Joint Panel Research Articles

Influence of diagonal reinforcement in grouted vertical joints between precast concrete wall panels, part I: Experimental investigation

AbstractMulti‐storeyed buildings are constructed using precast concrete large panels. Although the resistance to lateral loads during an earthquake can be provided by the walls, the vertical joints between the panels remain the weak links. Conventionally, a grouted vertical joint between precast panels is achieved using minimum number of overlapping transverse horizontal U‐bars or looped wire ropes from the adjacent panels, with a holder bar at the overlap, and subsequent grouting of the gap. It was observed that under in‐plane lateral loads, the shear behavior of such joints, especially those with looped wire ropes, is brittle. This paper presents a study to improve the behavior of conventional joints by introducing diagonal reinforcement (DR). Toward this, 13 specimens were tested under monotonic loading and 2 specimens were tested under quasi‐static cyclic loading. The parameters investigated were the types of transverse joint reinforcement, types and strengths of diagonal reinforcement. The compressive strengths of panel concrete and joint grout were kept similar to industry practice. The specimens with DR showed substantial increase of the shear strength and load retention beyond the peak. The presence of conventional transverse joint reinforcement in addition to DR, increases the retention capacity of the joint. Thus, the behavior of a joint with DR was found to be stronger and more ductile.

Heavy-weight impact sound insulation characteristics related with vibrational properties of Korean domestic CLT slabs with different species and joint types

Korea has the world's most strict inter-floor noise regulations. In order to build an apartment house with more than 30 units, it must meet the minimum requirement of impact sound level, single number quantities of 49 dB. These regulations make it hard to expand residential tall wood building in Korea. For making quality satisfied CLT floors, as the preliminary investigations, the effects of wood species and CLT panel joints on the vibration and sound insulation performance of CLT were analyzed. The natural frequency range of the CLT slabs is from 20 Hz to 22 Hz. There were no significant differences depending on wood species and CLT panel joint type. As the stiffness of the slabs increased, the floor impact sound insulation performance also improved. The deflection model for CLT slabs was developed and validated with the actual deflection derived by acceleration spectrum. The measured value was 62 ~ 87% of the predicted value.

An Innovative Technique for the Strengthening of RC Columns and Their Connections with Beams Using C-FRP ROPES

The application of the innovative C-FRP ropes for the strengthening of reinforced concrete columns is experimentally examined. Two real-scale specimens with the same geometrical characteristics and the same steel reinforcements were constructed for the needs of this investigation. The primary objective of the study is to investigate the efficacy of the use of C-FRP ropes as externally mounted reinforcement for the strengthening of deficient external columns. In this direction, (a) C-FRP ropes are applied as longitudinal reinforcement of the column for the increase in the flexural strength, (b) C-FRP ropes are applied as external confining stirrups in the critical end parts of the column for the improvement of the concrete strength and the development of local element ductility, and finally (c) C-FRP ropes are applied as external stirrups in the form of diagonal X-shaped reinforcement for the increase in the capacity of the part of the column connected with the beam (joint panel). Both specimens are tested under the same cyclic loading procedure that comprises seven steps and each step includes three full loading cycles. The maximum loads of the strengthened specimen at the three loading cycles of the seventh step were 40%, 72% and 87% higher than the corresponding ones of the unstrengthened specimen. On the other hand, the measured shear deformations of the joint panel of the pilot (unstrengthened) specimen at the sixth and the seventh steps were 43% and 44% higher than the corresponding ones of the strengthened specimen. In general, it is concluded that the strengthened column exhibited improved hysteretic response and the whole behavior was apparently improved compared to the pilot specimen without strengthening in terms of maximum loads per loading step, dissipated energy, and shear deformations of the joint panel. In particular, it is stressed that the measured shear deformations of the joint panel and strain gauge measurements have substantiated that the column and the connection panel of the strengthened specimen remain almost intact, whereas damage and eventually failure have been located in the column and the joint panel of the pilot specimen. Additionally, it is emphasized that the C-FRP ropes can easily be applied in structures with complex configuration without any geometrical restraints.

Investigation on shear performance of sliding-type rapid segmental joints for shield tunnels

This paper introduces a sliding-type rapid joint and investigates the joint's failure modes under compression-shear loading with a combination of numerical and experimental methods. The study analyzes the influence of axial force, arrangement methods, and segment thickness on the joint's shear resistance. Additionally, a detailed examination of stress distribution within the joints provides a deeper understanding of their mechanical behavior. The results reveal that four-stage exists in the shear-dislocation curve of joints, including static frictional stage, partial sliding stage, overall sliding stage, and descending stage. Increasing axial force enhances the joint's shear resistance, but excessively high axial forces raise the risk of shear failure in T-shaped components. Under the trans-arrangement, the sliding-type rapid segmental joint exhibits superior shear resistance, especially under high axial loads. The material strength of C-shaped components impacts the joint's shear resistance, and increasing segment thickness enhances the joint's shear resistance. Under reverse-radial shear conditions, the structure's shear capacity is not solely determined by the joint strength. Tangential shear occurs during the assembly process, emphasizing the need to avoid excessive assembly forces. The junction between the T-shaped structure and the joint panel is a vulnerable point for T-shaped components, and reinforcement by increasing size and thickness can prevent shear failure at this location.

Load Capacity and Bending Strength of Double-Acting Friction Stir Welded AA6061 Hollow Panels

Aluminum alloy hollow panels are essential components in both civil and mechanical structures, such as building floors or large vehicle platforms. They enhance rigidity while staying lightweight and conserving material volume. In its application, this panel must be joined using welding methods. One common issue encountered in aluminum welding is the formation of porosity defects. Solid-state welding methods like Friction Stir Welding (FSW) can be a solution to address this problem. The FSW joining process on hollow panels cannot be completed in one welding operation due to their thickness. The FSW process must be performed on both surfaces, which requires a relatively long time. Therefore, FSW needs to be developed into a Double-acting FSW that utilizes two tools simultaneously. These two tools introduce two sources of heat input, pressing force, and friction-stirring, resulting in a novel response that needs further research. This study delves into the impact of welding speed variations in Double-Acting FSW on the load capacity and bending strength of AA 6061 hollow panel joints. Welding speeds of 20, 30, and 40 mm/min were tested alongside rotational speed (1500 rpm), tilt angle (2°), and shoulder diameter (24 mm). It was discovered that reducing welding speed enhances both load capacity and bending strength. Notably, specimens welded at 20 mm/min exhibited a load capacity of 15.61 kN and bending strength of 52 MPa, highlighting the potential of slower speeds for superior weld performance. Doi: 10.28991/CEJ-2024-010-08-018 Full Text: PDF

Shear behavior of precast bridge deck panels with UHPC wet joints

Ultra-high performance concrete (UHPC) has been widely used in wet joints of precast bridge deck panels (PBDPs) due to its remarkable compressive strength, excellent tensile strength, and exceptional durability properties. However, there is a lack of consistent understanding regarding the mechanical properties of PBDPs with UHPC wet joints, especially shear behavior. To investigate the shear performance of PBDPs with UHPC wet joints, a total of seven bridge deck panels (BDPs) were designed and conducted by four-point bending tests. The test parameters included reinforcement types (straight bar and U-bar), lap details (contact lap and non-contact lap), joint widths (150 mm, 200 mm, 250 mm, and 500 mm), and filling materials (NC and UHPC). According to the test results, the shear behavior of seven BDPs was analyzed. The experiment results showed that all specimens exhibited shear failure, with critical shear cracks occurring in the shear span. For PBDPs with U-bars, the shear capacity of 200-mm-wide UHPC wet joints was 1.5 % higher than that of 500-mm-wide NC wet joints. In addition, the failure pattern had a tendency to gradually shift from shear failure to flexural failure when the width of UHPC wet joints was reduced from 250 mm to 150 mm. To establish 3D finite element (FE) models, a cohesion-friction hybrid model was proposed. The FE models had good simulation accuracy, with a maximum deviation of 7.0 %. Furthermore, a parametric analysis was performed to assess the influence of critical parameters on shear performance. The results showed that longitudinal reinforcement has a greater influence on the shear performance of PBDPs. Finally, shear capacity formulas in the design codes were verified in comparison with test results. The deviation of theoretically calculated values from test results was within 10 %.

Exhaled breath analysis for the discrimination of asthma and chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) and asthma are the most common chronic respiratory diseases. In middle-aged and elderly patients, it is difficult to distinguish between COPD and asthma based on clinical symptoms and pulmonary function examinations in clinical practice. Thus, an accurate and reliable inspection method is required. In this study, we aimed to identify breath biomarkers and evaluate the accuracy of breathomics-based methods for discriminating between COPD and asthma. In this multi-center cross-sectional study, exhaled breath samples were collected from 89 patients with COPD and 73 with asthma and detected on a high-pressure photon ionization time-of-flight mass spectrometry (HPPI-TOFMS) platform from 20 October 2022, to 20 May 2023, in four hospitals. Data analysis was performed from 15 June 2023 to 16 August 2023. The sensitivity, specificity, and accuracy were calculated to assess the overall performance of the volatile organic component (VOC)-based COPD and asthma discrimination models. Potential VOC markers related to COPD and asthma were also analyzed. The age of all participants ranged from to 18–86 years, and 54 (33.3%) were men. The age [median (minimum, maximum)] of COPD and asthma participants were 66.0 (46.0, 86.0), and 44.0 (17.0, 80.0). The male and female ratio of COPD and asthma participants were 14/75 and 40/33, respectively. Based on breathomics feature selection, ten VOCs were identified as COPD and asthma discrimination biomarkers via breath testing. The joint panel of these ten VOCs achieved an area under the curve of 0.843, sensitivity of 75.9%, specificity of 87.5%, and accuracy of 80.0% in COPD and asthma discrimination. Furthermore, the VOCs detected in the breath samples were closely related to the clinical characteristics of COPD and asthma. The VOC-based COPD and asthma discrimination model showed good accuracy, providing a new strategy for clinical diagnosis. Breathomics-based methods may play an important role in the diagnosis of COPD and asthma.

Clinical, Cultural, Computational, and Regulatory Considerations to Deploy AI in Radiology: Perspectives of RSNA and MICCAI Experts.

The Radiological Society of North of America (RSNA) and the Medical Image Computing and Computer Assisted Intervention (MICCAI) Society have led a series of joint panels and seminars focused on the present impact and future directions of artificial intelligence (AI) in radiology. These conversations have collected viewpoints from multidisciplinary experts in radiology, medical imaging, and machine learning on the current clinical penetration of AI technology in radiology and how it is impacted by trust, reproducibility, explainability, and accountability. The collective points-both practical and philosophical-define the cultural changes for radiologists and AI scientists working together and describe the challenges ahead for AI technologies to meet broad approval. This article presents the perspectives of experts from MICCAI and RSNA on the clinical, cultural, computational, and regulatory considerations-coupled with recommended reading materials-essential to adopt AI technology successfully in radiology and, more generally, in clinical practice. The report emphasizes the importance of collaboration to improve clinical deployment, highlights the need to integrate clinical and medical imaging data, and introduces strategies to ensure smooth and incentivized integration. Keywords: Adults and Pediatrics, Computer Applications-General (Informatics), Diagnosis, Prognosis © RSNA, 2024.

Study of microstructure and mechanical properties of SA553/SA537 steels joints using multi-pass welding for pressure vessels application

In this study, gas metal arc welding (GMAW or MIG) process was investigated for similar and dissimilar joints of SA553 and SA537 steel plates in different thicknesses with E NiCrMo-3 filler metal and 0–3 panel joint design that joined pressure vessels body to manholes. In order to examine the metallurgical behavior of the weld, optical and scanning electron microscopies were used. The effect of cooling rate (∂T∂t) on microstructure, strength and impact energy (cryogenic fracture toughness) were examined. By doubling the thickness (6–12 mm), the heat transfer rate or cooling rate (∂T/∂t) increased 4 times. Therefore, the strength and impact energy for the similar welding joint SA553 increased by about 8 % and for the similar welding joint SA537 by about 5 %. For dissimilar weld joints with different thicknesses, strength and impact energy are caused by the type of base metals and the different cooling rates of each base metal. Due to the high elongation of the E NiCrMo-3 electrode (30 %), there was continuous plastic deformation during bending tests. Also, by carrying out radiographic tests, the absence of cracks in welding structures was confirmed.

Effect of Selective Z-Pinning on the Static and Fatigue Strength of Step Joints between Composite Adherends

The z-pinning reinforcement technique, which involves inserting thin pins through the body of a laminate, has proven highly effective in enhancing the strength of various composite joint configurations. This investigation aims to explore the enhancements achievable through selective z-pinning at very low pin contents on both the static and fatigue performance of composite joints. Single-step joints between carbon/epoxy adherends were reinforced using steel pins arranged in two, three, or four rows of pins parallel to the edges of the overlap, resulting in pin contents ranging from 0.2% to 0.4%. Joint panels were manufactured through co-curing, and coupons were extracted from the panels for static and fatigue tensile testing. The experimental tests show that z-pinning improves the static strength (by about 15%) and extends the fatigue lives of the joints. The ultimate failure of both unpinned and pinned joints is due to the unstable propagation of a crack at the bond line. The superior performances of pinned joints are mainly due to the bridging tractions imposed between the crack faces by z-pins, which delay the growth of the debonding crack. The enhancements in static and fatigue strength achieved by z-pinning were essentially independent of the number of pin rows, and the pins positioned near the joint edges were found to play a dominant role in controlling the structural performance of pinned joints.

Inscribing a new page in the history of Ukrainian psychoanalysis during the wartime: The call for contributions

AbstractThis correspondence introduces several distinct current efforts by Ukrainian psychoanalytic practitioners and researchers from various clinical, scholarly, and applied fields to support the sustainable development of psychoanalytic training and work in the context of the ongoing 2022 Russian invasion of Ukraine. Among these developments are (a) the translation of the classic and contemporary psychoanalytic texts into the Ukrainian language, (b) the promotion of Ukrainian psychoanalytic contributions within Ukraine and abroad, and (c) the support of psychoanalysis and psychoanalytic psychotherapy as an evidence‐based practice to be officially recognized in Ukraine. The initiatives were integrated with the launch of a scholarly peer‐reviewed online open‐access journal—the Ukrainian Psychoanalytic Journal—which has been confirmed by the Ukrainian Ministry of Education and Science as a scientific periodical. In addition to describing these initiatives, this contribution serves as an invitation to international psychoanalytic audiences to contribute to these processes, including via workshops on psychoanalytic writing and publication, joint panel discussions, or collaborative research projects with Ukrainian psychoanalytic professionals. We also welcome submissions of original previously published (with copyright permission) or unpublished papers to be translated and published in the Ukrainian language.

Қоршау құрылымдарындағы жылу өткізгіш қосындылары

In order to reduce the heat loss of a building and meet the requirements of regulations, multi-storey building envelopes have been widely used in construction in recent years, including the placement of a thermal insulation layer inside the structure. Under the influence of economic considerations, one of the main types of building floors was a masonry cellular concrete block faced with brick with effective insulation between floors. Considering the modernization of existing types of building envelopes and the appearance of a large number of new structures, the question arose about the correct determination of the thermal properties (mainly thermal protection) of such structures. Temperatures are evenly distributed because the heat dissipated over the surface of the structure helps to balance their values when looking at the room. However, the length of the temperature field distortion region increases (due to the presence of interference). On the contrary, the temperature decrease (which extends over a short length of the enclosure) becomes more prominent and noticeable due to inclusions and inclusions located on the warm surface of the structure. Such peculiarities of temperature distribution in the zone of heat conducting inclusions of different types are confirmed by the experience of operation of buildings with corresponding design solutions for panel walls. If the walls at the joints of panels are covered with a thermally conductive protective and finishing layer on the warm side, the temperature distribution over the inner surface of the wall will be uniform; if there is not enough thermal conductive inclusions and inclusions located on the warm surface of the wall, the temperature distribution will be uniform.

ВІДНОВЛЕННЯ ОПОРНИХ ЧАСТИН ЗОВНІШНІХ СТІНОВИХ ПАНЕЛЕЙ СЕРІЇ ІІС-04-2 З ВРАХУВАННЯМ СЕЙСМІЧНИХ НАВАНТАЖЕНЬ РАЙОНУ 7 БАЛІВ

This paper presents the results of the study of the strength of the junctions of external wall panels and columns and crossbars and columns of the IIS-03-02 series, which was used in the construction of the building of the Faculty of Biology of the Uzhgorod State University in the city of Uzhhorod. The survey and research data, as well as the development of recommendations, which were carried out by the employees of the Physico-Mechanical Institute named after G.V. Karpenka of the National Academy of Sciences on the order of «Zakarpatzalizoboton» VO from July 19, 1991. The work describes basic information about the building, its design and construction. The main reasons that led to the need for research and development of recommendations for strengthening the junctions of panels and columns and crossbars and columns and strengthening their short consoles and support niches of panels are established. Also, the data on identified design errors, shortcomings and defects in the construction and manufacture and transportation of reinforced concrete structures are given. In particular, the own weight of panels and walls is significantly overestimated by up to 25%; in some panels, embedded parts are embedded in concrete and have deviations from the design position; also in some panels there is a deviation of up to 20-30 mm from flatness; sockets for supporting panels on the console of the columns are installed at different angles to the plane of the panel; size fluctuations between the axes of the columns in some places are higher than the norm up to 50-70 mm; poor-quality reinforcement of the panels in the places where the supporting parts of the panels rest on the short console of the column, etc. The verification calculation of the support table of the reinforcement of the column consoles and the supporting parts of the panels was performed. On the basis of field survey and relevant calculations, appropriate recommendations were developed for strengthening the joints of external wall panels and columns and crossbars and columns. In particular, the elimination of identified shortcomings and defects, ensuring the bearing capacity of short cantilevers of the IIS-04-02 series for seismic loads for the construction area of 7 points.

Seismic Behavior of T-Shaped Concrete-Filled Steel Tubular Column to Steel Beam Joints with Side Plates

This study investigates the seismic behavior of the T-shaped concrete-filled steel tubular (CFST) column to steel beam joints, aimed at expanding their applicability in areas with high-seismic fortification intensity. A construction form of T-shaped CFST column to steel beam joint with side plates is presented. The variables studied in these experiments include the side plate length, the axial compression ratio, the presence of side plates, and the presence of binding bars. The force mechanism, failure modes, load–displacement curves, strength, stiffness, ductility, and energy dissipation capacity of seven specimens were evaluated under low-cycle reciprocating load. The experimental results demonstrate that the joints of side plates show a full hysteresis curve, with the ductility coefficient ranging from 1.67 to 2.49, and the equivalent viscous damping coefficient between 0.147 and 0.234. The joint panel zone displays strong deformation and energy dissipation capacity. The inclusion of side plates and binding bars improves the seismic behavior of the joint. The setting of side plates enables the formation of a plastic hinge on the steel beam, creating a beam hinge failure mechanism and satisfying the seismic design principle of “strong column and weak beam, strong joint and weak member” as required by the building structures.

Experimental and Numerical Study on the Shear Performance of the Stone Panel–Panel Joint in Stone Cladding

The evaluation of the shear performance of stone panel–panel joints (SPPJs) in stone cladding has important engineering significance, as it plays a crucial role in stone cladding failure. The purpose of this paper is to analyze and predict the influence of the dimension and the Young’s modulus of sealant on the shear performance of SPPJs. Based on monotonic and cyclic loading tests, the effects of Young’s modulus and the dimension of sealant on the failure characteristics, stress–strain characteristics, stiffness degradation, and energy dissipation capacity of an SPPJs were investigated. According to finite element analysis, the strain distribution of an SPPJ under monotonic loading was analyzed for different sealant widths and number of sealant layers. The results indicate that the failure modes of SPPJs change with the variation of sealant amount. As the Young’s modulus of the sealant increases, the shear failure strength and shear yield strain of SPPJs increase. The increase in sealant thickness reduces the shear failure strength and stiffness of SPPJs. Based on the same shear strain, the increase in the sealant thickness enhances the cumulative energy consumption of SPPJs. The strain concentration zone of the specimens with two sealant layers in unilateral SPPJs becomes larger with the increase in sealant width.

4 Evaluating Plasma GFAP for the Detection of Alzheimer’s Disease Dementia

Objective:Blood-based biomarkers represent a scalable and accessible approach for the detection and monitoring of Alzheimer’s disease (AD). Plasma phosphorylated tau (p-tau) and neurofilament light (NfL) are validated biomarkers for the detection of tau and neurodegenerative brain changes in AD, respectively. There is now emphasis to expand beyond these markers to detect and provide insight into the pathophysiological processes of AD. To this end, a reactive astrocytic marker, namely plasma glial fibrillary acidic protein (GFAP), has been of interest. Yet, little is known about the relationship between plasma GFAP and AD. Here, we examined the association between plasma GFAP, diagnostic status, and neuropsychological test performance. Diagnostic accuracy of plasma GFAP was compared with plasma measures of p-tau181 and NfL.Participants and Methods:This sample included 567 participants from the Boston University (BU) Alzheimer’s Disease Research Center (ADRC) Longitudinal Clinical Core Registry, including individuals with normal cognition (n=234), mild cognitive impairment (MCI) (n=180), and AD dementia (n=153). The sample included all participants who had a blood draw. Participants completed a comprehensive neuropsychological battery (sample sizes across tests varied due to missingness). Diagnoses were adjudicated during multidisciplinary diagnostic consensus conferences. Plasma samples were analyzed using the Simoa platform. Binary logistic regression analyses tested the association between GFAP levels and diagnostic status (i.e., cognitively impaired due to AD versus unimpaired), controlling for age, sex, race, education, and APOE e4 status. Area under the curve (AUC) statistics from receiver operating characteristics (ROC) using predicted probabilities from binary logistic regression examined the ability of plasma GFAP to discriminate diagnostic groups compared with plasma p-tau181 and NfL. Linear regression models tested the association between plasma GFAP and neuropsychological test performance, accounting for the above covariates.Results:The mean (SD) age of the sample was 74.34 (7.54), 319 (56.3%) were female, 75 (13.2%) were Black, and 223 (39.3%) were APOE e4 carriers. Higher GFAP concentrations were associated with increased odds for having cognitive impairment (GFAP z-score transformed: OR=2.233, 95% CI [1.609, 3.099], p<0.001; non-z-transformed: OR=1.004, 95% CI [1.002, 1.006], p<0.001). ROC analyses, comprising of GFAP and the above covariates, showed plasma GFAP discriminated the cognitively impaired from unimpaired (AUC=0.75) and was similar, but slightly superior, to plasma p-tau181 (AUC=0.74) and plasma NfL (AUC=0.74). A joint panel of the plasma markers had greatest discrimination accuracy (AUC=0.76). Linear regression analyses showed that higher GFAP levels were associated with worse performance on neuropsychological tests assessing global cognition, attention, executive functioning, episodic memory, and language abilities (ps<0.001) as well as higher CDR Sum of Boxes (p<0.001).Conclusions:Higher plasma GFAP levels differentiated participants with cognitive impairment from those with normal cognition and were associated with worse performance on all neuropsychological tests assessed. GFAP had similar accuracy in detecting those with cognitive impairment compared with p-tau181 and NfL, however, a panel of all three biomarkers was optimal. These results support the utility of plasma GFAP in AD detection and suggest the pathological processes it represents might play an integral role in the pathogenesis of AD.

К ВОПРОСУ РЕШЕНИЯ ПРОБЛЕМ ЭКСПЛУАТАЦИИ ПАНЕЛЬНЫХ ЗДАНИЙ

This article discusses issues related to the overhaul of large-panel residential buildings. The authors pay attention to a key aspect of this process, namely the repair of the joints of wall panels, as well as methods to identify places where the tightness of the seams in panel houses is broken. One of the important stages of the study is thermal imaging scanning, which allows you to accurately determine areas with the greatest heat loss and identify problem areas that require immediate intervention. The article also provides a brief description of the different types of sealants and their applications in the context of wall joint repairs. This is significant because choosing the right sealants and applying them correctly can greatly improve the effectiveness and longevity of a repair. The authors of the study emphasize not only the importance of proper repair of wall panel joints, but also the need to comply with building maintenance requirements and timely major repairs using high-quality materials. This is key to ensuring the durability of wall panel joints. Effective major renovations help create a favorable indoor microclimate and reduce energy costs, which is important not only from the point of view of improving living conditions, but also from an economic point of view in the modern construction industry.

Development of Free-Form Assembly-Type Mold Production Technology Using 3D Printing Technology

Free-form molds are used for one-time curve configuration, and because they are produced through manpower, they have issues with reduced precision and the occurrence of errors. In this study, 3D printing technologies were used to ensure precision, and polylactic acid and reusable eco-friendly materials to develop free-form assembly-type side-mold production technologies. In verifying the side mold, a free-form concrete panel was produced to check whether deformation occurs due to lateral pressure. Therefore, in this study, to verify this, a free-form concrete panel was produced and 3D-scanned to analyze the error at the side mold and the cause of the error to confirm the performance of the mold. The results showed that the error at each part was small, with a standard deviation of 1.627 mm, and there was little error at the panel joint part, around 1°. Such research is expected to be used in studies related to mold production technologies using 3D printers and on the production of free-form side molds.

Seismic performance of bidirectional bolted drilled cut RBS-CFT connections under cyclic loads

Welded connections were widely used in different regions of the world for ease of fabrication and good performance under gravity load. However, Northridge (1994) and Kobe (1995) earthquakes demonstrated that seismic performance of welded connections has been inferior as compared to that of bolted connections. Reduced beam section (RBS) has been one of the effective methods to enhance seismic performance in terms of energy dissipation capacity and ductility. Drilled-cut RBS-CFT connections have been gaining acceptance for enhancing overall seismic performance of steel moment resisting frames. However, no comparative study has been reported in the literature on RBS-CFT connection with bidirectional bolts for evaluation of their seismic performance. In view of the above, experimental study has been carried out for evaluation of seismic performance of two variants of RBS-CFT connections with constant drilled cut (CD-cut) and varied drilled cut (VD-cut) RBS. Both the drilled cut RBS-CFT connections are found to be semi-rigid in nature and exhibited stable hysteretic behavior. Test results showed that the cumulative energy dissipation capacity in the VD-cut connections is marginally higher than CD-cut connection. VD-cut RBS-CFT connections effectively reduced the lateral-torsional deformation. The load-carrying capacity and stiffness degradation ratio of VD-cut RBS-CFT connection is higher than CD-cut RBS-CFT connection. Damping of the both connections are nearly of similar order. Recorded strain data of both connections showed that plastic hinge confined only on drilled zone of the beam. Further, a detailed numerical simulation of force-deformation envelope curve of RBS-CFT connections was carried out using ABAQUS software. Simulated force-deformation envelope curves are found to be in close agreement with those obtained from experimental investigation. Both connections meet the seismic requirements of the AISC specified for composite special moment-resisting frames (SMRFs) by achieving rotational capacity of 0.04 radians without any damage in the joint panel region.

Analysis and evaluation on seismic performance of the composite wallboard joints integrating thermal insulation and load bearing

This study aimed to present a structurally integrated, insulated composite wall panel with joint components to enhance the insulation technology of exterior wall boards in complex construction technology, that has a poor fire performance has been accelerated in recent years. The development of modern constructions toward green architecture, environmental protection, and prefabrication was accelerated. The mechanical and seismic properties of three-wall panel T-joint specimens were studied via low-cycle quasi-static loading tests. The test results showed that the ductility coefficient of the sample was 2.9, which was higher than that of the ordinary composite wallboard. The stiffness of the specimen gradually reduced. Further, the wall panel joint conformed to the code requirements and showed a good seismic performance. Additionally, we simulated this kind of wall panel, and the critical parameters of the finite element method suitable for this joint were proposed. On the basis of these tests and simulations, the finite element method was used to analyze the factors affecting the energy dissipation ratio under different thicknesses of this type of wallboard. The joint optimization scheme of the wall panel conformed to the general specification, and the effect was remarkable. This study defined the relationship between axial compression ratio, wall thickness, and total energy consumption. The study conformed to the current development trend of prefabricated construction and has significant engineering application.