Plan Geometry Research Articles

COMPARATIVE STUDY OF FLAT SLAB DESIGN USING VARIOUS INTERNATIONAL CODES

The structural function of beamless floor system is to collect the gravity load and other load such as wind load etc. and to transfer to the vertical structural elements i.e. column through the combined capacity in flexure and shear. In Flat slab, the slab is directly supported on the columns. Moments and shear values are usually the largest over the columns. However, when spans are relatively small and imposed load is low, the thickness of slab can be increased to reduce the stresses at slab-column joint which would result in providing greater effective depth for negative moments occurring near the column. With increasing span and live load intensity, the thickness requirement increases which does not give economical solution. So, to tackle this problem flaring of the column at top is done such that the plan geometry at the column head is similar to that of the column. The column capital is intended primarily to increase the capacity of the slab to resist punching shear. The column capital stiffens the slab, which help in controlling the floor deflection. Thus, the floor span can be increased to some extent. Beyond a certain range of span, further stiffening of the slab is required which is achieved by increasing the slab thickness of the slab panel around the column capital. This portion of the slab is known as drop panel. For flat slabs and flat plates supported directly by columns, shear may be the critical factor in design. In almost all tests of such structures, failures have been due to shear or perhaps shear and torsion. These conditions are particularly serious around the exterior columns. In the present study, attempt has been made to understand different methods of analysis of flat slab and parameters, which governs the design parameters of the flat slab. Attempts have been made to study the provisions of flat slab in well-known international standards such as ACI 318, EC-2 and IS 456:2000. Keywords: Flat slab, drop panel, Column head, IS 456:2000, ACI 318, EC-2

Multi-institutional investigation into the robustness of intra-cranial multi-target stereotactic radiosurgery plans to patient setup errors

PurposeThis study aimed to analyse correlations between planning factors including plan geometry and plan complexity with robustness to patient setup errors. MethodsMultiple-target brain stereotactic radiosurgery (SRS) plans were obtained through the Trans-Tasman Radiation Oncology Group (TROG) international treatment planning challenge (2018). The challenge dataset consisted of five intra-cranial targets with a 20 Gy prescription. Setup error was simulated using an in-house tool. Dose to targets was assessed via dose covering 99 % (D99 %) of gross tumour volume (GTV) and 98 % of planning target volume (PTV). Dose to organs at risk was assessed using volume of normal brain receiving 12 Gy and maximum dose covering 0.03 cc of brainstem. Plan complexity was assessed via edge metric, modulation complexity score, mean multi-leaf collimator (MLC) gap, mean MLC speed and plan modulation. ResultsEven for small (0.5 mm/°) errors, GTV D99 % was reduced by up to 20 %. The strongest correlation was found between lower complexity plans (larger mean MLC gap and lower edge metric) and higher robustness to setup error. Lower complexity plans had 1 %–20 % fewer targets/scenarios with GTV D99 % falling below the specified tolerance threshold. These complexity metrics correlated with 100 % isodose volume sphericity and dose conformity, though similar conformity was achievable with a range of complexities. ConclusionsA higher level of importance should be directed towards plan complexity when considering plan robustness. It is recommended when planning multi-target SRS, larger MLC gaps and lower MLC aperture irregularity be considered during plan optimisation due to higher robustness should patient positioning errors occur.

Influence of the rock mass structure and the blasting technique on blast results in the Heliopolis quarry

Purpose. To find a relative methodology which will help the systematic analysis of the parameters influencing the blasting plan and a better understanding of the mechanisms of fragmentation of rocks with explosives. Methodology. The approach uses the Kuz-Ram model to predict blast performance. Three models were used to consider the effect of blast plan geometry on the quality of blast rock fragmentation. A new blasting plan is proposed using the Langefors method and the Kuz-Ram empirical model. The results obtained were compared with those of previous blasts. Findings. The research results show that the optimal fragmentation of 89.2 % with a balance between fine particles of 5.7 % and outsized blocks of 5.1 % of rocks by explosive in the Heliopolis aggregates quarry is highly dependent on the type and quantity of explosive used, the direction of initiation, and the cracks caused by the waves of shock (back effects). Originality. The present work is concerned with the problem of the quality of rock blasting which will ultimately affect the costs of drilling, blasting and the efficiency of all mining operations. Parameters influencing the processes of rock fragmentation during mining operations are specified. Practical value. The purpose of blasting is to disaggregate the material in order to facilitate its recovery by the extraction equipment. It is therefore necessary to correctly define the blasting plan by optimizing these geometric parameters, the nature and the quantity of explosive, the initiation sequences aim to have the right particle size distribution.

The Effect of Plan Geometry on Progressive Collapse of Tall Buildings with Diagrid Structure Based on Nonlinear Static and Dynamic Analyses

The Effect of Plan Geometry on Progressive Collapse of Tall Buildings with Diagrid Structure Based on Nonlinear Static and Dynamic Analyses

Multi-institutional investigation into the robustness of intra-cranial multi-target stereotactic radiosurgery plans to delivery errors.

The use of modulated techniques for intra-cranial stereotactic radiosurgery (SRS) results in highly modulated fields with small apertures, which may be susceptible to uncertainties in the delivery device. This study aimed to quantify the impact of simulated delivery errors on treatment plan dosimetry and how this is affected by treatment planning system (TPS), plan geometry, delivery technique, and plan complexity. A beam modelling error was also included as context to the dose uncertainties due to treatment delivery errors. Delivery errors were assessed for multiple-target brain SRS plans obtained through the Trans-Tasman Radiation Oncology Group (TROG) international treatment planning challenge (2018). The challenge dataset consisted of five intra-cranial targets, each with a prescription of 20Gy. Of the final dataset of 54 plans, 51 were created using the volumetric modulated arc therapy (VMAT) technique and three used intensity modulated arc therapy (IMRT). Thirty-five plans were from the Varian Eclipse TPS, 17 from Elekta Monaco TPS, and one plan each from RayStation and Philips Pinnacle TPS. The errors introduced included: monitor unit calibration errors, multi-leaf collimator (MLC) bank offset, single MLC leaf offset, couch rotations, and collimator rotations. Dosimetric leaf gap (DLG) error was also included as a beam modelling error. Dose to targets was assessed via dose covering 98% of planning target volume (PTV) (D98%), dose covering 2% of PTV (D2%), and dose covering 99% of gross tumor volume (GTV) (D99%). Dose to organs at risk (OARs) was assessed using the volume of normal brain receiving 12Gy (V12Gy), mean dose to normal brain, and maximum dose covering 0.03cc brainstem (D0.03cc). Plan complexity was also assessed via edge metric, modulation complexity score (MCS), mean MLC gap, mean MLC speed, and plan modulation (PM). PTV D98% showed high robustness on average to most errors with the exception of a bank shift of 1.0mm and large rotational errors ≥1.0° for either the couch or collimator. However, in some cases, errors close to or within generally accepted machine tolerances resulted in clinically relevant impacts. The greatest impact upon normal brain V12Gy, mean dose to normal brain, and D0.03cc brainstem was found for DLG error in alignment with other recent studies. All delivery errors had on average a minimal impact across these parameters. Comparing plans from the Monaco TPS and the Eclipse TPS, showed a lesser increase to V12Gy, mean dose to normal brain, and D0.03cc brainstem for Monaco plans (p<0.01) when DLG error was simulated. Monaco plans also correlated to lower plan complexity. Using Spearman's correlation coefficient (r) a strong negative correlation (r≤-0.8) was found between the mean MLC gap and dose to OARs for DLG errors. Reducing MLC complexity and using larger mean MLC gaps is recommended to improve plan robustness and reduce sensitivity to delivery and modelling errors. For cases in which the calculated dose distribution or dose indices are close to the clinically acceptable limits, this is especially important.

Is noncoplanar plan more robust to inter-fractional variations than coplanar plan in treating bilateral HN tumors with pencil-beam scanning proton beams?

Noncoplanar plans (NCPs) are commonly used for proton treatment of bilateral head and neck (HN) malignancies. NCP requires additional verification setup imaging between beams to correct residual errors of robotic couch motion, which increases imaging dose and total treatment time. This study compared the quality and robustness of NCPs with those of coplanar plans (CPs). Under an IRB-approved study, CPs were created retrospectively for 10 bilateral HN patients previously treated with NCPs maintaining identical beam geometry of the original plan but excluding couch rotations. Plan robustness to the inter-fractional variation (IV) of both plans was evaluated through the Dose Volume Histograms (DVH) of weekly quality assurance CT (QACT) sets (39 total). In addition, delivery efficiency for both plans was compared using total treatment time (TTT) and beam-on time (BOT). No significant differences in plan quality were observed in terms of clinical target volume (CTV) coverage (D95) or organ-at-risk (OAR) doses (p>0.4 for all CTVs and OARs). No significant advantage of NCPs in the robustness to IV was found over CP, either. Changes in D95 of QA plans showed a linear correlation (slope=1.006, R2 >0.99) between NCP and CP for three CTV data points (CTV1, CTV2, and CTV3) in each QA plan (117 data points for 39 QA plans). NCPs showed significantly higher beam delivery time than CPs for TTT (539±50vs. 897±142s; p<0.001); however, no significant differences were observed for BOT. NCPs are not more robust to IV than CPs when treating bilateral HN tumors with pencil-beam scanning proton beams. CPs showed plan quality and robustness similar to NCPs while reduced treatment time (∼6min). This suggests that CPs may be a more efficient planning technique for bilateral HN cancer proton therapy.

Image-Based OA-Style Paper Pop-Up Design via Mixed-Integer Programming.

Origami architecture (OA) is a fascinating papercraft that involves only a piece of paper with cuts and folds. Interesting geometric structures 'pop up' when the paper is opened. However, manually designing such a physically valid 2D paper pop-up plan is challenging since fold lines must jointly satisfy hard spatial constraints. Existing works on automatic OA-style paper pop-up design all focused on how to generate a pop-up structure that approximates a given target 3D model. This article presents the first OA-style paper pop-up design framework that takes 2D images instead of 3D models as input. Our work is inspired by the fact that artists often use 2D profiles to guide the design process, thus benefited from the high availability of 2D image resources. Due to the lack of 3D geometry information, we perform novel theoretic analysis to ensure the foldability and stability of the resultant design. Based on a novel graph representation of the paper pop-up plan, we further propose a practical optimization algorithm via mixed-integer programming that jointly optimizes the topology and geometry of the 2D plan. We also allow the user to interactively explore the design space by specifying constraints on fold lines. Finally, we evaluate our framework on various images with interesting 2D shapes. Experiments and comparisons exhibit both the efficacy and efficiency of our framework.

Numerical Investigation on Impact of Wind Loading on High Rise Structure Using Ansys

In modern architecture, irregular geometries have become increasingly popular. However, when designing tall buildings, it is crucial to consider the impact of wind loads, which can cause dangerous torsion if the plan geometry is irregular. To properly assess wind loads, it is necessary to analyse them during the design process. One way to mitigate wind loads is through aerodynamic modifications. This research aims to evaluate the effectiveness of different aerodynamic modifications on various shaped models using computational fluid dynamics simulation software called ANSYS. The modifications include chamfered and recessed corners, as well as Y-shaped and tapering forms. The study examines coefficients of drag and lift, as well as the dynamic behaviour of the models. Material changes are also evaluated. The findings highlight the importance of considering wind loading in the design and analysis of high-rise structures. Ultimately, this research can help improve the safety and design of high-rise buildings located in areas prone to high wind speeds.

Comparative Analysis of Single Column Square, Rectangular, Circular Shape Structure

Abstract: Due to increasing urbanization and rapid infrastructural development, scarcity of land is a problem. Multi-story structures have been constructed to eliminate this problem. But for the requirement of large service spaces and good aesthetic appearances, the mono column structural system achieved popularity. They require less area for providing foundation and gives more space for parking. The design and analysis of RCC structure supported on a single column is done in this project. This project presents effects of three different plan configurations i.e., Square, Circular, rectangular, with same plan area. Mono column structure withdifferent plan geometry reacts adversely in contrast to earthquake loads.

Statistical Subspace-Based Damage Detection and Jerk Energy Acceleration for Robust Structural Health Monitoring

This paper introduces a multistep damage identification process that is both straightforward and useful for identifying damage in buildings with regular plan geometries. The algorithm proposed in this study combines the utilization of a multi-damage sensitivity feature and MATLAB programming, providing a comprehensive approach for the structural health monitoring (SHM) of different structures through vibration analysis. The system utilizes accelerometers attached to the structure to capture data, which is then subjected to a classical statistical subspace-based damage detection test. This test focuses on monitoring changes in the data by analyzing modal parameters and statistically comparing them to the structure’s baseline behavior. By detecting deviations from the expected behavior, the algorithm identifies potential damage in the structure. Additionally, the algorithm includes a step to localize damage at the story level, relying on the jerk energy of acceleration. To demonstrate its effectiveness, the algorithm was applied to a steel shear frame model in laboratory tests. The model utilized in this study comprised a total height of 900 mm and incorporated three lumped masses. The investigation encompassed a range of scenarios involving both single and multiple damages, and the algorithm proposed in this research demonstrated the successful detection of the induced damages. The results indicate that the proposed system is an effective solution for monitoring building structure condition and detecting damage.

Normal faulting and landsliding in morpho-structural domes related to buried salt stocks, Zagros Mountains, Iran. Insights into salt breakout

Normal faulting in domal structures above diapirs has important implications in hydrocarbon geoscience, but studies on surface faulting on exposed growing domes are scarce. Moreover, there is limited work addressing the erosional processes involved in the unroofing of active diapirs preceding salt emergence. This investigation analyses two morpho-structural domes (Gavbast Dome: GD; Kooh Bedoo Dome: KBD) associated with growing anticlines related to the rejuvenation of precursor buried salt stocks in the Zagros Mountains. The structural relief of the domes (1330 m in GD and 400 m in KBD) and the available chronological data on fold development indicate long-term uplift rates of around 0.1–0.4 mm/yr. GD displays three domains with different fault patterns: (1) fold-normal grabens in one half; (2) polygonal faulting with multiple enclosed graben depressions in the crest; and (3) fold-parallel faulting on the other half. KBD shows a major fold-normal graben restricted to the crest and one flank of the dome. The lack of the typical radial pattern related to multidirectional hoop extension can be attributed the suppression of extension in the fold-normal direction by regional shortening. Other factors such as complexities in the folding structure, outer-arc extension in the anticline crests, and plan geometry seem to play a local control on fault patterns. The studied domes display an extraordinarily high density of large slope movements, indicating that they play an instrumental role in the unroofing process. The slope failures, with sliding planes mainly developed in argillaceous units overlain by thick limestone packages, include incipient planar rock slides more than 5 km2 in area expressed as buckle folds in the lower part of the slopes. The main preparatory factors involved in the development of these slope collapses include rock mass weakening by faulting and slope over-steepening, both related to doming. Our detailed mapping and the examination of a number of salt diapirs in the Fars Arc suggest that episodic landsliding and more gradual fluvial dissection, often controlled by grabens, are the main erosional processes involved in the unroofing of active diapirs leading to salt emergence.

Interactive Exploration of Tension-Compression Mixed Shells

Achieving a pure-compression stress state is considered central to the form-finding of shell structures. However, the pure-compression assumption restricts the geometry of the structure's plan in that any free boundary edges cannot bulge outward. Allowing both tension and compression is essential so that overhanging leaves can stretch out toward the sky. When performing tension-compression mixed form-finding, a problem with boundary condition (BC) compatibility arises. Since the form-finding equation is hyperbolic, boundary information propagates along the asymptotic lines of the stress function. If conflicting BC data is prescribed at either end of an asymptotic line, the problem becomes ill-posed. This requires a user of a form-finding method to know the solution in advance. By contrast, pure-tension or pure-compression problems are elliptic and always give solutions under any BCs sufficient to restrain rigid motion. To solve the form-finding problem for tension-compression mixed shells, we focus on the Airy's stress function, which describes the stress field in a shell. Rather than taking the stress function as given, we instead treat both the stress function and the shell as unknowns. This doubles the solution variables, turning the problem to one that has an infinity of different solutions. By enforcing equilibrium in the shell interior and prescribing the correct matching pairs of BCs to both the stress function and the shell, a stress function and shell can be simultaneously found such that equilibrium is satisfied everywhere in the shell interior and thus automatically has compatible BCs by construction. The problem of a potentially over-constrained form-finding is thus avoided by expanding the solution space and creating an under-determined problem. By varying inputs and repeatedly searching for stress function-shell pairs that fall within the solution space, a user is allowed to interactively explore the possible forms of tension-compression mixed shells under the given plan of the shell.

Classification of the Structural Behavior of Tall Buildings with a Diagrid Structure: A Machine Learning-Based Approach

We study the relationship between the architectural form of tall buildings and their structural response to a conventional seismic load. A series of models are generated by varying the top and bottom plan geometries of the buildings, and a steel diagrid structure is mapped onto their skin. A supervised machine learning approach is then adopted to learn the features of the aforementioned relationship. Six different classifiers, namely k-nearest neighbour, support vector machine, decision tree, ensemble method, discriminant analysis, and naive Bayes, are adopted to this aim, targeting the structural response as the building drift, i.e., the lateral displacement at its top under the considered external excitation. By focusing on the classification of the structural response, it is shown that some classifiers, like, e.g., decision tree, k-nearest neighbour and the ensemble method, can learn well the structural behavior, and can therefore help design teams to select more efficient structural solutions.

Discontinuity in Equilibrium Wave-Current Ripple Size and Shape and Deep Cleaning Associated With Cohesive Sand-Clay Beds.

Mixtures of cohesive clay and noncohesive sand are widespread in many aquatic environments. Ripple dynamics in sand-clay mixtures have been studied under current-alone and wave-alone conditions but not combined wave-current conditions, despite their prevalence in estuaries and the coastal zone. The present flume experiments examine the effect of initial clay content, C 0, on ripples by considering a single wave-current condition and, for the first time, quantify how changing clay content of substrate impacts ripple dimensions during development. The results show inverse relationships between C 0 and ripple growth rates and clay winnowing transport rates out of the bed, which reduce as the ripples develop toward equilibrium. For C 0≤10.6%, higher winnowing rates lead to clay loss, and thus the presence of clean sand, far below the base of equilibrium ripples. This hitherto unquantified "deep-cleaning" of clay does not occur for C 0>10.6%, where clay-loss rates are much lower. The clay-loss behavior is associated with two distinct types of equilibrium combined flow ripples: (a) Large asymmetric ripples with dimensions and plan geometries comparable to their clean-sand counterparts for C 0≤10.6% and (b) small, flat ripples for C 0>10.6%. The 10.6% threshold, which may be specific to the experimental conditions, corresponds to a more general 8% threshold found beneath the ripple base, suggesting that clay content here must be <8% for clean-sand-like ripples to develop in sand-clay beds. This ripple-type discontinuity comprises a threefold reduction in ripple height, with notable implications for bed roughness.

Using heritage building registers to characterise unreinforced masonry buildings of Brisbane, Australia

ABSTRACT Worldwide, unreinforced masonry (URM) buildings are present in abundance with many holding cultural and heritage value. URM buildings have a known history of poor performance during past earthquakes because of the weak tensile properties and lack of mechanical connections between elements. Information about the construction of URM buildings for a region is important because it can help engineers and policy makers to perform seismic assessment, risk and loss studies. In this regard, this study includes a characterisation of the heritage URM buildings in Brisbane City, Australia, and its surrounding suburbs using the Queensland Heritage Register (QHR). The QHR includes a total of 1775 heritage sites, of which 323 are identified as URM buildings in Brisbane City and surrounding suburbs. The studied building characteristics obtained from QHR included the architectural styles, construction year, function/use, number of storeys, roof material and load-bearing wall materials. Other features such as roof types (shapes), plan geometry, isolated or interconnected buildings, verandas and openings, and finally the presence of seismic hazards such as gable-end walls, chimneys, and parapets have been obtained using online 3D maps. It was concluded that heritage registers in combination with online digital resources can be successfully utilised to characterise URM buildings.

Diagrid Mono Column Structures with Different Geometry in Plan: A Review

Abstract: Due to increasing urbanization and rapid infrastructural development, scarcity of land is a problem. Multi-story structures have been constructed to eliminate this problem. But for the requirement of large service spaces and good aesthetic appearances, the mono column structural system achieved popularity. Mono column structures are complicated since the mono column supports the whole structure and all other member acts as cantilevers. Mono column structures are vulnerable to seismic loads and adding a diagrid structural system on the periphery of the building improves seismic performances. This review paper aims to review the previous studies on mono column structure and diagrid structural system. It also focuses to review the performance of different plan geometry buildings.

Seismic Analysis of Unsymmetrical Buildings Compering with Regular Building

Structural analysis of building is taken into account for finding out the behaviors of a structure when subjected to some external force acting on building. Building structural design for seismic loads is critical for structural safety during large ground movementsBuildings with symmetrical and unsymmetrical plan geometry, strength, and stiffness are also varied. During earthquakes, structures with a symmetric distribution of stiffness and strength in plan experience combined lateral and torsional motions.Previous earthquakes, in which many reinforced concrete structures were badly damaged or collapsed, highlighted the need to assess building seismic performance. Earthquakes can cause irregular distribution of mass, stiffness and strengths i.e., unsymmetrical buildings may cause heavy damage in structural members. Buy referring this paper it is concluded that symmetric buildings perform better than un-symmetric buildings when subjected to earthquake forces.

Form-finding of shells containing both tension and compression using the Airy stress function

Pure-compression shells have been the central topic in the form-finding of shells. This study investigated tension-compression mixed-type shells by utilizing a NURBS-based isogeometric form-finding approach that analyses Airy stress functions to expand the possible plan geometry. A complete set of smooth version graphic statics tools is provided to support the analyses. The method is validated using examples with known solutions, and a further example demonstrates the possible forms of shells that the proposed method permits. Additionally, a guideline to configure a proper set of boundary conditions is presented through the lens of asymptotic lines of the stress functions.

Modeling secondary cancer risk ratios for proton versus carbon ion beam therapy: A comparative study based on the local effect model.

Ion beam therapy allows for substantial sparing of normal tissues. Besides deterministic normal-tissue complications, stochastic long-term effects like secondary cancer (SC) induction are of importance when comparing different treatment modalities. To develop a modeling approach for comparison of SC risk in proton and carbon ion therapy. The local effect model (LEM) is used to predict the relative biological effectiveness (RBE) of SC induction after particle therapy. A key feature of the new approach is the double use of the LEM, reflecting the competition between the two processes of mutation induction (leading to cancer development) and cell inactivation (leading to suppression of cancer development). Based on previous investigations, treatment plans were in this work analyzed for an idealized geometry in order to assess the underlying systematic dependencies of cancer induction. In a further step, relative SC risks were predicted for proton and carbon ion treatment plans prepared for 10 prostate cancer patients. We investigated the impact of factors such as treatment plan geometry, fractionation scheme, and tissue radiosensitivity to photon irradiation on the ion beam SC risk. Our model studies do not result in a clear preference for either protons or carbon ions, but rather indicate a complex interplay of different aspects. Reduced lateral scattering leads to a lower SC risk for carbon ions compared to protons at the lateral field margins in the entrance channel, while an increased risk was found closely behind the tumor due to projectile fragmentation. The fractionation scheme had little impact on the expected risk ratio. With respect to sensitivity parameters, those characterizing RBE for cell killing of potentially cancerous cells as well as of the primary tumor had the most significant impact. The observed general systematic dependencies are in agreement with results from previous model studies. The prostate patient study reveals reduced SC risks predictions for skin and bones for carbon ions as compared to protons, but higher mean risks for bladder and rectum. The methods established in this work provide a basis for further investigating treatment optimizing strategies for ion beam therapy with regard to SC risk comparisons.

Using Nonlinear Time History Analysis Find a Performance of Diagrid Structure with different Plan Geometry

Using Nonlinear Time History Analysis Find a Performance of Diagrid Structure with different Plan Geometry