bluuebunny/crossref_metadata_2025 huggingface dataset:
A Review on Fly Ash-Based Geopolymer Concrete
Authors: Ramin Hosseini Kupaei  , U.Johnson Alengaram  , Mohd Zamin Bin Jumaat
Published: August 2022

Ordinary Portland cement (OPC) is conventionally used as the primary binder to produce concrete. The environmental issues associated with the production of OPC are well known. Binders could be produced by a polymeric reaction of alkaline liquids with the silicon and the aluminium in source materials of geological origin or by-product materials such as fly ash. Low-calcium fly ash-based geopolymer is used as the binder, instead of Portland or other hydraulic cement paste, to produce concrete. The manufacture of geopolymer concrete is carried out using the usual concrete technology methods. As in the case of OPC concrete, the aggregates occupy about 75-80 % by mass, in geopolymer concrete. The silicon and the aluminium in the fly ash react with an alkaline liquid that is a combination of sodium silicate and sodium hydroxide solutions to form the geopolymer paste. Geopolymerisation in fly ash based concrete could be occur by using different solutions with the solution-to-fly ash ratio by mass of 0.25 to 0.30. The best compressive strength will be more than 60 MPa for mixtures that used a combination of sodium hydroxide and sodium silicate solution, after curing the specimens for 24 hours at 65oC. The proportion of alkaline solution to alumino-silicate powder by mass should be approximately 0.33 to allow the geopolymeric reactions to occur. Alkaline solutions forms a thick gel instantaneously upon mixing with the alumino-silicate powder. By the use of the mass ratio of the solution to the powder of about 0.39 and mixing 57% fly ash with 15% kaolin or calcined kaolin and the alkaline liquid comprise 3.5% sodium silicate, 20% water and 4% sodium or potassium hydroxide the maximum compressive strength will be 75 MPa when fly ash and builders’ waste are used as the source material.
Geopolymer Concrete: A Building Material for the Future
Authors: B.A. Al MUHIT  , K.Y.FOONG  , U.J. ALENGARAM  , MOHD. Z. JUMAAT
Published: August 2022

The consumption of Ordinary Portland Cement (OPC) as construction material is one of the main sources of CO2 emission and global warming.. The manufacturing process of ‘clinker’ which is an essential element of cement requires burning of fossil fuels, thus increasing the CO2 emission and decreasing the global stock of fuels. Concept of a novel binding material named ‘Geopolymer’ appeared in the 1940s as a viable solution to these issues. Geopolymer concrete (GPC) is produced from industrial byproducts such as Fly Ash (FA) rich in aluminosilicate, Blast furnace slag (BFS) or natural minerals such as Kaolinite clay using alkalis as activators. In this paper, economical, social and ecological sustainability of GPC have been put forth. Comparison have been made between the behavior of low-calcium fly ash based GPC and metakaolin based GPC under different environmental conditions using alkali activators such as Sodium hydroxide (NaOH) or Potassium hydroxide (KOH) with Sodium silicate (Na2SiO3) . Evolution of GPC, hydration process as opposed to OPC, mechanical properties, structural behavior, alkali-silica resistance (ASR), fire and acid resistance behavior of GPC have also been discussed in this paper.
Research on Recycled Concrete Aggregates at NUS
Authors: C.T Tam  , K.C.G. Ong  , A. Akbarnezhad  , M.H. Zhang
Published: August 2022

Sustainable concrete construction is critical to the economic development of infrastructures. The need and demand for infrastructure development is crucial to economic and social well-being of all nations. Of all the constituents in concrete coarse aggregate forms the biggest volume. As the reserve of aggregates is finite, the availability of suitable recycled concrete aggregate from demolition of concrete structures provides an alternate source to meet the increasing demand of new construction. Research on recycled concreteaggregate (RCA) at NUS was first conducted in the 1980’s. In recent years, further studies cover two main areas. The first is on the technique to improve the quality of recycled coarse concrete aggregate by means of microwave treatment. The other is to develop a modified acid treatment method to fully remove all attached materials from RCA coarse particles. This provides a more reliable basis for determination of the mortar content in RCA thus achieving a more precise relationship between properties of RCA and mortar content. Results on the relationship between 24-hour water absorption, bulk density and Los Angeles abrasion resistance of RCA and mortar content show a higher regression coefficient compared to others in published literature.
Designing Perpetual Energy Harvesting Systems explained with RiverMote: A Wireless Sensor Network Platform for River Monitoring
Authors: Philipp Maria Glatz  , Leander Bernd Hörmann  , Christian Steger  , Reinhold Weiss
Published: August 2022

Wireless Sensor Network (WSN) motes are devices of small form factor. They are tailored to cost-effectiveness for monitoring and control applications. Different optimizations exist for the robust lifetime improvement of such devices, but the community still lacks a clear approach of how to achieve a robust system design that is of low cost and implements low-power optimizations. In particular, it is a demanding task to efficiently utilize energy harvesting system (EHS) technology for WSNs. However, that is the only way for implementing battery-free mote devices for achieving perpetual operation of WSNs. We demonstrate the design methodology that let us implement RiverMote. RiverMote is a case study for designing a low cost hardware system architecture combining low-power mote and a highly efficient EHS architecture. First, we provide a detailed explanation for how to deduce the prototype dimensioning parameters given the application requirements of an energy-autarkic river level monitoring system. Then we show how to select proper energy harvesting device (EHD) technologies and design all EHS stages for fitting the application-depending power state model of the integrated mote. Finally, we implement and evaluate tests of all stages for their energy efficiency as well as RiverMote’s self-measurement accuracy which is crucial for robust perpetual designs.
Analysis of Isotropic Beams Using Method of Initial Functions (MIF)
Authors: Rakesh Patel  , S. K. Dubey  , K. K. Pathak
Published: August 2022

In this paper, method of initial functions (MIF) has been used to analyse the isotropic beams. The method of initial function is an analytical method of elasticity theory. No assumptions regarding the distribution of stress or displacements are needed in this method. This method has applications in various fields of structural engineering such as plates, shells and beams. The equations of two dimensional elasticity have been used for deriving the governing equations. Numerical solutions of the governing equations have been presented for simply supported beam loaded with uniformly distributed load. Two cases with varying depth to span ratio have been considered for analysis and compared the results with the bending theory.
Seismic Behaviour of High-Rise Buildings with Transfer Floors
Authors: A. K. Elawady  , H. O. Okail  , A. A. Abdelrahman  , E.Y. Sayed-Ahmed
Published: August 2022

A comparative analytical study for the seismic response of high-rise buildings with transfer floors is presented. A number of prototype models were analyzed using elastic linear response spectrum and inelastic nonlinear time history techniques using three-dimensional finite element models. The analyzed models had different transfer floor system: transfer slabs and transfer girders. The vertical position of the transfer system with respect to the building height was investigated. Global seismic response of the buildings such as storey shear and bending moment distribution, and inter-storey drift were numerically evaluated. The results showed the localization of damage in the vicinity of the transfer floor in addition to the first floor; the location of the transfer floor influenced the global seismic response of the structure. The numerical analysis revealed that the transfer girders system is a competitive alternative to the slab system in terms of reducing the seismic weights as well as the material cost with a slight change in the global seismic behaviour of the building. Transfer girders system is more flexible compared to slab system and generate lower straining actions on the structural vertical elements.
Shear Response of SFRC Beams Constructed with SCC and Steel Fibers
Authors: Hassan Aoude  , Michael Cohen
Published: August 2022

This paper presents the experimental results from eleven slender beams constructed with highly workable SFRC tested under four-point loading. In the study self-consolidating concrete (SCC) was combined with steel fibers to improve workability and concrete placement. The response of the beams in terms of shear versus deflection response, crack control and damage tolerance is reported. The results demonstrate that the combined use of SCC and steel fibers in shear-deficient beams results in significant improvements in shear resistance and enhancements in flexural ductility. In the second part of the paper a model is proposed for predicting the shear capacity of SFRC beams. The proposed model and various equations proposed in the literature are used to predict the shear capacity of the beams tested in the experimental program. The results demonstrate the need for developing accurate and reliable equations for predicting the shear capacity of SFRC beams constructed with SCC and steel fibers.
A Bayesian Damage Identification Technique Using Evolutionary Algorithms - a Comparative Study
Authors: M. Varmazyar  , Haritos Nick , M. Kirley
Published: August 2022

In this paper, a one-stage model-based damage identification technique based on the response power spectral density of a structure is investigated. The technique uses a finite element updating method with a Bayesian probabilistic framework that considers the uncertainty caused by measurement noise and modelling errors. The efficacy of two different evolutionary algorithms – a genetic algorithm and a covariance matrix adaptation evolution strategy – is examined via numerical simulation of time-history response data for a beam structure. A range of different damage scenarios have been considered including: both single and multiple damage locations; varying damage severity; the introduction of noise and modelling errors and incompleteness in the number of captured modes and measurement response data. The results clearly show that both evolutionary algorithms implemented are effective and their overall performance, measured in terms of accuracy, is very similar. However, the covariance matrix strategy is found to be significantly superior in terms of its convergence rate and the number of function evaluations required to find the solution for both noisy and noise-free response data.
Damage and Seismic Performance Assessment of FRP-Retrofitted Multi-Storey RC Buildings
Authors: S. S. MAHINI
Published: August 2022

Structures should be designed for a long in-service life at the lowest cost. Performance based design (PBD) can be used for damage and performance assessment of older FRP-retrofitted multi-storey RC moment resisting frames (MRFs). PBD can be performed using nonlinear pushover analysis according to current codes. In this paper, performance of an existing/older RC frame that has been retrofitted with steel-braced by other researchers is assessed in order to evaluate the ability of the FRP-web bonded system to upgrade the performance level and ductility of RC MRFs. Initially, the flexural stiffness of FRP-retrofitted exterior and interior joints of each level of an existing RC ordinary moment resisting frame (OMRF) is determined using nonlinear finite element (FE) analysis. The stiffness obtained is then used in a mathematical model for pushover analysis of the FRP-retrofitted frame. The plain and the retrofitted frames (both steel-braced and FRP-retrofitted) are analysed using a nonlinear pushover analysis method. The seismic performances of the retrofitted frames are then compared with the plain frame. Finally, the global damage index of the frames at the performance point (and at the life safety (LS)) are determined from the capacity curves and discussed. This evaluation demonstrates that the damage degree of the frame is reduced after retrofitting particularly by FRP. In addition, the FRP-retrofitted frame has a lower damage index at the LS level.
Dynamic Analysis of Overhead Transmission Line under Turbulent Wind Loading
Authors: Alok Dua  , Mathias Clobes  , Thomas Höbbel
Published: August 2022

This paper compares the dynamic response of a test transmission line with the response due to static loads given by Eurocode. Finite element design software SAP2000 was used to model towers and power-lines. Nonlinear dynamic analysis including the large displacement effects was carried out. Macroscopic aspects of wind coherence along element length and integration time step were investigated. An approach is presented to compare the probabilistic dynamic response due to 7 different stochastically simulated wind fields with the response according to EN-50341. The developed model is used to study the response recorded on a test line due to the actual wind speed time history recorded. It was found that static load as calculated from EN-50341 underestimates the response of conductor cables. The response of coupled system considering towers and cables was found to be different from response of only cables with fixed supports.
Heavy concrete on cement with slag of low-carbon ferrochrome
Authors: Zyryanov, F. A.  , A. B. Bukreev  , O. O. Zyryanova
Published: August 2022

This research work is aimed to determinate a possibility of stabilization of a low-carbon ferrochrome slag into a dry slag and further recycling it into a commercial product. Research was done with petrographic analysis of the structure of the artificial stone. The influence of a commercial product on constructional and technical properties of concrete and concrete mixture was determined according to the requirements of the standards for this product. As the result of the investigations of low-carbon ferrochrome slag the common regularities of formation of minerals of CaO-SiO2-Al2O3-MgO-Cr2O3 system in artificial stone were determined. Depending on the conditions of stabilization, the main minerals, formed during industrial stabilization of slag, and the structure of stabilized slag were studied in detail. The laboratory research was done and as the result new common influence patterns of fine powdered stabilized slag upon the properties of concrete mixes and concrete were reached.
Effect of Plan Area of the Building on Period of Vibration of RC Framed Structures
Authors: P. Sangamnerkar  , S. K. Dubey
Published: August 2022

Fundamental natural period of vibration T of the building is an important parameter for evaluation of seismic base shear. Empirical equations given in the Indian seismic code for the calculation of the fundamental period of a framed structure, primarily as a function of height, and do not consider the effect of stiffness of the structure, base dimensions of the structure, number of panels in both the directions, plan are of the building and amount of infill as well as properties of the infill. The fundamental natural period can be evaluated using simplified expressions found in codes, which are based on earthquake recordings in existing buildings, laboratory tests, numerical or analytical computations. These technical codes provide expressions which depend on basic parameters such as building height or number of stories. Building periods predicted by these expressions are widely used in practice although it has been observed that there is a scope for further improvement in these equations, since the height alone is inadequate to explain period variability. It is also known that the period of a RC frame structure differs depending on whether the longitudinal or transverse direction of the structure is considered. The aim of this study is to find the effects of plan area of the building to predict the fundamental natural period of vibration of reinforced concrete buildings with moment resisting frames (MRF). A few examples of dynamic analysis are presented in this study in order to show that the effect of plan area of the structure in calculating the time period of the structure.
Prediction of Railway Vehicles’ Dynamic Behavior with Machine Learning Algorithms
Authors: N. Nadarajah  , A. Shamdani  , G. Hardie  , W.K.Chiu  , H. Widyastuti
Published: August 2022

The dynamic performance of railway vehicles needs to be carefully monitored to ensure their safe operation. Presently a number of systems such as the Vehicle Track Interaction Monitor and the Instrumented Revenue Vehicles, utilize a number of on-board inertial sensors to obtain near-real time information on the dynamic performance of railway vehicles. These systems provide rich data sets that give an indication of the underlying track condition and the corresponding dynamic response. This paper outlines the use of Machine learning to develop dynamic behavior predictive models for railway vehicles from measured data. This study worked on the development of 2 types of predictive models, viz. regression and classification model. The regression model predicted the time series dynamic response amplitude and the classification model classified the track sections based on the response distribution over it. Train speed and parameters estimated from the unsprung mass were used as predictors in the model. After the trial of a number of predictive models the Ensemble Tree Bagger method was found to have highest overall prediction accuracy. These predictive models can be utilized as a decision making tool to determine safe operational limits and prioritize maintenance interventions.
Water Pipe Condition Assessment Using Submersible Quasi-distributed Optical Fibre based Pressure Transducers
Authors: L. Wong  , R. Deo  , S. Rathnayaka  , B. Shannon  , C. S. Zhang  , J. Kodikara  , W. K. Chiu  , H. Widyastuti
Published: August 2022

Transient based technique is known as one of the most economical ways for pipeline condition assessment. This technique involves monitoring and analysing pressure transient profiles at multiple points in a distributed system. Its application is restricted due to its low spatial resolution (10 m). It is hypothesised that by increasing the number of pressure transducers and reducing the gauge length (distance between the transducers), the spatial resolution of the measurements would highly be improved. However, the deployment of pressure transducers is restricted to the location of the hydrants. In this paper, a submersible quasi-distributed optical fibre based pressure sensors were proposed, constructed and tested in laboratory to verify this concept. For this context, this paper describes the proposed optical device and presents some preliminary analysis and results obtained from a set of experiments. The experimental results show that using the quasi-distributed optical fibre based pressure transducers for pressure transient analysis can potentially detect small anomalies (200 mm) and measure the growth of the anomalies along a water pipe.
Effects of Elevated Temperature Curing on Glass Transition Temperature of Steel/CFRP Joint and Pure Epoxy Adhesive
Authors: Chandrathilaka E.R.K. , Gamage J.C.P.H. , S. Fawzia
Published: August 2022

Glass transition temperature (Tg) of the steel/epoxy/CFRP composite bond can affect the service and fire performance of the system. Two test series were conducted to evaluate the Tg of the pure epoxy adhesive and the steel/epoxy/CFRP bond. A total of twenty-six double strap joints and pure epoxy adhesive samples were prepared under different curing conditions to check the Tg of bond. Six different curing conditions were used. The test results revealed that the elevated temperature curing has a significant affect on the Tg of steel/epoxy/CFRP bond and pure epoxy adhesive. A considerable improvement of Tg was noted in the joint with elevated temperature curing when compare with the epoxy adhesive samples cured under the samecondition. The strength degradation of the bond for a certain temperature exposure is also reduced with increased Tg of the joint.
Experimental and Numerical Investigation of an Eccentrically Loaded Strip Footing on Reinforced Sand Slope
Authors: A. Abdi  , K. Abbeche  , R. Boufarh  , B. Mazouz
Published: August 2022

An experimental program and numerical computations were performed to investigate the slope effect on the bearing capacity of an eccentrically loaded strip footing. Two cases were considered: unreinforced sand slope and reinforced slope by geogrid. Tests were conducted on scaled footing models under various eccentric loads. A parametric study was carried out to examine the effect of the slope on the bearing capacity and the depth of geogrid layers under different eccentric loads. It was shown that the location of the eccentricity of applied load with respect to the slope face has a significant effect on the bearing capacity. This latter increase when the distance from applied eccentric load to the slope face also increases. Obtained results also showed that the bearing capacity of strip footing also depends on the inclination of ground surface in comparison to that predicted from horizontal ground.
Elastic Buckling Loads of Fixed Frames By The Newmark Method
Authors: A. Badir
Published: August 2022

A numerical method for the solution of the elastic stability of fixed frames is presented. The Newmark iterative procedure to perform elastic buckling analyses for isolated columns is extended for use in computing buckling loads and buckling modes in frames with fixed columns. The method is illustrated in details by means of different cases of single-storey portal frames commonly used in commercial buildings. Compari-sons of obtained results with other well known methods show very good agreement.
Study of Landslide Prevention Schemes Options Using Probability Dom-inance Decision-Making Model
Authors: Fei Wang  , Hui Zhang  , Dongjun Li
Published: August 2022

Optimum selections of landslide scheme and scientific treatment are of great theoretical and practical importance to avoid or reduce the unnecessary loss of life and money. In this study, we shall first briefly introduce a Probability Dominance Decision-Making model to evaluate the effectiveness degree of landslide scheme considering the weights of relationship between decision attributes. Firstly, several meas-ured indicators of landslide control (Total Project Investment U1, Construction Difficulty U2, etc.) are selected as key impacting indicators to appraise alternative schemes correctly. Moreover, the attribute values of inter-val information for each landslide scheme is defined, and then the Attribute Dominance Relation is proposed to solve the index weights as well as the problem of unknown attribute weight in landslide control schemes. Next, the attribute weight values are ranked and picked by the dominance index relationship between the de-cision schemes and overall schemes. Simultaneously, this paper analyzed the probability decision making problem of using attribute value as Interval Number. In this procedure, we introduced the detailed derivation and analyzed the same and different points between the proposed model with the Deviation Maximization Al-gorithm. Finally, an example is given to illustrate the effectiveness and feasibility of the model.
Acceptable movements of road embankments
Authors: G.P. Papageorgiou  , N. Alamanis  , N. Xafoulis
Published: August 2022

The stability of slopes and embankments under the influence of static and seismic loads has been the subject of study for many researchers. This paper stands for an attempt to present tolerable move-ments, based on caused damage on slopes of the embankments, as well as to connect them with natural disas-ters of the environment.
Stochastic Finite Fault Modeling and Simulation of Strong Ground Motion of Mosha Fault in Iran
Authors: H. Saffari  , A. Roohafzayan  , A. Mahdavian  , M. Yari
Published: August 2022

This study aims at predicting large earthquakes caused by Mosha fault in Tehran, the capital of Iran with population of more than 13 million people which located alongside active faults. This study uses the EXSIM program to do the finite fault modeling of simulation. Using Geopsy software and programming in MATLAB we evaluated the site effect of 13 station. Using other required parameters of Mosha fault in EXSIM, we gained the artificial strong motions of the stations. Finally, using SeismoSignal and MATLAB software, we depicted the Acceleration -time graph and the semi-logarithm frequency spectrum with “Fourier transform” of each station. we compared the results of the finite fault simulation with Ambraseys attenuation relationship, semi-logarithm frequency spectrum with Fourier transform and spectrum-response graphs of 2009 earthquake in Shahr-e Rey measuring Mw = 4.2. In both cases of comparing meaningful results were found. Finally, in order to generalize the results to the city of Tehran, we evaluated the seismicity using Arc GIS software. The results show that if Mosha fault is activated, east of Tehran is influenced the most. Consequently, it is of high importance to study different ways to reduce the risk of the possible earthquake caused by Mosha fault.
influence of plasterboard clad walls on the structural behaviour of low rise residential buildings
Authors: Y.L. Liew  , Duffield Colin , Emad Gad
Published: August 2022

While the design and technology of conventional low rise light framed residential structures are relatively simple, their response to lateral loading is quite complex. This is due to the high degree of redundancy, the irregular geometry and interaction between the structural and non-structural components. In addition, the designated lateral bracing elements within one structure may exhibit significantly different behaviour due to the different bracing actions and different materials. This paper focuses on the bracing capacity of plasterboard clad walls which could be considered either structural or non-structural. While such walls may be installed purely as partition walls, they may provide lateral strength and stiffness due to the complex load paths. The paper presents in detail the possible load transfer mechanisms to a variety of typical walls. It also highlights the difficulty with performing racking tests on isolated walls due to the complex boundary conditions surrounding walls in real structures. In addition, the paper reports racking test results that demonstrate the effects of different boundary conditions on the load carrying capacity and the failure modes.
Investigation of Joints Behavior in Seismic Response of Arch Dams
Authors: Lotfi V , Espandar Radin
Published: August 2022

There has been extensive research to examine the effects of contraction joints opening in the nonlinear seismic response of arch dams. However, there has been less attention on the effects of perimetral joint on the response. In this study, a special finite element program is developed, that is described and verified initially. Based on this program, the nonlinear dynamic behavior of a typical thin arch dam is studied. The perimetral joint, as well as, contraction joints are included in the nonlinear cases analyzed. It is shown that the distributions of the maximum tensile stresses are very sensitive to the properties used for the joints. Moreover, the modified joint model proposed for the modeling of perimetral joint is found to be less sensitive and very effective in seismic analysis of concrete arch dams.
Nondestructive damage detection in large structures via vibration monitoring
Authors: Sooyong Park  , Yeon-Bok Kim  , Norris Stubbs
Published: August 2022

In this paper Nondestructive Damage Detection (NDD) in large/complex structures is investigated via vibration monitoring of such structures. The theory of NDD for truss type structures is formulated. To examine the feasibility of the theory, a finite element model of a 3-D truss structure, which consists of sixteen bays and includes 246 elements, is developed to simulate damage. Four damage cases are simulated numerically. The cases range from the structure being damaged in one location to the structure being damaged in three locations. Next, the theory is applied to the experimental results of a 1:6 scale model of a typical hexagonal truss. These tests consist of 17 damage scenarios subjected to three different types of damage. The performance of the method on simulating experimental data is evaluated and discussed.
Analysis and shape optimization of variable thickness box girder bridges in curved platform
Authors: M. Özakça  , N. Tayşi
Published: August 2022

This paper deals with the development of reliable and efficient computational tools to analyze and find optimum shapes of box girder bridges in curved planform in which the strain energy or the weight of the structure is minimized subject to certain constrains. The finite strip method is used to determine the stresses and displacements based on Mindlin-Reissner shell theory. An automated analysis and optimization procedure is adopted which integrates finite strip analysis, parametric cubic spline geometry definition, automatic mesh generation, sensitivity analysis and mathematical programming methods. It is concluded that the finite strip method offers an accurate and inexpensive tool for the optimization of box girder bridges having regular prismatic-type geometry with diaphragm ends and in curved planform.
Qualitative & Semi-Quantitative Reasoning Techniques for Engineering Projects at Conceptual Stage
Authors: M. H. Gedig  , S. F. Stiemer
Published: August 2022

During the development of engineering projects, the level of uncertainty is not static. The level of uncertainty typically diminishes from the early, conceptual stages of the project to the latter, detailed stages. At the present time there are many tools available to the engineer for reasoning with relatively low levels of uncertainty. Unfortunately there are few resources available for drawing sound conclusions from information that is characterized by a high level of uncertainty. Since decisions made early in the project cycle generally have a greater financial impact than those made later, it is worthwhile to investigate tools which are able to provide  systematic and logical evaluation of preliminary or conceptual designs. This paper investigates sound techniques for evaluating projects at the early stages, including qualitative reasoning and semi-quantitative reasoning. The paper shows that qualitative analysis methods enable the engineer to reason with a high level of abstraction. As a normal engineering project progresses, more numeric information becomes available, and the results of semi-quantitative reasoning become more useful.
FE Analysis of Complex Discontinuous and Jointed Structural Systems
Authors: A.D. Tzamtzis  , P.G. Asteris
Published: August 2022

In this part, a non-linear 3D finite element model for the analysis of unreinforced masonry walls subjected to static and seismic loads is presented, in order to demonstrate the applicability and potential of the method proposed in Part 1. The work reported here could also stand “on-its-own”, due to the detailed investigation made on this particular subject. The model developed considers masonry as a two-phase material, treating bricks and mortar joints separately, thus allowing for nonlinear deformation characteristics and  progressive local failure of both bricks and mortar joints. The influence of the mortar joints is taken into account by using ‘interface’ elements to simulate the timedependent sliding and separation along the interfaces. Analytical and experimental solutions available in the literature have been employed to verify the results obtained from the present finite element model, showing that it is capable of a high degree of accuracy.
Non-linear analysis of dowelled timber connections: a new approach for embedding modelling
Authors: P. Racher  , J.F. Bocquet
Published: August 2022

A finite element modelling is developed to analyse the behaviour of timber connections taking into account the plastic behaviour of the timber beneath the fasteners. The local non linearities control the stiffness and the load-carrying capacity of the timber joints. It results in interaction effects on the stress states in the timber and the load distribution among the fasteners that can lead to brittle failure modes such as the block shear failure.This paper presents a new approach based on the development of a pseudo three-dimensional model for the timber in the vicinity of the fasteners. According to the observed behaviour, this finite element model was developed to describe the geometrical and  mechanical non-linear behaviours at the micro-scale of the wood beneath the fasteners. Considering the orthotropic behaviour of the timber, the timber around the fasteners is modelled as a structure made up of elementary finite elements. The model accounts also for the friction, the contact and the various irreversible deformations which appear within the timber. An analysis of the embedding behaviour is carried out for three species: spruce, hem-fir and iroko. The comparison of experimental and simulated results shows that this new approach provides a good approximation. An additional sensibility analysis calibrates the model efficiency for coupling the fastener deformation and the timber stresses in the analysis of timber connections.
Equilibrium based evaluation of stress distribution under steel column base plates. I: Governing Equations
Authors: D. S. Sophianopoulos  , P. G. Asteris  , G. T. Michaltsos
Published: August 2022

The present paper, being the first part of two relevant studies, deals with the evaluation of the stress distribution under steel base-plate connections, acted upon statically by axial forces and bending moments. The whole approach is formulated on the basis of the proper equilibrium equations that are valid for both elastic and plastic plate behaviour adopting a nonlinear stress distribution function under the base plate of catenary type, depending on only one parameter. Taking into account the compatibility and geometric conditions valid for all the connection components, the aforementioned equations are fully assessed, considering the base-plate connection as semi-rigid. Numerical results, parametric studies and comparison with existing relevant investigations will be demonstrated in the companion paper, being the product of advances symbolic computations of the theoretical findings of the present work.
Effects of Damping Ratio of Restoring force Device on Response of a Structure Resting on Sliding Supports with Restoring Force Device
Authors: A. Krishnamoorthy
Published: August 2022

Effects of damping ratio of the restoring force device on the response of a space frame structure resting on sliding type of bearing with restoring force device is studied. The NS component of the El – Centro earthquake and harmonic ground acceleration is considered for earthquake excitation. The structure is modeled considering six-degrees of freedom (three translations and three rotations) at each node. The sliding support is modeled as a fictitious spring with two horizontal degrees of freedom. The response quantities considered for the study are the top floor acceleration, base shear, bending moment and base displacement. It is concluded from the study that the displacement of the structure reduces as the damping of the restoring force device increases. Also, the peak values of acceleration, bending moment and base shear decreases as the damping of the restoring force device increases.
New approach to improving distortional strength of intermediate length thin-walled open section columns
Authors: R. S. Talikoti  , K. M. Bajoria
Published: August 2022

This paper describes a method which can be adopted to improve the torsional and also distortional strength of thin-walled cold-formed steel columns used in pallet racking systems. Elastic buckling analysis on two different types of column sections of  intermediate length was done first in our study, after finding the buckling strength and mode of failure, the column sections were made distortionally stronger by adding simple spacers. Spacers are simple concentric tubes which are used to connect the flanges of open thin walled column sections (Fig. 3.). More than 22 laboratory experiments were carried out with different spacer spacing to asses the strength and behavior of these two different column sections. All these columns tested were investigated using finite element analysis software ANSYS [1]. The experimental results were verified with finite element analysis results obtained by solving the sections using ANSYS [1] software. Details of the experimentation and finite element analysis are presented here.
Decision Tools for the Engineering of Steel Structures
Authors: Michael Gedig  , Siegfried Stiemer
Published: August 2022

This paper gives an overview of currently available tools for decision making in the field of steel structures engineering. The theory of decision making in business, economics, and politics is well established. There is a wide array of methods and software that is used to implement the theory. In particular, the realm of decision making under conditions of uncertainty is of particular importance to the practicing engineer. This paper describes methods and software that may be used to inform and guide the decision making process in engineering practice. Examples are provided to illustrate the application of these tools to steel structures engineering.
Load Rating of Impaired Bridges Using a Dynamic Method
Authors: B. Samali  , J. Li  , K.I. Crews  , M. Al-dawod
Published: August 2022

Local Government in Australia is responsible for the operational management and maintenance of over 20,000 bridges. More than 70% of these bridges comprise aging timber bridges, the load capacity and structural adequacy of many of which have been impaired over time. This is partly due to increased vehicular loads with little attention to consequence of such increases. It is now necessary to determine the load carrying capacity of these bridges using simple yet reliable methods to allow local authorities to upgrade, replace or sign post at-risk bridges. In this paper a novel dynamic based method is presented by which the in-service stiffness of the bridge is estimated first. From this stiffness the load carrying capacity of the bridge is estimated following a statistically based analysis.
Estimating 3-second and maximum instantaneous gusts from 1-minute sustained wind speeds during a hurricane
Authors: S.A. Hsu
Published: August 2022

Formulas for estimating 3-second and maximum instantaneous gusts from 1-minute sustained mean wind speeds are derived for operational applications. These formulas are verified by measurements recorded during Hurricanes Katrina and Rita.
Modelling reinforced concrete structures subjected to impulsive loading using concrete lattice model
Authors: Ngo Tuan , Mendis Priyan
Published: August 2022

A two dimensional behavioral rate dependent lattice model (RDLM) capable of analyzing reinforced concrete members subjected to impulsive loading is presented. As a result of the impulsive loads reaching their peak intensity in extremely short durations of time, material nonlinearities and strain rate effects play an important role in the analysis. A numerical approach based on an explicit finite element formulation is introduced to solve two dimensional planar structural problems under impulsive loads. The procedure  incorporates equilibrium and compatibility conditions and utilizes realistic rate dependent stressstrain relationships for cracked concrete. The model inherently takes into account some major influencing factors, progressive cracking of concrete in tension, the inelastic response in compression, the yielding of reinforcing steel, and strain rate sensitivity of concrete and steel. Correlation studies between analytical and experimental results on reinforced concrete beams subject to impulsive loading are conducted and are shown to be in good agreement.
Theoretical Evaluation on Effects of Opening on Ultimate Load-carrying Capacity of Square Slabs
Authors: Chee Khoon Ng  , Timothy Julius Edward  , Daniel Kim Tee Lee
Published: August 2022

Reinforced concrete slabs are the most common structural elements found in building construction. Despite the large number of slabs designed and built, the details of the elastic and plastic behaviour of slabs are not always appreciated or taken into account. Studies on slabs with openings are also scarce in the research on reinforced concrete elements. Therefore, a study on simply-supported and fixed-end, square slabs with opening at ultimate limit state using the yield line method was carried out and the results are presented herein. For simply-supported slabs, the analytical study on the ultimate load capacity of the slab shows that the ultimate total load decreases with the size of the opening. However, when the ultimate total load is converted to ultimate area load, the results show otherwise. In the study of fixed-end slabs, the results show that the opening has insignificant effect on the ultimate area load capacity for a small opening size of up to 0.3 times the slab dimension. For opening size of more than 0.5 times the slab dimension, the ultimate area load capacity increases drastically. The ultimate total load of a fixed-end slab with opening up to 0.3 times the slab dimension is also not affected by the opening. However, the ultimate total load increases drastically for opening size of 0.5 times or more of the slab dimension. All the results in this study are plotted in nomographs form and can be used as guidelines for the design of slabs with opening particularly in determining the ultimate load capacity.
Research on Moving Force Estimation of the Bridge Structure using the Adaptive Input Estimation Method
Authors: Tsung-Chien Chen  , Ming-Hui Lee
Published: August 2022

An on-line adaptive input estimation method that estimates the moving force inputs of the bridge structure is presented in this research. By using the inverse method, input forces acting on bridge structural system can be estimated from the measured dynamic responses. The algorithm includes the Kalman filter (KF) and the recursive least squares estimator (RLSE). This work presents an efficient weighting factor r of the RLSE, which is capable of improving the estimation results. The capability of the proposed algorithm is demonstrated through several examples of the bridge structure system with different types of the time-varying moving forces as the unknown inputs.
Experimental and theoretical dynamic system identification of damaged RC beams
Authors: F. Daneshjoo  , A. Gharighoran
Published: August 2022

Dynamic system identification of RC beams i.e. natural frequencies, damping ratios and mode shapes is of high importance due to their special role in most civil engineering structures. In this paper, the effects of damage on dynamic characteristics of reinforced concrete beams are investigated experimentally. The possibility of obtaining load displacement curves through dynamic testing for in situ reinforced concrete beams is evaluated and the proposed methods are verified. Damage is considered as reduction in the flexural stiffness with increasing degree of cracking. A vibrating motor with aluminum flywheels to which masses could be attached at varying eccentricities are used for producing the dynamic cyclic loads. The variation in natural frequency, amplitude of vibration, damping and bending stiffness with increasing eccentric mass and for increasing degree of cracking are evaluated through steady state vibration at resonance with gradual increase of concentrated load at mid span. The changes in the secant stiffness with increasing degree of cracking and for increasing and decreasing concentrated static loads are obtained. Damping values are calculated from free vibration decay function using logarithmic decrement method. The results indicate that the damping ratio in the vicinity of the cracked region is not merely viscous, but rather is a combination of viscous and frictional damping. The contribution of the frictional damping will increase by increasing degree of cracking.
Seismic Behaviour of Buildings with Transfer Structures in Low-to- Moderate Seismicity Regions
Authors: R.K.L. Su
Published: August 2022

A literature review has been conducted aimed at improving the general understanding of the seismic response of concrete buildings with transfer structures in low-to-moderate seismicity regions. This paper summarizes and discusses the existing codified requirements for transfer structure design under seismic conditions. Based on the previous shaking table test results and numerical findings, the seismic effects on the inelastic behaviours of transfer structures are investigated. The mechanisms for the formation of a soft storey below transfer floors, the abrupt change in inter-storey drift near transfer storeys and shear concentration due to local deformation of transfer structures are developed. Design principles have been established for controlling soft-storey type failure and minimizing shear concentration in exterior walls supported by transfer structures. The influence of the vertical positioning of transfer floors on the seismic response of buildings has also been reviewed.
Seismic Drift Demand and Capacity of Non-seismically Designed Concrete Buildings in Hong Kong
Authors: R.K.L. Su  , Lam Nelson , H.H. Tsang
Published: August 2022

This paper reviews the seismic engineering research conducted in Hong Kong with special emphasis on the prediction of the seismic drift demand and capacity of existing buildings which have not been designed and detailed to address potential seismic hazards. The paper begins with a comprehensive summary of the local construction and detailing practice of concrete structures, followed by a summary of the drift ratio capacity, ductility capacity, stiffness variation and non-linear damping properties of the non-seismically designed reinforced concrete components. Seismic design response spectra for rock sites developed from Chinese Code GB50011-2001 are compared with the uniform hazard response spectra developed at the University of Hong Kong. The over-conservatism of the Chinese Code particularly in the long period range (T > 2 sec) is highlighted. A direct displacement based method used for the prediction of the maximum drift demands of existing buildings in Hong Kong is also introduced. Phenomena such as stiffness degradation, period shifting, non-linear damping and higher mode effects have been incorporated into the modelling. Lastly, the predicted maximum inter-storey drift demand of 0.3% is compared with the minimum ultimate drift capacity of approximately 1.5%. The capacity predictions were based on results from experimental cyclic load testings of concrete sub-assemblages undertaken in Hong Kong in recent times. The potential risk of damage in Hong Kong buildings under seismic attacks is discussed.
Modelling of the Stresses and Strains Distribution in an RCC Pavement Using the Computer Code "Abaqus"
Authors: M. Zdiri  , N. Abriak  , J. Neji  , M. Ben Ouezdou
Published: August 2022

The Roller Compacted Concrete (RCC) pavements are built employing the Portland cement. The design of the rigid RCC pavements was developed gradually through methods of design. These methods were established by various organisms for the determination of the necessary thicknesses of roadways. In this study a numerical 3D modelling was used by introducing to the computer code "Abaqus" the behaviour law of the RCC. Several other methods of 2D modelling were applied for the determination of the stress and the strains in the RCC slab such as the Closed-form Formulas and the Portland Cement Association (PCA) method. Finally the results of 3D modelling are compared with those obtained by the various other methods. The comparison shows good correspondences although the 3D modelling gives results slightly lower than those given by the 2D methods in stresses.