In light of growing environmental concerns, the reduction of CO2 emissions is increasingly vital. Particularly in the construction industry, a major contributor to global carbon emissions, addressing ...this issue is critical for environmental sustainability and mitigating the accelerating impacts of climate change. This study proposes the Optimal Green Design Model for Mega Structures (OGDMM) to optimise CO2 emissions, cost-effectiveness, and serviceability in highrise buildings with mega structures. The OGDMM examines the impact of each material and structural design of main members on these three critical aspects. Analytical results for high-rise buildings (120–200 m, slenderness ratio: 2.0–8.0) demonstrate that OGDMM can reduce CO2 emissions and costs by an average of 4.67% and 3.97%, respectively, without compromising serviceability. To ensure comprehensive evaluation, this study introduces five new evaluation indicators encompassing environmental, economic, and serviceability performances of high-rise buildings. Based on these criteria, optimised structural designs for high-rise buildings are classified into four categories according to slenderness ratio, leading to the formulation of corresponding design guidelines. The model’s applicability is further validated through its application to a 270-m-tall high-rise building in Korea, showing reductions in CO2 emissions and costs by 8.99% and 18.50%, respectively, while maintaining structural serviceability.
Unexpected damages or failures of steel pipes in refineries cause significant disruption to economic activity. While research has been conducted on the prevention of damage to steel pipes, no ...systematic methods or practical techniques for monitoring of vibrations to estimate the state of pipeline system have been reported. In this study, vibration safety evaluation model consisting of design – evaluation – control steps was developed to measure and control the vibration level during operation of the piping system of an oil refinery. The measurement location was designed by examining the structure of the pipe, and the vibration level measured at each location was compared with the allowable vibration level. Subsequently, two types of vibration reduction measures, namely, dynamic absorbers and viscous dampers, were introduced to reduce the vibration level. The effect of the application of the monitoring system was evaluated by comparing the vibration levels of the steel pipes before and after the application of the dynamic absorbers and viscous dampers. The vibrations of steel pipes in the oil refinery during operation decreased by over 50%. Upon applying the dynamic absorbers and viscous dampers, the responses of the frequency component also exhibited local and global reductions of approximately 50–80%.
Repetitive and severe thermal loads and load changes affect not only the physical properties of the coke drum but also its dynamic properties, possibly leading to structural failure. In particular, ...the operation weight of the drum, which increases up to 10 times or more, affects the dynamic properties of the structure and may threaten safety. Therefore, a vibration safety evaluation model for coke drums in operation is proposed to provide critical feedback on damage accumulation and to evaluate the vibration stability. A monitoring system was also developed to validate the model predictions by measuring the vibration patterns and corresponding modal parameters of the coke drums in operation. The proposed technique was applied to two coke drums in operation, and the vibration safety and factors causing vibration in the target structures were analyzed. The maximum vibration pattern was observed in the target structures at a feeding ratio of 71%. It exceeded the vibration criteria of the vibration safety evaluation model by up to 406%. Moreover, the analysis determined that the rapid increase in operating weight of the coke drums due to the influx of heavy crude oil, and the down-shift in their mode frequency induced superimposition and resonance with the structural mode, causing vibration.
This study proposes a sandwiched composite locally resonant metamaterial (SLRM) system and SLRM-embedded plate structure (SLRMeP) to effectively control low-frequency vibrations and sound radiation. ...The wave control mechanism and configuration of the proposed system are more suitable and realistic to address practical low-frequency vibro-acoustic problems. A numerical model was proposed based on the material properties, unit dimensions, and mass ratios to determine the local resonance characteristics and bandgap formation. The experimental results on a full-scale SLRMeP measuring 3000 × 4200 × 210 mm confirmed the efficacy of the local resonance bandgap for controlling vibrations and sound radiation, achieving a 94.08% reduction in the acceleration response and a 15.13 dB reduction in the sound pressure level. Additionally, variations in mass ratio, achieved by altering the mass density or dimensions, yield distinct bandgap behaviors, offering strategies to enhance vibro-acoustic performance.
•Sandwiched locally resonant metamaterial (SLRM) systems for low-frequency vibration and noise control.•Numerical models for designing bandgap formation.•Application to reinforced concrete slabs for addressing practical low-frequency vibro-acoustic issues.•Full-scale experiments showing a 94.08% reduction in acceleration response and a 15.13 dB decrease in sound pressure level.•Comparative analysis of bandgap behavior with two approaches to increase the mass ratio.
In this study, a plate‐type locally resonant metamaterial (PTLRM) is proposed to control bending vibrations and low‐frequency noise of civil members. Considering the ease of design, installation, and ...workability, the PTLRM was fabricated using high‐density and soft materials. The PTLRM design includes a resonance frequency calculation of the unit and band gap estimation of the PTLRMs‐coupled structure. Three indicators were developed and experimentally analyzed to evaluate the vibration attenuation performance of the PTLRM: the response suppression in the resonance of PTLRMs, peak response suppression ratio, and distance between peaks. Experimental results of a 5‐m long steel beam with PTLRMs indicated that the bending modal responses of the steel beam were suppressed at frequencies closer to the local resonance of the PTLRM. This showed reasonable agreement with the results of the estimation. The acceleration of the PTLRMs‐coupled beam was reduced by up to 98.58% in the frequency response function. The time history of acceleration also decreased significantly over the entire time period. The damping of the soft material had little effect on the bandwidth of the band gap. However, it was found that a proper increase in the damping of the soft material could increase the vibration suppression performance.
•Locally resonant metamaterials-based RC metaslabs for broadband flexural vibration control.•Hybrid vibration control behavior integrating local resonance bandgap and vibration isolation.•Numerical ...models for designing local resonance bandgap and vibration isolation.•Full-scale experiments for validating the proposed technique and analytical models.•Up to 99.94 % reduction in initial four modal responses of the fabricated RC metaslab.
In this study, a novel method is introduced, integrating the principles of the local resonance bandgap (LRBG) with vibration isolation techniques to achieve broadband flexural vibration control in plate structures. This methodology employs locally resonant metamaterial units incorporated into a reinforced concrete (RC) slab, making it suitable for real-world engineering applications. Concurrently, the construction specifics associated with this methodology are elucidated. The mechanisms behind LRBG and vibration isolation within the metaslab were examined using numerical analyses. From these analyses, the frequency range conducive for broadband flexural vibration control was estimated, factoring in both material properties and geometric dimensions. Experimental results on a full-scale RC metaslab, measuring 4,200 × 3,000 × 210 mm, validate that the fabricated metaslab introduces a broadband vibration control region attributed to both the LRBG and vibration isolation phenomena. These findings closely align with the numerical estimations. All bending modal responses inherent in the unmodified RC slab were encompassed within this broadband frequency range. Furthermore, the maximal and initial four modal responses of the RC metaslab were attenuated by up to 81.19 %, 99.57 %, 99.94 %, 99.71 %, and 99.79 %, respectively.
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In this paper, a new locally resonant metamaterial (LRM) is proposed to attenuate noise and vibration of floors in residential buildings. The band gap behavior of LRMs has recently attracted ...attention in the field of noise and vibration absorption. However, no research has been reported in the literature on the practical application of LRMs in buildings and their generalization to civil engineering developments. The LRMs were designed and applied to a floor in an under-construction residential building to perform an in-depth investigation of vibro-acoustic control of the floor impact sound. Experiments were conducted to perform a multifaceted analysis of the band gap behavior of a host structure coupled with LRMs, as well as the effects of attaching different number of LRMs and mode response of the host structure. The experimental results indicated that the acceleration and sound pressure levels of the LRM-coupled structure was attenuated within the band gaps, and the band gap of the host structure that was coupled with LRMs widened to the upper and lower regions of the local resonance frequency.
•Locally resonant metamaterials (LRMs) was designed and applied to a floor system.•The bandgap of the floor coupled with LRMs widened to the upper and lower regions of the local resonance frequency.•Full-scale experiments were conducted by applying the LRMs to 20-story residential buildings under construction.•Bandgap of the host structure coupled with LRMs widened to the upper and lower regions of the local resonance frequency.
As the emission of CO2 is directly proportional to the nature of the materials used in the construction of buildings, an eco-friendly economic design is required for waffle slabs used in large ...buildings such as stores, shopping malls. In this study, a multi-objective optimization design model, denoted as an eco-friendly and economically optimal design model (EEODM), is proposed to reduce the CO2 emissions and costs of long-span waffle slabs. The developed model was analyzed to determine the change in CO2 emissions and costs with respect to design variables in 20 types of long-span waffle slabs. Based on the results of the analysis, CO2 emission efficiency analysis (CEEA) and cost-efficiency analysis (CEA) are proposed as the new qualitative scales to determine environmental and economic feasibility, respectively. Through CEEA and CEA, a new design standard is proposed to overcome the limitations of existing waffle forms. To verify the applicability of the EEODM, the model proposed in this study was applied to the actual waffle slab of Gimpo International Airport in Korea. The results indicate that the two proposed waffle forms reduced CO2 emissions and costs compared to the existing sections of the airport.
•Eco-friendly and economically optimal design model (EEODM) for long-span waffle slabs is proposed.•New quantitative measures of eco-friendliness and cost were defined by CEEA and CEA.•New waffle slab design standards that can be used in various construction environments were proposed.•The proposed two waffle forms reduced both emissions and cost compared to the existing sections of Gimpo Airport.
The mega columns used in super-tall buildings are several meters in size; thus, a greater quantity of construction materials are required than for a general column. Considering the environmental ...impact, research on a green design model for super-tall buildings is necessary. This design model should minimize both CO2 emissions and cost in the mega-column construction and design phases with consideration of the member or building size. In this regard, a multi-objective green design model (MOGDM) capable of minimizing construction cost and reducing CO2 emissions is proposed in this study. The MOGDM is applied to the design of mega columns for a super-tall building and its performance is evaluated based on the average environmental impact reduction rate (AER) and the average increase-in-cost reduction rate (AICR); these indexes are developed to assess the CO2 emission and construction cost reduction capability. Under the loading scenarios considered in this study, the average AER and AICR for the MOGDM output are 6.76% and 58.02%, respectively. Thus, the evaluation results confirm that the MOGDM proposed in this study can effectively reduce CO2 emissions and cost in the design and construction phases of mega columns for super-tall buildings.
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•A multi-objective green design model (MOGDM) for mega columns is presented.•The MOGDM minimizes CO2 emissions and construction cost in design and construction.•Two assessment indexes are newly developed to evaluate the MOGDM performance.•The MOGDM is shown to effectively reduce CO2 emissions and construction costs.•The proposed model can be applied to reduce mega-column environmental impact.
Prestressed concrete (PC) slab using tendons is one of the most frequently used slab systems in the construction of buildings with long-span slabs. To simultaneously minimize the construction cost ...and the environmental impact, a green design model for PC slabs in long-span structures is necessary. In this paper, a multi-objective green design model for prestressed concrete slabs (MGDPCS) was developed to minimize both CO
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emissions and the construction costs of PC slabs. MGDPCS provides the optimized PC slab thickness, diameter and yield strength of the rebar, size and yield strength of the tendon using the Non-dominated Sorting Genetic Algorithm (NSGA-II) for the input PC slab size and load. Furthermore, the effects of changes in the long- and short-side of span and tendons of PC slabs on construction costs and environmental impact are analyzed using the proposed model. Accordingly, we developed two indicators, that is, the environmental and economic scores and the eco-friendly coefficient, to evaluate the performance of the practical green designs using MGDPCS. To verify the applicability of MGDPCS, the model was applied used to analyze the designs of PC slabs in an actual six-story industrial building with a slab span of 10 m × 10 m. The results showed that the optimal designs obtained from MGDPCS outperformed existing slab designs for buildings by 8.12% and 13.62% based on the reductions in CO
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emissions and costs, respectively.
