bluuebunny/crossref_metadata_2025 huggingface dataset:
MECHANICAL PROPERTIES OF STRUCTURAL STEEL AND HIGH-TENSION BOLT AT ELEVATED TEMPERATURE
Authors: Shin Kyung-Jae , Lee Hee-Du , Kim So-Yeong , Chu Da-Som , Woo Jong-Hun
Published: March 2020

This paper presents the test results of the mechanical properties of three types of structural steel at high temperature, which are generally used for the Pre-Engineered Building (PEB) system. The PEB system is generally used for non-residential buildings, such as factories and warehouses. The structural steel members are installed without fire resistance protection, which means they are very weak in the case of fire. The end-plate connection could be critical in the case of fire because most of the moment is resisted by the tensile force of the bolts. Therefore, the mechanical properties of bolts at elevated temperatures are tested. Coupon test specimens for SS400(SS275), SM490(SS355), and F10T bolts were tested according to ASTM E8M. The high-temperature coupon tests were performed at 20°C, 400°C, 500°C, 600°C, 700°C, and 800°C. The test results were compared with the design reduction factors obtained from the American and European standards. The yield strength and tensile strength satisfied the minimum strength of the specified standards at 20°C. However, the reduction factor for yield strength obtained at a high temperature was lower than that of the standard value suggested by the code. In particular, the reduction factors for the high-strength bolt (F10T) were lower than those of the structural steel members (SS400(SS275), SM490(SM355)).
MODELING CONSTRUCTION ORGANIZATION PERFORMANCE IN POST-CONFLICT ENVIRONMENT
Authors: Amarkhil Qais , Elwakil Emad
Published: March 2020

In the field of the construction industry, research work has widely focused on identifying Key performance indicators and critical success factors without assessing the impact of conflict environment factors. This study focusses on the impact of post-conflict environment factors on local construction organization performance. This paper presents a framework for improving construction organization performance in a post-conflict environment. The proposed framework consists of four stages: identify post-conflict environment impacting factors, determine critical success factors (CSFs), determine key performance indicators (KPIs), and adopt the best strategy to improve performance. Analytical hierarchy process (AHP) and multiple linear regression (MLR) modeling has been used to analyze quantitative and qualitative variables obtained from the literature and expert opinion through comprehensive literature search, meetings, and survey to determine critical success factors and to identify performance improvement strategy. The study finding suggests that twenty factors from the questioner have a critical impact on the identified five performance measures. The presented CSFs helps the organization management team to consider the impact of these factors on their firm and to formulate a competitive strategy in a post-conflict environment.
MODELING CONTRACT PRACTICES RESULTING IN RISK MISALLOCATION
Authors: Tembo-Silungwe Chipozya
Published: March 2020

Risk misallocation has been a topic of discussion in the extent literature for some time now. The literature points out that risk management is the key to ensuring that optimal risk allocation is achieved. While the focus on risk allocation has been about the party best suited to carry a given risk, the issue of how misallocation occurs is rarely dealt with. This paper modeled how risk misallocation can result from contract practice. This was done through a literature review and 15 purposive heterogeneous semi-structured interviews conducted with clients, project managers, architects, engineers and quantity surveyors in the Zambian building sector. The derived model suggests that misallocation could result from inappropriate selection of risk mitigation mechanisms provided for in the contract, poor selection of contracts and use of inappropriate procurement routes. These findings advance knowledge that necessitates the allocation of risk appropriately as the areas of contract practice and risk management are rarely researched with regards to risk misallocation.
NEURAL NETWORK AND PROBABILTY BASED COST EXPECTATION LIMIT MODEL FOR RESIDENTIAL BUILDING COST
Authors: Amusan Lekan , Opeyemi Joshua , Ebuoluwa Adeyemi , Omuh Ignatius
Published: March 2020

The aim of this study is to develop a Cost Expectancy Limit Model that could assist clients in having proactive information about construction cost expectation of a particular building type with a view of assisting the client in proactive determination of expected construction cost of a building under predetermined conditions. Two population frames were used in this context. First, a population frame of 1500 samples of actual construction cost of residential building in Lagos state Nigeria out of which 1000 samples of As-built cost (Actual cost) of residential buildings were used, in artificial neural network data training and model development using MATLAB Neuro tools. The second population sample was 250 samples of construction professionals, out of which 200 samples was picked for purpose of questionnaire administration to capture data on factors that could influence building cost expectancy. Mean Item Score, Simple Percentage, and Relative Agreement Index of SPSS package was used to analyze and process the data. Cost expectancy limit was developed with parameters trained with Artificial Neural Networks, while factors that influence the accurateness of the expectancy model were articulated, such as economic factors, political factors, activity of maestros, macro and micro economic variables, and corruption factors, among others. The study recommends the use of the model and strategy for effectiveness in accurate prediction of construction cost among other things.
QUALITY MANAGEMENT IN CONSTRUCTION PROJECT: EMPIRICAL STUDY OF COVENANT UNIVERSITY SPORTS COMPLEX
Authors: Oyebisi Solomon , Ede Anthony , Olutoge Festus , Ngene Ben , Ofuyatan Olatokunbo , Oluwafemi John
Published: March 2020

The acceptable level of quality in construction projects has long been a problem. Significant resources are wasted on construction projects because of inefficient or non-existent quality management procedures. Therefore, this study evaluates the quality management and the quality grading practices in the construction project with emphasis on the Covenant University Sports Complex. The quantitative research strategy and questionnaire survey were used as the main data collection instrument for soliciting information from the project participants in order to determine the best key for quality management practice. Moreover, an ultrasonic pulse velocity tester was engaged to assess and evaluate the conditions of concrete structural members. It was found out that management commitment to quality is the most key for effective quality management practices in the construction project. In addition, the ultrasonic pulse velocity (UPV) test carried out on the randomly selected structural members varied in the range 4.2km/sec to 4.6km/sec. From this, it is inferred that the quality grading and homogeneity of concrete in the tested reinforced concrete columns, beams and slabs fall in the range of "good to excellent concrete". The findings would assist project participants in implementing an efficient quality grading and management while executing construction projects.
REHABILITATION OF MARINE TERMINAL PIERS
Authors: Seniwongse Muangsangop
Published: March 2020

This paper presents practical methods and techniques for rehabilitation and strengthening marine terminal piers in the USA. These piers are waterfront structures for berthing of large cargo vessels and cruise vessels. Typically, the piers consist of timber or concrete deck supported on multiple pile bents. The piers are subjected to large impact forces from the mooring of the vessels acting at the fenders and bollards, in addition to the other normal vertical dead and live loads. Depending on the size of the vessels, the design service loads on the bollards are in the range of 100 tons to 200 tons. Other possible severe loads are from the winds and waves during the hurricanes. The piers are continuously exposed to outdoor, marine and coastal environments, which are corrosive in nature. For these reasons, all piers of 15 years or more are normally up for repair/rehabilitation. Typical deteriorations found are: cracked and spalled concrete, rust in exposed reinforcing bars, broken timber piles, timber piles with reduced cross sections, cracked concrete piles, corroded steel piles, and displaced out-of-plumb piles. The paper presents the methods for repairing the above-mentioned defects. For concrete crack and spall repair: sealing with epoxy, concrete patching and shotcrete are used. For pile repair: concrete jacketing of piles is used for splicing or strengthening of piles.
RETROFITTING METHODS AGAINST FATIGUE CRACKING IN STEEL GIRDER WEB PENETRATION
Authors: Sakamoto Chihiro , Sakano Masahiro , Konishi Hideyuki , Fujii Takashi
Published: March 2020

Fatigue cracking in steel girder web penetration details is so dangerous that it can break steel girders. Since a number of highway bridges have such web penetration details in Japan, it is of urgent importance to grasp these fatigue strength properties and develop effective retrofitting methods. In a previous report, we investigated the stress distributions around web penetration details, and fatigue cracking behavior, using steel girder specimens with web penetration details. In this study, we investigate effects of retrofitting methods against fatigue cracking in web penetration details through fatigue tests using large girder specimens with web penetration details in which cross beam lower flanges are connected to lower surface of a slot by welding. Principal results obtained through this study are as follows: (1) Weld toe grinding can extend fatigue life more than 5 times, (2) Two-face attachment can extend fatigue life more than 10 times, and (3) Two-face attachment with weld toe grinding can extend fatigue life more than 25 times.
RHEOLOGY OF SELF-COMPACTING CONCRETE USED FOR SUPERTALL BUILDINGS
Authors: Tran Mien , Cu Yen
Published: March 2020

Nowadays, self-compacting concrete (SCC) is widely being used for supertall building construction in Vietnam. With high workability, SCC allows us to speed up pumping, placing, and surface finishing, which results in a reduction in building cost. Popular methods such as slump flow, T500, and V funnel test are used to indirectly determine rheological properties of SCC. However, these methods do not present yield stress and plastic viscosity, which are the most parameters affecting the pumping property. In this paper, the SCC rheology is determined directly through yield stress and plastic viscosity with the flow curve test and stress growth test by using the rheometer equipment. Thereby, limitation of the yield stress and the plastic viscosity is recommended for vertically pumping to supertall building project without segregation and bleeding.
SEISMIC EVALUATION OF SQUARE HSS BRACES IN SCBF USING REGRESSION ANALYSIS
Authors: Faytarouni Mahmoud , Seker Onur , Akbas Bulent , Shen Jay
Published: March 2020

Since the 1990s, structural engineering practice geared toward the use of hollow structural sections (HSS), notably square HSS, for their economy, and ease of design and construction. According to the AISC Seismic Provisions, during a severe earthquake, these braces could undergo post-buckling axial deformations 10 to 20 times their yielding deformation. However, recent experimental studies indicate that braces made of square HSS, depending on their size, width-to-thickness, and slenderness ratio, are vulnerable to fracture even prior to 10. Therefore, relying on past experimental studies comprised of a few square HSS specimens to develop seismic requirements for SCBF with square HSS could lead to underestimation of the seismic risk. This paper aims to evaluate the fracture risk of braces in existing SCBFs designed in accordance with AISC 341-05 and AISC 341-16 through incremental dynamic analyses (IDA) along with experimentally developed regression model that estimates fracture.
ANALYSIS OF BUCKLING AND BENDING FAILURE OF ALUMINIUM COLUMN SECTIONS USED IN EMERGENCY RESTORATION TOWERS
Authors: Ramji Sarah , Pasini Ciro , Chang Yongjian , Mercan Oya
Published: March 2020

This paper presents an experimental analysis of buckling and bending failure modes of a 2.58 m long, 460×460 mm2 6061-T6 Aluminum alloy column section used in emergency restoration towers. The main objective is to determine the bending and buckling load capacities of the column section through experiments, as these values are critical in an emergency tower (guyed mast) design. Within the context of this overarching goal, a secondary objective is to ascertain whether the presence of certain manufacturing non-conformance affects the loading capacity of the section significantly. Finally, finite-element analysis (FEA) simulations are conducted in order to compare the experimental data with numerical results. The results show that the ultimate bending and buckling load capacities of the column section are 383 kN and 3,868 kN respectively. Furthermore, the results indicate that the presence of manufacturing non-conformances such as air bubbles and delamination do not have a detrimental effect on the load capacity of the column. Of the two non-conformances studied, the specimen with bubbles had a 1% difference from the good specimen, and the delaminated specimen had a 10% deviation. Comparison of experimental data with FEA simulation results shows that the numerical solution tends to overestimate the stiffness of the column, and that the FEA approach may require further calibration.
STRENGTHENING METHOD OF UNREINFORCED MASONRY WALLS BY BRACE ELEMENTS
Authors: Ganbaatar Ariunaa , Yamamoto Haruyuki
Published: March 2020

The ductility and strength properties of lightweight steel brace element for structural strengthening of unreinforced masonry (URM) wall is reported in this study. The performance of URM wall without brace and with brace is evaluated by an elastoplastic nonlinear analysis including the yield criterion, flow rule and hardening rule. Masonry constituent is implemented into two-dimensional finite element model developed in Fortran code. The brittle failure of URM wall is analyzed using by an interface element to model bricks and joints. Two types of steel brace elements which can resist only tension and both tension and compression have been considered to increase the ductility of URM wall. The comparison between experimental and numerical results adopted in simplified-micro masonry modeling is illustrated with the relationship between force and displacement. The ductility and strength of masonry wall with the tension and the tension-compression brace element were different results of URM wall by in-plane pushover analysis. As for the simplification for a calculation of masonry wall, equivalent masonry model is discussed and besides diagonal brace elements, the additional vertical brace element is assumed for the high masonry wall by the numerical analysis.
STRESS INTENSITY FACTOR ANALYSIS OF AN EDGE CRACK PERPENDICULAR TO THE INTERFACE IN BI-MATERIALS
Authors: Hou Yongkang , Zhang Shuo , Duan Shujin , An Ruimei
Published: March 2020

The purpose of this paper is to investigate the stress intensity factor in the problem of a crack perpendicular to the interface in bi-materials. Based on the theory of an edge crack perpendicular to the interface between two dissimilar isotropic half-planes, the stress intensity factor was yield out from the stress singularity eigen-equation. The stress intensity factor for a composite beam segment with an edge crack under bending and tension was computed by the ordinary finite element and the singular finite element, and it was found that the singular element method is more accurate and applicable than the ordinary element method. The influence of the distance from the crack tip to the interface and the material’s mechanical properties to the stress intensity factor were analyzed. The results show that the stress intensity factor increases first, and then decreases with decreasing of the distance from the crack tip to the interface, and the stress intensity factor increases with increasing of the elastic modulus of the cracked material.
STUDENTS' HOUSING SATISFACTION IN PRIVATE HIGHER INSTITUTIONS
Authors: Aghimien Douglas , Aigbavboa Clinton , Adama Joshua , Thwala Wellington
Published: March 2020

Student housing is essential to the attainment of quality education, most especially in higher institutions were students come from far distance to study. While research abounds on happenings with regards to student housing in public higher institutions, there is a paucity of information on this situation within the private higher institutions. This study, therefore, presents the result of an investigation of the satisfaction of students with housing facilities in private higher institutions in Nigeria. The study adopted a survey design and quantitative data were gathered through the use of a questionnaire administered to 216 students selected through stratified random sampling. The students' residence satisfaction was assessed from the physical, and social/management stands. Data gathered were analysed using percentage, mean score and Mann-Whitney U-Test. The study revealed that on a general level, while private institution students are more satisfied with the social and management characteristics of the residence than the physical characteristics. The study observed that although overall satisfaction is derived, there is still adequate room for improvement in order to deliver better housing for students. The outcome of this study provides a possible direction for the management of private higher institutions in improving their students' housing delivery in order to achieve higher students' satisfaction.
THE INFLUENCE OF BAMBOO REINFORCEMENT AND ADDITION OF FIBERS ON HOLLOW BEAMS
Authors: Ananda Faisal , Saputra Hendra , Sukri Armada
Published: March 2020

The development of the artistic value of a building with reinforced concrete material continues to grow, one of which burrows the pipeline so as unexposed so that the condition of a building looks beautiful. This condition makes a weakening of the strength of concrete. As for the weakness of the concrete caused by a small crack due to deflection or the other anticipated by the addition of fiber one of the rebar tie wire (bendrat). Based on this condition, the beam testing was done with size by 150mm x 200mm x 1200mm with using one-point loading. Concrete mix design using SNI 03-2834-2000. The load obtained without fibers using the steel reinforcement by 12.9% greater than the use of bamboo reinforcement. This is because the tensile strength of bamboo is smaller than the tensile strength of iron. Likewise, on the beam that added fiber as much as by 2% on the bamboo reinforcement, there is a difference of loading is smaller than the steel reinforcement by 25%. The interesting result is found in the 0.5 inch diameter beam which has an increase in load with the initial crack conditions close to the same as the beam without a hole.
APPLICATION OF LEAN METHODS FOR PRODUCTIVITY IMPROVEMENT IN STEEL FABRICATION SHOPS: A CASE STUDY
Authors: Dufresne Manuel , Mok Ho-Yan , Shakeri Reza , Elbarkouky Mohamed , Sharma Vishal
Published: March 2020

The objective of this paper is to identify tools and methodologies to increase productivity in commercial steel fabrication shops. The effectiveness of these tools and methodologies has been demonstrated through a case study in a Canadian steel fabrication shop. Three different productivity improvement concepts were identified as suitable for the steel fabrication environment. Lean, Six Sigma, and the Theory of Constraints (TOC). Lean was retained as being the most suitable to steel fabrication due to its low cost, focus on quality, and built in continuous improvement process. In the case study, Lean tools were identified and applied to address three top productivity issues. A baseline was established for existing productivity for a fitting station over a period of two weeks. Selected tools were implemented, and a session was conducted to educate the workers on the new processes and tools. Lastly, the productivity was recalculated, the results were analyzed, and recommendations were made.
VISIBLE TEST ON BUGHOLE GENERATION OF FLUIDITY CONCRETES FOR TUNNEL LINING
Authors: Yoshitake Isamu , Hieda Masahiro , Okamoto Kenta , Maeda Tomoyuki
Published: March 2020

Bughole (surface air-void) is a concern for surface quality though it rarely decreases strength properties of the concrete structure. In particular, sidewall of NATM tunnel lining which generally has negative angle is a significant concern in the bughole problem. To reduce the surface imperfection of concrete, the authors examined the bughole properties and discussed on construction methods in previous investigations. The present study focuses on the relation of bughole generation and concrete viscosity. A visible test of bughole generation was conducted using high and medium fluidity concretes in addition to the conventional concrete. Bughole distribution and properties were analyzed by the image analysis which was developed in our previous study. This paper reports the effect of concrete fluidity on decrease of bugholes on concrete surface. A remarkable observation in the experimental study is that number and area-ratio of bugholes increased with concrete viscosity while large voids can be decreased by using high/medium fluidity concrete.
PERIODIC BOLT PLACEMENT IN STEEL STRUCTURES FOR GUIDED DAMAGE DETECTION
Authors: Zhang Lu , Ozevin Didem , Okudan Gorkem
Published: March 2020

Connections form the weakest link in structural systems. Bolted connections are especially susceptible to stress corrosion cracking due to stress-riser points at the bolt edges and the intrusion of water between plates leading to galvanic corrosion. Bolts are conventionally placed based on minimum and maximum spacing requirements guided by American Institute of Steel Construction. Unfortunately, the detectability of crack and corrosion is currently not a design variable. In this study, bolts are placed in periodic pattern such that they exhibit unique frequency response. The periodic placement allows modeling only unit cell in the shape of hexagon with periodic boundary conditions to obtain the frequency response. When damage occurs, the periodic pattern is broken, and the frequency response behavior changes. The influence of crack to vibration modes is numerically modeled, and the damage detection ability with unique bolt placement is demonstrated. It is shown that the spatial distribution of bolt can assist the damage detection ability, which should be considered as a criterion in the design of bolted connections.
DETERIORATION OF CONCRETE SULFUR STORAGE TANK UNDER ACIDIC VAPOR ATTACK
Authors: Khalifah Hassan A. , Rahman Muhammad K. , Hamdan Omar M. , Abu Haid Mohammed , Ibrahim Mohammed , Gadhib Ali H.
Published: March 2020

Sulfur storage tanks are integral parts of refineries and gas plants. During the gas sweetening process, liquid sulfur is separated in the sulfur recovery units and is stored in underground reinforced concrete tanks in liquid phase by steam-generated temperatures of 315 °F. Roof of the sulfur pit is about 300 – 400 mm thick reinforced concrete structure with two layers of reinforcement. Inside the sulfur pit, the ceiling and walls are subjected to high temperatures and highly corrosive acidic vapors above liquid sulfur line which leads to severe deterioration of concrete and corrosion of reinforcement in the roof slab. This paper presents the NDT based investigations of the roof slab of the tank using the Ground Penetrating Radar (GPR) in a typical sulfur pit with 30 years in service. GPR survey is compared with ultrasonic pulse echo and half-cell potential measurements on the slab. Compressive strength and petrographic examination of selected concrete cores and SEM/EDS and XRD tests on powder samples, from inside the pit are presented.
IMPROVING COMPETITIVENESS IN INTERNATIONAL CONSTRUCTION
Authors: Gunhan Suat
Published: March 2020

Historically, U.S. contractors have a successful track record in international markets. They built that track record by bringing advanced technologies and applying efficient project management methodologies to projects. According to ENR data from the early 1980s to early 2008, U.S. contractors led the international construction arena. However, starting from 2009, Chinese construction firms lead the international construction with increasing revenue volume. The study analyzes the U.S. construction firms’ competitiveness in international markets between 1980 and 2017. The results of the analysis indicate that the U.S. contractors need to be competitive in creative financing. Creating joint ventures from companies that are active in Middle East, and Asia can improve the U.S. activities in those markets. To improve capabilities in delivering full-cycle services, U.S. construction companies can acquire facilities management companies. Involvement in emerging delivery methods and contracts such as build-operate-transfer, design-build-finance-maintain-operate, and public-private-partnerships can improve the competitiveness of U.S. contractors in international markets.
BEHAVIOR OF RC BEAM RETROFITTED USING ULTRA HIGH-PERFORMANCE CONCRETE UNDER IMPACT LOADS
Authors: Al-Osta Mohammed Ali
Published: March 2020

Several new types of materials have recently been used as retrofitting materials for structural elements such as ultra-high performance concrete with steel fiber reinforcement (UHPFRC). These materials are used as jacking to enhance the strength and ductility reinforced concrete (RC) beams. Considerable attention has been focused on the response of retrofitted RC beam under static loads but the behavior of such beam under impact loading is somewhat lacking. Therefore, in this study, a 3-D finite element model (FEM) of retrofitted RC beams under impact loading using non-linear finite element software (ABAQUS) was investigated. Since experimental work on this topic is scarce, the FEM is validated using the results of retrofitted RC beam under static loads. The impact load was applied in ABAQUS as equivalent to an initial velocity of 2500 mm/s. A parametric study was carried out to study the flexural response of RC beams retrofitted with different thicknesses and strengthening configurations of UHPFRC under impact loading.
A MEASUREMENT INSTRUMENT FOR THE TECHNOLOGY EXTENT AND PROCESS EFFICIENCY IN BIM ENABLED CONSTRUCTION PROJECTS
Authors: Ozturk Gozde Basak
Published: March 2020

Technology use in all fields can play an important role as the booster in creating lean and efficient processes. Technology use may result in reduced duplications and delays in workflows while helping to speed up task realization. Building Information Modeling (BIM) enhances knowledge share, use and reuse for better collaboration, communication, coordination, and monitoring as a knowledge base platform. BIM enhanced construction projects may positively affect the process efficiency. The aim of this paper is to define a measurement instrument of BIM usage as technology enhancer tool and of process efficiency of construction projects. Research leans on the prominent literature to concrete the measurement instrument. A survey is established to construction project professionals to understand the technology efficiency and process efficiency in BIM enabled construction projects. The research based on the related data collected from 92 professionals experienced both in traditional project delivery methods and BIM enabled construction projects. The respondents are the construction industry experts comprised of construction project managers, BIM managers, and BIM implementation experts (architects, civil engineers, mechanical engineers, electrical engineers etc.). Data is analyzed and tested with structural equation modeling software to verify the proposed measurement instrument. The technology efficiency and process efficiency factors for BIM enabled construction projects are tested and refined. Research findings present the measurement instrument for both technology and process efficiency in BIM enabled construction projects.
BLENDED METAKAOLIN AND WASTE CLAY BRICK POWDER AS SOURCE MATERIAL IN SUSTAINABLE GEOPOLYMER CONCRETE
Authors: Ahmed Mahmood F. , Khalil Wasan I. , Frayyeh Qais J.
Published: March 2020

Recently, sustainability and ecological related problems have attracted more attention around the world. The construction sector incorporates directly and indirectly in global warming, natural resources depletion, and environmental pollution. This study aims, firstly; to identify the optimum mix of metakaolin (MK) geopolymer concrete required to achieve high compressive strength with respect to the concentration of the alkaline solution and curing system. Secondly, to reduce the impact of brick waste on the environment, by producing geopolymer concrete based on blended MK and waste clay brick powder (WBP). The compressive strength, splitting tensile strength and flexural strength of MK-based geopolymer concrete specimens were studied. Different contents of waste clay brick powder (WBP) (0%, 10%, 15%, and 20%) as a replacement by weight of (MK) were investigated. The results appear that it is possible to produce MK-based geopolymer concrete with a compressive strength of 44.03 MPa, while it was 34.76 MPa at 28 days for specimens with 15% WBP replacement of main source binder. Finally, it could be concluded that green moderate strength geopolymer concrete can be produced and used in different civil engineering applications.
BUILDING A SUSTAINABLE WORLD: ECONOMY INDEX OF GEOPOLYMER CONCRETE
Authors: Oyebisi Solomon , Ede Anthony , Olutoge Festus , Ofuyatan Olatokunbo , Alayande Tolulope
Published: March 2020

Geopolymer concrete offers a considerable solution not only to the environmental problem but also to the structural deterioration confronting the world. But, limited or no study is found on its cost implications. Consequently, this study evaluates the production cost and the economy index of geopolymer concrete (GPC) and compares it with the Portland cement concrete (PCC). Corncob ash (CCA) and ground granulated blast furnace slag (GGBFS) were used as source materials in the production of geopolymer concrete. Alkaline liquids were prepared to obtain 12 molar concentrations. The concentration was used to activate the source materials. Grade 30 concrete (M30) was adopted as a mix design proportion. GGBFS was replaced by CCA in varying percentages as 0%, 20%, 40%, 60%, 80%, and 100%. The research findings reveal that GPC is 27.71% lesser than the PCC in terms of production cost while the economy index of GPC is higher than the PCC for the same grade of concrete. The results infer that GPC is cheaper and more viable than the PCC. Thus, geopolymer concrete proves to be an innovative product and appears to be a feasible solution not only to the environmental and structural deteriorating problems but also to the problem of high cost of Portland cement in the construction industry.
BUILDING INFORMATICS NEURAL NETWORK AND REGRESSION HEURISTICS PROTOCOL FOR MAKING DECISIONS IN BUILDING CONSTRUCTION PROJECTS
Authors: Amusan Lekan M. , Omuh Ignatius O. , Mosaku Timothy O.
Published: March 2020

Building Informatics is a body of knowledge that uses the ICT computer system, digital systems, building information modeling, and state-of-the-art software in solving technical and management issues in building and construction fields. One of the modern methods used in data forecasting and modeling is Artificial Neural Networks, considering its advantage over traditional regression method. A data sample was taken of 1500 residential building projects' completion costs. Regression analysis was carried out and model validated with functionality and Jackknife re-sampling technique. 150 Questionnaires were used to capture data on factors influencing application of heuristics protocol for decisions in residential building construction projects and data samples were analyzed using severity index, ranking, and simple percentages. Analysis of data brought up some factors that influence effective application of heuristic protocol in solving decision problems in construction decision process. The linearity analysis was carried out on the model and results indicated high level of tolerance and-0.0876 lowest variation prediction quotients to 0.9878 highest variation quotients. Also, 0.069 regression model fitness coefficient (R-square) was generated with 0.9878 highest variation quotients with standard error of 0.045. The results data attests to the stability of the model generated and the model is flexible in accommodating new data and variables, thus, allows for continuous updating.
A PREVENTIVE STRENGTHENING STRATEGY FOR AGED STEEL STRUCTURES
Authors: Taniguchi Nozomu , Lin Weiwei , Hiroe Masaaki
Published: March 2020

Steel columns are widely used in buildings, bridge piers, and railway platform roofs etc. With aging, those steel columns are vulnerable to corrosion and fatigue, and can deteriorate for a variety of reasons, especially in great earthquakes. In order to avoid the unrecoverable damage of existing steel columns, the high cost of the structure owners and the great impact on the public use, effective preventive maintenance methods on the aged steel piers are necessary. On this background, a strengthening method for aged steel columns by using new construction materials such as glass fiber reinforced polymer (GFRP) plates, rapid hardening concrete, rubber-latex mortar, and reinforcing bars, is introduced in this study. Depending on possible applied load directions and corrosion conditions, two specimens were used in the loading tests. Static loading tests were performed on steel columns with and without strengthening. Applied load and deflection relationship and strain distribution on original and strengthened columns were measured and compared. Moreover, three-dimensional FE models were built, and the numerical results were compared with the test results. Both experimental and numerical results indicate that the present strengthening method can significantly enhance both rigidity and ultimate load carrying capacity of aged steel columns.
COLLAPSE AND BUCKLING OF STAINLESS STEEL PRESTRESSED STAYED COLUMNS
Authors: Machacek Josef , Pichal Radek
Published: March 2020

Buckling and collapse of stainless steel elements loaded in compression are studied experimentally and numerically. Based on four tests of single crossarm stayed columns the numerical analysis using ANSYS software package is validated and presented in a detail. First, for a completeness, the study refers to columns with one central crossarm, but the main emphasis is devoted to columns with two crossarms located in the thirds of the element length. The analysis employed geometrically and materially nonlinear analysis (GMNIA) to respect a change of inner energy during buckling of an "ideal" (perfect) column, initial deflections of an "imperfect" column (covering various initial deflection modes and amplitude values) and nonlinear stress-strain relationship belonging to stainless steel material. The results cover both critical buckling and maximal collapse loads of the columns in compression. Finally, the important comparisons of the load capacities concerning stayed columns in compression with one/two crossarms and ratios of critical/maximal loadings, elastic/inelastic material and fixed/sliding support of the stays at the crossarms are provided. Conclusions comprise evaluation of these results and principal recommendations for the design of stayed columns.
COST OPTIMIZATION OF MULTIPLE RESOURCES ALLOCATION FOR MULTI-PROJECTS
Authors: Aboul Fotouh Sarah , Ezeldin A. Samer
Published: March 2020

As the construction industry grows year by year, optimization of resources is becoming essential to reduce their required number, their costs and as a consequence the total cost of the project. Project managers have to face problems regarding management of cost, time, and available resources for single projects. What is more challenging is to optimize the available resources for multiple projects, which would result in appreciable savings. Most of the companies in the construction industry commonly optimize the resources for single project. However, with the presence of several mega projects in many developing countries running at the same time, there is a need for a model to enhance the efficiency of available resources among multiple simultaneous projects. This paper discusses a numerical model of cost optimization and allocation of up to nine resources for up to three projects for a given company, taking into consideration the transportation of resources from one project to another and the cost of unused resources. The model was developed using a genetic algorithm, and it is used on the identified critical resources. It calculates the cost of each resource, minimizes the cost of extra resources, cost of unused resources, and generates the schedule of each project within a selected overall program.
EXPERIMENTAL AND NUMERICAL STUDIES OF STRUCTURAL PERFORMANCE OF NOTCH DAMAGED STEEL BEAMS
Authors: Elkholy Said , El-Ariss Bilal
Published: March 2020

Performance of notch damaged unrepaired steel I-shaped beam specimens was examined experimentally and numerically simulated using finite element modeling. Nine U-shaped notch damaged specimens and one control beam specimen were considered. The nine unrepaired laterally unsupported I-shaped full-scale steel specimens were tested in two-point loadings and the parameters considered in the study were the size and location of the notch. The notch size was 30 mm, 40 mm, and 60 mm in depth with a constant opening width of 20 mm. The location of the notch was at one-quarter, one third, and middle of the specimen clear span. All pre-damaged specimens had notches on one side of the tension flange with respect to the beam web except for two specimens where two notches were cut at the middle of the specimen clear span on both sides of the tension flange. The test specimens were modeled analytically using three-dimensional models of the bare-steel I-shaped specimens for comparison of the analytical predictions with experimental results. The test results showed the strength of the notched beams was hardly affected by the notch size or location. However, the stiffness of the beams was slightly decreased as the notch got closer to the mid-span with increased ductility. The corresponding analytical results were in good agreement with the test data.
FLEXURAL BEHAVIOR OF HIGH STRENGTH GEO-POLYMER CONCRETE BEAMS
Authors: Bhikshma Vankudothu , Promodkumar Kandiraju , Panduranghiah Putta
Published: March 2020

The demand for concrete is increasing day by day. As the consumption of cement is increased, environmental issues arise due to the release of CO2 during the manufacturing of cement. The objective of this research work is to produce a pollution free concrete with a combination of fly ash and GGBS (Ground granulated blast furnace slag) and without the use of cement. In this paper an attempt was made to study the mechanical properties of high strength geo-polymer concrete of grade M60 using GGBS, fly ash and micro silica. The testing program was planned for the mechanical properties of geo-polymer concrete and flexural behavior of corresponding beams. The experimental results indicated that the geo-polymer concrete M60 grade has a compressive strength of 70.45 MPa at the age of 28 days cured at ambient condition. Further, flexural strength and split tensile strengths for M60 grade high strength geo-polymer concrete at 28 days were observed to be 5.45 MPa and 3.63 MPa respectively. The modulus of elasticity was higher than the theoretical value proposed by IS 456-2000. It was also observed that the load carrying capacity of M60 grade high strength geo-polymer concrete found to be more than corresponding grade conventional concrete. The load-deflection, moment-curvature relationships were studied. The experimental results were encouraging to continue for further research in the area high strength geo-polymer concrete.
IMPACT OF INTRODUCING SEMI-RIGID MOMENT FRAMES ON SEISMIC RESPONSE OF BRACED FRAMES
Authors: Faytarouni Mahmoud , Seker Onur , Akbas Bulent , Shen Jay
Published: March 2020

Maximum seismic inelastic drift demand in a steel building with braced frames as primary seismic-force-resisting (SFR) system tends to concentrate in few stories without considering inherent participation of designed gravity-force-resisting (GFR) system in actual structural stiffness and strength. The influence of GFR system on stiffness and strength can be taken into account by considering the composite action in beam-to-column shear connections that exist in modern steel building construction to form actual semi-rigid moment-resisting frames. Therefore, modeling semi-rigid moment frames as an equivalent to the GFR system in braced frame buildings could be utilized as a representative to the strength provided by gravity frames. This paper presents a seismic evaluation of a six-story chevron braced frame, with and without semi-rigid moment frame. Four different cases are investigated under a set of ground motions and results are discussed in terms of story drift distribution along the height. The results pointed out that the current findings lay a foundation to conduct further investigation on the seismic performance of braced frames as designed SFR system together with GFR system.
INCREASING THE HEIGHT OF A GUYED STEEL STACK WHICH IS SUPPORTED ON AN INDUTRIAL BUILDING
Authors: Okelo Roman , Russell Bradford
Published: March 2020

The paper studied the rehabilitation and increase in height of an existing 30 ft tall, industrial, guyed steel stack, which was built around 1977. The stack is supported on an industrial building. Stacks are an essential part of the industrial facilities. They allow the discharge of chemical waste gases from industries to the atmosphere, under stringent pollution control guidelines. The height of the stack is increased by 40 ft to comply with the new guidelines. Analytical and numerical simulations were performed using MecaStack software (local model) and SAP2000 V.20 software (global model). Analysis and design are based on the ASME STS-1-2016 standard code. Discontinuity around the manhole at the bottom of the stack is investigated with SAP2000 V.20 finite element software. Results in terms of principle stresses, and Von-Mises stress, were used to prepare recommendations, repair and construction documents for the project.
INFLUENCE OF CURVED WEB CLOSED STEEL SECTIONS IN BRIDGE DESIGN
Authors: Van Staen Gilles , De Backer Hans , Van Bogaert Philippe
Published: March 2020

A bridge is nowadays more than a structure that connects people over an obstacle. When a bridge has to be built in an urban area, either it has to be a landmark or it should blend away in the environment. The use of curved steel panels is one option to obtain these requirements. However, due to a lack of knowledge, engineers end up with a conservative design to implement these structural elements. For that reason, a Finite Element Model is made of a railway bridge, where the outer webs of the main girders have a varying web curvature. Six different models are made and compared. The most important parameters that are compared are the deformations and the stresses in the webs. The study finds that curved webs have an equal or even better behavior than flat webs, even with smaller web thickness. This makes that designers can use curved webs in their design, without needing extra steel to make their design safe.
INVESTIGATION ON THE EFFECT OF COUNTERMEASURES FOR SUBSIDENCE AT THE APPROACHING AREAS OF ABUTMENTS
Authors: Kajita Yukihide , Onoda Kazuki , Matsuda Taiji , Uno Kunihiko , Kitahara Takeshi
Published: March 2020

The purpose of this study is to confirm the effect of soil improvement methods on preventing ground subsidence at the back of abutments. Earthquake seismic analysis is performed for three models. One is a model with no ground improvement. Next is a model with deep mixing method. The third is the model with lightweight banking method. As a result, from the perspective of the passage possibility of the emergency vehicles, both the deep mixing method and lightweight banking method are effective in preventing ground subsidence at the approaching area of abutments. However, in the case of the deep mixing method, it is found that the maximum bending moment of the pile under the liquefaction layer increases because a lump of improved rigid soil that falls down toward the piles.
The Important Role of the Designer
Authors: Carp Belinda
Published: March 2020

This was the sound advice given by British designer Vivienne Westwood, when she was asked in 2018 about ethical and environmental issues in the fashion industry. It remains equally valid in 2020 and will continue to be the ethical code by which we should shop in the future. People in
the textile and apparel industry are well aware of their responsibility to create a more sustainable supply chain, to reduce waste in production processes, and to recycle materials whenever possible. And much of the responsibility for these activities starts with the design team—groups
of unsung heroes who have to juggle budgets, logistics, strategic plans, technology, aesthetics, functionality, and so much more. Designing goods for sustainability can mean many things—including: • designing high quality, durable products; • designing products
that can be disassembled easily at their end-of-life, so that the materials and components can be easily recycled; • designing products which are made from organic, biodegradable, reclaimed or recycled materials and components; • designing products which generate a minimal
amount of waste and pollution during their manufacture; • designing products which can be manufactured using machinery that can run on renewable energy, and consume a minimal amount of water; and • choosing manufacturing locations and distribution methods to minimize carbon
emissions.
Economic returns to households participating in different models of commercial tree plantations in Lao PDR
Authors: van der Meer Simo A. , Kanowski P. , Barney K.
Published: March 2020

Four tree plantation models implemented in Lao PDR and a hypothetical model were compared in terms of the projected economic benefits and those realised by participating rural households, and households' attitudes to further plantation expansion. Models comprised two forms of land-sharing
plantation concessions, and contract and independent tree growing. Benefits and costs over the plantation cycle were used to calculate net present values. Tree plantations contributed most to household livelihoods when companies engaged in a participatory land use planning process, where opportunities
for household labour were greatest, and where plantation models allowed for intercropping by households. In contrast, where contracts were not honoured, crops cannot be grown jointly, or labour opportunities are limited, returns were not competitive with traditional swidden agriculture. Households
were generally open to expansion of more beneficial models. These results suggest a set of principles for developing locally appropriate and beneficial tree plantation systems in Lao PDR.