Long-term Performance Analysis Research Articles

Long-term performance analysis of operational efficiency of a grid-connected solar power plant under Mauritania climate

This work examines a solar power plant connected to the Nouakchott electricity grid in Mauritania. Operating since 2013, the 15 MWp plant's reliability and energy yield have been evaluated using a performance index. The assessment involves three phases. First, the plant's meteorological environment and technical indicators are presented. In the second phase, mathematical performance models specified by the International Energy Agency (IEA) are applied to calculate performance indices using data from the data acquisition system (SCADA). The third phase compares actual production data for 2015, 2017, and 2020 with results simulated for PVsyst for the same years. The obtained results are thoroughly analyzed to highlight relevant physical phenomena. The analysis focuses on the plant's 7-year operating period and its impact on performance indicators for electricity production fed into the grid. This study provides insights into the solar power plant's reliability and energy yield, aiding future operational enhancements. It underscores the importance of performance monitoring and assessment in optimizing solar power generation systems.

Finite element model analysis of long-term performance of composite anchorage based on double-material parameters

Carbon fibre-reinforced polymer (CFRP) tendons demonstrate the advantages of light weight, high strength, and superior corrosion resistance and have broad application prospects for long-span cable structures. However, given the low transverse shear strength of CFRP tendons, how to achieve long-term and reliable anchorage for CFRP tendons is a critical issue. The long-term performance (LTP) of a novel composite anchorage for CFRP tendon was assessed in this study. Then, a finite element model (FEM) with double-material creep parameters was established to reliably model the LTP experiment according to the creep parameters of the bonding medium and CFRP tendon. Finally, the effects of the free section tendon length, pre-tightening force, over-tensioning force, and elastic modulus of the bonding medium were analysed using the established FEM with double-material creep parameters. Results revealed no visible damage to the CFRP tendon and anchorage after the LTP experiment. The maximum tendon slippage was 0.054 mm, and the residual load ratio was 0.826. These phenomena indicate that the novel composite anchorage has excellent LTP. The FEM modelling results based on double-material creep parameters were in good agreement with the experiment results. The residual load ratio calculated by the FEM was 1% lower than the experimental value. Through the parameter analysis, the residual load ratio of the specimen was effectively improved under longer free section tendon condition, but tendon slippage increased to a certain extent. In addition, the LTP of the composite anchorage can be effectively improved by appropriately decreasing pre-tightening force and over-tensioning force. When the over-tensioning force was 1.4 times the test load, the tendon slippage was reduced by 34.2%, and the residual load ratio increased by 4.8%. The greater elastic modulus of the bonding medium in the range of 2.1 GPa–3.1 GPa, the worse the LTP of the composite anchorage.

Long-term performance and degradation analysis of a 5 MW solar PV plant in the Andaman & Nicobar Islands

Renewable energy is being advocated as a new strategy in response to rising energy demand and global climate change. Solar photovoltaic technology is of great significance to climatic conditions due to the good solar intensity and availability to generate energy. In this paper, the 10-year operating performance of a 5 MW solar PV plant installed in tropical climate of the Andaman and Nicobar Islands was analysed. In 2015, the PV plant achieved its highest electricity production of 7216 MWh, while its lowest, 4757 MWh, was observed in 2022.The maximum performance ratio was recorded as 84.28 % in 2016 due to lower operating cell temperature whereas the maximum CUF as 16.17 % was recorded in 2015. The highest module, inverter and system efficiency for the ten year was observed 12.03 %, 97.64 % and 11.75 % respectively in year 2016. In 2014, the highest values for reference yield, array yield, and final yield were recorded as 4.92, 4.08, and 3.98 kWh/kW/day, respectively. Higher capture losses were observed in the plant over the year which varies upto 1.65 h/d. The plant exhibited a degradation rate of 1.99 % per annum, determined by employing an initial PR of 80.03 %, which declined to 64.11 % by 2022. Degradation analysis of the present system was also performed using visual inspection technique. Mostly found defects in plant was corrosion, delamination of encapsulant material, browning of cell material, burn mark on the back of module, milky patterns, cracks in top facing glass and solar cells. Since, the plant is located in the coastal area, it was seen that the plant is facing a severe issue of algae growth. Some PV modules were covered by more than 90 % algae which significantly contribute in capture losses.

A Study on the Long-Term Performance of Mergers in the Korean Stock Market

This study analyzes the merger-related hypotheses which are managerial overconfidence hypothesis, controlling shareholder interest hypothesis, synergy hypothesis, financial constraint hypothesis, and momentum hypothesis through long-term performance analysis of acquiring firms. As a result of empirical analysis, first, the three-year event-time buy-andhold excess return (BHAR) was about -10% for both the average and median values which is statistically significant. Second, through both calendar-time portfolio excess return and BHAR, we find that the stronger the management's overconfidence is, the lower the longterm performance is. On the other hand, in the case of mergers by horizontal combinations, there was a positive synergy effect. This means that the management overconfidence hypothesis, the financial constraint hypothesis, the momentum hypothesis of merger performance, and the synergy hypothesis are established. Despite the poor long-term performance of mergers between domestic companies, this study provides implications that the merger may be mainly due to unreasonable overconfidence of managers and short-term perspectives of management.

A climate-spatial matrix growth model for major tree species in Lesser Khingan Mountains and responses of forest dynamics change to different representative concentration path scenarios

IntroductionClimate change affects forest distribution, species composition, structure, and yield due to the sensitivity of forests to temperature, precipitation, and CO2. Therefore, for forest management decisions regarding climate change, it is crucial to explore the response of forest growth, mortality, and recruitment to future climate. We aimed to establish tree species’ responses by introducing variables such as climate, stand spatial structure parameters, and diversity indices.MethodsWe produced fixed parameter transition matrix model (FM), climate-sensitive matrix growth model (CM) and climate-spatial matrix growth model (SCM) using data from 786 plots collected during the 7th (2010), and 8th (2015), Chinese National Forest Inventories in Heilongjiang Province, and long-term predictive performance of CM, SCM, and FM were compared using same data. The models were compared using tenfold cross-validation and long-term predictive performance analysis. To predict the response of major tree species in the Lesser Khingan Mountains to three future climate change scenarios (RCP2.6, RCP4.5, RCP8.5).Results and discussionThe cross-validation results show small significant differences among the three models for short-term prediction (5 years), with the FM performing slightly better than the CM and the SCM. In contrast, for long-term projections (85 years), SCM outperformed FM and CM under three different RCPs, and SCM and CM under three representative concentration paths (RCPs), i.e., RCP2.6, RCP4.5, and RCP8.5, suggesting that rather different dynamics are more reliable, since climatic factors are taken into account which may significantly affect forest dynamics, while changes in stand spatial structure also affect the sensitivity of trees to climate, especially in long-term prediction interval, the results of this paper may provide a theoretical basis for optimizing forest management strategies under climate change.

Numerical investigation on the long-term heating performance and sustainability analysis of medium-deep U-type borehole heat exchanger system

Exploiting low-carbon, clean, and stable medium-deep geothermal energy is critical to achieving clean and sustainable heating for buildings in northern China. The medium-deep U-type borehole heat exchanger (MDUBHE) system is a novel technology that has emerged recently for exploiting deep geothermal energy. However, previous studies mainly analyzed the heating characteristics of the MDUBHE system in a single building type (i.e., continuous operational conditions), and the long-term (15-year) heating performance under different operational conditions is still unclear. Moreover, the heating sustainability of the system in different regions has not been clarified. Therefore, to promote the application of the MDUBHE system, this paper conducts numerical simulations to analyze the system's long-term heating performance, thermal recovery characteristics of rock and soil, and the system's energy efficiency under different operational conditions and regions. The results show that the MDUBHE system has high heating sustainability under different working conditions. After 15 years of operation, the maximum decay rate of MDUBHE's outlet water temperature is less than 3.15 % under different operating conditions and less than 3.01 % in different regions. In addition, the maximum decay rate of total system heating capacity is less than 8.86 % under different operating conditions and less than 7.60 % in different regions. Furthermore, the intermittent operation of the system and the higher thermophysical properties of rock and soil can enhance the rock-soil's thermal recovery. The MDUBHE system can efficiently operate over the long term under different working conditions. The maximum decay rates of the system's energy efficiency are less than 1.86 % under different operating conditions and less than 1.60 % in different regions. The study could promote the application of the MDUBHE system in different regions.

Corporate investment sensitivity to equity market misvaluation

PurposeThe purpose of this paper is to investigate the effect of equity market misvaluation on manager behavior. Using a sample of 535 French-listed over 2000–2018, the authors analyze whether corporate investment decision is sensitive to equity market overvaluation.Design/methodology/approachThe study adopts market-to-book (M/B) decomposition developed by Rhodes-Kropf and Viswanathan (2004, RKV) that proxies for market misvaluation at the firm and industry levels. The authors conducted a long-term performance analysis via a portfolio sorting procedure and a Carhart (1997) four-factor pricing model. The authors tested the relationship between equity misvaluation, corporate investment decisions and equity issuance. The authors ran several robustness tests.FindingsThe empirical results show that equity market misvaluation affects corporate investment positively as the stock price deviates further away from its fundamental. Based on market timing theory, the authors find that corporate investment occurs in periods of high valuation motivated by equity issuance to benefit from the low cost of capital. This effect is more prominent for financially constrained firms. Consistent with the catering channel, the authors find that the misvaluation-investment nexus is more pronounced in firms with short-horizon investors. By examining the stocks’ long-term performance of misvalued firms, via a sorting portfolio procedure, the authors find that undervalued firms outperform and generate higher abnormal returns (Jensen’s alpha) than overvalued firms, suggesting that mispricing-driven investment appear to be short-lived and lead to lower return in the long term.Practical implicationsCorporate decision-makers and governance structures should pay attention to the rationality of the corporate investment decision in the context of equity market misvaluation. Managers who focus on maximizing the stock market value in the short-run at the expense of its long-term performance must give preference to value-creating investment, not driven by an external mechanism such as equity market mispricing. More generally, investors and portfolio managers must take into account the market mispricing process in decision-making. Nonetheless, from the portfolio sorting perspective, decision-makers must act in terms of high governance quality to mitigate suboptimal investment due to stock market mispricing (Jensen, 2005). Finally, equity market overvaluation, leading managers to invest via equity financing in particular, should be a signal to attract investors’ attention to seize the window of opportunity and embark on a short-term portfolio strategy. Such a strategy promises high returns in the short term.Originality/valueThis paper investigates jointly two theoretical channels: equity market timing and catering. The authors propose for the analysis three components of the M/B decomposition to dissociate market misvaluation at the firm and industry level from the fundamental component of market value (growth). This procedure provides a better understanding of the role of firm and industry misvaluation in explaining corporate investments. The authors provide evidence of the equity market misvaluation via a portfolio sorting procedure and a Carhart (1997) four-factor pricing model. The authors examine the effect of misvaluation on both the investment and the financing decisions.

An analysis of long-term Everglades Stormwater Treatment Areas performance using structural equation models

Phosphorus (P) retention in Stormwater Treatment Areas (STAs) is influenced by various external and internal variables, making it necessary to employ multivariate techniques to understand the complex relationships among them. This study used 14 years of monthly data from four STAs (STA-1E, -1W, −2, and − 3/4) to explore the factors influencing long-term STA performance and function related to P retention. Structural Equation Model (SEM) with predictive variables of inflow total P (TP), total nitrogen (TN) and calcium (Ca) concentration, hydraulic loading rate (HLR), and water pH and temperature was applied to evaluate similarities and differences among individual STA performance. The SEM results suggested an improvement in operational performance of STAs over time. All models explained a substantial portion of the variation in retention rate of TP (R2 > 0.63), but only a small portion of the variation in outflow TP concentration (R2 < 0.24). Notable differences were observed among the four STAs. The relationship between inflow and outflow TP concentration differed among the STAs. Furthermore, inflow TN concentration was positively correlated with the TP retention rate in STA-1W, and outflow TP concentration in STA-2, while the co-precipitation of P with Ca likely played a critical role in STA-3/4. These findings highlight the complexity of P removal in STAs and emphasize the need for site-specific management strategies. Further studies should consider incorporating long-term observation of key vegetation and soil variables (e.g. vegetation coverage and soil TP content, etc.) to inform more effective approaches to optimize P removal and enhance the performance of STAs in water treatment and ecosystem restoration efforts.

A Climate-Sensitive Transition Matrix Growth Model for Masson Pine (Pinus massoniana Lamb.) Natural Forests in Hunan Province, South-Central China

Masson pine natural forests are ecologically and economically valuable forest ecosystems extensively distributed across China. However, they have been subject to deforestation due to human disturbance. Moreover, climate change affects the growth, mortality, and recruitment of forests, yet available forest growth models do not effectively analyze the impacts of climate. A climate-sensitive transition matrix model (CM) was developed using data from 330 sample plots collected during the 7th (2004), 8th (2009), and 9th (2014) Chinese National Forest Inventories in Hunan Province. To assess model robustness, two additional models were created using the same data: a non-climate-sensitive transition matrix model (NCM) and a fixed probability transition matrix model (FM). The models were compared using tenfold cross-validation and long-term predictive performance analysis. The cross-validation results did not show any significant differences among the three models, with the FM performing slightly better than the NCM. However, the application of the CM for long-term prediction (over a span of 100 years) under three representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5) revealed distinct dynamics that demonstrated enhanced reliability. This is attributed to the consideration of climate variables that impact forest dynamics during long-term prediction periods. The CM model offers valuable guidance for the management of Masson pine natural forests within the context of changing climatic conditions.

Long-term performance of grid-integrated solar photovoltaic system on institutional buildings in tropical wet and dry climates of India - a practical study.

This study presents a long-term performance analysis of a one-mega-watt power grid-connected PV plant installed on the rooftop of GITAM University,Visakhapatnam,Andhra Pradesh, India for 3 years. The 1000 kWp PV plant design, performance analysis, economic feasibility, and greenhouse gas reduction are provided. For 3 consecutive years (2018-2019, 2019-2020 and 2020-2021), the energy yields, performance ratio (PR), capacity utilisation factor (CUF) and efficiency are evaluated. The plant was established in 2018 with a peak power of 1000 kWp. The system feeds the state grid with all of the electricity it produces. The system is continuously monitored and analysed using yield, efficiency and performance parameters for 36 months (September 2018 to August 2021). Solar irradiation data has been collected from the National Renewable Energy Laboratory (NREL) database for these years. The system comprises 3078 PV modules, 23 inverters rating 20 kW/50 kW, a data logger and a Net-metering unit. The annual energy generation of the PV plant recorded during the study period is 1376.29 MWh, 1265.541 MWh and 1115.73 MWh. The annual average performance ratio for the first three consecutive years is observed as 0.68, 0.62 and 0.58, whereas the yearly average capacity factors are 15.5%, 14.11% and 12.72%, respectively. The overall system efficiency of the PV system during the study period is 11.39%. Compared to the country's current conventional thermal power plants, we predict that rooftop PV systems may reduce CO2 emissions by 2145.406 tCO2eq for the base year, based on the electricity produced by this PV plant. The grid-integrated photovoltaic plant in this study is compared to other systems in the literature for performance assessment.

Extensive Green Roofs: Different Time Approaches to Runoff Coefficient Determination

Stormwater runoff in green roofs (GRs) is represented by the runoff coefficient, which is fundamental to assess their hydraulic performance and to design the drainage systems downstream. Runoff coefficient values in newly installed GR systems should be estimated by models that must be feasible and reproduce the retention behavior as realistically as possible, being thus adjusted to each season and climate region. In this study, the suitability of a previously developed model for runoff coefficient determination is assessed using experimental data, and registered over a 1 year period. Results showed that the previously developed model does not quite fit the experimental data obtained in the present study, which was developed in a distinct year with different climate conditions, revealing the need to develop a new model with a better adjustment, and taking into consideration other variables besides temperature and precipitation (e.g., early-stage moisture conditions of the GR matrix and climate of the study area). Runoff coefficient values were also determined with different time periods (monthly, weekly, and per rain event) to assess the most adequate approach, considering the practical uses of this coefficient. The monthly determination approach resulted in lower runoff coefficient values (0–0.46) than the weekly or per rain event (0.017–0.764) determination. When applied to a long-term performance analysis, this study showed no significant differences when using the monthly, weekly, or per rain event runoff, resulting on a variation of only 0.9 m3 of annual runoff. This indicates that the use of monthly values for runoff coefficient, although not suitable for sizing drainage systems, might be used to estimate their long-term performance. Overall, this pilot extensive GR of 0.4 m2 presented an annual retention volume of 469.3 L, corresponding to a retention rate of 89.6%, in a year with a total precipitation of 1089 mm. The assessment of different time scales for runoff coefficient determination is a major contribution for future GR performance assessments, and a fundamental decision support tool.

Borsa İstanbul'da Pandemi Dönemindeki Uzun Vadeli İHA Performansına İlişkin Karşılaştırmalı Bir ÇKKA Uygulaması

The aim of the study is to help financial decision makers by making long-term performance analysis of initial public offerings with a comparative analysis perspective. Multi-criteria decision analysis (MCDA) methods are used in problems with complex answers. The pandemic, which spreads throughout the world in the first quarter of 2020, created a short-term shock effect in the capital markets, but capital markets survived this shock with new investors. While the number of shareholders in Borsa Istanbul was 1.3 million before the pandemic, this number exceeded 3.3 million afterwards. An increase in this number also means an increase in the number of financial decision makers. At this research, the long-term performance of 49 initial public offerings, which took place in Borsa Istanbul before the pandemic is analyzed with a comparative MCDA perspective. To that end, the study, in which CRITIC weighting technique and ARAS, MOORA, TOPSIS, COPRAS and ELECTRE III methods were used, examined 10 periods during the pandemic process. As a result of the research, which is the most comprehensive MCDA study in the field of IPOs, the MOORA method has been recommended to financial decision makers because it produced superior results compared to other 4 methods analyzed.

Long-term performance analysis of BDS-3 precise point positioning (PPP-B2b) service

Long-term performance analysis of BDS-3 precise point positioning (PPP-B2b) service

Multi-gene genetic programming extension of AASHTO M-E for design of low-volume concrete pavements

The American Association of State Highway and Transportation Officials Mechanistic-Empirical Pavement Design Guide (AASHTO M-E) offers an opportunity to design more economical and sustainable high-volume rigid pavements compared to conventional design guidelines. It is achieved through optimizing pavement structural and thickness design under specified climate and traffic conditions using advanced M-E principles, thereby minimizing economic costs and environmental impact. However, the implementation of AASHTO M-E design for low-volume concrete pavements using AASHTOWare Pavement ME Design (Pavement ME) software is often overly conservative. This is because Pavement ME specifies the minimum design thickness of concrete slab as 152.4 ​mm (6 in.). This paper introduces a novel extension of the AASHTO M-E framework for the design of low-volume joint plain concrete pavements (JPCPs) without modification of Pavement ME. It utilizes multi-gene genetic programming (MGGP)-based computational models to obtain rapid solutions for JPCP damage accumulation and long-term performance analyses. The developed MGGP models simulate the fatigue damage and differential energy accumulations. This permits the prediction of transverse cracking and joint faulting for a wide range of design input parameters and axle spectrum. The developed MGGP-based models match Pavement ME-predicted cracking and faulting for rigid pavements with conventional concrete slab thicknesses and enable rational extrapolation of performance prediction for thinner JPCPs. This paper demonstrates how the developed computational model enables sustainable low-volume pavement design using optimized ME solutions for Pittsburgh, PA, conditions.

Long-term thermal performance analysis of a large-scale water pit thermal energy storage

Large-scale water pit thermal energy storage (PTES) promotes solar district heating (SDH) system as one of the most potential renewable applications for carbon neutrality. PTES needs vast investment and operates in a complicated system with numerous components, highlighting the need for a suitable simulation tool for tech-economic and feasibility investigations. This paper experimentally and theoretically investigated the long-term thermal performance of a 60,000 m3 PTES in Dronninglund, Denmark. Five years measurements were analyzed to investigate the development of temperatures, heat flows, and thermal stratification in heat storage. A modified 2D model was proposed to calculate the thermal performance of the large-scale PTES based on the XST model in TRNSYS. The results showed that the developed model predicts well the storage temperatures and the heat flows. For one-year validation, the deviations of annual charged/discharged energy, internal energy content, and annual thermal loss between the model and the measurements were 2.0%/1.8%, 2.8% and 1.3%, respectively. The Dronninglund PTES showed 90.1% storage efficiency in the five-year investigation due to its high storage utilization cycle of 2.16. Even without any insulation on the sidewall and the bottom of the PTES, the average thermal loss from the two parts only accounted for 32.3% of total heat loss. Meanwhile, the soil region needed four years to stabilize. Approx. 24.4% of the heat loss in summer from the sidewall and the bottom is regained by the PTES in winter, when there is a low temperature in the heat storage. The findings of the paper serve as a good reference for designers and practitioners of water pit heat storage.

Directly foamed geopolymers: A review of recent studies

Geopolymers have been a frequently studied topic during the last decades due to waste materials utilization, low energy demands, and low carbon dioxide emissions related to their production, which makes them very attractive within the current environmental trends. However, the original idea to use them as a concrete replacement showed to be unattainable in the nearest future, so other alternatives of geopolymers applications are being sought that could exploit the efforts spent and research progress made so far. This review paper summarizes the recent progress in the field of directly foamed geopolymers, as one of the alternatives, focusing on the material base, foaming and stabilization processes, and assessments of selected material parameters, as related to raw materials used and treatment techniques applied. As the main result, several gaps and challenges are identified that deserve more attention and deeper investigations, which can help to move the geopolymer foams closer towards their regular application in civil engineering. A detailed knowledge of hygric parameters and their influence on thermal properties, long-term performance analyses in real-world applications, or extension of the material base to achieve environmental more friendly solutions represent the most topical issues that are supposed to be addressed.

A Machine Learning Study on Internal Force Characteristics of the Anti-Slide Pile Based on the DOFS-BOTDA Monitoring Technology.

Long-term monitoring of constructed anti-slide piles can help in understanding the processes by which anti-slide piles are subjected to the thrust of landslides. This paper examined the landslide control project of Badong No. 3 High School. The internal force of an anti-slide pile subjected to long-term action of landslide thrust was studied by Distributed Optical Fiber Sensing (DOFS) technology. The BP neural network was used for model training on the monitored strain values and the calculated bending moment values. The results show the following: (1) The monitoring results of the sensor fibers reflect the actual situation more accurately than steel rebar meters do and can locate the position of the sliding zone more accurately. (2) The bending moments distributed along the anti-slide pile have staged characteristics under the long-term action of landslide thrust. Three stages can be summarized according to the development trend of the bending moment values. These three stages can be divided into two change periods of landslide thrust. (3) The model produced by the BP neural network training can predict the bending moment values. In this paper, the sensing fibers monitoring over a long time interval provides a basis for long-term performance analysis of anti-slide piles and stability evaluation of landslides. Using the BP neural network for training relevant data can provide directions for future engineering monitoring. More novel methods can be devised and utilized that will be both accurate and convenient.

Long-term performance and degradation analysis of different PV modules under temperate climate

The share of solar photovoltaic in the energy mix is achieving significant growth worldwide. Accurate forecasts of return on investment and a good choice of optimal PV technology for different regions require proper PV studies. Long-term performance and degradation analysis, as well as an economic investigation of three based-silicon PV technologies including amorphous silicon (a-Si), polycrystalline silicon (p-Si), and monocrystalline silicon (m-Si) have been performed in this work. This study has been done based on different performance indicators such as AC energy production (EAC), reference yield (Yr), final yield (Yf), performance ratio (PR), temperature corrected performance ratio (PRSTC), degradation rate (Dr), and levelized cost of energy (LCOE). The results of the performance ratio analysis revealed that crystalline silicon technologies are better than amorphous PV system with values of 84.25% for m-Si, 84.32% for p-Si, and 79.14% for a-Si. The degradation analysis was performed using linear regression (LR) and classical seasonal decomposition (CSD) statistical techniques. The results of these latter indicate that a-Si degrades faster than its counterparts with a ratio of 0.9 ± 0.009%/year and 0.75 ± 0.003%/year, followed by m-Si (0.53 ± 0.01%/year and 0.41 ± 0.003%/year), and p-Si (0.36 ± 0.01%/year and 0.28 ± 0.004%/year) using LR and CSD, respectively. However, these degradation rates are comparable to other degradation rates obtained in studies performed in different climates in Morocco. Finally, the LOCE results demonstrate that p-Si technology is the most cost-effective system with a value of 0.09 USD/kWh compared to 0.1 USD/kWh for m-Si, and 0.13 USD/kWh for a-Si. According to the obtained findings, p-Si is the most optimal and suitable technology to be installed in the mountain temperate climate.

Analysis of Factors Affecting Field Applicability and Long-Term Performance Analysis of LCP Woven Geotextile for Soft Ground Reinforcement

In recent years, natural disasters have been increasing worldwide due to rapid climate change, and the damage to ground structures is increasing due to the destruction of the ground. Damage to the ground structure can be reduced or eliminated by using LCP woven geotextiles as ground reinforcement. Therefore, in this study, the tensile properties, reduction factor affecting long-term performance, creep behavior, and fatigue properties of LCP woven geotextile were tested and analyzed. As a result, in the case of tensile properties, the maximum tensile strength of the LCP woven geotextile was 192.94 kN/m2 in the MD direction, and it was generally constructed so that the load was transmitted. The total reduction factor is 1.86, which could be applied within 53.8% of the design strength when applied to the field. In addition, it was considered that the effect of the reduction factor for creep deformation on the long-term performance was dominant. Through the analysis of the creep behavior and fatigue characteristics, considering that the creep limit strain was 10%, if an earthquake occurred after 50 years of construction, it can be predicted that up to 90% of UTS would exhibit seismic performance. When LCP woven geotextile was applied as reinforcement, if the cyclic load due to fatigue failure was less than 478,000 times per year, it was considered that there was little possibility of the collapse of the ground structure.

Analysis of instant and long-term performance of timber-concrete floors with boundary conditions other than simply supported

This paper describes an analytical procedure for designing timber-concrete composites (TCC) subjected to boundary conditions other than simply supported. Currently available investigations of TCCs are mainly focused on simply supported slabs, as it is a typical configuration for timber buildings. However, in other structural applications, and remarkably for reinforced concrete buildings, the boundary conditions of the TCC slabs are not likely to be simply supported. Such distinct boundary conditions can significantly reduce the cross section height, mid-span deflection and self weight of the structure, the last one being crucial in seismic regions. The proposed procedure is derived from two simplified methods available in the literature, one general in its nature while the other being valid for simply supported beams. The short-term analytical model was compared against finite element models (FEM) and to the only experimental investigation on partially restrained TCCs available in the literature, while the long-term analytical model was compared only against FEM. At the end of the investigation, a full-scale continuous TCC beam was tested in the serviceability range, to compare with the prediction of the proposed analytical model. The model underestimated the mid-span deflection at 4.5 kN by 13%, concluding that the proposed simplified procedure is valid for boundary conditions other than simply supported. Further experimental campaigns are needed in the future to assess the versatility of the model in a wider range of boundary conditions, including short-term and long-term tests, which should enhance the applicability of TCC slabs in structures different from timber buildings and bridges.