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The purpose of this study is to mitigate the dimensional inaccuracy due to vertical curling/bending deformation of three-dimensional (3D) printed parts produced by selective laser sintering (SLS) using PA12 based on dimensional compensation of the computer-aided design (CAD) model.

To carry out this study, specially designed features are initially produced as references, and the dimensional deviations from the vertical bending deformation of the SLS process are analyzed. Next, the deformation patterns are formulated using a polynomial regression model in the global Cartesian coordinates of the building platform. Then, the compensation algorithm is implemented and the original 3D CAD file is preprocessed with an inverse transformation of the features to compensate the deformation errors.

It was found that the 3D printed parts from the SLS process have the dimensional inaccuracy due to the vertical bending pattern of the quadratic form. By implementing the compensation algorithm, it was statistically shown to effectively reduce bending deformations of various sample parts, including the automotive components, in SLS.

The position of samples in a batch has a direct impact on not only bending deformation but also on horizontal shape geometry error. However, the application of this algorithm is focused on the vertical bending deformation, which is estimated as a major part of dimensional inaccuracy.

This paper provides a practical case study with a real vehicle part. The algorithm was shown to provide a more realistic solution to the dimensional deformation of printed products, which is not manageable by simply using the constant scale factors provided by SLS 3D printer manufacturers.

This paper suggests that the vertical bending deformation from SLS’s 3D printed complex parts can be improved through the proposed compensation algorithm. The compensation algorithm was constructed by using the predictive regression model created from the bending deformation patterns of reference samples. The proposed compensation algorithm can be further used and applied for other complex samples without making additional reference parts.

Double-jacquard technique is referred as the most advanced technology for forming patterns on both layers of a 3D fabric knitted on a double-needle bar warp-knitting machine. In order to realize the computer-aided design and simulation of jacquard patterns, the purpose of this paper is to propose a mathematic model for representation of jacquard structures and an improved mass-spring model to improve the simulation of structural deformation behavior.

Primarily, it analyzes the jacquard patterning method and displacing principle to design jacquard structures on each layer and linking structures of two layers. Based on that, a loop geometry defined by six key points and segmental lines is built to transfer the jacquard bitmap and lapping movements into a fabric of loops and therefore realizing patterns visualization. Afterwards, an improved mass-spring model is built to simulate structural deformation, in which the fabric is simplified as a mesh of uniformly distributed mass particles. Each loop is treated as a massless particle while underlaps are referred as structural springs connecting loops particles. Elastic forces of these springs on each loop particle is calculated according to the Hook’s law and Newton’s second law, and then based on the explicit Euler’s equations, motion state of each particle is solved including the velocity and the shift.

Based on the above method, a simulator for double-layer jacquard fabrics is developed via Visual C++ language to visualize the patterned fabrics with pitting effects. With a jacquard shoe fabric as an example, this simulation model is proved to be practical and efficient by comparing the simulation result and real fabric.

Because of limited researches, 3D simulation modeling of this double-layer jacquard fabric will be studied in the further research.

The implement of this simulation method will offer the industries a time-saving and cost-saving approach for new fabrics development.

This approach can be used as a reference for simulating other knitted fabrics with jacquard patterns, such as jacquard garment fabrics and home textile fabrics.

The consolidation behavior of prefabricated vertical drain (PVD)-installed soft deposits mainly depends on the PVD performance. The purpose of this study is to propose a numerical solution for the consolidation of PVD-installed soft soil using the large-strain theory, in which the reduction of discharge capacity of PVD according to depth and time is simultaneously considered.

The proposed solution also takes into account the general constitute relationship of soft soil. Subsequently, the proposed solution is applied to analyze and compare with the monitoring data of two cases, one is the experimental test and another is the test embankment in Saga airport.

The results show that the reduction of PVD discharge capacity according to depth and time increased the duration required to achieve a certain degree of consolidation. The consolidation rate is more sensitive to the reduction of PVD discharge capacity according to time than that according to the depth. The effects of the reduction of PVD discharge capacity according to depth are more evident when PVD discharge capacity decreases. The predicted results using the proposed numerical solution were validated well with the monitoring data for both cases in verification.

In this study, the variation of PVD discharge capacity is only considered in one-dimensional consolidation. However, it is challenging to implement a general expression for discharge capacity variation according to time in the two-dimensional numerical solution (two-dimensional plane strain model). This is the motivation for further study.

A geotechnical engineer could use the proposed numerical solution to predict the consolidation behavior of the drainage-improved soft deposit considering the PVD discharge capacity variation.

The large-strain consolidation of PVD-installed soft deposits could be predicted well by using the proposed numerical solution considering the PVD discharge capacity variations according to depth and time.

The purpose of this paper is to show that the growing global trend of quality assurance indicates the potential of precast concrete (PC) to improve construction quality and productivity, reduce wasteful construction, and achieve design standardization and to accelerate construction time. However, its current approach for dynamic characteristics, such as stiffness and displacement on beam-column connection system design, is not effective in achieving the required quality and operational requirements.

A design tool based on the literature and data analysis in product planning and safety is proposed for the practice of PC building construction.

The results reveal the need for improvement of PC building performance in the construction industry, especially for the beam-column connection system. The issues include improper design, improper specification and defective concrete and steel components compared to other manufacturing methods.

A novel and sophisticated technique based on physical internet-enabled building information modeling (PI-BIM) is proposed to improve the planning process and safety for PC buildings in Malaysia.

Terrestrial laser scanning (TLS) point clouds have been widely used in deformation measurement for structures. However, reliability and accuracy of resulting deformation estimation strongly depends on quality of each step of a workflow, which are not fully addressed. This study aims to give insight error of these steps, and results of the study would be guidelines for a practical community to either develop a new workflow or refine an existing one of deformation estimation based on TLS point clouds. Thus, the main contributions of the paper are investigating point cloud registration error affecting resulting deformation estimation, identifying an appropriate segmentation method used to extract data points of a deformed surface, investigating a methodology to determine an un-deformed or a reference surface for estimating deformation, and proposing a methodology to minimize the impact of outlier, noisy data and/or mixed pixels on deformation estimation.

In practice, the quality of data point clouds and of surface extraction strongly impacts on resulting deformation estimation based on laser scanning point clouds, which can cause an incorrect decision on the state of the structure if uncertainty is available. In an effort to have more comprehensive insight into those impacts, this study addresses four issues: data errors due to data registration from multiple scanning stations (Issue 1), methods used to extract point clouds of structure surfaces (Issue 2), selection of the reference surface S_ref to measure deformation (Issue 3), and available outlier and/or mixed pixels (Issue 4). This investigation demonstrates through estimating deformation of the bridge abutment, building and an oil storage tank.

The study shows that both random sample consensus (RANSAC) and region growing–based methods [a cell-based/voxel-based region growing (CRG/VRG)] can be extracted data points of surfaces, but RANSAC is only applicable for a primary primitive surface (e.g. a plane in this study) subjected to a small deformation (case study 2 and 3) and cannot eliminate mixed pixels. On another hand, CRG and VRG impose a suitable method applied for deformed, free-form surfaces. In addition, in practice, a reference surface of a structure is mostly not available. The use of a fitting plane based on a point cloud of a current surface would cause unrealistic and inaccurate deformation because outlier data points and data points of damaged areas affect an accuracy of the fitting plane. This study would recommend the use of a reference surface determined based on a design concept/specification. A smoothing method with a spatial interval can be effectively minimize, negative impact of outlier, noisy data and/or mixed pixels on deformation estimation.

Due to difficulty in logistics, an independent measurement cannot be established to assess the deformation accuracy based on TLS data point cloud in the case studies of this research. However, common laser scanners using the time-of-flight or phase-shift principle provide point clouds with accuracy in the order of 1–6 mm, while the point clouds of triangulation scanners have sub-millimetre accuracy.

This study aims to give insight error of these steps, and the results of the study would be guidelines for a practical community to either develop a new workflow or refine an existing one of deformation estimation based on TLS point clouds.

The results of this study would provide guidelines for a practical community to either develop a new workflow or refine an existing one of deformation estimation based on TLS point clouds. A low-cost method can be applied for deformation analysis of the structure.

Although a large amount of the studies used laser scanning to measure structure deformation in the last two decades, the methods mainly applied were to measure change between two states (or epochs) of the structure surface and focused on quantifying deformation-based TLS point clouds. Those studies proved that a laser scanner could be an alternative unit to acquire spatial information for deformation monitoring. However, there are still challenges in establishing an appropriate procedure to collect a high quality of point clouds and develop methods to interpret the point clouds to obtain reliable and accurate deformation, when uncertainty, including data quality and reference information, is available. Therefore, this study demonstrates the impact of data quality in a term of point cloud registration error, selected methods for extracting point clouds of surfaces, identifying reference information, and available outlier, noisy data and/or mixed pixels on deformation estimation.

Growing awareness of the importance of preserving the built environment has created an increasing demand for experts capable of performing building inspections to ensure a high level of preservation. Technical surveys include a set of procedures and tests that have become essential tools providing the necessary knowledge required for maintenance, preservation and improvement of buildings. The paper aims to discuss these issues.

Within this set of inspection techniques, this paper presents a method developed to produce vertical deformation plans from the levelling data obtained from different floors of a building. It also explains how to perform accurate levelling and an outcome analysis to provide displacement maps. Thus, based upon obtained measurements, it is possible to achieve 2D contour maps and three-dimensional (3D) surface mapping by means of specialized software that is typically used for cartographic and territorial analysis.

The developed methodology provides easier analysis of the deformation of buildings and structures. Consequently, the method produces relatively accurate outcomes that are sufficient to make a proper assessment that facilitates the diagnostic and decision-making process. The case studies analysed show the applicability and usefulness of the procedure.

This sustainable and non-destructive system is an essential instrument for providing valuable and useful information to the specialist. The 2D/3D graphical data displays enable easier analysis of survey results, also aiding comprehension of these results in the context of liability claims.

This paper aims to analyse the effect of soft soil grouting on the deformation of the closed shield tunnel with the measured data.

Combining the measured data of vertical, horizontal and convergence deformation of the adjacent tunnel during the grouting construction in foundation pit engineering, the influence of grouting on metro tunnel in soft soil area is analyzed.

The researches indicate that early grouting has the main effect on the horizontal displacement of the tunnel; Due to the disturbing effect of the uninterrupted grouting construction on the soil and the transfer pressure of the rheological soil to the bottom of the tunnel, the tunnel is obviously lifted; And the convergence deformation of the tunnel increases caused by the overburden pressure in the vertical direction, so that the tunnel appears the phenomenon of staggered seam, large opening of bolted joint, damaged segment even leakage of water.

The study based on the field monitoring data is rarely reported, especially the topic about inadvertent grouting in soft soil area is likely to cause severe deformation of adjacent metro tunnel.

Under the repeated action of the construction load, opening deformation and disturbed deformation occurred at the precast box culvert joints of the shield tunnel. The objective of this paper is to investigate the effect of construction vehicle loading on the mechanical deformation characteristics of the internal structure of a large-diameter shield tunnel during the entire construction period.

The structural response of the prefabricated internal structure under heavy construction vehicle loads at four different construction stages (prefabricated box culvert installation, curved lining cast-in-place, lane slab installation and pavement structure casting) was analyzed through field tests and ABAQUS (finite element analysis software) numerical simulation.

Heavy construction vehicles can cause significant mechanical impacts on the internal structure, as the construction phase progresses, the integrity of the internal structure with the tunnel section increases. The vertical and horizontal deformation of the internal structure is significantly reduced, and the overall stress level of the internal structure is reduced. The bolts connecting the precast box culvert have the maximum stress at the initial stage of construction, as the construction proceeds the stress distribution among the bolts gradually becomes uniform.

This study can provide a reference for the design model, theoretical analysis and construction technology of the internal structure during the construction of large-diameter tunnel projects.

Understanding the structural performance of external glass curtain walls (façades) during fire exposure is critical for the safety of the occupants as their failure can lead to fire spread throughout the entire building. This concern is magnified by the recent increase in fire incidents and wildfires. This paper presents the first simplified technique to model single-skin façades during fire exposure and then utilizes it to examine the structural behaviour of vertical, inclined and oversized façade panels.

The proposed technique is based on conducting simplified heat transfer calculations and then utilizing a widely used structural analysis software program to analyze the façade. Validation for the proposed technique with reference to available experimental and numerical studies by others is presented. A parametric study is then conducted to assess the structural performance of different glass façade systems during exposure to fire.

The proposed technique was found to provide accurate predictions of the structural performance of glass façades during fire exposure. The structural performance of inclined façade systems during fire exposure was found to be superior to vertical and oversized façade systems.

This research paper is the first to provide a simplified technique that can be utilized to model single-skin facades under fire. The presented technique along with the conducted parametric study will improve the understanding of the fire behaviour of single-skin glass facades, which will lead to safer applications.

The purpose of this paper is to present an analysis of the effect of the temperature on the creep deformation during vertical well drilling in salt rocks in selected cases.

The authors performed numerical simulations by Finite Element Method, using non-linear viscoelastic models and weak thermomechanical coupling. The authors evaluated, in selected cases, the effect of temperature during salt rock vertical well drilling. Numerical examples were performed to validate the studies. More specifically, the authors considered the problem of vertical well drilling for oil exploration below these salt layers.

The authors concluded that the biggest reduction in the wellbore closure rate occurs when the wellbore is at low temperature with respect to the rock initial. This is due to two factors, namely, a reduced salt viscous strain rate and the thermal strain contrary to the well radial closure caused by the temperature variation. Beyond the creep effect, the thermal strain also affects the stress in the creep constitutive equation.

With recent oil discoveries in deep water, for example, in the pre-salt, where temperatures are high, the study of the influence of temperature is important, since it contributes to the increase of the creep. The results here presented are relevant, although the engineering aspects of a practical solution for reducing the wellbore displacement based on temperature variation is challenging. Such approach requires cooling mechanisms that delay the heating of the drilling fluid, which is surrounded by rocks at high temperature.

The main contribution of this paper is to present a numerical study, in selected cases, of the effect of temperature on the creep deformation during vertical well drilling in salt rocks, analyzing a possible reduction of these deformations when subjected to a temperature variation.