Increased Construction Costs Research Articles

Wind driven natural ventilation through multiple gridirons of a pile-supported wharf to prevent atmospheric corrosion in the marine environment

Salt fog originating from the offshore zone can easily accumulate in the semi-enclosed space (called the gridiron space) formed by the beams and slabs of a pile-supported wharf. Such accumulation can lead to the premature failure of the durability of the wharf’s substructure. Previous works have mainly focused on material-level measures to eliminate the adverse effects of salt fog accumulation, such as the use of anti-corrosion concrete and anti-corrosion coatings, which could result in increased construction costs. In fact, salt fog can be extracted from a gridiron by natural ventilation in some cases, so it is important to examine the flow characteristics of the gridiron space. In this work, a numerical simulation was conducted with natural ventilation and auxiliary ventilation groups. The critical value of the shield ratio (defined as the height ratio of edge stringer to air inlet) that led to the weakest turbulence of airflow inside the gridiron was studied in the natural ventilation group. In addition, the effect of various configurations of vents was discussed; in accordance with the results, design recommendations were proposed to enhance the durability of a pile-supported wharf.

An Investigation of the Polishing Behavior of Calcined Bauxite Aggregate

The application of top-grade calcined bauxite to improve the skid resistance of pavement surface coatings increases construction costs and causes excessive tire wear. Therefore, it is necessary to investigate the polishing behavior of different grades of calcined bauxite aggregate. The polished stone value of calcined bauxite was measured after the standard polishing time and the extended polishing time. The Los Angeles (L.A.) abrasion and the crushing value, profile roughness, hardness, X-ray diffraction, and micromorphology were also tested. The results showed that the calcined bauxite above 75# (the ratio of corundum to mullite by weight, C/M > 1) satisfied the requirement of the ultra-thin friction course. Compared with basalt, the calcined bauxite above 80# (C/M > 3) has better long-term skid resistance, even though the pavement surface is subject to heavier traffic. Due to the higher cohesion of lower porosity, more hard minerals to keep the surface roughness, and less soft minerals to smooth the surface roughness, calcined bauxite with a higher corundum content has the better skid resistance. There is a power law relationship between C/M and Polished Stone Value (PSV). Considering the diminishing returns of higher-grade calcined bauxite, it is necessary to accurately select the appropriate C/M of calcined bauxite before use in pavement surface coatings.

Quantifying the Environmental and Economic Performance of Remote Communities

Remote communities such as oil production sites, post-disaster housing camps, and military forwardoperating bases (FOB) are often detached from established infrastructure grids, requiring a constantresupply of resources. In one instance, a 600-person FOB required 22 trucks per day to delivernecessary fuel and water and remove generated wastes. This logistical burden produces negativeenvironmental impacts and increases operational costs. To minimize these consequences,construction planners can implement sustainability measures such as renewable energy systems,improved waste management practices, and energy-efficient equipment. However, integration ofsuch upgrades can increase construction costs, presenting the need for a tool that identifies tradeoffsamong conflicting criteria. To assist planners in these efforts, this paper presents the development ofa novel remote site sustainability assessment model capable of quantifying the environmental andeconomic performance of a set of infrastructure alternatives. Through field data and literatureestimates, a hypothetical FOB is designed and evaluated to demonstrate the model’s distinctivecapability to accurately and efficiently assess construction alternatives. The proposed model willenable construction planners to maximize the sustainability of remote communities, creating sitesthat are more self-sufficient with reduced environmental impacts.Keywords: Sustainability, infrastructure, remote communities

Estimation of Loss Ratio of Fine Sediments for Dredging and Land Reclamation

Kim, D.H.; Ryu, H.R.; Lim, H.S., and Hwnag, K.-N, 2019. Estimation of loss ratio of fine sediments for dredging and land reclamation. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 246-250. Coconut Creek (Florida), ISSN 0749-0208.Dredged sediments from the sea bottom are being used as filling material in the Saemangeum reclamation area located on the west coast of Korea. The dredged sediments of Saemangeum contain sediments such as silt or mud from which the coarse sediments can be immediately deposited, whereas the fine sediments can remain in suspension in the spillway. Consequently, when the fine-sediment content in the dredged sediments is extremely high, the resulting loss ratio of sediments may become significantly larger than expected, thereby resulting in increased construction costs. In addition, the suspended sediments released through the outflow can increase the turbidity of seawater, which can form one of the major causes of seawater pollution. Therefore, for economical dredging and reclamation in the case of high content of fine sediments, estimation of the loss ratio of sediments is essential. In this study, we develop a novel approach based on the theory of cohesive fine-sediment transport to measure the loss ratio of sediments at the Saemangeum reclamation site. We perform a series of deposition experiments with an annular flume to determine the equilibrium suspended-sediment concentration for a given flow velocity or shear stress, which is used to estimate the loss ratio of sediments. In addition, we perform settling experiments for the purpose of reducing the loss ratio near the spillway. Unlike previous methods of assessing the loss ratio, our method has the great advantage of providing detailed information that can be used to reduce the loss ratio. Deposition experiments show that the loss ratio for dredged sediment is ∼14.9–20.5%, which is very reasonable when compared with field data value of 15.3%. Further, the loss ratio can be greatly reduced if the travel time (at least 6 h) of the dredged sediment is increased to reach the equilibrium concentration and sufficient settling time (at least 1.4 h) is provided through the construction of a sediment basin near the outflow.

The use of jigilin gravel as road material in North Nigeria

This paper presents the rationalization of jigilin soil as pavement layer material in Northern Nigeria, where quality laterite and stone aggregates are either in short supply or unavailable. The regions are covered mostly by sandy soils, extending over the semi-arid zones of West Africa. Haulage of quality materials over long distances increases construction cost, causing delay in materials delivery and leading to greenhouse gas emissions. The potentials of a naturally occurring soil material, locally known as Jigilin, and commonly found in the region, were evaluated for suitability as pavement layers construction. The performance characteristics of the jigilin material under traffic loading was carried out, while the cost of constructing pavement layers with jigilin and lateritic soils were estimated. Results show that jigilin soil satisfies the density criterion and specifications for pavement subbase and base courses. In addition, the cost of producing a kilometer long and 7.3 m width of pavement using jigilin and lateritic materials were N56,910,000.00 and N63,042,000.00, respectively, resulting in cost saving of 9.727% when jigilin is used as the material for the pavement layers. Jigilin soil is, hence technically and financially feasible, and therefore, recommended for use as pavement layer material in Northern Nigeria.

Evaluation of Excavation-Damaged Zone around Underground Tunnels by Theoretical Calculation and Field Test Methods

Excavation-damaged zones (EDZs) induced in underground mining and civil engineering potentially threaten tunnel safety and stability, and increase construction and support costs. In this paper, an investigation of the excavation damaged zone (EDZ) around roadways in Fankou lead-zinc mine in Guangzhou, China is performed by applying a seismic velocity method accompanied by SET-PLT-01 nonmetallic ultrasonic detector. Meanwhile, the in situ stress in the mining area was measured based on the stress relief method with the Swedish high-precision LUT system. The results indicate that the stress field is dominated by the maximum horizontal tectonic stress, and the extents of the EDZ on the roof-floor region are greater than that on the sidewall. In addition, both of the in situ stresses and EDZs show an increasing trend with an increase of depth. Analytical solutions of EDZ around circular openings in the brittle rock mass subjected to non-hydrostatic stress fields are presented in terms of the Mohr–Coulomb and generalized Hoek–Brown criteria, and validated by several cases mentioned above. The extents of EDZ solved by closed-form solutions were found to be in a great agreement with those obtained in the field. Finally, a series of parametric studies are conducted to investigate the effects of cohesion (c), friction angle (φ), geological strength index (GSI), mi, uniaxial compressive strength (σc), and disturbance factor (D) on EDZ. It is shown that the effects of c, φ, GSI, and σc are significant; however, more attention should be paid to consider the dynamic disturbances induced by mechanical drilling, blasting, and seismic waves in tunnel excavations or operations.

Renovation of apartment buildings with prefabricated modular panels

New recast of the EPBD requires that that Member States shall establish a long-term strategy facilitating the cost-effective transformation of existing buildings into nearly-zero energy buildings. Lack of fund and lack of awareness is often considered to be the main barrier for the renovation. Experiences with renovation grant scheme in Estonia showed that large scale renovation scheme is a challenge to the construction industry and increased demand creates new problems like labour shortage and increased construction costs. Current renovation rate of apartment buildings in Estonia is approximately 200 buildings (~1%) per year. Demand is higher but current renovation technologies makes it difficult to significantly increase the renovation rate. Achieving the deep renovation goals with current technologies would require expansion of the whole construction sector (designers, contactors, material industry), which is difficult to achieve. Therefore, innovation and new technologies are needed. The prefabrication would be one solution to allow automation of the renovation process and renovate the existing housing stock within a reasonable time period.

Full‐Scale Impact Test and Numerical Simulation of a New‐Type Resilient Rock‐Shed Flexible Buffer Structure

Rock sheds have been widely used to protect against rockfall. Traditionally, a cushion layer is placed on the top of a rock shed to reduce the impact force and dissipate energy. However, heavy cushion layers lead to high dead loads and increased construction costs. This paper discusses the concept of an impact‐resilient flexible buffer structure. On the basis of that concept, it also proposes a buffer structure mainly composed of springs, ring nets, spring rods, and support ropes, which can be used to replace the traditional cushion layer on a shed for rockfall protection. Full‐scale impact tests were conducted to study the impact‐resilient characteristic of the structure combined with numerical simulation. The dynamic responses of the buffer structure, including force, deformation, and energy dissipation, were analysed in depth. Finally, parametric numerical simulations of 33 models were conducted; the spring stiffness of these models ranged from 300 kN/m to 1500 kN/m; the impact energy ranged from 100 kJ to 2000 kJ. Moreover, simple approaches for estimating the impact force and braking distance of the buffer structure were proposed and verified using measured data obtained from the impact test.

A COST-BENEFIT ANALYSIS OF GREEN BUILDINGS WITH RESPECT TO CONSTRUCTION WASTE MINIMIZATION USING BIG DATA IN HONG KONG

It is generally accepted that the extra construction costs involved in the construction of green buildings will result in benefits including lower operation costs, higher sale/rental prices, and better sustainability performance. However, there has been little recognition of construction waste minimization (CWM) as one of the important benefits of sustainability performance as designated in green building. This paper aims to provide a better understanding of the cost benefit of green buildings with respect to CWM by using big data in the context of Hong Kong. The study is innovative in that it conducts a cost-benefit analysis specifically on CWM of green buildings by mining large-volume datasets. A surprise finding is that Hong Kong's green building rating system (GBRS), i.e. the BEAM Plus, has a negligible effect on CWM, while it generally increases construction costs by approximately 24%. Hence, the increased construction cost of green buildings cannot be offset by CWM if corresponding items in the BEAM Plus are not properly incentivized. This paper demonstrates the necessity of emphasizing CWM-related items in GBRSs and of taking appropriate measures to deal with them. It also provides better decision-support information on the increased construction costs and the attainable benefits of green building that developers may wish to consider when initiating a green building project.

Application of Tower Girder Asynchronous Construction Technology

When constructing the tower beam in a traditional way, the tower beam will be simultaneously constructed with the tower column, it asks for a complicated construction procedure, difficult construction organization, long operating cycle, and highly increased construction cost. With the progress of technology, Asynchronous construction scheme of the tower column and tower beam is adopted and applied. This paper is based on the case of asynchronous construction of the H-type cable tower and beam of the six large-span Ao jiang Bridges.

Regional Development of Residential and Commercial Real Estate in Poland and the Risk of Real Estate Cycles

The property market is local and thus regional factors have a very important impact on its evolution. However, global factors also have an impact. This paper explains that fast economic growth can lead to strong cycles in the market and also cause problems for the stability of the economy. With a case study of the housing market in Warsaw we show that very different economic and regulatory factors can create cycles which look quite similar at first sight. We conclude that one needs to understand the fundamentals of a given cycle to be able to smooth it. The main driver of the cycle in Poland is the significant shortage of housing units, and thus people react very strong to any possibility of improving their living conditions. Rises in income or declines of mortgage costs trigger a demand boom, while the supply side is constrained by regulations and increasing construction costs. The excessive demand leads to quite strong cycles which could be smoothed with a large amount of rental housing.

Role of Predisaster Construction Market Conditions in Influencing Postdisaster Demand Surge

The postdisaster survival of cities and communities depends on their capabilities to reconstruct and repair damaged buildings following large-scale natural disasters. The socioeconomic phenomenon of increased construction costs following large-scale natural disasters, also called demand surge, cripples our capabilities to recover from disasters effectively. Labor cost fluctuation following natural disasters is known to be a driving factor in demand surge measurement. The relationship between construction labor wage fluctuations and disaster’s magnitude has been defined in the literature. Despite the significant role of the construction industry in postdisaster labor cost fluctuations, the relationship between predisaster construction market conditions and postdisaster labor cost fluctuations has not been studied. The objective of this study is to quantify the relationship between predisaster residential construction market conditions and residential labor wage fluctuations following weather-related disasters. The historical county-level data on five construction market indicators (establishment count, contribution level, average weekly wages, employment level, and building permits) prior to disasters along with disaster magnitudes (property damage) were collected for more than 35 of the largest weather-related disasters (floods, storms, and tornadoes) in the United States. These disasters affected more than 400 counties from 2007 to 2014. Residential building labor cost changes were first measured for counties impacted by weather-related disasters. The multiple linear regression method was then utilized to quantify the relationship between predisaster residential construction market indicators and the percent change in residential building labor wages after weather-related disasters. The results show that changes in residential building labor wages following weather-related disasters depend on the predisaster level of construction market indicators and the interactions between indicators. It is expected that the results of this study will help cost engineers to prepare more accurate bids in the volatile postdisaster construction markets and help capital planners and postdisaster risk-mitigation agencies to identify the more vulnerable construction markets.

Beyond the Limitations of API RP-14E Erosional Velocity -A Field Study for Gas Condensate Wells

Fluid velocity has the potential to cause severe erosion damage to oil & gas production infrastructure. In order to avoid or alleviate damage due to erosion, the American Petroleum Institute Recommended Practice (API RP) 14E recommends a threshold fluid velocity for production tubing and pipelines. However, field and laboratory data have proven that the applied empirical constants, known as C-factors, within the formula are not valid for all conditions. In many cases the calculated API RP 14E erosional velocity is significantly underestimated or overestimated due to insufficient consideration of fluid characteristics. In addition, accurate field data on erosional velocity can assist proper pipe sizing calculations for prospective oilfield projects. Oversizing of tubing unnecessarily increases construction costs whilst underestimating required size of tubulars can lead to catastrophic erosion/corrosion failures. In this study new values for erosional velocity constants, beyond those suggested by API RP 14E, are proposed based on experimental data achieved from sidestream pilot test units. The experimental pilot test units were installed on four different gas condensate production fields in the south of Iran. Electrical Resistance (ER) probes were employed to gather online erosion-corrosion data from the pilot units, each of which was in service for about nine months. The results showed that higher C-factors can be safely applied for these gas condensate fields in comparison with those recommended by API RP 14E. Furthermore, it was revealed that pilot test units exposed to a higher Condensate Gas Ratio (CGR) experienced a greater rate of erosion.

Finite service life evaluation method of production casing for sour-gas wells

The material selection and design for oil and gas wells containing hydrogen sulfide and carbon dioxide is very difficult due to the uncertainties such as the changeable production capacity, partial pressure of corrosive medium (like CO2 and H2S). For oil and gas wells, there is a high production rate in the initial stage while the production rate is very low in the rest of stage. Meanwhile, some wells may have water outflow in the very early period but they even become flooded in the following process. According to relevant standards, Nickel-based alloys must be used in these conditions. However, using Nickel-based alloys could greatly increase construction cost. In this paper, we propose an evaluation method for those types of wells based on a finite life design theory, which utilizes a high pressure high temperature (HPHT) flow corrosion test. Furthermore, phase state and transformation kinetics are introduced into the evaluation. The simulation covers the formation of water corrosion in three periods, which include the condensate water gas production period, the water-carrying gas production period and the water accumulation period. Corroded casing strength was derived according to API Specification 5CT, and the residual strength including residual tensile strength, residual internal pressure, and the residual collapsing strength of the casing. Finally, residual strength data was used for the finite life theory based on the resistance safety method, and compared with the Offshore Drilling Manual, the finite service life can be predicted.

Aspects of using ground and above-ground transport for urban passenger transportation

Abstract A need for having high-speed and cost-effective transportation systems in large cities is substantiated. A potential dramatic decrease in power consumed by public and private transport means in large cities is outlined due to reducing the number of transport means per citizen. It is established that the risk of fatal outcome is much higher for road accidents involving automobiles than for road accidents involving alternative types of transport. Above-ground transport means allowing increasing passenger transportation safety and significantly reducing power consumption are listed as a group of innovative transport technologies. Cable and light-weight overhead road or string types of above-ground transport are distinguished as the most promising. A comparative analysis of transportation systems, most popular in large cities, is given comprising the subway, monorail, high-speed tram, tram, trolleybus, bus, cable car, and string transport, using three technical and economic parameters: costs for the construction of one km of a transportation system line, average speed of transport means and specific reduced power consumption. Specifics in applying light-weight overhead road transport (also referred to as string transport) are outlined. Currently, this type of transport is at the design stage, i.e. it is not as developed as other types of transport featuring greater or lesser implementation degree. According to development engineers, string transport rails will have a bunch of stressed steel wires or carbon fibers in the cross-section. In order to implement the principle of gravity energy recovery, claimed by developers of string transport, anchor supports-stations in string transportation systems should be located at a significant height, thus, increasing construction costs. Average speeds for string transport modules are established based on the gravity energy recovery principle. Graphic images are plotted for transportation system indicators. Potential advantages and disadvantages of cable and string transport are examined. A conclusion is made that, under modern conditions, limited construction of cable and light-weight overhead transportation lines to supplement and duplicate the existing roads in large cities is expedient.

Conceptual weather environmental forecasting system for identifying potential failure of under-construction structures during typhoons

In this study, we developed a conceptual weather environmental forecasting system (CWEFS) for predicting the failure of under-construction structures during typhoons. Major functions of the developed system include 1) forecasting hourly typhoon wind velocity, 2) analyzing structure reference load during the construction stage, 3) identifying potential failure of under-construction structures, and 4) evaluating the weather in future hours to determine whether the conditions are suitable for work. Data-driven models, namely support vector machines for regression (SVRs), regression, and two decision trees (namely C5.0 and CART) were employed in this study as forecasting techniques to predict the wind velocity on Orchid Island, Taiwan, the study site. Structure reference load analysis was performed using a finite element model to evaluate the reference load on an experimental tank under construction. Typhoons Nanmadol (2011) and Saola (2012) were selected for real-time simulation by using the proposed CWEFS. This study identified potential collapses by using 1- to 6-h-ahead wind speed predictions. However, prediction errors inevitably occur. The results showed that the SVRs provided excellent prediction accuracy compared with regression, C5.0, and CART regarding the average time error between the observed and predicted values in all structure scenarios. A high forecast time error might result in increased construction costs and delays in construction schedules. Thus, we suggest that shorter prediction windows (e.g., 1 and 2 h) and models with higher prediction accuracy (e.g., SVR and C5.0) be employed to create a reasonable warning system.

Identifying the Global Performance of the Construction Industry

This paper presents a literature research assessing the performance and issues of delivering construction services worldwide, by exploring reasons for delays and increased construction costs. The study shows a comparison of the performance of the construction industry between different continents and countries. Multiple research databases were looked through and performance information was taken from over 95 publications. The results reveal that although the construction industry is growing throughout the world, there are many of the same problems being experienced in delivering construction projects in developing countries and developed countries. The literature reveals that all countries and continents are experiencing the same issues. On average, 72% of projects are delayed with 38% increase in original contracted duration, also, 63% of projects experienced cost overruns with 24% increase in original contracted cost. Additionally, rework is also a factor that affects performance and accounts for 6% increase in total project costs. Customer satisfaction on projects is low, and 90% of all major issues causing non-performance are due to people. A best value approach was identified as a potential solution to overcome the poor performance on construction projects with the following results: tested over 1900 times, totaling over $6B of procured services, a 94% on time and 97% on budget, and 98% customer satisfaction.

Use of XPS thermal insulator boards in design of educational spaces

This research refers to case study, Haghpanah girls' primary school that is of the standard schools designed and implemented by Isfahan Province Schools Renovation Organization. It deals to the importance and creation of an operational method for applying modern materials such as XPS thermal insulator in architectural design and its effect on educational spaces in section of primary school and how to design. It also deals to its effect and advantages on interior spaces that will help educational optimization significantly. Perhaps some believe that the implementation of thermal insulation of the building increases construction costs. However, we note that the implementation of thermal insulation not only saves energy consumption but also has a significant role in consumption of wasted heating and cooling energy of educational spaces. For example, the position of mentioned school is on the ground floor (pilot) and with external walls around the building. As it is obvious, the building floor and three sides of its perimeter are a part of the external shell (in contact with the outside perimeter). Cooling and heating of such a building requires spending high costs to provide equipment with high capacities. Heating and cooling equipment capacity becomes smaller than half after proper implementation of thermal insulation. As air conditioning equipment becomes small, implementation of optimization not only becomes free but also reduces the overall cost of construction. Keywords: School, modern materials, Building and Housing Research Center, XPS boards

국내 모듈러 주택의 특성 및 MC 설계를 통한 건축자재 표준화 효과 분석

Modular construction is a process in which a building is produced off-site in module boxes using standard materials. Since the introduction of prefabrication in building construction, Modular Coordination (MC) has become an essential design tool in building design and construction. However, in Korea, the design standardization has not been adequately applied to modular construction. This study intends to analyze the current status of modular construction in Korea and explore the applicability of MC design in the construction industry. The analysis of the current status of MC design within Korean four major modular construction companies indicates that an incremental dimension is not properly used in horizontal planning modules, which results in a problem of increasing construction cost by high material loss rate. But, in vertical planning modules, a incremental dimension of 100 mm (1 M) is found to be used although the structural system varies among manufacturers, which demonstrates the potential for an open system to be well applied in modular construction, despite different structural systems.

공동주택의 하자진단에 기초한 공종별 하자보수비용의 분석

This study investigated defect status by work type, based on the report data of defect inspection results, acquired by consumers’ request to safety inspection agencies, before the expiration of legal defect repair warranty period. In fact, the data was not acquired by centering on suppliers, namely, construction companies in relation with the defects becoming causes to increase construction cost of apartments. This study aims to provide objective and basic data for quality improvement at construction stage and for solution to defect disputes. The study results are presented below: (1) The number of defect cases occurring from architectural work among total work types were 1,986, defect occurrence rate was 62.5%, and defect repair cost was KRW 25,851/㎡, which stood at 78.2% of the total work types. This means the defect occurrence rate and defect repair cost in architectural work are bigger than those of other work types. (2) Major defects in architectural work were revealed in the following order: cracks from frame work, inferior interior finishing work, inferior finishing work of plaster/masonry works, water leak/damage from waterproof work and withering/omission from landscape work. The total repair cost of the major selected defects was KRW 12,220/㎡, and was analyzed to take up 37% of the total defect repair cost.