Construction Cost Research Articles

Environmental and socio-economic evaluation of a groundwater bioremediation technology using social Cost-Benefit Analysis: Application to an in-situ metal(loid) precipitation case study

Bioremediation can be an alternative or complementary approach to conventional soil and water treatment technologies. Determining the environmental and socio-economic impacts of bioremediation is important but rarely addressed. This work presents a comprehensive sustainability assessment for a specific groundwater bioremediation case study based on In-situ Metal(loid) Precipitation (ISMP) by conducting a social Cost-Benefit Analysis (CBA) using two different approaches: environmental Life Cycle Costing (eLCC) and Impact Pathway Approach (IPA). Externalities are calculated in two ways: i) using Environmental Prices (EP) to monetize Life Cycle Assessment (LCA) results and metal(loid)s removed at field scale, and ii) following the IPA steps to determine the social costs avoided by removing arsenic contamination at full scale. The results show that, in the baseline scenario, the project is not socio-economically viable in both cases as the Net Present Value (NPV) is −129,512.61 € and − 415,185,140 € respectively. Sensitivity and scenario analyses are performed to identify the key parameters and actions needed to reach a positive NPV. For instance, increasing the amount of water treated per year to 90 m3 and assuming a 20 % increase in operation costs and a 60 % increase in construction costs can make the project socio-economically viable at the field scale, while a reduction in the social discount rate from a 4 % to a 2 % can lead to a positive NPV at the full scale. The approaches proposed in this work may be useful for practitioners and policymakers when evaluating the environmental and socio-economic impacts of bioremediation technologies at different scales and regions, as well as human health impacts caused by contaminants at the current legal limits.

Labor Cost Estimation: Factors Influencing Labor Costs in Civil Construction and Methods for Accurate Forecasting

Labor Cost Estimation: Factors Influencing Labor Costs in Civil Construction and Methods for Accurate Forecasting

AP-Net: Attention-fused volume and progressive aggregation for accurate stereo matching

Stereo matching plays an important role in advancing substantial applications such as 3D reconstruction, autonomous driving, depth sensing, and has recently made tremendous progress. It still poses a significant challenge, however, in the extraction of disparities from a pair of rectified images to achieve accurate stereo matching. In this paper, we propose an attention-fused cost volume construction and progressive cost aggregation network, namely AP-Net, to elevate the accuracy of stereo matching. Specifically, we introduce attention fusion to learn feature similarity between corresponding points on the left and right images while capturing long-dependent contextual information to construct attention-fused cost volumes. Moreover, we propose progressive cost aggregation, which consists of two stages to fully exploit information from different cost volumes. Furthermore, to make more accurate adjustments to the initial disparity, we implement an information entropy-guided disparity refinement module, which leverages information entropy as an explicit confidence measure of the initial disparity estimation to guide the refinement module in calculating the disparity residual more accurately and improving the overall accuracy of disparity estimation. Our implemented disparity refinement module can also be seamlessly embedded into a variety of stereo matching networks, significantly improving the model’s performance with only a small increase in computation and parameters. Experimental results across various stereo datasets confirm that our proposed AP-Net consistently delivers competitive performance. The code is available at https://github.com/zhuys-bupt/AP-Net.

How to combine different types of prefabricated components in a building to reduce construction costs and carbon emissions?

In the context of industrialized construction and carbon emission reduction globally, prefabrication has gained considerable attention. However, most studies cared the carbon emissions and construction costs from the perspective of a whole prefabricated building rather than the prefabricated components. It makes it difficult to understand the role of prefabricated components play and make improvements from the prefabricated components level. To fill this gap, this study proposes a model to optimize the selection and combination of prefabricated components in a building project to simultaneously reduce the construction costs and carbon emissions. Six common component types were considered: shear wall, beam, floor slab, stair, balcony, and air-conditioning slab. Their costs and carbon emissions were quantified when adopting prefabrication and cast-in-situ technologies. To obtain the optimal solution, we developed an improved multi-objective mayfly algorithm (IMOMA), which incorporates enhanced circle chaos mapping and a global best guiding strategy to generate Pareto solution sets. The performance of IMOMA was evaluated using the Zitzler-Deb-Thiele series test functions, demonstrating its advantages in convergence, diversity, and comprehensive performance through metrics such as generation distance, diversity metric Δ, and inverse generational distance. A case study validated the effectiveness of this proposed method, demonstrating an average reduction of 9.05% in total construction costs and 8.04% in carbon emissions when compared to the initial scheme. Further study revealed that different prefabrication rates correspond to different optimal components combination schemes, with different trends in the costs and carbon emission curves as the prefabrication rate increases. Additionally, carbon trading policies influence the components combination, with construction costs reduced by 10.88% at a carbon trading price of 42.80 CNY/t CO2eq. This study provides valuable guidance for general contractors to design optimal component combinations and for governments to promote the sustainable development of prefabricated construction.

A novel two-stage optimal layout model of hydrogen refueling facility network based on green electricity hydrogen production: Beijing-Tianjin-Hebei region of China as case study

Green electricity hydrogen production(GEHP) is fundamental support for developing new-type power system and achieving the green and low-carbon transformation in the transportation sector. It is key issue to build a hydrogen refueling facility network(HRFN) to link hydrogen production and consumption. Firstly, the framework of HRFN is proposed including hydrogen production points(HPP), hydrogen refueling stations(HRS) and hydrogen demand points(HDP). Secondly, a two-stage model is built. In the first stage, the siting model of HRS cluster is constructed considering the service capacity, service radius, and construction, operation and penalty costs. In the second stage, the bi-objective planning model of HRFN is constructed considering network stability, hydrogen storage and transportation forms and producing total costs. Finally, the Beijing-Tianjin-Hebei region of China(BTH) is taken as case study to verify the effectiveness. Sensitivity analyses are conducted on four factors:HRSs’ service radius, service capacity, GEHP’s efficiency and HDPs’ scope. The key findings are: 1)the service radius and capacity of HRSs and HDPs’ scope all affect the layout of HRSs, with HDPs’ scope further influencing HPPs’ number; 2)the construction and operation costs are more impacted by changes in GEHP's efficiency compared to network stability;3)the network should be strengthened to cover the whole processes from hydrogen production to consumption.

The third dimension of alpine plant leaf traits is related to cold-tolerance

Alpine plants possess unique traits to adapt alpine environments. Whether leaf trait relationships of alpine plants can be captured by the two trait dimensions of organ size and resource economics is unknown. We hypothesized that, beyond the trait dimensions of leaf size and resource economics, non-structured carbohydrates (NSC) would reflect a dimension of cold-tolerance in alpine plants. To test this hypothesis, we measured 12 leaf traits critical to leaf construction and growth in 143 species across 7 sites ranging from alpine steppes to alpine meadows along an environmental gradient on the Tibetan Plateau. Furthermore, a cold resistance experiment was conducted at one of these sites to estimate the lethal temperature causing 50% frost damage (LT50) of 11 alpine species. The majority of variations in 12 leaf traits of alpine plants were captured by three trait axes, in which leaf carbon (LCC) and NSC (including starch, LSC and soluble sugars, LSS) were clustered in a new dimension (PC3) beyond leaf size and structure, and resource economics. Although LCC, LSC and LSS all showed negative correlations with MAT, a significant negative correlation was only found between LSS and LT50. It indicated that PC3 was able to reflect the cold-tolerance of alpine plants to some extent, in which LSS was the most critical trait. The storage and transformation of NSC under stressful conditions could reflect a dimension of long-term metabolic adaptation and cold-tolerance, which is an extension of the resource-utilization strategy beyond construction cost and growth.

Experimental study to unraveling the seismic behavior of CFRP retrofitting composite coupled shear walls for enhanced resilience

This study focuses on the empirical examination of the nonlinear seismic performance of carbon fiber-reinforced polymer (CFRP)-strengthened composite coupled reinforced concrete (RC) shear walls. The experimental setup involves testing the structure in two distinct states, wherein CFRP sheets are utilized for retrofitting and reinforcement. In the initial phase, three samples undergo reinforcement utilizing distinct patterns of CFRP sheets. In the subsequent stage, an additional trio of specimens is fabricated and tested without the application of CFRP sheets. Subsequently, all structures are exposed to a load equivalent to 60 % of their flexural capacity. Following this, the tested specimens undergo retrofitting with CFRP sheets, utilizing the same patterns as in the initial phase. The retrofitted composite coupled shear walls are then subjected to retesting. The principal aim of CFRP retrofitting is to amplify the flexural and shear capacities of the specimens, empowering them to endure heightened seismic loads in comparison to their original configurations. This research contributes by evaluating ductility, ultimate strength, energy dissipation, and construction costs associated with composite coupled steel plate-concrete shear walls. All specimens underwent cyclic loading in accordance with the ATC-24 guidelines [1], which provide standard protocols for testing the cyclic performance of structural components. These guidelines, outline procedures for simulating seismic loading conditions in laboratory settings to evaluate the performance of structural systems under cyclic loading. Finally, a parametric study explores the impact of CFRP sheets and their adhesion patterns on the seismic behavior of composite coupled shear walls. The selection of the optimal retrofitting scheme considers the construction cost of each specimen based on the total area of CFRP sheets utilized.

Determination of Submerged Breakwater Efficiency Using Computational Fluid Dynamics

Wind-induced waves can lead to the partial or complete wash-over of beaches, causing erosion that impacts both the landscape and tourist infrastructure. In some regions of the world, e.g., Croatia, this process, which usually occurs during a harsh winter, has a major impact on the environment and the economy, and preventing or reducing this process is highly desirable. One of the simplest methods to reduce or prevent beach erosion is the use of innovative underwater structures designed to decrease wave energy by reducing wave height. In this study, submerged breakwaters are numerically investigated using various topologies, positions, and angles relative to the free surface. Not only is the optimal topology determined, but the most efficient arrangement of multiple breakwaters is also determined. The advantage of newly developed submerged breakwaters over traditional ones (rock-fixed piers) is that they do not require complex construction, massive foundations, or high investment costs. Instead, they comprise simple floating bodies connected to the seabed by mooring lines. This design makes them not only cheap, adaptable, and easy to install but also environmentally friendly, as they have little impact on the seabed and the environment. To evaluate wave damping effectiveness, the incompressible computational fluid dynamics (ICFD) method is used, which enables the use of a turbulence model and the possibility of accurate wave modelling.

Geomorphological and Sedimentological Rationale for Staged Sand Dam Construction

ABSTRACTStream sediment transport results from a convolution of climate, weather, geology, topography, biology, and human influence. In addition to providing water and food security for rural dryland communities, sand dams—small weirs designed to trap only the coarse fractions of transported sediments in seasonal and ephemeral streams—highlight many complexities of geomorphological dynamics. Sand dams store water in interstitial riverbed pores and the size of deposited sediment particles largely determines the recoverability of stored water: Fine materials limit transmission and provide lower volumetric yield. In this study, we seek to identify a practical method for evaluating the theoretical effect of staged sand dam crest construction on key sediment‐trapping processes for a proposed dam site. We argue that the Rouse number provides a useful criterion for identifying regimes where the target material grades are trapped. These ideas were tested using sediment data collected in Kenya and US Army Corps of Engineers River Analysis System numerical simulations to evaluate the sensitivity of sedimentation processes to crest height. We show that constructing sand dams in stages results in more targeted trapping of coarse material. Sedimentation is shown to be more sensitive to variation in crest height than the flood hydrograph, especially when a dam's crest height is small. By introducing a method to assess the necessity and inform design of staged crest construction based on local flow dynamics, this study offers a framework for optimising sand dam performance in data‐scarce environments. This approach provides a means to balance construction costs with expected benefits, enhancing the sustainability and functionality of sand dams in arid and semi‐arid regions.

Improved multi-objective method for the selection of driverless taxi site locations

To expedite the large-scale deployment of driverless taxis and advance the autonomous driving industry, research on the location of integrated parking and charging facilities for driverless taxis has emerged as a significant issue in urban traffic. This study employs a progressive “preliminary selection-screening-optimal selection” approach for site selection. First, the preliminary selection of parking sites is conducted by clustering various Points of Interest (POI) types. Subsequently, a multi-objective site selection model is developed to maximize the coverage of demand points, minimize construction costs, address the largest population demands, and minimize the distance between demand points and candidate sites. The improved genetic algorithm NSGA-II is adopted to obtain several Pareto optimal solutions. The evaluation indexes are selected according to operators, users, and the public transport system to estimate the Pareto optimal solutions, and then the final location solution can be obtained. The calculation methods of several key parameters are improved during the modeling process. Location potential and location influence coefficient are selected to adjust the number of driverless taxi parking spaces. Additionally, isochrones drawn based on the actual road network and path planning represent the service range of candidate points. Meanwhile, distance based on actual road network rather than Euclidean distance is introduced to calculate the distance between candidate points. Finally, a case study shows that the method proposed in this study could reduce the total initial travel time to reach the demand points by 64%, which is independent of operational scheduling.

A phase separation prediction model for CO2 capture by biphasic amine absorbents

The biphasic amine absorbent upon absorbing CO2, separates into CO2 poor and CO2 rich phases, making it a third-generation chemical absorbent with energy-saving potential. However, the current method of constructing biphasic amine absorbents involves screening phase separation agents through a large number of experiments, which involves significant amount of trial and error. In this study, a phase separation prediction model was built for CO2 capture by biphasic amine absorbents for quick screening of phase separation agents. The phase separation of CO2 absorption by organic amine 2-amino-2-methyl-1-propanol (AMP) using 34 phase separation agents was statistically analyzed based on 14 molecular descriptors of the solvents. The factors influencing the phase separation were thoroughly explored. It is proposed that the relative dielectric constant or molecular polarity index can replace the traditional polarity evaluation index, dipole moment, to better describe the phase separation situation. Additionally, it is found that the ability of phase separation agents to form hydrogen bonds, particularly as a hydrogen bond donor is the determining factor for phase separation to occur. Ultimately, the preferred molecular descriptors are used as predictors, leading to the development of a prediction model for phase separation that achieves high-accuracy predictions solely through theoretical calculation parameters. The model considerably reducing the construction costs of biphasic amine absorbents.

Parametric optimization of SIP connection geometry in CFS-MRF structures: A finite element study

The structural buildings should be designed to resist both static and dynamic loads. There are different types of structural systems that can support seismic loads. Moment-resisting frames (MRFs) are widely used for seismic purposes, relying on the plastic deformations occurring between the beam and column. The main problems of cold-formed steel sections in MRFs during seismic loads are premature local and distortional buckling, which cause severe damage under strong earthquakes, such as early loss of connection strength, low ductility, and low energy dissipation. This paper clarifies the performance of the CFS section with steel interconnected part (SIP) in moment-resisting frames (MRFs) in many aspects using finite element (FE) procedures. The study summarizes the required dimensions of SIP to achieve optimal behavior for the beam-column connection. Additionally, an advanced connection consisting of SIP and four pairs of out-of-plane stiffeners has been examined. The locations of the out-of-plane stiffeners have been carefully selected to stabilize the connection. A cantilever beam connection has been used to represent an MRF in an advanced way. The connection consists of 2 C channel back-to-back beams connected with a through plate with sixteen bolts. Numerical models have been developed and verified with experimental tests under both monotonic and cyclic loading. The characteristics and creation of the numerical model are well illustrated in this paper. Cyclic loading has been applied according to AISC protocol, which is used to test the performance of the steel connections, as well as to classify the connection according to different design codes. The results show that increasing the plastic moment capacity of the CFS section decreases the required SIP dimensions to achieve optimal behavior by the connection. Additionally, it has been found that using out-of-plane stiffeners in particular locations with SIP increases energy dissipation on average by 74 %. Using stiffeners with SIP can upgrade the classification of the connection from an ordinary or intermediate moment connection to a special moment connection without the need to increase the CFS cross-section area or reduce the slenderness ratio, which in turn reduces the overall costs of construction.

Gansu, Qinghai and Ningxia regions of the new western land and sea corridor Freight network optimization

The new western land and sea corridor makes use of a variety of transport modes to reach major ASEAN countries such as Singapore to the south, connects Southeast Asia and North America to the east, and connects Chongqing, Lanzhou and Xinjiang to the north with the China-European Union (CEU) liner train, which is a composite opening-up corridor in the western region for realising the regional linkage and international co-operation with ASEAN and other countries, and organically connecting with the "One Belt, One Road". In order to explore the regional freight network of Gan-Qing-Ning region of the new western land and sea corridor, we establish the model of node socio-economic attractiveness, topological charisma and comprehensive utility maximization, and analyze the index factors by using entropy weighting, Delphi and comprehensive evaluation methods through the Matlab Genetic Algorithm Toolbox to study the influence of node socio-economic attractiveness, topological charisma, node freight volume, logistics and transportation costs and construction costs on the utility of nodes of the new western land and sea corridor. The influence of the regional node utility of Gansu, Qinghai and Ningxia in the corridor. Analyze the problems and factors affecting the selection of nodes in the existing freight transport corridors in the three provinces. Completing the site selection of Gan-Qing-Ning regional node of the new western land and sea corridor and combining the import and export cargo volume of the three provinces to propose the construction of the South-Middle East three-lane freight corridor, and completing the optimization plan of the freight network. The results show that: scientific optimization and improvement of Gan-Qing-Ning regional freight network can promote the construction of freight network in the northwest region of the new western land and sea corridor, to meet the demand for freight transportation in the corridor, and to promote the development of the corridor industry and economic growth. Thus, it provides reference for the development of Gansu, Qinghai and Ningxia region and freight network optimization.

A Comparative Study of Precast and Cast-in Place Concrete in Construction Home Project by Life Cycle Cost Analysis

Construction industry plays a significant role in economic growth, and the industry will continue to grow with the economic expansion. However, the industry is known for its labor-intensiveness, In order to shorten construction time and address labor issues, developers have explored new systems of construction such as a precast system. This paper is to present a comparative study of precast and cast-in place concrete system in construction home project by life cycle cost analysis by dividing project period into 3 phase (Preparing phase, Construction phase and O&M phase). In modelling life cycle costs, sensitivity analysis and Monte Carlo simulation will be employed to incorporate uncertainty of material and labor costs into the proposed model. The study also found that in 6 home projects, there have risk factors that impact to life cycle cost by using sensitivity analysis are construction cost, major repair and minor repair. The result from this study is life cycle cost from precast and cast -in place systems

Cost implications and sustainable design for warehouses considering fire safety regulations

This paper explores the impact of sustainable design practices on warehouse construction costs in the context of fire safety regulations. The inherent fire risk during the operation of industrial facilities is a critical consideration in their design. This study evaluates various cost and technological aspects of sustainable solutions within the “design and build” framework, focusing on fire protection systems across three different fire zone configurations. The modeling analysis examines how fire zones influence smoke dispersion, temperature variations at a specific location above the fire source, and visibility. Numerical results reveal variations in smoke distribution among the three configurations, though these differences do not significantly affect evacuation efficiency. The findings indicate that increasing the number of fire zones within the warehouse can mitigate the potential impact of a fire. This research underscores that fire protection and evacuation conditions significantly affect investment costs.

Towards Hydraulic Design Optimization of Shaft Hydropower Plants: A 3D-CFD Application Based on Physical Models

The shaft hydropower plant (SHPP) is a novel hydraulic concept for low-head hydropower sites with several environmental and operational advantages over conventional layouts. However, the first two projects implementing this concept have shown comparatively high construction costs and project risks. Therefore, further optimization is required to increase economic attractiveness and enable broader market adoption. Initial model tests recommend a square-shaped shaft inlet with a three-sided approach flow for low-loss and fish-friendly inflow conditions. Yet, this design requires significant space for structural implementation and may be unsuitable for use with multiple shafts or as an extension of non-powered dams and weirs. This research paper presents the application of a computational fluid dynamics simulation setup to evaluate the hydraulic performance of various design configurations, especially alternative design layouts with a one-sided approach flow without further physical model tests. The simulation setup is calibrated against observations including head loss and velocity measurements from the physical model tests, and its satisfactory performance enables the analysis of alternative design layouts. This study aims to derive the most significant design parameters for achieving the desired hydraulic conditions at the intake. Increasing the flow depth before the intake and enlarging the inlet area have the most significant impact, while increasing the overflow of the front gate has the least significant effect. The chosen CFD application is deemed suitable for hydraulic design optimization and provides guidance on the key parameters to focus on for tailored site-specific design development.

Prediction of the Nominal Side Resistance of Drilled Shafts in Dominantly Cohesive Soils using ANN

The conventional methods used in the design of drilled shafts might not fully consider the multiple sources of uncertainty in the soil such as the geometric and mechanical variability and/or the construction methods. These uncertainties can introduce nonlinearity to the analysis, leading to underestimation or overestimation of the resistance, which can be translated into expensive or even unsafe projects. Because of this, machine learning techniques such as artificial neural networks (ANNs), proven to be effective in solving nonlinear problems, are becoming popular in solving civil engineering problems. Therefore, the objective of this preliminary study is to evaluate a concept for predicting the nominal side resistance of drilled shafts with improved accuracy, using ANN. In this study, 45 load tests were collected from the extended version of the Nevada Deep Foundation Load Test Database and divided into 85% for training and 15% for testing. Then 1,638 ANN models were trained to determine the optimum model with a root-mean-squared error of 2,058 kips and an R-squared ( R2) of 85% on unseen load tests. The model was then benchmarked against the AASHTO predicted side resistance, with an average overall improvement of the prediction accuracy using ANN of 23%. This paper demonstrates that such models could be developed, improved, and used in the industry at an early stage and with limited data as supplemental tools that can help optimize designs in regard to construction safety, time, and cost.

Present Situation and Challenge of BlM Development in Construction Cost Industry

This paper analyzes the construction cost situation, BIM technology development, cost measurement methods, cost pricing system, cost control practice and cost management experience of our country and the United Kingdom, the United States and Japan. Finally, the outlook for the future development of engineering cost industry in our country is concluded. and the relevant suggestion is given, which provides a useful reference for the development of engineering cost industry in our country.

Evaluation of carbon sink and photovoltaic system carbon reduction along roadside space

As China's photovoltaic (PV) sector experiences rapid growth, the availability of land resources has become a pivotal policy focus, driving the need for comprehensive research and strategic planning for roadside PV initiatives. Utilizing a fuzzy multi-criteria decision-making approach, combined with GIS spatial analysis and a modular design framework, our study quantitatively compared the carbon reduction capabilities of PV systems against the carbon sequestration potential of various vegetative arrangements along the roadside space. The roadside space analysis modular considers a range of factors including topography, meteorology, and construction costs. We examined the spatial distribution of suitability for PV installation and vegetation establishment along the provincial expressway network in China. The results revealed that Inner Mongolia stood out as the frontrunner in carbon reduction potential within high-suitability zones for PV construction, achieving an impressive 4.845 million tons of carbon reduction—nearly four times greater than that of Shaanxi Province. In contrast, the carbon sequestration attributed to vegetation greening in areas less suited for PV development revealed a higher propensity in the southeastern provinces. Guangdong led the charge with an impressive annual carbon sequestration of 2.89 million tons. This was closely followed by Yunnan, Sichuan, Hebei, Guizhou, and Henan, each achieving carbon sequestration amounts exceeding 2 million tons. These results offer valuable quantitative support and practical recommendations for achieving low-carbon objectives in the construction of China's expressways.

Experimental void fraction measurement approach of small channel two-phase flow

This investigation presents a novel experimental approach for assessing void fraction parameters in two-phase flows within microchannels. The study critiques the conventional impedance methods that utilize alternating current (AC) for void fraction measurements, highlighting the inherent drawbacks such as ground capacitance interference and non-uniform current distribution. To circumvent these issues, the research introduces the use of direct current (DC), which ensures a homogeneous distribution across the conductor's cross-section, as a more reliable alternative. Termed the "Direct Impedance Method," this technique employs DC to enhance the accuracy of void fraction measurements. The study explores various geometric configurations of full-ring and half-ring electrodes, both vertical and horizontal, within a microchannel of 500 μm diameter. An empirical formula is derived to calculate the void fraction from the electrical data obtained. High-speed imaging at 4000 frames per second supplements the method by providing visual confirmation of the flow patterns. The comparative analysis of the direct impedance method and image processing using the homogeneous theoretical model reveals a deviation of approximately 2 %–10 % for the slug and annular flow pattern. In contrast, the deviation is more for the bubble pattern. The results affirm that the Direct Impedance Method is a cost-effective and reasonably precise technique for small-channel applications. Its accuracy is inversely proportional to the channel diameter, rendering it unsuitable for channels larger than 2 mm. The method's low construction cost further enhances its practical appeal.