Terrain Categories Research Articles

Site database for national strong motion stations in mainland China

Ground motion amplification and spectral content are significantly influenced by local soil and geological conditions. This article summarizes the development of the China Site Database (CNSDB) in the China Ground Motion Flatfile project. CNSDB contains site information for 1450 strong-motion recording stations within the National Strong Motion Observation Network System (NSMONS) in China. The primary site information in CNSDB includes the time-averaged shear-wave velocity in the upper 30 m (VS30), and site class according to the seismic design code in China. These site data are derived using different methods from various data sources. Priority is given to approaches that minimize bias and dispersion relative to measurement-based results. Recommended VS30 values and site class are derived from reliable velocity profiles or field survey results whenever available. A China-specific VS30 extrapolation model is developed using 6179 engineering boreholes and is then utilized to estimate VS30 for profiles <30 m. VS30 values and site class are estimated from horizontal-to-vertical spectral ratio (HVSR) curves of earthquake recordings using machine-learning techniques. For the remaining sites without velocity profiles or sufficient ground-motion recordings for HVSR computation, VS30 values are determined as the weighted average of proxy-based estimates using geological attributes, topographic slope, and terrain categories. We also discuss the potential application of CNSDB in the development of China seismic hazard map considering site amplification factors.

A Parametric Analysis of Wind-Loaded High-Rise Constructions in Various Terrain Types with Bracing

Abstract: This study tries to provide a hypothetical structural design for a tall building in a city. It is very important for civil engineering students to think about how structural systems can enhance the architectural expression of a building. Wind is the governing load when building high-rise structures in the city. A building can be structurally improved to resist wind pressure by making changes to the basic design, which gives it a unique architectural expression. In this study, G+10 and G+20 storey structures is designed and compared in two terrain categories and subjected to wind load. The ruggedness of the environment where the fabric structure is located is measured by the Terrain category. Wind speed, wind direction, and exposure to the elements are examples of such variables. Earthquake and wind loads are applied to the ETABS model according to the given National Standards. Finally, it is determined how strong and flexible the structure is under these stresses. The output of the calculation program and additional calculated products are compared to the Indian limit for structural serviceability.

JPSSL: SAR Terrain Classification Based on Jigsaw Puzzles and FC-CRF

Effective features play an important role in synthetic aperture radar (SAR) image interpretation. However, since SAR images contain a variety of terrain types, it is not easy to extract effective features of different terrains from SAR images. Deep learning methods require a large amount of labeled data, but the difficulty of SAR image annotation limits the performance of deep learning models. SAR images have inevitable geometric distortion and coherence speckle noise, which makes it difficult to extract effective features from SAR images. If effective semantic context features cannot be learned for SAR images, the extracted features struggle to distinguish different terrain categories. Some existing terrain classification methods are very limited and can only be applied to some specified SAR images. To solve these problems, a jigsaw puzzle self-supervised learning (JPSSL) framework is proposed. The framework comprises a jigsaw puzzle pretext task and a terrain classification downstream task. In the pretext task, the information in the SAR image is learned by completing the SAR image jigsaw puzzle to extract effective features. The terrain classification downstream task is trained using only a small number of labeled data. Finally, fully connected conditional random field processing is performed to eliminate noise points and obtain a high-quality terrain classification result. Experimental results on three large-scene high-resolution SAR images confirm the effectiveness and generalization of our method. Compared with the supervised methods, the features learned in JPSSL are highly discriminative, and the JPSSL achieves good classification accuracy when using only a small amount of labeled data.

Potential and performance for classifying Earth surface only with ICESat-2 altimetric data

The huge volume of data from the Ice, Cloud and land Elevation Satellite-2 (ICESat-2), designed for mapping polar ice, sea ice, and continental vegetation, requires a highly automated data analysis and reliable terrain classification. In particular, we have developed a method to identify 4 distinct terrain categories in observed terrain, namely ocean, land, sea ice, and ice sheets. This study performed the following efforts: first, the spatial distribution characteristics for each of the 4 categories within individual ICESat-2 “major frames” along the orbit were extracted; second, these features were fed into Classification and Regression Tree (CART) and Random Forest (RF) for training; and lastly, post-processing enhancement was used to improve the classification results. Based on the 76,891 major frame samples (10,764,740 m along track) acquired via various ICESat-2 datasets, the accuracy of the two model were calculated using ten-fold cross-validation. The results indicate that the RF algorithm obtained higher classification accuracy (average accuracy [AA] = 0.9353, overall accuracy [OA] = 0.9342, and Cohen’s Kappa coefficient [kappa] = 0.9122) when compared with the CART algorithm (AA = 0.9066, OA = 0.9057, and kappa = 0.8743). Overall, our approach can effectively reduce the workload of human field investigation or visual inspection of altimetry data, improve the accuracy for Earth surface classification, and add to the variety of ways to obtain global surface information from ICESat-2 data.

SURVEY AND ROAD MEASUREMENT TECHNIQUES IN POJA VILLAGE, SAPE SUB-DISTRICT.

The development of road access is currently a very important thing in infrastructure development in a country. Good road access can facilitate community mobility and support economic growth. Currently, the government is trying to improve road access in every region and village through the construction of new roads, repairing existing roads. The implementation method of measuring new roads is an important process in infrastructure development. This method involves the use of specialized equipment such as distance measuring devices and angle measuring devices. The purpose of this service activity is to determine the length, width, elevation and slope of the new road terrain. The location of the activity is Poja Village, Sape District, Bima Regency, West Nusa Tenggara. The results of the road terrain slope analysis on the Poja Village road section, Sape District, Bima Regency, were calculated at each STA with a distance of 500 meters for each STA. Obtained road terrain slope STA 00+000 - STA 00+500 is 0.2%, STA 00+0500 - STA 01+000 is 0.8%, STA 01+000 - STA 01+500 is 0.4%, STA 01+500 - STA 02+000 is 0.6, STA 02+00 - STA 02+500 is 1.8%, STA 02+500 - STA 03+00 is 1.2%. And the road section of Poja Village, Sape District, Bima Regency is included in the Flat (D) road terrain category, because all segments every 500 meters have a value smaller than 3%.

A Comparative Study of Analyzing the Impact of Various RCC Building Shapes on Wind Performance

The analysis, design, and creation of high-rise buildings necessitate a comprehensive information of wind-induced vibration, a critical factor that considerably impacts structural integrity. In this context, the existing study undertakes an exploration of the results of wind load on diverse building shapes, aiming to envision the most structurally stable configuration for multi-storey structures. Focusing usually on L-form and H-form buildings, the studies conduct a comparative evaluation to assess how wind load influences those distinct shapes. Each case study represents a structure located in Wind zone IV with Terrain category II, adhering to the specs mentioned in IS 875(part-3): 2015 standards. Emphasizing reinforced concrete (RCC) framed structures, the research delves into the repercussions of wind loads on critical parameters including maximum shear force, bending moment, and storey displacement. The resulting data is meticulously presented through tables and charts, elucidating the overall performance metrics for every case (H-shape and L-form) in terms of storey displacement, shear force, bending moment, and axial force. Eventually, an intensive evaluation is conducted to determine any disparities in structural behaviour and reaction to wind loads a number of the various constructing shapes, providing precious insights into most efficient design concerns for enhancing structural stability and resilience in excessive-rise constructions.

Structural parameters of Wrench – C shape building using CFD

Wind flow pattern and generation of strong and large eddies is mainly responsible to the wind pressure and suction intensity in and around the tall building. If the shape of the structure is not vary common then the wind generated effects need to evaluate for the high rise structure this is because of the reason that the data for the regular plan cross sectional shape is available in the various international standards. This study investigating the wind effects on irregular cross sectional shape tall building using CFD tool ANSYS CFX. The current study evaluates the wind impacts for a boundary layer atmospheric wind flow from 0° to 180° at a 15° interval. The power law described in IS: 875 (Part 3): 2015 for terrain category II follows the wind profile. For a rectangular model, the values of the pressure coefficients are compared using the numerical simulation and the information supplied in IS 875. Results are given at numerous locations, including pressure coefficients around the building model’s periphery and force and moment coefficients for wind incidence angles ranging from 0° to 180° at 15° intervals.

Safety of an express freight train running over a bridge in crosswind

Owing to the blunt car body and high design speed of express freight trains, the running safety is significantly affected by crosswinds when the train runs over a bridge; moreover, severe accidents, such as derailment or overturning may occur. Therefore, adequate measures should be adopted to avoid the occurrence of such accidents. In this study, a finite element model of the train, ballastless track, and parameterized 5-span simply supported girder bridge along with modal superposition method are adopted to establish the train-track-bridge coupling dynamic system. Numerical simulation of stochastic wind speed, wind tunnel tests, and computational fluid dynamics (CFD) simulation of vehicle-bridge scale model were conducted to calculate the wind load acting on the train and bridge. The dynamic responses of the bridge and train were evaluated to present the diagrams of wind and train speed limits for safe operation. The results indicated that the running safety of the vehicle declined with the wind and train speeds, and the wheel unloading rate was the most sensitive to wind speed. For safe operation, the train speed must be restricted if the mean wind speed is greater than 22.7 m/s, and an extreme scenario of derailment may occur for a mean wind speed of 34.0 m/s. In addition, the wind speed limit should be appropriately adjusted and improved according to the pier height of the bridge and terrain category. This research provides a theoretical basis and data support for the assessment of safety of express freight trains in actual operation.

Comparison of wind-resistant capacities of standing seam roof systems under static uniform pressures and dynamic non-uniform wind pressures

Static uniform pressure tests are widely recommended to determine the ultimate capacities of standing seam roof systems in many building standards and guidelines, but such ultimate wind-resistant capacities are usually much different from those under dynamic non-uniform wind pressures. Through the comparison of the ultimate capacities of standing seam roof systems under static uniform pressures and dynamic non-uniform wind pressures by finite element simulations, the definition and calculation steps of influence coefficients of dynamic non-uniform wind pressure distribution (ICDNWPD) are proposed to reflect the effects of actual wind pressure distributions on wind-resistant capacities of the roof cladding systems. The effects of roof zones, support spacings, and terrain categories on the ICDNWPDs of flat roofs are investigated. The results show that the ICDNWPDs of the edge and interior regions are approximately 1.27–1.42 times those of the corner zones, and the ICDNWPDs are more sensitive to the roof zone than the support spacings and terrain categories. The factors of safety of roof systems with larger spans or under smoother terrain or located in the roof corner zone should be greater, which cannot remain constant.

Systematical structural analysis of monolithic domes

Monolithic dome structures were built in the 1970s in Europe and America. These dome structures share common benefits of being cost efficient, earth-friendly, extremely durable, and easily maintained. Monolithic shells are easily constructed and are extremely cost-effective. Monolithic domes respond efficiently to any climate, even to extremely cold or hot temperatures. In terms of utility savings, monolithic domes can cut electricity consumption by up to one-third, thereby saving 60–70% of total energy costs. Moreover, monolithic structures provide the highest survivability rates from destructions. The interior of monolithic domes have perfect, concave shapes to ensure that sound travels through the dome and perfectly collected at different vocal points. These dome structures are utilized for domestic use because the scale allows the focal points to be positioned across daily life activities, thereby affecting the sonic comfort of the internal space. This study examines the various acoustic treatments and parametric configurations of monolithic dome sizes. A geometric relationship of acoustic treatment and dome radius is established to provide architects guidelines on the correct selection of absorption needed to maintain the acoustic comfort of these special spaces. In this study we cannot take the particular research paper for comparison of results. The location of structure for terrain category I calculated and so the wind speed varies according to terrain and this results in different value of load calculation for different terrain category.

A Heterogeneous Ensemble Approach for Terrain Classification with Tracked Mobile Robots

Terrain classification plays a vital role in the autonomous driving of tracked mobile robots. This article proposes a heterogeneous ensemble method to enhance the classification performance with weak classifiers. Combined with principal component analysis (PCA) and ReiefF, a feature selection approach aims to find an effective feature set. Based on the proposed method, the framework has been developed to simplify the signal process in feature extraction. Extreme Learning Machine (ELM) is utilized as the individual classifier for three kinds of signal sources. With the learning process experience, ensemble weights have been generated to support the whole ensemble flow, which is closely correlated with terrain categories, classifiers and signal sources. Due to the structure of tracked mobile robots, the application maneuvers are extended to the front and rear drive modes, while the steady-state turning and straight-line maneuvers. The results demonstrate that the proposed method can significantly enhance the performance of terrain classification.

Regional terrain-based VS30 prediction models for China

Time-averaged shear-wave velocity to 30 m (VS30) is commonly used in ground motion models as a parameter for evaluating site effects. This study used a collection of boreholes in Beijing, Tianjin, Guangxi, Guangdong, and three other municipalities and provinces, which were divided into three regions with reference to the seismic ground motion parameter zonation map of China, to establish VS30 prediction models based on terrain categories. Regional effects were verified by comparing morphometric parameter (topographic slope, surface texture, and local convexity) thresholds and terrain classification maps obtained from global digital elevation model (DEM) data and regional DEM data of the three regions. Additionally, VS30 prediction models for the three regions using both types of terrain classification maps were established and analyzed comparatively to provide credible regional VS30 models for China. Through analysis of the correlations between the measured VS30 values and the predicted VS30 values, calculation of the mean squared error and mean absolute percentage error in each region, and with consideration of the geological characteristics of the boreholes, the VS30 prediction models based on terrain classification maps from regional data were finally applied in developing regional VS30 models for China. Intercomparison of the VS30 prediction models for the three regions indicated that subregional consideration is necessary in terrain classification. Finally, a spatial analysis method adopting inverse distance weighting of the residuals was used to update the initial VS30 models. The developed VS30 models could be used both in developing regional ground motion models and in the construction of earthquake disaster scenarios.Graphical

Study The Effects Of Various Wind Loadings In High Rise Rc-Framed Structures In Zone –V

The construction of high-rise buildings, both residential and commercial, is increasing. Every structural designer must be aware of the forces such as earthquake and wind effects. Every engineer is challenged to provide stability and strength for loads such as lateral forces (wind and seismic loading). That is why wind loading has become one of the most important issues in high-rise buildings. Lateral loads are crucial for drift; therefore, drift must be considered for high-rise structures. This research work focuses on the effects of various wind loads on high-rise structures with the provision suggested in IS 875(part 3):2015 and for seismic load using IS code 1893(part1):2016. For the study, four irregular plan building is used with G+20 story in seismic zone V and terrain category II with a basic wind speed of 44, 47, 50, and 55 m/s that is analyzed and designed using the structural analysis software tool STAAD Pro. The bending moment, shear forces, story displacements, story shear, and story drift are analyzed on every level of height on the building, and the results are compared with them.

Wind Analysis of RCC Tube in Tube Structure Using ETABS Software

Abstract: The advancement in construction field is increased day by day. The numbers of buildings, height of building is increased. The effect of lateral load is increased with respect to the increase of height. Advance construction methods and structural systems are to be introduced to enhance the structural safety. There are different types of structural systems which are to be used to resist the effect of lateral loads on the buildings. tube, bundled tube, tube in tube, and tube mega frame structures tubular structures. A tube-in-tube structure Comprises of a peripheral framed tube and a core tube interconnected by floor slabs. The frame tube structure takes more of lateral load the efficiency of this system is derived from the great number of rigid joints acting along the periphery, creating a large tube. In which the horizontal slabs and beams connecting vertical elements are assumed as continuous connecting medium having Equivalent distributed stiffness properties. The tube-in-tube structure with central tube provides stability against lateral loading as well as gravity loading. The Static analysis is use for analysis of tubular structures and the output of the models are evaluate to have a comparative study of their wind performance in different terrain, Also, this system provides enough opening for stairways, elevators and ducts etc. It is suitable for high rise structure. The use of tube-in-tube structure allows speedy construction. It is suitable for RCC, constructions. This study is focused on wind behavior of tube in tube structure for varying terrain category in India for the parameters like wind displacement, story drift, and time period.

Refined prediction of crosswind forces on rectangular tall buildings with different side ratios

The crosswind responses of tall buildings are complicated due to numerous influencing factors. However, the relevant codes for estimating the crosswind responses have a limited application scope and the corresponding empirical formulas may cause inaccurate assessment of structural responses due to the fitting errors. This study aims to achieve more accurate and flexible predictions of the crosswind forces and wind-induced responses of rectangular tall buildings in comparison with using the conventional empirical formulas. A series of high-frequency force balance (HFFB) tests was conducted on rectangular tall buildings with side ratios from 0.2 to 5 to investigate the crosswind force spectra and the root mean square (RMS) base moment coefficients in two terrain categories. The crosswind force spectra and the crosswind responses of the structure were predicted by using the new proposed formulas and genetic algorithm-backpropagation (GA-BP) neural network, respectively. The results showed that the RMS crosswind base moment coefficients of rectangular tall buildings generally increase with the increase in the side ratio, and can be expressed as piecewise functions related to the side ratio. The proposed formulas can effectively predict the crosswind force spectra of rectangular tall buildings with different side ratios. Compared with the traditional nonlinear fitting method, the GA-BP neural network has higher fitting accuracy and stronger ability for extrapolation prediction. Combined with the random vibration theory, the GA-BP neural network can accurately predict the crosswind responses of rectangular tall buildings. By comparing with the relevant codes, it shows that the crosswind responses of rectangular tall buildings under different side ratios are overestimated to different degrees by GB 50009-2012.

Pressing and Rubbing: Physics-Informed Features Facilitate Haptic Terrain Classification for Legged Robots

Non-geometric hazards like sinkage and slipping, correlated to terrain categories, have an apparent effect on the locomotion of legged robots. Tactile-based terrain classification is a more accurate way to distinguish terrains in different properties than the vision, but selecting representative features instead of cumbersome ones in the complex foot-terrain interaction for efficient classification is still a challenge. In this letter, two specific leg motions are designed to inspect terrain bearing and friction properties, and manually designed features are extracted based on the foot-terrain interaction model for classification. These features are physics-informed, tidy and interpretable, and can be used with different classifiers under different foot configurations. Four classic classifiers with physics-informed features are trained for terrain classification and evaluated on our self-developed dataset. At the same time, the proposed method was compared with other two methods: an artificial feature extraction method and a CNN-based method. The results show that our proposed method reaches remarkable precision in terrain classification and can still guarantee a high accuracy under a small number of training samples.

Impact of Vertical and Horizontal Shape Modification on Tall Structure Subjected to Dynamic Wind Load: A Review

Abstract: In modern scenario rapidly increasing population resulted in scarcity of land. High-rise buildings are solution of this inevitable problem for providing accommodation to large amount of people in significantly less amount of land on affordable price. Skyscraper structures are more revered to twist powers at higher height focuses. At these points static analysis fails to give satisfactory results. To defeat these different nations incorporated the arrangement of Gust Effectiveness Method which considers the unique properties of construction, wind structure connection and afterward decides the breeze load as comparable to static burdens. In present work, research papers on dynamic behaviour of wind and Gust Effectiveness Method has been studied and conclusions are made. The effect of vertical and horizontal shape modification, plan ratio and aspect ratio with different terrain categories has also been studied.

Comparative Study on Deflection of a Multistoried Building with Shear Wall and Core Wall

Abstract: To ensure the seismic effectiveness of highrise buildings different systems of lateral restraints are provided e.g., bracings, shear walls, core walls etc. In the present study, deflection of various joints, storeys &amp; also the drifts have been gone through. For this purpose, 3 different models of multi-storeyed buildings were prepared consisting of a G+6 building with shear wall at the centre of edges on exterior walls, G+6 building with a core wall &amp; G+8 building with a core wall were prepared using an integrated building designing software known as ETABS- 2016 (student version). A 3-bay building was modelled using M30 concrete mix and reinforcing steel bars of HYSD 415 for beams, columns, slabs as well as shear walls. After this pier labels were assigned to the shear walls. A variety of load cases like joint loads, dead loads, live loads, wind load in x-direction for terrain category 4, earthquake loads in x &amp; y directions for zone II along with their combinations were assigned. The respective diaphragms were assigned to the three models &amp; analysis was carried out at the end. The table of results was obtained and the deflection analysis was carried out to compare the relative effectiveness of shear walls &amp; core walls at different locations of the multi-storeyed building. The codes taken into consideration during the progress of work were IS 456:2000 for plain and reinforced concrete, IS 875:2015 (Part 1) for wind loads &amp; IS 1893:2002 for earthquake loads. Keywords: Earthquakes, Shear wall, Core wall, Lateral deflection.

Numerical Study of Wind Loads on Y Plan-Shaped Tall Building Using CFD

The increase in the population is at an exponential rate, and the available land is in the form of irregular shapes. That is why irregular shapes are very commonly built. Wind load increases with respect to height, so wind load evolution is necessary for such high-rise structures. Wind forces majorly depend on the plan's cross-sectional shape. Therefore, for an irregular shape, an investigation is needed for tall buildings. This paper demonstrates a detailed study on velocity stream line, external pressure coefficients, pressure distribution on the surfaces of the building and the turbulence kinetic energy for the Y-shaped plan for tall buildings under wind excitation for wind incidence angles of 0o to 180o. k- turbulence model is utilized to solve the problem using computational fluid dynamics techniques in ANSYS for terrain category II as per IS: 875 (Part3), 2015. Wind ward faces in all building models show positive pressure distribution, while the leeward faces are under the effect of negative pressure distribution. Wind load can be reduced on building models by modifying the corners, such as chamfering, rounding, and double recessed. The variation of pressure distribution on different faces of a "Y" plan shaped tall building for 0° and 180° is investigated using ANSYS CFX, and the pressure contours are plotted for all the faces of different "Y" shaped buildings to compute the effect of corner modification on pressure distribution. In this research, it was found that building models with rounded corners are highly efficient in resisting the wind load. Doi: 10.28991/CEJ-2022-08-02-06 Full Text: PDF

Wind-structure interaction analysis of empty cylindrical silos for various slenderness ratio

Wind is the flow of air within the earth’s atmosphere, which affects any structure greatly. Studies on the effect of wind loading on shell structures is an important field of structural research. Many shell structures, such as, chimneys, silos, tanks etc. are an integral part of the advancement of the industry and agriculture. Such shell structures are vulnerable against aerodynamic excitation and can be subjected to structural failure due to vortex-induced vibration, ovalling, buckling, rupture, over-turning etc. The present study focuses on the static fluid–structure interaction analysis to assess the wind pressure and wind-induced deformation of cylindrical silo shells. Cylindrical silos are a type of shell structure for storing granular materials, such as grains, wheat, cement, coal, fly-ash etc. Cylindrical silos very much susceptible to radial deformation and buckling failure under wind loading in empty state. In the present study the authors have conducted the wind-structure interaction studies on intermediate to tall (slenderness ratio range: 1.5 to 4.0) cylindrical silo shells for terrain category 2, as per IS-875: part 3, 2015. The silos are flat topped with uniform thickness and fixed at the base, free at the top. The logarithmic law is used to simulate wind velocity profile. The circumferential mean wind pressure coefficient distribution for each silo, is calculated and compared with Indian standard. This study is conducted for smooth flow with very low turbulence intensity for simplicity. This study exhibits that, with the increase in slenderness ratio from 1.5 to 4.0, the magnitude of negative pressure coefficients decreases, however no significant increase can be seen for positive pressure coefficients. The sway of the silos increases with the increment in slenderness ratio. The radial deformation is dominant in the intermediate portion and the nature of deformation is typical for each silo. Based on the nature of radial deformation the critical locations can be identified, which need to be strengthened to resist wind-induced deformation. It is also seen that the presence of flat roof provides significant strengthening at the top of the silos against wind-induced radial deformation.