with low slope membrane roofs. This paper presents the data collected from November 2012 to November 2013 from the Ottawa, Ontario site.Based on the National Building Code of Canada׳s (NBCC) zoning procedure, pressure taps were installed to obtain data for the corner, edge and field roof zones. Occurrences of wind speed exceeding 16ms−1 were considered for various wind directions. Peak and mean pressure coefficients were calculated and compared with NBCC (2010)’s specifications. When instantaneous peak pressure coefficients were compared with the NBCC (2010), the measured data exceeded NBCC (2010)’s specifications for some wind directions. Nevertheless, when the pressure coefficients were compared by paring with their respective tributary area, the data concluded that the current NBCC (2010)’s specifications for the roof cladding and components are equally adequate for the wind load design of low slope membrane roofs.

Partial collapses experienced for a steel space truss roof structure induced by ice ponds

This paper presents investigations on the steel space truss roof of an industrial plant collapsed partially after exceptional snowfalls. This low sloped light weight roof structure supported on steel columns of 16.3m height and covering totally 26,080m2 closed area in plan was constructed as Mero type double layer grid steel space truss system having a height of 2m. Also, parapets of 90cm height were placed along the perimeter of the building and siphonic system was used for roof drainage. To find out the main reasons of the partial collapse of the roof structure, a site investigation was conducted and findings were collected, then conformity of the structural members were checked with respect to the current Turkish steel building design codes. The material properties of the primary load carrying members of the roof were scrutinized by performing tensile tests. Finally, it was understood that two unexpected catastrophic collapses were experienced as a consequence of ice ponds that occurred on the edge regions of the roof due to discontinuously heated roof parts by the radiant heaters mounted on the roof structure and the freezing of the siphonic system.

Wind Loads on the Frames of Industrial Buildings

The structural response of typical, gable-end, low roof pitch industrial buildings, in a windstorm is dependent on the wind loads used in the design of cladding and the portal frame structure. Critical, structural wind load effects derived from wind loads measured on a wind tunnel model show that standards such as AS/NZS 1170.2 can produce unconservative design load effects on the heavily loaded first internal frame. This paper forms part of wider study that assesses the vulnerability of hot rolled steel, industrial buildings to wind loads. The knee and ridge bending moments and horizontal and vertical reactions at the base of the frame are the critical load effects that are used in the design of structural members and connections of these types of buildings. This study found that some of these load effects based on external pressures are under-estimated by about 30%, when the building is located in a suburban environment. A dominant windward wall opening can effectively double the design load effects, thus significantly increasing the vulnerability, especially if this scenario has not been considered by the designer.

Structural Behavior for Low Cost Roof System of Steel Frame and Thermo-Stone Blocks

Structural Behavior for Low Cost Roof System of Steel Frame and Thermo-Stone Blocks

Low Cost Roof System For Rural Housing

1.1 Near about 5.6% of the total tribal population of India live in “MEWAR” and “VAGGAR” region of Rajasthan state. In this region, lot of tribals are residing in the out-skirts of Banswara, Udaipur, Pratapgarh and Dungarpur districts. They prefer to live in the jungle with the nature and build their huts by using local material and local skill. It is imperative to introduce the innovative technology of the construction of rural cost-effective huts, which is based on the adoption of the local environment and constructed with the house-hold themselves without the need of the modern tools & equipment. If, we analyze the building costs and its break up, it is observed that the main components of the building are foundation, wall, roof, door & window, flooring and finishing etc. The maximum expenditure for rural houses after construction of walls is in roofs which is 25 % of total expenditure. Therefore, to reduce the cost of the roof of the rural houses this study was under-taken. Necessary sustainable cost-effective techniques are developed for supporting system by use of Bamboo roof trusses and Bamboo spaced column for costeffective rural huts. The average cost break-up of rural hut are shown as below A rural house is a structure providing the suitable place for protecting rural people from heat, cold, rain and wild animals. It can be built with different types of roof covering materials like thatch, tiles, slate, galvanized iron sheets and corrugated asbestos sheets over a supporting structure at present it is a baulk or trunk of a tree and the mud walls. In place of the high cost of supporting structure, bamboo trusses are introduced as the cost-effective system for supporting the roof covering

Fuel Economy and Emissions Effects of Low Tire Pressure, Open Windows, Roof Top and Hitch-Mounted Cargo, and Trailer

To quantify the fuel economy (FE) effect of some common vehicle accessories or alterations, a compact passenger sedan and a sport utility vehicle (SUV) were subjected to SAE J2263 coastdown procedures. Coastdowns were conducted with low tire pressure, all windows open, with a roof top or hitch-mounted cargo carrier, and with the SUV pulling an enclosed cargo trailer. From these coastdowns, vehicle dynamometer coefficients were developed which enabled the execution of vehicle dynamometer experiments to determine the effect of these changes on vehicle FE and emissions over standard drive cycles and at steady highway speeds. The FE penalty associated with the rooftop cargo box mounted on the compact sedan was as high as 25-27% at higher speeds, where the aerodynamic drag is most pronounced. For both vehicles, use of a hitch mounted cargo tray carrying a similar load resulted in very small FE penalties, unlike the rooftop cargo box. The results for the SUV pulling a 3500 pound enclosed cargo trailer were rather dramatic, resulting in FE penalties ranging from 30%, for the city cycle, to 50% at 80 mph, at which point significant CO generation indicated protective enrichment due to high load. Low tire pressure cases resulted in negligiblemore » to 10% FE penalty depending on the specific case and test point. Driving with all four windows open decreased FE by 4-8.5% for the compact sedan, and 1-4% for the SUV.« less

하수처리구역 내 LID 적용에 대한 적정비율 및 효과분석 연구

지나친 도시개발은 불투수면적의 증가로 인한 유출 증가를 야기하며 이는 홍수 및 비점오염에 대한 문제 및 기저유출감소로 인한 지하수위 감소에 따라 하천을 건천화시키는 문제를 발생시킨다. 이러한 문제를 해결하기 위한 방안으로 저영향개발(LID, Low Impact Development) 기법이 제시되고 있다. 즉, LID 기법을 적용함으로써 개발 이전의 수문순환 상태를 모사하여 개발로 인한 영향을 최소화하고 물 순환구조를 개선하고자하는 연구가 진행되고 있다. 국내에서도 LID 개념의 도입이 지속적으로 증가함에 따라 소규모 배수 분구를 중심으로 연구가 진행되고 있다. 또한, 중규모 이상의 유역에 LID 기법을 적용 시 유역 내 수문학적 유출 특성과 오염 발생 특성 변화에 대한 분석 방안이 요구되지만 하수처리분구 단위의 수문학적 영향을 분석 할 수 있는 연구는 미흡한 실정이다. 본 연구에서는 하수처리 구역 내 LID 기법의 적용에 따른 물순환 개선효과와 비점오염 저감효과 분석 및 기존 관리기법과의 비교를 통해 유역관리 측면에서의 적정 LID 설치면적 추정 방안을 검토하였다. LID 적용효과 분석을 위하여 소규모 배수 분구인 부산시 동래천 유역과 하수처리구역인 온천천 유역을 대상유역으로 선정하였으며 동래천 유역을 대상으로 LID 요소기술의 적용가능 면적을 추출하고 비율로 환산한 후 온천천 유역으로 확대 적용하였다. LID 요소기술 중 우리나라의 토지이용 밀집도를 고려하여 적용이 용이한 Green Roof와 Porous Pavement 및 도로에 설치되는 Street Planter를 선정하였으며 유역별로 구축된 LID 기법 기반의 SWMM 모형을 이용하여 토양특성과 강우특성을 고려한 물순환 기능 개선효과 및 비점오염량 저감효과를 분석하였다. 또한 온천천 유역을 대상으로 기존 비점오염 관리방안인 오염원 및 방류량에 따른 처리효율과 LID 적용 시의 처리효율을 비교하였으며 비교자료를 토대로 유역관리와 비용적인 측면을 고려한 적정 LID 설치비율로서 기존 비점오염 관리방안의 처리효율을 만족하는 LID 설치비율을 선정하고 이에 대한 적용 가능성을 검토하였다. Increase of impervious area caused by overdevelopment has led to increase of runoff and then the problem of flooding and NPS were brought up. In addition, as decrease of base flow made groundwater level to decline, a stream that dries up is issued. low impact development (LID) method which is possible to mimic hydrological water cycle, minimize the effect of development, and improve water cycle structure is proposed as an alternative. As introduction of LID in domestic increases, the study on small watershed is in process mainly. Also, analysis of property of hydrological runoff and load on midsize watershed, like sewage treatment district, is required, the study on it is still insufficient. So, area applying LID practices from watershed of Dongrae stream is pinpointed and made the ratio and then expand it to watershed of Oncheon stream. Among low impact development practices, Green Roof, Porous Pavement, and Bio- retention are selected for the application considering domestic situations and simulated with SWMM-LID model of each watershed and improvement of water cycle and reduction of non-point pollution loads was analysed. Improvement of water cycle and reduction of non-point pollution loads were analyzed including the property of rainfall and soil over long term simulation. The model was executed according to scenario based on combination of LID as changing conductivity in accordance with soil type of the watershed. Also, this study evaluated area of LID application that meets the efficiency of conventional management as a criteria for area of LID practices applying to sewer treatment district by comparing the efficiency of LID application with that of conventional method.

Path Loss Correction for Signal Propagation amongst Low Roof Top Buildings using Fuzzy Logic

Performance of current path attenuation prediction models encounters huge deviation from their true behavior when deployed for the locality apart from the one for which it had been proven for. This work deals with introducing the path loss on the basis of measured data and representation of the same in a different approach for the mentioned Fuzzy Inference system based analysis. The empirical data collection followed by curve-fitting for path loss evaluation on decibel scale with Normal random variable distribution for representing the shadow fading. Our paper introduces a new methodology for prediction of path loss for betterment in QoS via. Network planning specifically for mobility prone communication systems deploying fuzzy approach. The Transmission discontinuities encountered during propagation has been differentiated in to a variety of factors defined as fuzzy sets such as free space, flat terrain, low foliage terrain, high foliage terrain, and country side terrain. path loss exponent (n) has been applied for varied propagation profiles, Mamdani Fuzzy Inference has been deployed for prediction of “n” path loss exponent for any kind of scenario, which was obtained on the basis of set of symbolic rules that avails an approximation to the known propagation scenarios. Bertoni’s model proposed by H.L. Bertoni’s has been used for the present analysis.

Calibrating air heating and power generation capacities of low and high efficient BIPV roofs for housing application in Scotland

This study was conducted with the aim to assess the potential performance of a photovoltaic thermal mechanical ventilation heat recovery (PV/T MVHR) system. The device is currently considered for the application to the Z-en house project undertaken by Scottish homebuilder. The house’s whole energy demand was calibrated based on the UK Government’s standard assessment procedure for energy rating of dwellings, while the PV/T performance was estimated using an ‘EESLISM’ energy and environmental design simulation tool developed by Kogakuin University. This study concluded that PV generates heat, which makes the fresh air running under the PV roof 10–15 °C warmer than the outside temperature even during the Scottish winter and this warm air extracted from roof-integrated PV modules can be used to help reduce the domestic space-heating demand. Thus, the building-integrated PV/T MVHR system was considered as one of the effective means to assist the net zero energy operation of housing in cool and cold climates, whose dominant domestic energy comsumption derives from space heating.

Effects of Geometrical Factors on Wind Pressure Characteristics of Cylindrical Roofs with Wind Tunnel Tests

With wind tunnel tests, simultaneous pressure measurements are made on 4 cylindrical roof models with different rise-span ratios and roof inclinations. Effects of these geometrical factors on wind pressure characteristics of the roofs are investigated, including mean pressure coefficients, RMS pressure coefficients, skewness, kurtosis, and probability distributions of wind pressure. Results show that the mean vertical wind force coefficient of high rise-span ratio roof is larger than that of the low rise-span ration roof; the mean pressure coefficient distribution of the low rise-span ratio roof is similar to that of RMS pressure coefficients and the skewness (or the kurtosis); the vortex center line occurs at the windward edge for the low rise-span ratio roof with inclination 0°, which occurs at the roof apex for the high rise-span ratio roof. The roof inclination has more effects on the low rise-span ratio roof, the vortex moves from the windward edge to the apex for the roof with inclination 7.2°when the wind flows from the low eave to the high eave. The distribution of the skewness is strongly correlative to that of the kurtosis. The probability distributions of the roof edges and corners deviate obviously from the Guass distribution. If this point is ignored, the peak suction pressure will be underestimated.

The Selection of the Difference Scheme in Numerical Simulation of Low-Rise Gable Roof Surface Pressure

Using the FLUENT software, this paper taking the wind load shape coefficient in the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on low layer double slope roof. It focused on the effect of four convective term difference schemes on the numerical simulation, such as First-Order Upwind, Second-Order Upwind, Power Law and Quadratic Upwind Interpolation for ConvectiveKinematics. It provided reasonable reference for selection of convective term difference format.

Equivalent Static Wind Loads on Low Rise Buildings

The many low rise roof structures are sensitive to the effects of fluctuating wind load. In engineering design for the structures, spatiotemporally varying wind loads on the low rise roofs are modeled as equivalent static wind loads. In this paper, the equivalent static load of the large span roofs is formulated in terms of either a weighted combination of modal inertial load components, and the resonant and background load components that was obtained by the POD (Proper Orthogonal Decomposition) and LRC (Load –Response -Correlation) techniques.

大岡實の「復元」建築

On 5 historic reconstructions designed by Minoru Ooka, especially external appearance, such as delicate curved roof shape, was faithfully recreated based on academic investigation. The structure was basically reinforced concrete, but he attempted to keep the original proportion of wooden structural members by means of, for instance, manipulation of sectional modification of posts and beams. Among his works, Yakushiji Golden Hall (1976) is one of the most characteristic specimen that reveals his idea toward historic reconstructions. He tried to revive original architect's design concept as representation of the aesthetics of the same period, which was shown in the number of columns (6×3) on the upper floor, the gradually raised ceiling heights toward the inner sanctum, and the roof shape; high pitched gable and low pitched hip roof(shikoro-buki) that has, he thought, aesthetical importance on the ancient architecture.

Practical Design Method of the Snow Load for the Low Rise Roof Structures

The large span roof structures need to be designed to withstand wind and snow loads. This paper presents practical design method of snow load for low rise roof structures in GB 50009-2001(China), ASCE 7-10, AIJ 2006, NBCC 2005 and Euro code 2003, and discusses approaches to improving consistency and uniformity of methods by comparison of the differences and similarities of wind and snow provisions in the codes of various countries.

The Turbulent Flow Model Selection for Numerical Wind Tunnel Simulation of the Low Layer Double Slope Roof

Using the FLUENT software, this paper taking the current code for the design of building structures as the comparison standard, have numerical wind tunnel simulation of the wind the surface wind pressure on low layer double slope roof. It focuses on the analysis of the effects of turbulence model selection on the numerical simulation results, such as Spalart-Allmaras、Standard k −ε、RNG k −ε、Realizable k −ε、Standard k −ω、SST k −ω and RSM, to provide a basis for the reasonable selection of turbulence models.

Method of the Snow Load for Design of the Low Rise Roof Structures in the Different Country Codes

Snow load is very important for the design of the large span roof structures in the cold region. The determine of the snow loads are influenced by many factors, such as wind, shape of the roof , terrain categories and so on, therefore comprehensive consideration of the transport and drift by the strong wind for design of the roof is very complex. Compared with other countries load codes, the China load code don’t detailed consider wind and snow interaction effect, the method of snow load for design has some further improved terms.