Modal Approach for Decoupling Damage Cost Dependencies in Building Stories
Dependencies between diverse factors involved in probabilistic seismic loss evaluation are recognized to be an imperative issue in acquiring accurate loss estimates. Dependencies among component damage costs have been rarely taken in to account in some conducted researches only considering two partial distinct states of independent or perfectly-dependent for component damage states; however, to our best knowledge, there is no available procedure to take account of loss dependencies in story level. This paper attempts to present a novel method called 'modal cost superposition method' for decoupling story damage costs subjected to earthquake ground motions dealt with closed form differential equations between damage cost and engineering demand parameters which should be solved in complex system considering all stories' cost equations by the means of the introduced 'substituted matrixes of mass and stiffness'. Costs are treated as probabilistic variables with definite statistic factors of median and standard deviation amounts and a presumed probability distribution. To supplement the proposed procedure and also to display straightforwardness of its application, one benchmark study has been conducted. Acceptable compatibility has been proven for the estimated damage costs evaluated by the new proposed modal and also frequently used stochastic approaches for entire building; however, in story level, insufficiency of employing modification factor for incorporating occurrence probability dependencies between stories has been revealed due to discrepant amounts of dependency between damage costs of different stories. Also, more dependency contribution in occurrence probability of loss could be concluded regarding to more compatibility of loss results in higher stories than the lower ones. Whereas, reduction in incorporation portion of cost modes provides acceptable level of accuracy and gets away from time consuming calculations including some limited number of cost modes in high mode situation.
Valorization of Sand Dredging in a Sand Concrete
This article presents the results of a study on the properties of sand concrete based sand dredging. Our goal consists to valorise the sand dredging considered as an inert waste by replacing a part of coarse aggregate of usual concrete to establish a concrete standard for the class environmental moist with moderately frost. The phase of characterization of all components showed that the percentage of fines in the dredged sand does not exceed 1%. For this purpose, in order to remain competitive to normal concrete in terms of proportion of cement and make up a deficit of fin aggregate in the concrete.
Several additions have been selected and studied to find the one that offers the best mechanical performance. The experimental results show that the ground glassy blast-furnace slag offers a correct workability and a satisfactory mechanical strength.
Some Examples of Concrete Achievements and Experiments of Reusing Dredged Sediment in Civil Engineering
Nord Pas de Calais is one of the French regions that records a large volume of dredged sediment in harbors and waterways. To ensure navigation within ports and waterways, harbor and river managers are forced to find solutions to remove sediment that contamination levels exceed levels established by regulations. Therefore, this non- submersible sediment must be managed on land and will be subject to the waste regulation. In this paper, some examples of concrete achievements and experiments of reusing dredged sediment in civil engineering and sector will be illustrated. These achievements are alternative solutions to sediment landfilling and guarantee the reuse of this material in a logic of circular economy and ecological transition. It permits to preserve the natural resources increasingly scarce and resolve issues related to the accumulation of sediments in the harbor basins, rivers, dams, and lakes, etc. Examples of beneficial use of dredged material illustrated in this paper are the result of different projects reusing harbor and waterways sediments in several applications. These projects were funded under the national SEDIMATERIAUX approach. Thus the technical and environmental feasibility of the reuse of dredged sediment is demonstrated and verified; the dredged sediment reusing would meet multiple challenges of sustainable development in relation to environmental, economic, social and societal.
Structural Optimization Method for 3D Reinforced Concrete Building Structure with Shear Wall
In this paper, an optimization procedure is applied for 3D Reinforced concrete building structure with shear wall. In the optimization problem, cross sections of beams, columns and shear wall dimensions are considered as design variables and the optimal cross sections can be derived to minimize the total cost of the structure. As for final design application, the most suitable sections are selected to satisfy ACI 318-14 code provision based on static linear analysis. The validity of the proposed method is examined through numerical example of 15 storied 3D RC building with shear wall. This optimization method is expected to assist in providing a useful reference in design early stage, and to be an effective and powerful tool for structural design of RC shear wall structures.
Seismicity and Ground Response Analysis for MP Tourism Office in Indore, India
In the last few years, it has been observed that earthquake is proving a threat to the scientist across the world. With a large number of earthquakes occurring in day to day life, the threat to life and property has increased manifolds which call for an urgent attention of all the researchers globally to carry out the research in the field of Earthquake Engineering. Any hazard related to the earthquake and seismicity is considered to be seismic hazards. The common forms of seismic hazards are Ground Shaking, Structure Damage, Structural Hazards, Liquefaction, Landslides, Tsunami to name a few. Among all the natural hazards, the most devastating and damaging is the earthquake as all other hazards are triggered only after the occurrence of an earthquake. In order to quantify and estimate the seismicity and seismic hazards, many methods and approaches have been proposed in the past few years. Such approaches are Mathematical, Conventional and Computational. Convex Set Theory, Empirical Green’s Function are some of the Mathematical Approaches whereas the Deterministic and Probabilistic Approaches are the Conventional Approach for the estimation of the seismic Hazards. Ground response and Ground Shaking of a particular area or region plays an important role in the damage caused due to the earthquake. In this paper, seismic study using Deterministic Approach and 1 D Ground Response Analysis has been carried out for Madhya Pradesh Tourism Office in Indore Region in Madhya Pradesh in Central India. Indore lies in the seismic zone III (IS: 1893, 2002) in the Seismic Zoning map of India. There are various faults and lineament in this area and Narmada Some Fault and Gavilgadh fault are the active sources of earthquake in the study area. Deepsoil v6.1.7 has been used to perform the 1 D Linear Ground Response Analysis for the study area. The Peak Ground Acceleration (PGA) of the city ranges from 0.1g to 0.56g.
Application of Multiwall Carbon Nanotubes with Anionic Surfactant to Cement Paste
The discovery of the carbon nanotubes (CNT), has led to a breakthrough in the material engineering. The CNT is characterized by very large surface area, very high Young's modulus (about 2 TPa), unmatched durability, high tensile strength (about 50 GPa) and bending strength. Their diameter usually oscillates in the range from 1 to 100 nm, and the length from 10 nm to 10-2 m. The relatively new approach is the CNT’s application in the concrete technology. The biggest problem in the use of the CNT to cement composites is their uneven dispersion and low adhesion to the cement paste. Putting the nanotubes alone into the cement matrix does not produce any effect because they tend to agglomerate, due to their large surface area. Most often, the CNT is used as an aqueous suspension in the presence of a surfactant that has previously been sonicated. The paper presents the results of investigations of the basic physical properties (apparent density, shrinkage) and mechanical properties (compression and tensile strength) of cement paste with the addition of the multiwall carbon nanotubes (MWCNT). The studies were carried out on four series of specimens (made of two different Portland Cement). Within each series, samples were made with three w/c ratios – 0.4, 0.5, 0.6 (water/cement). Two series were an unmodified cement matrix. In the remaining two series, the MWCNT was added in amount of 0.1% by cement’s weight. The MWCNT was used as an aqueous dispersion in the presence of a surfactant – SDS – sodium dodecyl sulfate (C₁₂H₂₅OSO₂ONa). So prepared aqueous solution was sonicated for 30 minutes. Then the MWCNT aqueous dispersion and cement were mixed using a mechanical stirrer. The parameters were tested after 28 days of maturation. Additionally, the change of these parameters was determined after samples temperature loading at 250°C for 4 hours (thermal shock). Measurement of the apparent density indicated that cement paste with the MWCNT addition was about 30% lighter than conventional cement matrix. This is due to the fact that the use of the MWCNT water dispersion in the presence of surfactant in the form of SDS resulted in the formation of air pores, which were trapped in the volume of the material. SDS as an anionic surfactant exhibits characteristics specific to blowing agents – gaseous and foaming substances. Because of the increased porosity of the cement paste with the MWCNT, they have obtained lower compressive and tensile strengths compared to the cement paste without additive. It has been observed, however, that the smallest decreases in the compressive and tensile strength after exposure to the elevated temperature achieved samples with the MWCNT. The MWCNT (well dispersed in the cement matrix) can form bridges between hydrates in a nanoscale of the material’s structure. Thus, this may result in an increase in the coherent cohesion of the cement material subjected to a thermal shock. The obtained material could be used for the production of an aerated concrete or using lightweight aggregates for the production of a lightweight concrete.
FEM and Experimental Studies on the Concrete Filled Steel I-Girder Bridge
Steel/concrete composite bridge with the concrete filled steel I-girder (CFIG) was proposed, and the bending and shear strength was studied by experiments and FEM analysis. The area surrounded by the upper and lower flanges and the web is filled with concrete in CFIG, which is used at the intermediate support of a continuous girder. The bending and shear tests of the CFIG were carried out, showing that the bending strength of CFIG was 2.8 times of the conventional steel I-girder and the shear strength was 3.0 times of the steel I-girder. Finite element models were established to clarify bending and shear behaviors and the load transfer mechanism of CFIG. FEM result agreed very well with the test results. The FEM model was also applied to simulate the shear tests of the CFIG specimens. A trail design was carried out for a four-span continuous highway bridge and the design method was established.
Using Recycled Wastes (Glass Powder) as Partially Replacement for Cement
Lately, with the environmental changes, enthusiasts trigger to stop the contamination of environment. Thus, various efforts were exerted for innovating environmental friendly concrete to sustain as a ‘Green Building’ material. Green building materials consider the cement industry as one of the most sources of air pollutant with high rate of carbon dioxide (CO₂) emissions. Several methods were developed to extensively reduce the influence of cement industry on environment. These methods such as using supplementary cementitious material or improving the cement manufacturing process are still under investigation. However, with the presence of recycled wastes from construction and finishing materials, the use of supplementary cementitious materials seems to provide an economic solution. Furthermore, it improves the mechanical properties of cement paste, in addition to; it modulates the workability and durability of concrete. In this paper, the glass powder was considered to be used as partial replacement of cement. This study provided the mechanical influence for using the glass powder as partial replacement of cement. In addition, it examines the microstructure of cement mortar using scanning electron microscope and X-ray diffraction. The cement in concrete is replaced by waste glass powder in steps of 5%, 10%, 15%, 20% and 25% by weight of cement and its effects on compressive and flexure strength were determined after 7 and 28 days. It was found that the 5% glass powder replacement increased the 7 days compressive strength by 20.5%, however, there was no increase in compressive strength after 28 days; which means that the glass powder did not react in the cement mortar due to its amorphous nature on the long run, and it can act as fine aggregate better that cement replacement. As well as, the 5% and 10% glass powder replacement increased the 28 days flexural strength by 46.9%. SEM micrographs showed very dense matrix for the optimum specimen compared to control specimen as well; some glass particles were clearly observed. High counts of silica were optimized from XRD while amorphous materials such as calcium silicate cannot be directly detected.
Laboratory Investigations on the Utilization of Recycled Construction Aggregates in Asphalt Mixtures
Road networks are increasingly expanding all over the world. Over the past decades, the buoyant economy, growing population and increasing freight volumes have created high demand for new road pavements as well as the maintenance of current road networks. The construction and maintenance of the road pavements require large amounts of aggregates. Due to considerable usage of various natural aggregates for constructing roads, these materials have started to deplete gradually. At the same time, the rate at which solid waste is generated in the society is increasing with the population growth, with the changes in the people life style, and with the changes in the technology. The management of solid wastes has become an acute problem due to enhanced economic activities and rapid urbanization. These challenges have attracted the attention of many researchers in the pavement industry to investigate the feasibility of the application of some of the waste materials as alternative materials in pavement construction. Among various waste materials, construction and demolition wastes, including Recycled Construction Aggregate (RCA) constitute a major part of the municipal solid wastes in Australia. Using RCA in asphalt mixtures conserves natural aggregates, reduces the impact on landfills, decreases energy consumption, can provide cost savings, and generally results in significant economic and environmental benefits. Accordingly, creating opportunities for the application of RCA in civil and geotechnical engineering applications is another way to increase the market value of RCA. However, in spite of such promising potentials, insufficient and inconclusive data and information on the engineering properties of RCA had limited the reliability and design specifications of RCA to date. It is therefore suggested here that further and comprehensive research is required to evaluate the physical and mechanical properties of RCA to provide a thorough understanding of RCA properties. In light of this, this paper, as a first step of a comprehensive research, aims to investigate the feasibility of the application of waste materials in asphalt mixtures, including RCA obtained from construction and demolition wastes, as a recycled material for the replacement of part of coarse aggregates.Since aggregates typically make up 90% to 95% by mass of asphalt mixes, they provide a substantial proportion of the load bearing capacity of the asphalt mixtures, and hence their type and properties play an important role in the performance of asphalt mixtures. As the suitability of aggregates for using in asphalt mixtures is determined based on the aggregate characteristics, including physical and mechanical properties of the aggregates, an experimental program is set up to evaluate the physical and mechanical properties of RCA. This laboratory investigation included the measurement of compressive strength and workability of RCA, particle shape, water absorption, flakiness index, crushing value, deleterious materials and weak particles, wet/dry strength variation, and particle density. In addition, the comparison of RCA properties with virgin aggregates has been included as part of this investigation and this paper presents the results of these investigations on RCA, basalt, and the mix of RCA/basalt.
Thermal Behavior of Green Roof: Case Study at Seoul National University Retentive Green Roof
There has been major concern about urban heating as urban clusters emerge and population migration from rural to urban areas continues. Green roof has been one of the main practice for urban heat island mitigation for the past decades, thus, this study was conducted to predict the cooling potential of retentive green roof in mitigating urban heat island. Retentive green roof was developed by Han in 2010. It has 320 mm height of retention wall surrounding the vegetation and 65mm depth of retention board underneath the soil, while most conventional green roof doesn’t have any retention wall and only maximum of 25 mm depth of drainage board. Seoul National University retentive green roof significantly reduced sensible heat movement towards the air by 0.5 kWh/m2, and highly enhanced the evaporation process as much as 0.5 – 5.4 kg/m2 which equals to 0.3 – 3.6 kWh/m2 of latent heat flux. These results indicate that with design enhancement, serving as a viable alternate for conventional green roof, retentive green roof contributes to overcome the limitation of conventional green roof which is the main solution for mitigating urban heat island.
Structural Health Monitoring Method Using Stresses Occurring on Bridge Bearings under Temperature
Functions of movable bearings are deteriorated by corrosion. Then the bending moments are generated by the horizontal reaction forces and the heights of girders. In the condition, the authors confirmed the following results by analyses. The tensile stresses due to the moments caused cracks on concrete slabs. The functional declines of bearings could be detected with the changes of strains according to temperature fluctuations. We also proposed that long-term health monitoring for bearings would be possible by using FBG (Fiber Bragg Grating) sensors and a wireless system.
Design Procedure of Cold Bitumen Emulsion Mixtures
In highways construction, Hot Mix Asphalt (HMA) is used predominantly as a paving material from many years. Around 90 percent of the world road network is laid by flexible pavements. However, there are some restrictions on paving hot mix asphalt such as immoderate greenhouse gas emission, rainy season difficulties, fuel and energy consumption and cost. Therefore, Cold Bitumen Emulsion Mixture (CBEM) is considered an alternative mix to the HMA. CBEM is the popular type of Cold Mix Asphalt (CMA). It is unheated emulsion, aggregate and filler mixtures, which can be prepared and mixed at ambient temperature. This research presents a simple and more practicable design procedure of CBEM and discusses limitations of this design. CBEM is a mixture of bitumen emulsion and aggregates that mixed and produced at ambient temperature. It is relatively easy to produce, but the design procedure that provided by Asphalt Institute (Manual Series 14 (1989)) pose some issues in its practical application.
Layouting for Phase II of New Priok Project Using Adaptive Port Planning Frameworks
The initial masterplan of New Priok in the Port of Tanjung Priok was developed in 2012 is being updated to cater to new developments and new demands. In the new masterplan (2017), Phase II of development will start from 2035-onwards, depending on the future conditions. This study is about creating a robust masterplan for Phase II, which will remain functional under future uncertainties. The methodology applied in this study is scenario-based planning in the framework of Adaptive Port Planning (APP). Scenario-based planning helps to open up the perspective of the future as a horizon of possibilities. The scenarios are built around two major uncertainties in a 2x2 matrix approach. The two major uncertainties for New Priok port are economics and sustainability awareness. The outcome is four plausible scenarios: Green Port, Business As Usual, Moderate Expansion, and No Expansion. Terminal needs in each scenario are analyzed through traffic analysis and identifying the key cargos and commodities. In conclusion, this study gives the wide perspective for Port of Tanjung Priok for the planning Phase II of the development. The port has to realize that uncertainties persevere and are very likely to influence the decision making as to the future layouts. Instead of ignoring uncertainty, the port needs to make the action plans to deal with these uncertainties.
Analyzing of Arch Steel Beams with Pre-Stressed Cables
By day-to-day developed techniques, it is possible to pass through larger openings by using smaller beam-column sections. Parallel to this trend, it is aimed to produce not only smaller but also economical and architecturally more attractive beams. This study aims to explain the structural behavior of arch steel beam reinforced by using post-tension cable. Due to the effect of post-stressed cable, the arch beam load carrying capacity increases and an optimized section in a smaller size can be obtained with a better architectural view. It also allows better mechanical and applicational solutions for buildings. For better understanding the behavior of the reinforced beam, steel beam and arch steel beam with post-tensioned cable are all modeled and analyzed by using SAP2000 Finite element computer program and compared with each other. Also, full scale test specimens were prepared to test for figuring out the structural behavior and compare the results with the computer model results. Test results are very promising. The similarity of the results between the test and computer analysis shows us that there are no extra knowledge and effort of engineer is needed to calculate such beams. The predicted (and proved by tests) beam carrying capacity is 35% higher than the unreinforced beam carrying capacity. Even just three full scale tests were completed, it is seen that the ratio (%35) may be increased ahead by adjusting the cable post-tension force of beams in much smaller sizes.
Key Issues in Transfer Stage of BOT Projects: Experience from China
The build-operate-transfer (BOT) project delivery system has provided effective routes to mobilize private sector funds, innovative technologies, management skills and operational efficiencies for public infrastructure development and have been widely used in China during the last 20 years. Many BOT projects in China will be smoothly transferred to the government in the near future, and the transfer stage which is considered as the last stage must be studied carefully and handled well in order to achieve the overall success of BOT projects. There will be many issues faced by both the public sector and private sector in the transfer stage of BOT projects, including project post-assessment, technology and documents transfer, personal training and staff transition, etc. and sometimes additional legislation is needed for future operation and management of facilities. However, most previous studies focused on the bidding, financing, building and operation stages instead of transfer stage. This research identifies nine key issues in the transfer stage of BOT projects through a comprehensive study on three cases in China, and also the expert interview and expert discussion meetings are held to validate the key issues and give detail analysis. A proposed framework for transfer management is prepared based on the experiences derived and lessons drawn from the case studies and expert interview and discussions, which is expected to improve the transfer management of BOT projects in practice.
Earthquake Hazards in Manipur: Casual Factors and Remedial Measures
Earthquake is a major natural hazard in India. Manipur, located in the North Eastern Region of India, is one of the most affected location in the region due to earthquake since it lies in an area where India and Eurasia tectonic plates meet and fall in Zone V of earthquake hazard, the most severe intensity zone, according to IS Code. Some recent earthquakes recorded are M 6.7 epicentre at Tamenglong (January 4, 2016), M 5.2 epicentre at Churachandpur (February 24, 2017) and most recent M 4.4 epicentre at Thoubal (June 19, 2017). In these recent earthquakes, some houses and buildings were damaged, landslides were occurred. A field study was carried out. The study gives an overview of the various causal factors involved in triggering of earthquake in Manipur. It is found that improper planning, negligences, structural irregularities, poor quality materials, construction of foundation without proper site soil investigation and non-implementation of remedial measures, etc., are possibly the main causal factors for damage in Manipur during earthquake. The study also suggests, though the proper design of structure and foundation along with soil investigation, ground improvement methods, use of modern techniques of construction, counseling with engineer, mass awareness, etc., might be effective solution to control the hazard in many locations. Present study also gives an overview on the analysis pertaining to earthquake in Manipur together with on-going detailed site specific geotechnical investigation.
Scientific Expedition to understand the Crucial Issues of Rapid Lake Expansion and Moraine Dam Instability Phenomena to justify the Lake Lowering Effort of Imja Lake, Khumbu Region of Sagarmatha, Nepal
The research enlightens the various issues of lake expansion and stability of the moraine dam of Imja lake. The Imja lake considered that the world highest altitude lake (5010m from m.s.l.), located in the Khumbu, Sagarmatha region of Nepal (27.90 N and 86.90 E) was reported as one of the fast growing glacier lakes in the Nepal Himalaya. The research explores a common phenomenon of lake expansion and stability issues of moraine dam to justify the necessity of lake lowering efforts if any in future in other glacier lakes in Nepal Himalaya. For this, we have explored the root causes of rapid lake expansion along with crucial factors responsible for the stability of moraine mass. This research helps to understand the structure of moraine dam and the ice, water and moraine interactions to the strength of moraine dam. The nature of permafrost layer and its effects on moraine dam stability is also studied here. The detail Geo-Technical properties of moraine mass of Imja lake gives a clear picture of the strength of the moraine material and their interactions. The stability analysis of the moraine dam under the consideration of strong ground motion of 7.8Mw 2015 Barpak-Gorkha and its major aftershock 7.3Mw Kodari, Sindhupalchowk-Dolakha border, Nepal earthquakes have also been carried out here to understand the necessity of lake lowering efforts. The lake lowering effort was recently done by Nepal Army by constructing an open channel and lowered 3m. And, it is believed that the entire region is now safe due to continuous draining of lake water by 3m. But, this option does not seem adequate to offer a significant risk reduction to downstream communities in this much amount of volume and depth, lowering as in the 75 million cubic meter water impounded with an average depth of 148.9m.
Finite Element -Based Stability Analysis of Roadside Settlements Slopes from Barpak to Yamagaun through Laprak Village of Gorkha, an Epicentral Location after the 7.8Mw 2015 Barpak, Gorkha, Nepal Earthquake
The research employs finite element method to evaluate the stability of roadside settlements slopes from Barpak to Yamagaon through Laprak village of Gorkha, Nepal after the 7.8Mw 2015 Barpak, Gorkha, Nepal earthquake. It includes three major villages of Gorkha, i.e., Barpak, Laprak and Yamagaun that were devastated by 2015 Gorkhas’ earthquake. The road head distance from the Barpak to Laprak and Laprak to Yamagaun are about 14 and 29km respectively. The epicentral distance of main shock of magnitude 7.8 and aftershock of magnitude 6.6 were respectively 7 and 11 kilometers (South-East) far from the Barpak village nearer to Laprak and Yamagaon. It is also believed that the epicenter of the main shock as said until now was not in the Barpak village, it was somewhere near to the Yamagaun village. The chaos that they had experienced during the earthquake in the Yamagaun was much more higher than the Barpak. In this context, we have carried out a detailed study to investigate the stability of Yamagaun settlements slope as a case study, where ground fissures, ground settlement, multiple cracks and toe failures are the most severe. In this regard, the stability issues of existing settlements and proposed road alignment, on the Yamagaon village slope are addressed, which is surrounded by many newly activated landslides. Looking at the importance of this issue, field survey is carried out to understand the behavior of ground fissures and multiple failure characteristics of the slopes. The results suggest that the Yamgaun slope in Profile 2-2, 3-3 and 4-4 are not safe enough for infrastructure development even in the normal soil slope conditions as per 2, 3 and 4 material models; however, the slope seems quite safe for at Profile 1-1 for all 4 material models. The result also indicates that the first three profiles are marginally safe for 2, 3 and 4 material models respectively. The Profile 4-4 is not safe enough for all 4 material models. Thus, Profile 4-4 needs a special care to make the slope stable.
Environmental Potential of Biochar from Wood Biomass Thermochemical Conversion
Soil polluted with hydrocarbons spills is a major global concern today. As a response to this issue, our experimental study tries to put in evidence the option to choose for one environmentally friendly method: use of the biochar, despite to a classical procedure; incineration of contaminated soil. Biochar represents the solid product obtained through the pyrolysis of biomass, its additional use being as an additive intended to improve the quality of the soil. The positive effect of biochar addition to soil is represented by its capacity to adsorb and contain petroleum products within its pores. Taking into consideration the capacity of the biochar to interact with organic contaminants, the purpose of the present study was to experimentally establish the effects of the addition of wooden biomass-derived biochar on a soil contaminated with oil. So, the contaminated soil was amended with biochar (10%) produced by pyrolysis in different operational conditions of the thermochemical process. After 25 days, the concentration of petroleum hydrocarbons from soil treated with biochar was measured. An analytical method as Soxhlet extraction was adopted to estimate the concentrations of total petroleum products (TPH) in the soil samples: This technique was applied to contaminated soil, also to soils remediated by incineration/adding biochar. The treatment of soil using biochar obtained from pyrolysis of the Birchwood led to a considerable decrease in the concentrations of petroleum products. The incineration treatments conducted under experimental stage to clean up the same soil, contaminated with petroleum products, involved specific parameters: temperature of about 600°C, 800°C and 1000°C and treatment time 30 and 60 minutes. The experimental results revealed that the method using biochar has registered values of efficiency up to those of all incineration processes applied for the shortest time.
Flexural Behavior of Composite Hybrid Beam Models Combining Steel Inverted T-Section and Rc Flange
This paper deals with the theoretical and experimental study of shear connection via simple steel reinforcement shear connectors, which are steel reinforcing bars bent into L-shapes, instead of commonly used headed studs. This suggested L-shape connectors are readily available construction material in steel reinforcement. The composite section, therefore, consists of steel inverted T-section being embedded within a lightly reinforced concrete flange at the top slab as a unit. It should be noted that the cross section of these composite models involves steel inverted T-beam, replacing the steel top flange of a standard commonly employed I-beam section. The paper concentrates on the elastic and elastic-plastic behavior of these composite models. Failure modes either by cracking of concrete or shear connection be investigated in details. Elastic and elastoplastic formulas of the composite model have been computed for different locations of NA. Deflection formula has been derived, its value was close to the test value. With a supportive designing curve, this curve is valuable for both designing engineers and researchers. Finally, suggested designing curves and valuable equations will be presented. A check is made between theoretical and experimental outcomes.
Influence of Metakaolin and Various Cements Types on Compressive Strength and Transport Properties of Self - Consolidating Concrete
The self-consolidating concrete (SCC) performance over ordinary concrete is generally related to the ingredients used. In recent years, the role of metakaolin as one of the pozzolanic materials in concrete has been considered by researchers. It can modify various properties of concrete, due to high pozzolanic reactions and also makes a denser microstructure. The objective of this paper is to examine the influence of three type of Portland cement and metakaolin on compressive strength and transport properties of SCC at early ages and up to 90 days. Six concrete mixtures were prepared with three different types of cement and substitution 15% of metakaolin by cement relative. The results show that the highest value of compressive strength was achieved for Portland Slag Cement (PSC) and without any metakaolin at age of 90 days. Conversely, the lowest level of compressive strength at all ages of conservation was obtained for Pozzolanic Portland Cement (PPC) and containing 15% metakaolin. As can be seen in results, compressive strength in SCC containing Portland cement type II with metakaolin is higher compared to that in relative to SCC without metakaolin from 28 days of age. On the other hand, the samples containing PSC and PPC with metakaolin had a lower compressive strength than plain samples. Therefore, it can be concluded that metakaolin has a negative effect on the compressive strength of SCC containing PSC and PPC. In addition, results show that metakaolin has enhanced chloride durability of SCCs and reduced capillary water absorption at 28, 90 days.
Resistance to Sulfuric Acid Attacks of Self-Consolidating Concrete: Effect of Metakaolin and Various Cements Types
Due to their fluidity and simplicity of use, self-compacting concretes (SCCs) have undeniable advantages. In recent years, the role of metakaolin as one of pozzolanic materials in concrete has been considered by researchers. It can modify various properties of concrete, due to high pozzolanic reactions and also makes a denser microstructure. The objective of this paper is to examine the influence of three type of Portland cement and metakaolin on fresh state, compressive strength and sulfuric acid attacks in self-consolidating concrete at early age up to 90 days of curing in lime water. Six concrete mixtures were prepared with three types of different cement as Portland cement type II, Portland Slag Cement (PSC), Pozzolanic Portland Cement (PPC) and 15% substitution of metakaolin by every cement. The results show that the metakaolin admixture increases the viscosity and the demand amount of superplasticizer. According to the compressive strength results, the highest value of compressive strength was achieved for Portland Slag Cement and without any metakaolin at age of 90 days. Conversely, the lowest level of compressive strength at all ages of conservation was obtained for Pozzolanic Portland Cement and containing 15% metakaolin. According to this study, the total substitution of Portland Slag Cement and Pozzolanic Portland Cement by Portland cement type II is beneficial to the increasing in the chemical resistance of the SCC with respect to the sulfuric acid attack. On the other hand, this increase is more noticeable by the use of 15% of metakaolin. Therefore, it can be concluded that metakaolin has a positive effect on the chemical resistance of SCC containing Portland cement type II, Portland Slag Cement and Pozzolanic Portland Cement.
On Strengthening Program of Sixty Years Old Dome Using Carbon Fiber
A reinforced concrete dome-built 60 years ago- of circular shape of diameter of 30 m was in distressed conditions due to adverse weathering effects, such as high temperature, wind, and poor maintenance. It was decided to restore the dome to its full strength for future use. A full material strength and durability check including petrography test were conducted. It was observed that the concrete strength was in acceptable range, while bars were corroded more than 40% to their original configurations. Widespread cracks were almost in every meter square. A strengthening program with filling the cracks by injection method, and carbon fiber layup and wrap was considered. Ultra Sound Pulse Velocity (UPV) test was conducted to observe crack depth. Ground Penetration Radar (GPR) test was conducted to observe internal bar conditions and internal cracks. Finally, a load test was conducted to certify the carbon fiber effectiveness, injection method procedure and overall behavior of dome.
Nondestructive Electrochemical Testing Method for Prestressed Concrete Structures
Prestressed concrete is used a lot in infrastructures such as roads or bridges. However, poor grout filling and steel bar corrosion are currently major issues of prestressed concrete structures. One of the problems with nondestructive corrosion detection of steel in prestressed concrete is a plastic pipe which covers steel bar. The insulative property of pipe makes a nondestructive diagnosis of prestressed concrete structures difficult; therefore a practical technology to detect these defects is necessary for the maintenance of infrastructures. The goal of the research is a development of an electrochemical technique which enables to detect these defects from the surface of prestressed concrete nondestructively. In this paper, empirical testing was conducted to ascertain the applicability of dielectric relaxation measurement to the prestressed concrete diagnosis. Dielectric relaxation measurement is one of the electrochemical techniques to find charge movements at each frequency of electric field and is widely used in various areas as a nondestructive internal inspection method for multilayer composite materials by measuring charge behaviors. Since prestressed concrete is constituted by concrete, grout, plastic pipe, and steel bar, it can be considered as multilayer substances. Therefore dielectric relaxation measurement is adopted in this research. Charges in materials move according to frequencies of an electric field applied by an external power supply, and the charge behaviors determine a dielectric and a conductive characteristics of the composite material and dominate the responses of capacitors which are formed by the charge movements in each interface of materials at each frequency. Therefore, the dielectric relaxation measurement can clarify internal structure of composite materials. Whereas, dielectric relaxation measurement can be applied to any insulative material in theory. For example, in the medical area, microstructure analyses of human body cells are carried out utilizing the dielectric relaxation measurement. In this research, the specimens which contain the buried insulative materials (styrene foam, wire net cage, and a chunk of polyethylene sheet), the specimens having cube cavities at different depths (5cm and 15cm), and the defect-free specimen were fabricated. The dielectric relaxation measurements were conducted from the surface of these specimens using two electrodes as the input and the output electrode. The magnitude of applied electric field was 1V, and the frequency range was from 106Hz to 10-2Hz. The frequency spectrums of dielectric relaxation indices, which relate to amount of charge reactions activated by an electric field, such as electric capacitance, conductance, and susceptance were measured to clarify the determination range and the effects of material configurations on dielectric indices. From the measurement results, the dielectric relaxation measurement is applicable to the insulative material measurement. At the same time, the frequency spectrums of dielectric indices show the difference of the material configuration and the defect depth. This is because the charge mobility reflects the variety of substances and also the measuring frequency of the electric field determines migration length of charges which are under the influence of the electric field. As described above, there is a possibility of the practical application of dielectric relaxation measurement on prestressed concrete diagnosis.
Characterization of Fatigue Damage in Bituminous Concrete Based on Energy Dissipation
Fatigue cracking is one of the most prominent distresses in flexible pavements, as a pavement is subjected to repeated loads of vehicular movement during its service life. Characterization of fatigue cracking has been an extremely researched subject in field of pavement engineering, where numerous attempts have been made to base the fatigue behavior on different theories and approaches. In this study, characterization of fatigue cracking in flexible pavements is done based on principles of dissipation. Bituminous Concrete (BC) is a viscoelastic material, and hence only a part of energy supplied to it during loading is recovered, and rest is dissipated. All the researches done so far on studying the fatigue cracking on dissipation can be classified into three categories – total dissipation approach, rate of change in dissipated energy (RDEC) approach and the pseudo-strain energy dissipation approach. The present study brings out certain limitations in each of these approaches in truly characterizing the fatigue behavior of BC material. The present study also shows that fatigue life of flexible pavements does not depend on mechanical dissipation, as the damage in BC material due to fatigue does not depend on the mechanical dissipation in load cycles. Fatigue tests on bituminous materials are generally carried out in one of the two modes of loading – stress (or load) controlled and strain (or displacement) controlled. The most common equipment used for fatigue tests is the four-point beam bending equipment. In this research, fatigue tests were conducted in Asphalt Mixture Performance Tester (AMPT) in direct dynamic tensile mode. Analysis of preliminary tests conducted on samples in displacement-controlled mode reveals that the RDEC approach and the approach using study of drop in dynamic modulus do not give matching results in all cases. The present research also shows how the pseudo-strain dissipation is not equal to dissipation due to fatigue fracture and hence, pseudo strain dissipation is not the true indicator of fatigue damage or fracture in bituminous materials, as claimed in many previous studies. Dissipation of energy takes place in the BC samples when subjected to cyclic loadings. The total dissipation in the material is the sum of the dissipation due to viscoelastic nature of the material and the dissipation due to fatigue cracking that takes place. This study proposes a methodology to differentiate the total dissipation and the dissipation due to fatigue cracking in a material under loading. In fact, both the types of dissipations have been calculated distinctly in all the tests conducted in this study. It is shown that the dissipation due to fatigue cracking is the actual indicator of the accumulation of fatigue cracking in the material. The findings of this study attempt to refine the theories of energy dissipations showing the effect of viscoelastic parameters on fatigue damage. It can serve as fundamental base for more researches in the field of fatigue characterization in flexible pavements.
Electrical Tortuosity across Electrokinetically Remediated Soils
Electrokinetic remediation is one of the most influential and effective methods to decontaminate contaminated soils. Electroosmosis and electromigration are the processes of electrochemical extraction of contaminants from soils. The driving force that causes removing contaminants from soils (electroosmosis process or electromigration process) is voltage gradient. Therefore, the electric field distribution throughout the soil domain is extremely important to investigate and to determine the factors that help to establish a uniform electric field distribution in order to make the clean-up process work properly and efficiently. In this study, small-sized passive electrodes (made of graphite) were placed at predetermined locations within the soil specimen, and the voltage drop between these passive electrodes was measured in order to observe the electrical distribution throughout the tested soil specimens. The electrokinetic test was conducted on two types of soils; a sandy soil and a clayey soil. The electrical distribution throughout the soil domain was conducted with different tests properties; and the electrical field distribution was observed in three-dimensional pattern in order to establish the electrical distribution within the soil domain. The effects of density, applied voltages, and degree of saturation on the electrical distribution within the remediated soil were investigated. The distribution of the moisture content, concentration of the sodium ions, and the concentration of the calcium ions were determined and established in three-dimensional scheme. The study has shown that the electrical conductivity within soil domain depends on the moisture content and concentration of electrolytes present in the pore fluid. The distribution of the electrical field in the saturated soil was found not be affected by its density. The study has also shown that high voltage gradient leads to non-uniform electric field distribution within the electroremediated soil. Very importantly, it was found that even when the electric field distribution is uniform globally (i.e. between the passive electrodes), local non-uniformity could be established within the remediated soil mass. Cracks or air gaps formed due to temperature rise (because of electric flow in low conductivity regions) promotes electrical tortuosity. Thus, fracturing or cracking formed in the remediated soil mass causes disconnection of electric current and hence, no removal of contaminant occur within these areas.
Electrokinetic Remediation of Nickel Contaminated Clayey Soils
Electrokinetic remediation of contaminated soils has undoubtedly proven to be one of the most efficient techniques used to clean up soils contaminated with polar contaminants (such as heavy metals) and nonpolar organic contaminants. It can efficiently be used to clean up low permeability mud, wastewater, electroplating wastes, sludge, and marine dredging. EK processes have proved to be superior to other conventional methods, such as the pump and treat, and soil washing, since these methods are ineffective in such cases. This paper describes the use of electrokinetic remediation to clean up soils contaminated with nickel. Open cells, as well as advanced cylindrical cells, were used to perform electrokinetic experiments. Azraq green clay (low permeability soil, taken from the east part of Jordan) was used for the experiments. The clayey soil was spiked with 500 ppm of nickel. The EK experiments were conducted under direct current of 80 mA and 50 mA. Chelating agents (NaEDTA), disodium ethylene diamine-tetra-ascetic acid was used to enhance the electroremediation processes. The effect of carbonates presence in soils was, also, investigated by use of sodium carbonate. pH changes in the anode and the cathode compartments were controlled by using buffer solutions. The results showed that the average removal efficiency was 64%, for the Nickel spiked saturated clayey soil.Experiment results have shown that carbonates retarded the remediation process of nickel contaminated soils. Na-EDTA effectively enhanced the decontamination process, with removal efficiency increased from 64% without using the NaEDTA to over 90% after using Na-EDTA.
The Development of a Low Carbon Cementitious Material Produced from Cement, Ground Granulated Blast Furnace Slag and High Calcium Fly Ash
This research represents experimental work for investigation of the influence of utilising Ground Granulated Blast Furnace Slag (GGBS) and High Calcium Fly Ash (HCFA) as a partial replacement for Ordinary Portland Cement (OPC) and produce a low carbon cementitious material with comparable compressive strength to OPC. Firstly, GGBS was used as a partial replacement to OPC to produce a binary blended cementitious material (BBCM); the replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of OPC. The optimum BBCM was mixed with HCFA to produce a ternary blended cementitious material (TBCM). The replacements were 0, 10, 15, 20, 25, 30, 35, 40, 45 and 50% by the dry mass of BBCM. The compressive strength at ages of 7 and 28 days was utilised for assessing the performance of the test specimens in comparison to the reference mixture using 100% OPC as a binder. The results showed that the optimum BBCM was the mix produced from 25% GGBS and 75% OPC with compressive strength of 32.2 MPa at the age of 28 days. In addition, the results of the TBCM have shown that the addition of 10, 15, 20 and 25% of HCFA to the optimum BBCM improved the compressive strength by 22.7, 11.3, 5.2 and 2.1% respectively at 28 days. However, the replacement of optimum BBCM with more than 25% HCFA have showed a gradual drop in the compressive strength in comparison to the control mix. TBCM with 25% HCFA was considered to be the optimum as it showed better compressive strength than the control mix and at the same time reduced the amount of cement to 56%. Reducing the cement content to 56% will contribute to decrease the cost of construction materials, provide better compressive strength and also reduce the CO2 emissions into the atmosphere.
Durability Transport and Mechanical Properties of Steam Cured Lightweight Concrete Made with Fly Ash Aggregate
In this paper, effect of steam curing on the compressive strength, rapid chloride ion permeability, and gas permeability of lightweight concrete made with fly ash aggregate was researched. From the total of six mixtures ten of them were replaced with a certain percentage by LWFA and containing Portland cement (PC) with amount of 450 kg/m³ and with a constant water/binder ratio of 0.35. The mixture, concrete samples were exposed to steam cured at 70°C maximum temperature over 17 h curing period. Test results revealed that steam curing enhanced the compressive strength at early age while leading to reduced long-term strength in line with earlier findings. At the end of the chloride ion permeability, and gas permeability tests, it was found that the steam cured concretes had higher chloride ion permeability and gas permeability values. Use of LWFA material extremely increased the value of chloride ion permeability, and gas permeability of concretes.
A Methodology of Testing Beam to Column Connection under Lateral Impact Load
Beam to column connection can be considered as the most important structural part that affects the response of buildings to progressive collapse. However, many studies were conducted to investigate the beam to column connection under accidental loads such as fire, blast and impact load to investigate the connection response. The study is a part of a PhD plan to investigate different types of connections under lateral impact load. The conventional test setups, such as cruciform setup, were designed to apply shear forces and bending moment on the connection, whilst, in the lateral impact case, the connection is subjected to combined tension and moment. Hence, a review is presented to introduce the previous test setup that is used to investigate the connection behaviour. Then, the design and fabrication of the novel test setup is presented. Finally, some trial test results to investigate the efficiency of the proposed setup are discussed. The final results indicate that the setup was efficient in terms of the simplicity and strength.