Excellence in Research and Innovation for Humanity

International Science Index

Commenced in January 1999 Frequency: Monthly Edition: International Abstract Count: 48522

Structural and Construction Engineering

221
83350
Finite Element Analysis of Cold Formed Steel Screwed Connections
Abstract:
Steel Structures are commonly used for rapid erections and multistory constructions due to its inherent advantages. However, the high accuracy required in detailing and heavier sections, make it difficult to erect in place and transport. Cold Formed steel which are specially made by reducing carbon and other alloys are used nowadays to make thin-walled structures. Various types of connections are being reported as well as practiced for the thin-walled members such as bolting, riveting, welding and other mechanical connections. Commonly self-drilling screw connections are used for cold-formed purlin sheeting connection. In this paper an attempt is made to develop a moment resting frame which can be rapidly and remotely constructed with thin walled sections and self-drilling screws. Semi-rigid Moment connections are developed with Rectangular thin-walled tubes and the screws. The Finite Element Analysis programme ABAQUS is used for modelling the screwed connections. The various modelling procedures for simulating the connection behavior such as tie-constraint model, oriented spring model and solid interaction modelling are compared and are critically reviewed. From the experimental validations the solid-interaction modelling identified to be the most accurate one and are used for predicting the connection behaviors. From the finite element analysis, hysteresis curves and the modes of failure were identified. Parametric studies were done on the connection model to optimize the connection configurations to get desired connection characteristics.
Digital Article Identifier (DAI):
220
83189
Non-Linear Static Analysis of Screwed Moment Connections in Cold-Formed Steel Frames
Abstract:
Cold-formed steel frames are preferable for framed constructions due to its low seismic weights and results into low seismic forces, but on the contrary, significant lateral deflections are expected under seismic/wind loading. The various factors affecting the lateral stiffness of steel frames are the stiffness of connections, beams and columns. So, by increasing the stiffness of beam, column and making the connections rigid will enhance the lateral stiffness. The present study focused on Structural elements made of rectangular hollow sections and fastened with screwed in-plane moment connections for the building frames. The self-drilling screws can be easily drilled on either side of the connection area with the help of gusset plates. The strength of screwed connections can be made 1.2 times the connecting elements. However, achieving high stiffness in connections is also a challenging job. Hence in addition to beam and column stiffness’s the connection stiffness are also going to be a governing parameter in the lateral deflections of the frames. SAP 2000 Non-linear static analysis has been planned to study the seismic behavior of steel frames. The SAP model will be consisting of nonlinear spring model for the connection to account the semi-rigid connections and the nonlinear hinges will be assigned for beam and column sections according to FEMA 273 guidelines. The reliable spring and hinge parameters will be assigned based on an experimental and analytical database. The non-linear static analysis is mainly focused on the identification of various hinge formations and the estimation of lateral deflection and these will contribute as an inputs for the direct displacement-based Seismic design. The research output from this study are the modelling techniques and suitable design guidelines for the performance-based seismic design of cold-formed steel frames.
Digital Article Identifier (DAI):
219
83153
Steel Concrete Composite Bridge: Modelling Approach and Analysis
Abstract:
India being vast in area and population with great scope of international business, roadways and railways network connection within the country is expected to have a big growth. There are numerous rail-cum-road bridges constructed across many major rivers in India and few are getting very old. So there is more possibility of repairing or coming up with such new bridges in India. Analysis and design of such bridges are practiced through conventional procedure and end up with heavy and uneconomical sections. Such heavy class steel bridges when subjected to high seismic shaking has more chance to fail by stability because the members are too much rigid and stocky rather than being flexible to dissipate the energy. This work is the collective study of the researches done in the truss bridge and steel concrete composite truss bridges presenting the method of analysis, tools for numerical and analytical modeling which evaluates its seismic behaviour and collapse mechanisms. To ascertain the inelastic and nonlinear behaviour of the structure, generally at research level static pushover analysis is adopted. Though the static pushover analysis is now extensively used for the framed steel and concrete buildings to study its lateral action behaviour, those findings by pushover analysis done for the buildings cannot directly be used for the bridges as such, because the bridges have completely a different performance requirement, behaviour and typology as compared to that of the buildings. Long span steel bridges are mostly the truss bridges. Truss bridges being formed by many members and connections, the failure of the system does not happen suddenly with single event or failure of one member. Failure usually initiates from one member and progresses gradually to the next member and so on when subjected to further loading. This kind of progressive collapse of the truss bridge structure is dependent on many factors, in which the live load distribution and span to length ratio are most significant. The ultimate collapse is anyhow by the buckling of the compression members only. For regular bridges, single step pushover analysis gives results closer to that of the non-linear dynamic analysis. But for a complicated bridge like heavy class steel bridge or the skewed bridges or complicated dynamic behaviour bridges, nonlinear analysis capturing the progressive yielding and collapse pattern is mandatory. With the knowledge of the postelastic behaviour of the bridge and advancements in the computational facility, the current level of analysis and design of bridges has moved to state of ascertaining the performance levels of the bridges based on the damage caused by seismic shaking. This is because the buildings performance levels deals much with the life safety and collapse prevention levels, whereas the bridges mostly deal with the extent damages and how quick it can be repaired with or without disturbing the traffic after a strong earthquake event. The paper would compile the wide spectrum of modeling to analysis of the steel concrete composite truss bridges in general.
Digital Article Identifier (DAI):
218
83050
Limit State Assessment of Bridge According to Peak Ground Acceleration
Abstract:
In the past, the criteria and procedures for the design of concrete structures were mainly based on the stresses allowed for structural components. However, although the frequency of earthquakes has increased and the risk has increased recently, it has been difficult to determine the safety factor for earthquakes in the safety assessment of structures based on allowable stresses. Recently, limit state design method has been introduced for reinforced concrete structures, and limit state-based approach has been recognized as a more effective technique for seismic design. Therefore, in this study, the limit state of the bridge, which is a structure requiring higher stability against earthquakes, was evaluated. The finite element program LS-DYNA and twenty ground motion were used for time history analysis. The fracture caused by tensile and compression of the pier were set to the limit state. In the concrete tensile fracture, the limit state arrival rate was 100% at peak ground acceleration 0.4g. In the concrete compression fracture, the limit state arrival rate was 100% at peak ground acceleration 0.2g.
Digital Article Identifier (DAI):
217
82921
Review for Mechanical Tests of Corner Joints on Wooden Windows and Effects to the Stiffness
Abstract:
Corner joints are the weakest part of windows, where the members are connected together. Since the dimensions of the windows started become bigger, the strength requirements for corner joints started to increase as well. Therefore, the aim of this study was to test the samples of corner joints of wooden windows. Moisture content of test specimens was stabilized in the climate chamber. After conditioning, test specimens were loaded in the laboratory conditions onto an universal testing machine and the failure load was measured. Data was recalculated by using goniometric, bending moment and stiffness equation to the stiffness coefficients and the bending moments were investigated. The results showed difference that was observed for the mortise with tenon joint and the dowel joint. This difference was explained by a varied adhesive bond area, which is related to the dimensions of dowels (diameter and length) as well. The bending moments and stiffness ware (except of type of corner joint) also affected by type of used adhesive, type of dowels and wood species.
Digital Article Identifier (DAI):
216
82654
Correction Requirement to AISC Design Guide 31: Case Study of Web Post Buckling Design for Castellated Beams
Abstract:
In the design of Castellated beams (CB), the web post buckling acted by horizontal shear force is one of the important failure modes that have to be considered. It is also a dominant governing mode when design following the AISC 31 design guideline which is just published. However, the equation of the web post buckling given by the guideline is still questionable for most of the engineers. So the purpose of this paper is to study and provide a proposed equation for design the web post buckling with more simplified and convenient to use. The study is also including the improper of the safety factor given by the guideline. The proposed design equation is acquired by regression method based on the results of finite element analysis. An amount of Cellular beam simulated to study is modelled by using shell element, analysis with both geometric and material nonlinearity. The results of the study show that the use of the proposed equation to design the web post buckling in Castellated beams is more simple and precise for computation than the equations provided from the guideline.
Digital Article Identifier (DAI):
215
82564
Owners Perspective on Causes of Delays in Power Transmission Projects
Abstract:
Power transmission (PT) projects are at the very heart of the electric power system and act as an essential link between power generation and distribution. Timely completion of PT projects is therefore crucial to support the growth of any country. Despite the importance, PT projects are undergoing widespread delays worldwide. These delay causes are idiosyncratic and identifying the critical factors responsible for the delays is essential if PT industry professionals are to complete their projects efficiently and within the expected timeframes. This study identifies, categorises and ranks 63 causes of PT project delay under ten major groups using 18 sector expert’s recommendations studied by preliminary questionnaire survey. Based on the experts’ strong suggestions, two new groups are introduced in the questionnaire: sector-specific factors (SSF) and general factors (GF). SSF pertain to delay factors applicable only to the PT projects, while GF represents the shared responsibilities of all parties involved in a project. The study then uses 110 final questionnaire survey from the project owners to rank delay factors using a relative importance index (RII). The results of this analysis reveal that SSF, GF, and external/unavoidable factors are the most critical groups, while the highest ranked delay factors include the right of way (RoW) problems of transmission lines (TL), frequent changes in TL routes, accessibility to TL tower locations, and political interventions. Spearman rank order correlation also reveals that there is a significant interdependencies are exist between the factors in each group. This study concludes with recommendations for how the identified delay factors can be mitigated. The findings are expected to be of substantial benefit to professionals in minimizing time overrun in PT projects, as well as power generation, power distribution, and non-power linear projects worldwide.
Digital Article Identifier (DAI):
214
82497
Characterization and Pozzolanic Activity Index of a Biomass Fly Ash
Abstract:
The environmental concerns of carbon emissions by the energy industry have led to a change in the way energy is generated as the UK moves to a low carbon future. Biomass and co-firing coal and biomass is now considered as the most promising technology and renewable energy source. This paper is a part of ongoing research investigating the use of biomass fly ash generated from biomass power stations as a supplementary cementitious material. The chemical and mineralogical compositions of fly ash were characterized by X-ray Fluorescence (XRF) and X-ray Diffraction (XRD) techniques. The pozzolanic activity index of biomass fly ash mortars with partial replacement of cement at 10%, 17%, and 25% was also investigated and compared with commercial coal fly ash mortars. The XRF results showed that the chemical composition of biomass fly ash is similar to class F fly ash according to American Standard Testing and Materials (ASTM) C618 and satisfies the main chemical compositions requirements of EN450-1 specification. The results also showed that the biomass fly ash can be considered reactive as it contains 85% amorphous phase and its activity index at 28 and 90 days met the EN450-1 specifications. This indicates that the incorporation of biomass fly ash in cement may give similar properties to concrete with coal fly ash.
Digital Article Identifier (DAI):
213
81641
Mechanical Properties of Ancient Timber Structure Based on the Non Destructive Test Method: A Study to Feiyun Building, Shanxi, China
Abstract:
The structural assessment is one of a crucial part for ancient timber structure, in which this phase will be the reference for the maintenance and preservation phase. The mechanical properties of a structure are one of an important component of the structural assessment of building. Feiyun as one of the particular preserved building in China will become one of the Pioneer of Timber Structure Building Assessment. The 3-storey building which is located in Shanxi Province consists of complex ancient timber structure. Due to condition and preservation purpose, assessments (visual inspections, Non-Destructive Test and a Semi Non-Destructive test) were conducted. The stress wave measurement, moisture content analyzer, and the micro-drilling resistance meter data will overview the prediction of Mechanical Properties. As a result, the mechanical properties can be used for the next phase as reference for structural damage solutions.
Digital Article Identifier (DAI):
212
81610
Seismic Behavior of Concrete Filled Steel Tube Reinforced Concrete Column
Abstract:
Pseudo-dynamic test (PDT) method is an advanced seismic test method that combines loading technology with computer technology. Large-scale models or full scale seismic tests can be carried out by using this method. CFST-RC columns are used in civil engineering structures because of their better seismic performance. A CFST-RC column is composed of four CFST limbs which are connected with RC web in longitudinal direction and with steel tube in transverse direction. For this study, a CFST-RC pier is tested under Four different earthquake time histories having scaled PGA of 0.05g. From the experiment acceleration, velocity, displacement and load time histories are observed. The dynamic magnification factors for acceleration due to Elcentro, Chi-Chi, Imperial Valley and Kobe ground motions are observed as 15, 12, 17 and 14 respectively. The natural frequency of the pier is found to be 1.40 Hz. The result shows that this type of pier has excellent static and earthquake resistant properties.
Digital Article Identifier (DAI):
211
81402
Effect the Use of Steel Fibers (Dramix) on Reinforced Concrete Slab
Abstract:
Currently, concrete technology continues to grow and continue to innovate one of them using fibers. Fiber concrete has advantages over non-fiber concrete, among others, strong against the effect of shrinkage, ability to reduce crack, fire resistance, etc. In this study, concrete mix design using the procedures listed on SNI 03-2834-2000. The sample used is a cylinder with a height of 30 cm and a width of 15cm in diameter, which is used for compression and tensile testing, while the slab is 400cm x 100cm x 15cm. The fiber used is steel fiber (dramix), with the addition of 2/3 of the thickness of the slabs. The charging is done using a two-point loading. From the result of the research, it is found that the loading of non-fiber slab (0%) of the initial crack is the maximum crack that has passed the maximum crack allowed with a crack width of 1.3 mm with a loading of 1160 kg. The initial crack with the largest load is found on the 1% fiber mixed slab, with the initial crack also being a maximum crack of 0.5mm which also has exceeded the required maximum crack. In the 4% slab the initial crack of 0.1 mm is a minimal initial crack with a load greater than the load of a non-fiber (0%) slab by load1200 kg. While the maximum load on the maximum crack according to the applicable maximum crack conditions, on the 5% fiber mixed slab with a crack width of 0.32mm by loading 1250 kg.
Digital Article Identifier (DAI):
210
81370
Integral Abutment Bridge: A Study on Types, Importance, Limitations and Design Guidelines
Abstract:
This paper aims to study in general about bridges without expansion joints. Integral Abutment Bridges (IAB) fall into this category of bridges. They are having a continuous deck and also the girders are integrated into the abutments. They are most cost effective system in terms of construction, maintenance, and longevity. The main advantage of IAB is that it is corrosion resistant since water is not allowed to pass through the structure. The other attractions of integral bridges are its simple and rapid construction, smooth and uninterrupted deck which provides a safe ride. Also damages to the abutments can be avoided to a great extent due to better load distribution at the bridge ends. Damages due to improper drainage are not seen in IAB because of its properly drained approach slabs thus eliminating the possibility of erosion of the abutment backfill and freeze and thaw damage resulting from saturated backfill.
Digital Article Identifier (DAI):
209
80648
Evaluation for Punching Shear Strength of Slab-Column Connections with Ultra High Performance Fiber-Reinforced Concrete Overlay
Abstract:
This paper presents the test results on 5 slab-column connection specimens with UHPFRC overlay including 1 control specimen to investigate retrofitting effect of UHPFRC overlay on the punching shear capacity. The test parameters were the thickness of the UHPFRC overlay and the amount of steel re-bars in it. All specimens failed in punching shear mode with abrupt failure aspect. The test results showed that by adding a thin layer of UHPFRC over the RC substrates, considerable increases in global punching shear resistance up to 82% and structural rigidity were achieved. Furthermore, based on the cracking patterns the composite systems appeared to be governed by two failure modes: 1) diagonal shear failure in RC section and 2) debonding failure at the interface.
Digital Article Identifier (DAI):
208
80617
A Study of Fatigue Life Estimation of a Modular Unmanned Aerial Vehicle by Developing a Structural Health Monitoring System
Abstract:
Unmanned aerial vehicles (UAVs) have now become of predominant importance for various operations, and an immense amount of work is going on in this specific category. The structural stability and life of these UAVs is key factor that should be considered while deploying them to different intelligent operations as their failure leads to loss of sensitive real-time data and cost. This paper presents an applied research on the development of a structural health monitoring system for a UAV designed and fabricated by deploying modular approach. Firstly, a modular UAV has been designed which allows to dismantle and to reassemble the components of the UAV without effecting the whole assembly of UAV. This novel approach makes the vehicle very sustainable and decreases its maintenance cost to a significant value by making possible to replace only the part leading to failure. Then the SHM for the designed architecture of the UAV had been specified as a combination of wings integrated with strain gauges, on-board data logger, bridge circuitry and the ground station. For the research purpose sensors have only been attached to the wings being the most load bearing part and as per analysis was done on ANSYS. On the basis of analysis of the load time spectrum obtained by the data logger during flight, fatigue life of the respective component has been predicted using fracture mechanics techniques of Rain Flow Method and Miner’s Rule. Thus allowing us to monitor the health of a specified component time to time aiding to avoid any failure.
Digital Article Identifier (DAI):
207
80225
Hygrothermal Assessment of Internally Insulated Prefabricated Concrete Wall in Polish Climatic Conditions
Abstract:
Internal insulation of external walls is often problematic due to increased moisture content in the wall and interstitial or surface condensation risk. In this paper, the hygrothermal performance of prefabricated, concrete, large panel, external wall typical for WK70 system, commonly used in Poland in the 70’s, with inside, additional insulation was investigated. Thermal insulation board made out of hygroscopic, natural materials with moisture buffer capacity and EPS board was used as interior insulation. Experience with this natural insulation is rare in Poland. The analysis was performed using WUFI software. First of all the impact of various standard boundary conditions on the behavior of the different wall assemblies was tested. The comparison of results showed that the moisture class according to the EN ISO 13788 lead to too high values of total moisture content in the wall. Given that the boundary condition according to the EN ISO 15026 should be usually applied. Then hygrothermal 1D-simulations were conducted by WUFI Pro for analysis of internally added insulation, and the weak point like the joint of the wall with the concrete ceiling was verified using 2D simulations. Results showed that in the Warsaw climate and the indoor conditions adopted in accordance with PN-EN 15026, in the tested wall assemblies, regardless of the type of interior insulation, there would not be any problems with moisture - inside the structure and on the interior surface.
Digital Article Identifier (DAI):
206
80067
Optimum Design of Dual-Purpose Outriggers in Tall Buildings
Abstract:
In this study, outriggers, which are horizontal structures connecting a building core to distant columns to increase the lateral stiffness of a tall building, are used to reduce differential axial shortening in a tall building. Therefore, the outriggers in tall buildings are used to serve the dual purposes of reducing the lateral displacement and reducing the differential axial shortening. Since the location of the outrigger greatly affects the effectiveness of the outrigger in terms of the lateral displacement at the top of the tall building and the maximum differential axial shortening, the optimum locations of the dual-purpose outriggers can be determined by an optimization method. Because the floors where the outriggers are installed are given as integer numbers, the conventional gradient-based optimization methods cannot be directly used. In this study, a piecewise quadratic interpolation method is used to resolve the integrality requirement posed by the optimum locations of the dual-purpose outriggers. The optimal solutions for the dual-purpose outriggers are searched by linear scalarization which is a popular method for multi-objective optimization problems. It was found that increasing the number of outriggers reduced the maximum lateral displacement and the maximum differential axial shortening. It was also noted that the optimum locations for reducing the lateral displacement and reducing the differential axial shortening were different. Acknowledgment: This research was supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science and ICT (NRF-2017R1A2B4010043) and financially supported by Korea Ministry of Land, Infrastructure and Transport(MOLIT) as U-City Master and Doctor Course Grant Program.
Digital Article Identifier (DAI):
205
80060
The Effect of Heat Treatment on the Corrosion Behavior of Stainless Steel
Abstract:
The work described in this report examines the aqueous corrosion behavior of duplex grades of stainless steel which are used as corrosion resistant castings for applications such as valve and pump bodies. The corrosion behavior of steels in the as-cast condition has been examined using potentiostatic studies to illustrate the need for correct thermal treatment. A metallurgical examination and chemical analysis were carried out to establish the morphology of the steel structure. Optical and scanning electron microscopy examinations confirmed that the austenitic steels will suffer from severe localized interdendritic pitting attack, while highly alloyed duplex steels will give inferior corrosion resistance if castings are not homogenized and solution treated by water quenching before service.
Digital Article Identifier (DAI):
204
80028
Practical Methods to Predict the Actual Completion Date of the Project
Abstract:
One of the most important issues for stakeholders, managers and the entire body of the project is to know the actual completion date of the project. Lack of knowledge of this subject and lack of familiarity with the techniques of estimating the actual completion date of the project, additional to the mistaken decisions made by the project managers and stakeholders, will result in financial and credibility losses for the project implementers. This paper presents some of the most practical techniques for predicting the actual completion date used in construction projects, reviewing the conditions of use, and the strengths and weaknesses of each of the techniques.
Digital Article Identifier (DAI):
203
79730
Performance-Based Design Analysis for Vertical Extension of Residential Structure
Abstract:
There is no reinforcement example for the vertical expansion of existing of structures in Korea. Among these existing structures, the shear wall structures are rare from overseas, while Korea has many shear wall apartment houses. Recently, in Korea, few researchers are trying to confirm the possibility of vertical expansion in existing building with shear walls. This study evaluates the possibility of expansion by applying performance-based seismic design to existing buildings with shear walls in the analysis phase of the structure. In addition, force-based seismic design, used by general structural practitioners in Korea, is carried out to compare the amount of reinforcement of wall, which is the main component of the wall structure. As a result, it suggested that the performance-based design obtain more economical advantages than the force-based seismic design.
Digital Article Identifier (DAI):
202
79186
Influence of Cathodic Protection on High Strength, Pre-Stressed Corroded Tendons
Abstract:
Cathodic protection (CP) is a technique commonly used to arrest corrosion of steel in infrastructure. However, it is not generally used on high strength, pre-stressed tendons due to the risk of hydrogen generation, leading to possible embrittlement. This paper investigates its use in such circumstances where the applied protection potential is varied to determine if CP can be safely employed on pre-stressed tendons. Plain steel tendons measuring 5.4 mm diameter were pre-stressed in timber moulds and embedded in sand/cement mortar, formulated to represent gunite. Two levels of pre-stressing were investigated (400MPa and 1200MPa). Pre-corrosion of 0% (control), 3% and 6% target loss of cross-sectional area was applied to replicate service conditions. Impressed current cathodic protection (ICCP) was then applied to the tendons at two levels of potential to identify any effect on strength. Instant-off values up to -950mV were used for normal protection with values of -1100mV or more negative to achieve overprotection. Following the ICCP phase, the tendons were removed from the mortar, cleaned and weighed to confirm actual percentage of corrosion. Tensile tests were then conducted on the tendons. The preliminary results show the influence of normal levels and overprotection of CP on the ultimate strength of the tendons.
Digital Article Identifier (DAI):
201
79139
Investigation of Light Transmission Characteristics and Co2 Capture Potential of Microalgae Panel Bioreactors for Building Façade Applications
Abstract:
Algae-culture offers new applications in sustainable architecture with its continuous productive cycle, and a potential for high carbon dioxide capture. Microalgae itself has multiple functions such as carbon dioxide fixation, biomass production, oxygen generation and waste water treatment. Incorporating microalgae cultivation processes and systems to building design to utilize this potential is promising. Microalgae cultivation systems, especially closed photo bioreactors can be implemented as components in buildings. And these systems be accommodated in the façade of a building, or in other urban infrastructure in the future. Application microalgae bio-reactors of on building’s façade has the added benefit of acting as an effective insulation system, keeping out the heat of the summer and the chill of the winter. Furthermore, microalgae can give a dynamic appearance with a liquid façade that also works as an adaptive sunshade. Recently, potential of microalgae to use as a building component to reduce net energy demand in buildings becomes a popular topic and innovative design proposals and a handful of pilot applications appeared. Yet there is only a handful of examples in application and even less information on how these systems affect building energy behavior. Further studies on microalgae mostly focused on single application approach targeting either carbon dioxide utilization through biomass production or biofuel production. The main objective of this study is to investigate effects of design parameters of microalgae panel bio-reactors on light transmission characteristics and CO2 capture potential during growth of Nannochloropsis occulata sp. A maximum reduction of 18 ppm in CO2 levels of input air during the experiments with a % light transmission of 14.10, was achieved in 6 day growth cycles. Heat transfer behavior during these cycles was also inspected for possible façade applications.
Digital Article Identifier (DAI):
200
78953
Analysis and Design of Offshore Triceratops under Ultra-Deep Waters
Abstract:
Offshore platforms for ultra-deep waters are form-dominant by design; hybrid systems with large flexibility in horizontal plane and high rigidity in vertical plane are preferred due to functional complexities. Offshore triceratops is relatively a new-generation offshore platform, whose deck is partially isolated from the supporting buoyant legs by ball joints. They allow transfer of partial displacements of buoyant legs to the deck but restrain transfer of rotational response. Buoyant legs are in turn taut-moored to the sea bed using pre-tension tethers. Present study will discuss detailed dynamic analysis and preliminary design of the chosen geometric, which is necessary as a proof of validation for such design applications. A detailed numeric analysis of triceratops at 2400m water depth under random waves is presented. Preliminary design confirms member-level design requirements under various modes of failure. Tether configuration, proposed in the study confirms no pull-out of tethers as stress variation is comparatively lesser than the yield value. Presented study shall aid offshore engineers and contractors to understand suitability of triceratops, in terms of design and dynamic response behaviour.
Digital Article Identifier (DAI):
199
78664
Quantification of Factors Contributing to Wave-In-Deck on Fixed Jacket Platforms
Abstract:
Wave-in-deck phenomenon for fixed jacket platforms at shallow water condition has been reported as a notable risk to the workability and reliability of the platform. Reduction in reservoir pressure, due to the extraction of hydrocarbon for an extended period of time, has caused the occurrence of seabed subsidence. Platform experiencing subsidence promotes reduction of air gaps, which eventually allows the waves to attack the bottom decks. The impact of the wave-in-deck generates additional loads to the structure and therefore increases the values of the moment arms. Higher moment arms trigger instability in terms of overturning, eventually decreases the reserve strength ratio (RSR) values of the structure. The mechanics of wave-in-decks, however, is still not well understood and have not been fully incorporated into the design codes and standards. Hence, it is necessary to revisit the current design codes and standards for platform design optimization. The aim of this study is to evaluate the effects of RSR due to wave-in-deck on four-legged jacket platforms in Malaysia. Base shear values with regards to calibration and modifications of wave characteristics were obtained using SESAM GeniE. Correspondingly, pushover analysis is conducted using USFOS to retrieve the RSR. The effects of the contributing factors i.e. the wave height, wave period and water depth with regards to the RSR and base shear values were analyzed and discussed. This research proposal is important in optimizing the design life of the existing and aging offshore structures. Outcomes of this research are expected to provide a proper evaluation of the wave-in-deck mechanics and in return contribute to the current mitigation strategies in managing the issue.
Digital Article Identifier (DAI):
198
78577
Damage Assessment and Repair for Older Brick Buildings
Authors:
Abstract:
The experience of engineers and architects practicing today is typically limited to current building code requirements and modern construction methods and materials. However, many cities have a mix of new and old buildings with many buildings constructed over one hundred years ago when building codes and construction methods were much different. When a brick building sustains damage, a structural engineer is often hired to determine the cause of damage as well as determine necessary repairs. Forensic studies of dozens of brick buildings show an appreciation of historical building methods and materials is needed to correctly identify the cause of damage and design an appropriate repair. Damage on an older, brick building can be mistakenly attributed to storms or seismic events when the real source of the damage is deficient original construction. Assessing and remediating damaged brickwork on older brick buildings requires an understanding of the original construction, an understanding of older repair methods, and, an understanding of current building code requirements.
Digital Article Identifier (DAI):
197
78324
Influence of Alccofine on Semi-Light Weight Concrete under Accelerated Curing and Conventional Curing Regimes
Abstract:
This paper deals with the performance of semi-light weight concrete, prepared by using wood ash pellets as coarse aggregates which were improved by partial replacement of cement with Alccofine. Wood ash is a tamarind bark combustion product composed of fine particles that falls in the bottom of the modern rice mill dryers. Alccofine is a mineral admixture which contains high glass content obtained through the process of controlled granulation. These cementitious materials are much finer than cement and carries its own pozzolanic property. Therefore, cement could be replaced by Alccofine as 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, and 70% to enhance the strength and durability properties of concrete. High Range Water reducing admixtures (HRWA) was used in these mixes which were dosed up to 1.5% weight of the total cementitious materials content. It also develops the weaker transition zone into more impermeable layer. Specimens were subjected to accelerated curing method as well as conventional curing method. Experimental results were compared and reported that a maximum 28th day compressive strength of 32.6 MPa has achieved at 30% replacement level with a density of 2200 kg/m³ in conventional curing while in accelerated curing, the maximum compressive strength has achieved at 40% replacement level. Rapid chloride penetration test output results of conventional curing method for 0% and 70% gives 3296.7 and 545.6 coulombs.
Digital Article Identifier (DAI):
196
78084
Modelling of Factors Affecting Bond Strength of Fibre Reinforced Polymers Externally Bonded to Timber and Concrete
Abstract:
In recent years, fibre reinforced polymers as applications of strengthening materials have received significant attention by civil engineers and environmentalists because of their excellent characteristics. Currently, these composites have become a mainstream technology for strengthening of infrastructures such as steel, concrete and more recently, timber and masonry structures. However, debonding is identified as the main problem which limits the full utilisation of the FRP material. In this paper, a preliminary analysis of factors affecting bond strength of FRP-to-concrete and timber bonded interface has been conducted. A novel theoretical method through regression analysis has been established to evaluate these factors. Results of proposed model are then assessed with results of pull-out tests, and satisfactory comparisons are achieved when measured failure loads compared against of predicted loads.
Digital Article Identifier (DAI):
195
77884
Cable Supported Facades under Blast Loading
Abstract:
Structural Glass Facades (SGFs) are used in most modern buildings due to their unique architectural aesthetics and energy performance. Cable Supported Facades (CSFs), both cable truss facades and cable net facades are gaining in popularity among the SGFs due to their increased transparency and minimal and highly flexible supporting structures. With the increased threat of terrorist attacks around the world, designers are concerned in making these facades blast resistant for credible blast events as impact of flying glass fragments has been the primary cause of injury during a blast event. Early approaches to designing blast resistant facades identified Laminated Glass (LG) panels as the preferred glass type due to their high energy absorption capacity and the specific interlayer properties. Several design standards were developed for blast resistant design. However, these standards are conservative and less applicable to today’s innovative structural glass façade systems. There has been some recent research on developing methods to design CSFs subjected to blast events. However, most of these studies suggested the use of external devices to mitigate the adverse effects of a blast event on the façade. These developed systems have limitations in application and installation of external devices significantly increases the cost of the façade and the difficulty in construction. There is hence a need to develop a practical CSF system with a blast resisting capacity under credible blast loads. With this in mind, a research project has been undertaken to develop a CSF system without installing any expensive external devices, instead varying the system parameters to create a cost effective and efficient system for a credible blast event. The applications of systems and technology used in innovative wind resisting CSFs are considered for blast applications. Towards this end, this paper investigates the behavior of CSFs under blast loading by a numerical analyses carried out with the finite element models developed using LS DYNA simulation software. Modular units of cable net facades are created in FE code and modelling techniques are validated with existing numerical and experimental data. The behavior of facade elements under a pressure acting on the front face due to unconfined surface burst is evaluated. The material models, element formulations and connections and contact types for the different components of the cable supported façade are confirmed in an iterative manner by investigating different combinations. Finally, a comprehensive numerical model that can be used to analyze the global behavior of a CSF under credible blast pressure is proposed. This model can be used to study the influence of the controlling parameters and thereby to develop an optimized blast resistant CSF.
Digital Article Identifier (DAI):
194
77546
Computational Modeling of Perpendicular to Grain Stress in a Non-Standard Glulam Beam
Abstract:
This paper focuses on the analysis of tensile stresses perpendicular to the grain in simply supported beams with different geometry made of glued laminated timber. Two types of beams are considered: standard double-tapered beams described in Eurocode 5 and non-standard glulam beams with a flattened apex. The beams are analyzed using two methodology approaches: a code design verification method and a finite element method (FEM) in terms of the linear theory of elasticity with plane stress assumption. The performed analyses proved that both methodologies lead to consistent results in case of standard glulam beams and therefore, the FEM can be used in case of non-standard structures, which are not included in Eurocode 5. Moreover, the FE analysis of the glulam beam with a flattened apex showed that it can be treated as a structure with two apex zones.
Digital Article Identifier (DAI):
193
77169
An Overview of Electronic Waste as Aggregate in Concrete
Abstract:
Rapid growth of world population and widespread urbanization has remarkably increased the development of the construction industry which caused a huge demand for sand and gravels. Environmental problems occur when the rate of extraction of sand, gravels, and other materials exceeds the rate of generation of natural resources; therefore, an alternative source is essential to replace the materials used in concrete. Now-a-days, electronic products have become an integral part of daily life which provides more comfort, security, and ease of exchange of information. These electronic waste (E-Waste) materials have serious human health concerns and require extreme care in its disposal to avoid any adverse impacts. Disposal or dumping of these E-Wastes also causes major issues because it is highly complex to handle and often contains highly toxic chemicals such as lead, cadmium, mercury, beryllium, brominates flame retardants (BFRs), polyvinyl chloride (PVC), and phosphorus compounds. Hence, E-Waste can be incorporated in concrete to make a sustainable environment. This paper deals with the composition, preparation, properties, classification of E-Waste. All these processes avoid dumping to landfills whilst conserving natural aggregate resources, and providing a better environmental option. This paper also provides a detailed literature review on the behaviour of concrete with incorporation of E-Wastes. Many research shows the strong possibility of using E-Waste as a substitute of aggregates eventually it reduces the use of natural aggregates in concrete.
Digital Article Identifier (DAI):
192
76164
Studying the Structural Behaviour of RC Beams with Circular Openings of Different Sizes and Locations Using FE Method
Abstract:
<p class="Abstract">This paper aims to investigate the structural behaviour of RC beams with circular openings of different sizes and locations modelled using ABAQUS FEM software. Seven RC beams with the dimensions of 1200 mm&times;150 mm&times;150 mm were tested under three-point loading. Group A consists of three RC beams incorporating circular openings with diameters of 40 mm, 55 mm and 65 mm in the shear zone. However, Group B consists of three RC beams incorporating circular openings with diameters of 40 mm, 55 mm and 65 mm in the flexural zone. The final RC beam did not have any openings, to provide a control beam for comparison. The results show that increasing the diameter of the openings increases the maximum deflection and the ultimate failure load decreases relative to the control beam. In the shear zone, the presence of the openings caused an increase in the maximum deflection ranging between 4% and 22% and a decrease in the ultimate failure load of between 26% and 36% compared to the control beam. However, the presence of the openings in the flexural zone caused an increase in the maximum deflection of between 1.5% and 19.7% and a decrease in the ultimate failure load of between 6% and 13% relative to the control beam. In this study, the optimum location for placing circular openings was found to be in the flexural zone of the beam with a diameter of less than 30% of the depth of the beam.
Digital Article Identifier (DAI):