Plastic Design Research Articles

Morphological and structural-compositional features of the historical block development of St. Petersburg

The development of the historical center of St. Petersburg has special parameters and characteristics that form the uniqueness of the city as a whole and its individual fragments. At the moment, due to the emerging urban planning errors and violations, there is a need to clarify the strategy of urban planning regulation of the historical center in order to preserve the uniqueness, integrity and quality of its architectural and urban environment. In this regard, the task of moving to a detailed and comprehensive study of the parameters of fragments of the urban environment becomes urgent. The purpose of this study is to study the existing architectural and urban planning characteristics of the residential development of St. Petersburg. The object of research is the historical block within the boundaries of Moskovsky Prospekt, Klinsky Prospekt, Bronnitskaya Street, Zagorodny Prospekt. The subject of the study is morphological and structural-compositional features of the building. On the basis of the conducted historical, archival and bibliographic surveys and a full-scale survey, the enlarged stages of the formation of the block were identified and the main patterns of the construction of the front front were determined. The morphotype of the block is a perimeter building of the historical center of St. Petersburg of the XIX century with the inclusion of objects of the mid–XX century, with irregular surveying and an incomplete system of courtyard buildings. The nature of surveying and urban fabric, which developed mainly in the second half of the XIX – mid XX century, was influenced by the planning structure laid down in the XVIII century and the location of the block in the structure of the city. The compositional organization of the front along Moskovsky Prospekt is subject to uniform principles, which made it possible to form a high-quality urban environment. The front facades have fragmentary losses of decorative elements and structural violations at the ground floor level, which can be eliminated provided that the historical rules of formation and decorative and plastic design of buildings are observed.

Assessing Provisions and Requirements for the Sustainable Production of Plastics: Towards Achieving SDG 12 from the Consumers’ Perspective

Plastics are used widely, and modern civilization would have to behave differently without them. However, plastics pose a threat to sustainable life. This paper focuses on some of the provisions being made for sustainable production to date and focuses on one key sector-plastic manufacturing-where sustainable production patterns are urgently needed. The paper describes the latest trends related to plastic production, its environmental impacts, and how this sector is adjusting its processes in order to meet the current and forthcoming legal requirements and consumer demands. The methodological approach of the study has focused on both a literature review on the one hand and the consumers’ perspective obtained via a survey on the other. These two approaches were then crosschecked in order to assess current trends in plastic manufacturing and to understand how consumers see these trends as being consistent with the aims of the UN Sustainable Development Goal 12. The results obtained suggest that a greater engagement of consumers is needed in supporting the efforts to manage plastic more sustainably. Based on its findings, the paper provides useful insights linked to principles and tools for sustainable plastic production and design, and it demonstrates the usefulness and urgency of a sound materials management in order to tackle plastic pollution, one of today’s major environmental problems.

RANCANG BANGUN CETAKAN PLASTIK SARINGAN PEMBUANGAN AIR KAMAR MANDI

The main purpose of the design of plastic molding molds is to participate in advancing the world of the machining industry and can help the mold industry to simplify and shorten the time in doing a work of making molds, especially plastic molding molds. The design of this plastic molding mold by designing the shape of the injection machine then calculates the volume in the injection machine, the volume of this bathroom drain filter mold is 26838,475 mm3. Calculations on the design of this bathroom drain filter mold use references from the book by Scharcus, Edward and Herman Jutjz, "Westerman table for the metal Trade", Willestern Limited, new Delhi, 1985. The result of this plastic molding design is a filter. disposal of water using materials from PVC (Polyvinyl Chloride) seeds with an injection molding work system in the Sriwijaya State Polytechnic Mechanical Engineering laboratory.

Experimental testing of aluminum‐core buckling restrained knee braced Truss moment frames for earthquake resistance

AbstractApplication of Buckling Restrained Braces (BRBs) with Truss Moment Frames (TMFs) results in a robust seismic force‐resisting system, herein referred to as Buckling Restrained Knee Braced Truss Moment Frame (BRKB‐TMF), which utilizes the advantages of both BRBs and TMFs. Although steel is commonly used to make the core of BRBs, previous studies have demonstrated the efficacy of annealed aluminum as a preferred core material because of its high ductility and high over‐strength. However, the deformation compatibility of the truss members with the aluminum‐core BRB in BRKB‐TMFs at high drifts is not well studied in the literature. Hence, an experimental study is performed on a scaled sub‐assemblage of a BRKB‐TMF frame designed using the Performance‐Based Plastic Design method. Cyclic tests are performed on 1:3 scale models of aluminum‐core BRB and BRKB‐TMF to evaluate their performance at drifts corresponding to Maximum Considered Earthquake intensity. Also, to further compare the performance of steel and aluminum as suitable BRB core materials, cyclic tests are performed on BRBs with steel and aluminum cores designed using a consistent criterion. The experiments demonstrated the superior performance of aluminum core BRB over steel core BRB. The experimental studies on the BRKB‐TMF concluded that per the design intent, the BRB acted like a fuse for the frame by restricting all the inelastic deformations to itself and the study frame could successfully meet the target drift criteria.

Behaviour and design of high strength steel homogeneous and hybrid welded I-section beams

The behaviour and design of high strength steel (HSS) beams are addressed in the present study. Six in-plane three-point bending tests on three different welded I-sections − two homogeneous S690 steel welded I-sections and one hybrid welded I-section with S690 steel flanges and an S355 steel web, were first conducted. The beam tests were carried out in major axis bending and a bespoke restraint system was designed and employed in the test programme to prevent lateral-torsional buckling. Following the experimental investigation, a thorough finite element (FE) modelling programme was performed, which included a validation study confirming the accuracy of the developed FE models in replicating the flexural behaviour of HSS welded I-section beams, and a parametric study generating additional FE data on HSS welded I-section beams over a broader range of cross-sectional slendernesses, steel grades and loading configurations. The test results obtained in the present study and collected from the literature, together with the generated FE data from the parametric study, were used to evaluate the suitability of the current Eurocode 3 cross-section slenderness limits for HSS homogeneous and hybrid welded I-sections in bending. It is shown that the current Eurocode Class 2 and Class 3 slenderness limits are suitable for the classification of the outstand flange (in compression) and internal web (in bending) elements of both HSS homogeneous and hybrid welded I-sections subjected to major axis bending, while stricter Class 1 slenderness limits are considered necessary to achieve sufficient rotation capacity for plastic design. The findings from the present study indicate that plastic design can be used for HSS structures, provided the proposed stricter Class 1 slenderness limits are employed.

Closed-form solutions for the elastic–plastic buckling design of shell structures under external pressure

This paper deals with the elastoplastic buckling analysis of shell geometries traditionally encountered in pressure vessels subjected to external pressure loading. The objective is to propose in a unified way original analytical closed-form solutions giving rise to reliable results, with a good accuracy and a wide range of applications in a straightforward and low time-consuming way, for efficient dimensioning purposes. The present study is based on the plastic bifurcation theory, classically used in the context of conservative systems, where additional terms are incorporated here due to the follower external pressure acting normally to the deformed surface of the shell still after buckling. Cylindrical shells are first considered, which certainly represent the most fundamental components of pressure vessels in practice. Owing to the external pressure also acting on the closure ends of a cylinder, the influence of the induced axial compression is investigated thereafter. It appears to be non-negligible for short cylinders in elasticity and it becomes very significant in the case of plastic buckling. Then, closed-form solutions for the critical external pressure of a complete sphere are also obtained, both in elasticity and plasticity. Finally, all these new closed-form solutions are validated against reference numerical results obtained through finite element computations, and compared to current design rules.

Biomass yield and biofiber properties of select industrial fiber crops in Lithuania

AbstractThe versatility, flexibility, design, and lightness of plastic are the most attractive features that enable its useability in our daily life. As production of disposable plastic increases, so does the amount of waste. Plastic waste is nondegradable. Its accumulation over time increases the risk of environmental pollution and contributes to environmental hazards. This has resulted into finding more renewable sources that could replace plastics. One renewable resource is agricultural plant biomass rich in cellulose. This work is aimed at evaluating the chemical composition and structure of industrial fiber crops. Three types of crops were selected: Miscanthus (Miscanthus giganteus), Virginia mallow (Sida hermaphrodita Rusby), and mugwort (Artemisia dubia Wall.). Their properties were compared with wheat straw (Triticum spp.). The industrial fiber crops and wheat straw were fertilized with mineral fertilizer at 90 kg ha−1. Experiments were performed to evaluate chemical and physical composition and biofiber parameters of crops. The highest cellulose content of 54.5 ± 2.17% was in mugwort with the lowest value of 42.5 ± 1.31% in Miscanthus. The carbon/nitrogen (C/N) ratio was the lowest in mugwort (114.8 ± 3.91%). This means mugwort biomass can be easily degraded by microorganisms and has better biomass pretreatment properties. The best fiber quality was found in Virginia mallow. However, the yield of Miscanthus fiber per hectare was higher, compared with other tested crops. The study presented opportunities for mugwort and Miscanthus as verifiable industrial fiber crops. They hold huge potential as raw materials for biorefinery production with less cost and high productivity under temperate climatic conditions.

Performance-based plastic design of multi-story hybrid braced frames with buckling-restrained braces and shape memory alloy braces

By employing two or more types of braces, hybrid braced frames (HBFs) combine the merits of the adopted braces and offsets their drawbacks. However, the corresponding seismic design method is still under development. To this end, this paper develops a performance-based seismic design (PBSD) method, based on the performance-based plastic design (PBPD) method. In current work, the buckling-restrained braces (BRBs) and shape memory alloy braces (SMABs) are introduced, because they are known for high energy-dissipating capacity and excellent self-centering capability, respectively. The participation extent of BRBs and SMABs is controlled by the stiffness contribution factor. The equations governing the design results are derived and the step-by-step procedure is detailed. A six-story benchmark frame is selected to demonstrate the design method. The designed HBF is subjected to a suite of earthquake ground motions, and the mean demands of seismic responses are compared against performance targets. It indicates that the HBF designed by the design method can well meet the design targets. A parametric analysis is conducted to reveal the effect of changing the stiffness contribution factor on the seismic demands of the HBF. This study validates the proposed design method for HBF, and it may also shed light to the PBSD method of the structures equipped with the other types of displacement-dependent damping braces.

A plastic design method based on multi-objective performance for high-strength steel composite K-shaped eccentrically braced frame

A plastic design method based on multi-objective performance (PDMP) for high-strength steel composite K-shaped eccentrically braced frame (HSS-KEBF) is developed in this study, which explicitly considers the different seismic fortification objectives of the structure and the shear distribution relationships of the brace-frame system. The performance objectives of the structure under three seismic hazard levels were obtained by combining different roof drift ratios and displacement ductility demands, and a trilinear capacity curve of HSS-KEBF considering the change of post-yield stiffness was proposed. The energy balance principle was used to calculate the elastic and elastic–plastic shear distributions of the brace-frame system under different performance objectives, to facilitate the elastic–plastic design of HSS-KEBF. A ten-story HSS-KEBF structure was designed using the proposed design method, and an elastic-plastic finite element model of the structure was established using OpenSees for analysis. The results show that the structural model achieves the expected performance objectives in terms of capacity curves, roof drift ratios, base shears, and failure modes. From the SLE level to MCE level, the base shear distribution ratio borne by the frame component increased from 36% to 46%, which satisfies the design idea of multi-aspect fortification.

Polydiketoenamines for a Circular Plastics Economy.

The mismanagement and leakage of plastic waste into the environment are failures of modern society. Once in the environment, plastic waste degrades into microplastics on a time scale dependent on the resin chemistry and the associated biotic or abiotic process. The high surface area of microplastics results in the contamination of ecosystems through the leaching of toxic chemicals compounded with plastics during manufacturing. In addition, the small size of microplastics increases the likelihood that they will be inhaled or ingested, which has led to the bioaccumulation of microplastics with documented harm. Furthermore, microplastics are more readily aerosolized and distributed by weather systems to areas remote from locations where plastic waste has been mismanaged. Consequently, the carbon cycle must now account for plastic waste discharge, degradation, and dispersal in the environment after the end of useful life on a global scale.Circularity in plastics recycling endeavors to solve the waste problem while promoting greater sustainability. Circularity can be conducted at different stages in the plastics life cycle. Post-industrial recycling enabling scrap recovery in manufacturing is desirable for industrial material efficiency. However, the degradation of polymer chains currently limits the extent to which scrap recovery may be practiced repeatedly on the same material, particularly when the conversion of secondary resin to various plastic products is intolerant to deviations in polymer properties. Post-consumer recycling, on the other hand, is desirable for erasing the manufacturing history and use history of plastic-containing products. Post-consumer recycling involves cleaning and sorting plastic waste into bales, followed by mechanical recycling to produce dense feedstocks for downstream chemical processes required for deconstruction, monomer refinement, and secondary resin production. The efficiency and intensity of chemical processes used to recover reusable monomers or polymers remain low for most plastics. Consequently, there is an urgent need for novel polymers with useful or advantageous properties designed for recycling by addressing the challenges of resource recovery for reuse.In this Account, I discuss the design, discovery, and development of circular plastics based on the chemistry of polydiketoenamines. The diketoenamine bond provides a vantage point for the creation of thermoplastics, elastomers, and thermosets from polytopic triketone and amine monomers. The dynamic covalent character of the diketoenamine bond can be exploited during scrap recovery to provide resilience during mechanical recycling, maintaining baseline properties of the primary resin through multiple cycles of reuse. Furthermore, the hydrolyzability of the diketoenamine bond in strong acid can be exploited for efficient monomer recovery during chemical recycling. A systems-level analysis of polydiketoenamine circularity reveals substantive benefits in low-carbon manufacturing as well as a context to quantify the market potential, identifying use cases where circularity might be most effective. Leveraging these insights, it is possible to guide the process chemistry development necessary to scale monomer and resin production to meet imminent needs for more circular plastics in the market. These insights also provide a glimpse into the underlying molecular mechanisms critical to circularity in a new plastics economy while firmly establishing a role for creativity in polymer chemistry to provide innovative solutions.

Perencanaan Konsep Desain Daur Ulang Plastik Untuk Bahan Bangunan

<p class="7Abstract">The purpose of community service is for residents to have skills in planning plastic recycling designs into items of economic value as an alternative to building materials and have an entrepreneurial spirit. The method used is observation, interviews, and training. Based on the training that has been carried out, the following results are obtained: 1. Residents are able to process other recycled plastic materials with various functional process design concepts. 2. Residents are able to create attractive design concepts in the marketing phase of building materials. 3. Residents are able to market plastic recycling designs through social media and marketplaces as alternative activities for online entrepreneurship.</p><p class="8Abstractcontent"> </p>

Seismic performance of knee-braced frames equipped with NiTi BRBs

Knee braces (KBs) are often installed at locations near to the beam-to-column connections in frames. In comparison to concentrical and eccentrical braces, KBs have advantages of occupying less space, less affecting the architectural view, and ease of installing and replacing if necessary. As a comparative analysis, this paper evaluates the seismic performance of knee braced frames (KBFs) equipped with steel or NiTi buckling-restrained braces (BRB). Through machining raw bars into bamboo shape, this paper fabricated two types of KBs and conducted cyclic loading tests on reduced-scale specimens. The testing results show that both KBs have stable cyclic properties under loading reversals. The steel BRB has typical elasto-plastic hysteresis, whereas the NiTi BRB has a flag-shape hysteresis. At the system level, the 3- and 6- story KBFs were first designed by performance-based plastic design (PBPD) method and then subjected to a suite of earthquake records. It indicated that the KBFs equipped with either steel or NiTi BRBs can well meet the prescribed drift target. The major advantage of NiTi BRBs over steel BRBs is that they successfully eliminated residual drift ratios for the protected frames, which means the KBFs with NiTi BRBs have higher seismic resilience.

From the archive: Strength is easy! Or the development of plastic design

To mark the 100th anniversary of The Structural Engineer, Alan Rathbone looks back at several key papers that helped advance the development of plastic design of steel portal frames.

Seismic performance quantification of buckling-restrained steel plate shear wall-RC frame structures

The beam-connected buckling-restrained steel plate shear wall (SPSW) has the advantages of high bearing capacity, strong energy dissipation and good ductility, and flexible arrangement in the structure, which can reduce the force acting on the frame columns and avoid premature failure of the frame columns. To determine the SPSW configuration in structures to fully exploit the seismic performance, a plastic design method of the steel plate shear wall-RC frame structure (SPSW-RCF) was proposed based on energy balance in this paper. The expected global failure mechanism was constructed and the double lateral resistance SPSW-RCF system was decomposed into SPSW system and RC frame system by using shear force ratio. The design base shear was calculated based on the energy balance principle to determine the design lateral story shear forces of the SPSW and RC frame systems, and then the design of SPSWs could be completed. Considering the post-yield behavior of SPSWs and the plastic internal force distribution mechanism, internal forces of beams and columns were calculated, and then the design of the RCF could be completed. 56 SPSW-RCF structures with different story numbers and story shear ratios were designed, SPSW thickness and reinforcements of the SPSW-RCF were compared. By performing the nonlinear dynamic analysis under 22 ground motions, the maximum interstory drift ratios, SPSW maximum displacement ductility, yield mechanism, residual drift ratio and story shear ratio of structures with different story numbers and story shear ratios were comparatively investigated. Furthermore, the actual SPSW-resisted story shear ratio was quantified and the recommended design SPSW-resisted story shear ratio was suggested.

Performance‐based plastic design and seismic performance evaluation of twisted diagrids with shear links

SummaryTwisted diagrid tube structures have become popular due to their significant lateral resistance and esthetic potential. However, the ductility and energy dissipation capacity of twisted diagrid structures are poor. This paper presents a seismic resilient fused structural system named the twisted diagrids with shear links (TDSL), and the performance‐based plastic design (PBPD) method is introduced for designing a 24‐story prototype structure. The numerical model of the TDSL prototype is established, then nonlinear static and dynamic analyses are conducted to evaluate the seismic behavior of the prototype. The results reveal that the TDSL system can significantly improve the post‐yield performance compared to the conventional twisted diagrid structure, and the performance objectives are achieved properly. Subsequently, incremental dynamic analyses are carried out to investigate the collapse fragility of the TDSL prototype, and the collapse risk of the prototype is assessed by FEMA P695. The results indicate that the TDSL prototype has satisfactory collapse‐resisting capacity under earthquakes. It is also found that corner columns can improve the seismic safety of the prototype against collapse. In general, the TDSL system is an appealing choice for twisted buildings in seismic regions.

Detection and formation mechanisms of secondary nanoplastic released from drinking water bottles

Since nanoplastics are currently considered potentially hazardous to the environment and human health, reliability of studies on nanoplastic exposure becomes crucial. However, analytical challenges limit our understanding of their formation and detection, thus hampering their biological interactions assessment. Here we provide a combined approach to quantitatively and qualitatively detect the release of nanoplastics in water matrix and, in particular, to measure direct exposure of consumers by simulated use of drinking water plastic bottles. We measured that the polyethylene sealing of the bottles released particles with a size distribution ranging from few hundreds nanometers up to about one micron and estimated a mass release in the order of few tenths of nanograms per opening/closing cycle. We observe that mechanical stress alters the physical-chemical characteristics of the generated secondary nanoplastics and degrades the material properties compared to the original bulk source, thus complicating their spectroscopic chemical identification. Our findings demonstrate that understanding material degradation processes is therefore crucial for identifying and quantifying nanoplastics in real samples. Moreover, methods allowing quantitative studies on the release of nanoplastic as a source of exposure are considered essential for proper assessment of their potential health hazards and to promote improvements in consumer products plastic packaging design.

Comparative study and performance evaluation of steel moment resisting frames design with: Force-based design and performance-based plastic design

Incremental Dynamic Analysis (IDA), Nonlinear Response History Analysis (NLRHA) and Nonlinear Static Pushover Analysis (NSPA) has been carried out to evaluate seismic performance of Steel Moment Resisting Frames (SMRF). SMRF’s are used as the lateral resisting systems which consist of columns and beams joined by welding or using high strength bolts or combination of both. The resistance offered to the lateral forces is due to rigid frame action which develops bending moment and shear force in the frame members and joints. The 9-storey SMRF is been evaluated for two frames designed by Force Based Design (FBD) method and Performance Based Plastic Design (PBPD) method. The FBD frame is designed by using codal provision of ASCE 7 (American Based Seismic Code) and AISC (American Institute of Steel Construction) whereas PBPD frame is designed as per proposed work of Lee and Goel (2001) in which energy balance equation and pre-selected yield mechanism is considered. The evaluation study showed that the PBPD method for steel moment resisting frame is significantly more efficient in achieving a certain inelastic displacement/ductility for given seismic hazards compared to the existing design standards/specification for this system. By Nonlinear Static Pushover Analysis (NSPA) the PBPD method has achieved the target yield drift of 1.11% and FBD method has achieved 1.22% where the assumed yield drift was 1%. From NLRHA the percentage difference in achieved ductility factor for frame design by FBD method is 46.28% whereas for PBPD method it is 16.81%. From IDA inter storey drift is observed maximum in AISC design frame compared to PBPD design frame. Therefore, PBPD method frames responded as intended in design with much improved performances over those of the corresponding FBD method.

Seismic fragility analysis of buckling-restrained brace-strengthened reinforced concrete frames using a performance-based plastic design method

An easily-operated performance-based plastic design (PBPD) method for buckling-restrained braced (BRB) reinforced concrete (RC) moment frames is adopted in this research to strengthen existing moment frames by BRBs. The appropriate range of the story base shear ratio p (i.e., the ratio of the base shear resisted by the BRBs to that of the total system) is suggested through a seismic fragility analysis. With an earthquake ground motion set of thirty far-field records, the seismic fragility analysis and risk assessment of an 8-story RC moment frame structure and its strengthened structures with BRBs are reported in this article, in which the fragility curves for different limit states and the corresponding annual exceedance probability are calculated. The applicability of 16 ground motion intensity measures (IMs) in the fragility analysis of the structure before and after strengthening under three damage limit states is further reviewed. As indicated by the fragility analyses, a higher seismic resistance capacity can be obtained for the strengthened structure when the ratio p varies between 0.5 and 0.8. The seismic performance of the structures strengthened using the PBPD method can increase steadily till the advent of the preset target ultimate drift limit, after which the improvement efficiency decreases. The IM Sa,gm(Ti) that considers both effects of softened period and higher mode has a better performance in each limit state of the structure both before and after strengthening.

Study on Intrinsic Influence Law of Specimen Size and Loading Speed on Charpy Impact Test.

Charpy impact energy/impact toughness is closely related to external factors such as specimen size. However, when the sample size is small, the linear conversion relationship between the Charpy impact energy of the sub-size and full-size Charpy specimens does not hold; the Charpy impact toughness varies with the size of the specimen and other factors. This indicates that studying the internal influence of external factors on impact energy or impact toughness is the key to accurately understanding and evaluating the toughness and brittleness of materials. In this paper, the effects of strain rate on the flow behavior and the effects of stress triaxiality on the fracture behavior of 30CrMnSiNi2A high-strength steel were investigated using quasi-static smooth bar and notched bar uniaxial tensile tests and Split Hopkinson Tensile Bar (SHTP). Based on the flow behavior and strain rate dependences of the yield behavior, a modified JC model was established to describe the flow behavior and strain rate behavior. Charpy impact tests were simulated using the modified JC model and JC failure model with the determined parameters. Reasonable agreements between the simulation and experimental results have been achieved, and the validity of the model was proved. According to the simulation results, the impact energy was divided into crack initiation energy, crack stability propagation energy and crack instability propagation energy. On this basis, the effects of striker velocity and specimen width on the energy and characteristic load of each part were studied. The results show that each part of the impact energy has a negligible dependence on the hammer velocity, but there is a significantly different positive linear relationship with the width of the sample. The energy increment of each part also showed an inverse correlation with the increase in the sample width. The findings reveal that the internal mechanism of Charpy impact toughness decreases with the increase in sample width; to a certain extent, it also reveals the internal reason why the linear transformation relationship of Charpy impact energy between sub-size specimens and standard specimens is not established when the specimens are small. The analytical method and results presented in this paper can provide a reference for the study of the dynamic behavior of high-strength steel, the relationship between material properties and sample size, and the elastic–plastic impact dynamic design.

LETTER FROM THE EDITOR

LETTER FROM THE EDITOR