Geo-polymer binder as portland cement alternative: challenges, current developments and future prospects

Ordinary Portland Cement (OPC), a material which built the world is now devastating it. Environmental impact has raised concerns over its continued usage while its multifaceted problems are also biting the production companies hard. Hence, alternative geopolymer binder has demonstrated excellent properties to stand ordinary Portland cement even though it is still being faced with technical drawbacks. Therefore, these paper reviews attempt made on improving discoveries and understanding about proper implementation of geopolymer binder. The geopolymer binder is curable at ambient temperature by the use of Fly Ash/Ground Granulated Blast Furnace Slag (GGBS) blend. This has been an alternative have been discovered for cheaper activating solutions rather than the expensive Sodium Hydroxide/Sodium Silicate solution. However, various of chemical composition known as Supplementary Cementitious Materials (SCMs) still an issues to fabricate a geopolymer binder

Evaluation of the role of the contractor’s personnel in enhancing the project constructability

Contractors’ personnel play a prominent role in enhancing the constructability of facilities design, construction and assessment. Looks at the constructability concepts identified by the Construction Industry Institute at Austin, Texas (CII) and represents and describes the constructability concepts in relation to contractors’ personnel. Discusses the role of each of them in enhancing constructability of facilities projects. Concludes that a set of obligations are the answer to the question of “How can the contractor’s personnel enhance the project constructability?”

Behavior of mortarless wall subjected to in-plane combine loading

The ability of mortarless wall to restrain/sustain lateral load become important aspect to be consider in the design of wall. Therefore, this paper presents analyses of mortarless wall subjected to in-plane combined loading using finite element programs. The developed 2D finite element program is used in this research. The finite element models are developed based on micro modelling approach where each constituent of masonry (block and dry joint) connected each other by joints at their actual position. Eight nodded isoparametric plane element and six nodded zero thickness isoparametric interface element are used to represent block unit and dry joint respectively. The developed models are analysed under nonlinear environment. The most relevant results concern the strength response of the dry joint masonry walls subjected to in-plane combined compressive and shear loading. The results of finite element analysis compared with corresponding experimental results and its show good agreement. Parametric study also performed to consider the important parameters that effect the design of wall under combined loading. Significant features of the structural behaviour, ultimate capacity and observed failure mechanisms are addressed and discussed

Optimization of earthquake energy dissipation system by genetic algorithm

Numerous recent studies have assessed the stability and safety of structures furnished with different types of structural control systems, such as viscous dampers. A challenging issue in this field is the optimization of structural control systems to protect structures against severe earthquake excitation. As the safety of a structure depends on many factors, including the failure of structural members and movement of each structural node in any direction, the optimization technique must consider many parameters simultaneously. However, the available literature on optimizing earthquake energy dissipation systems shows that most researchers have considered optimization processes using just one or a few parameters applicable only to simple SDOF or MDOF systems. This article reports on the development of a multiobjective optimization procedure for structural passive control systems based on genetic algorithm; this research focused on systems that would minimize the effects of earthquake based on realistic structural responses considering plastic hinge occurrence in structural elements and three-directional displacement in all structural nodes. The model was applied to an example of three-dimensional reinforced concrete framed building and its structural seismic responses were investigated. The results showed that the optimized control system effectively reduced the seismic response of structures, thus enhancing building safety during earthquake excitations

A comparative study between codes of spectrum for a single degree of freedom (sdof) system in two different hazardous regions.

Since in structure and earthquake engineering design of structures using response spectrum method (RSM) is very important, this study has been performed for a single degree of freedom (SDOF) system. Firstly the concept and the way of construction of response spectrum has been briefly explained. Then the records of some strong earthquakes in USA and Iran as two hazardous regions have been plotted, after that selected response spectrums (RS) of each country has been compared with each other and finally with standard response code of its own country. It was concluded:1) For a given ground motion the response of a SDOF system only depends on its natural vibration period (T) and damping ratio(ζ).2) When the effective damping ratio of a structure increases, its dynamic responses will decrease which demands the use of higher value of damping ratio in the structure. Also the FORTRAN computer programme for solving the Duhamel's Integral has been improved in this paper

Non-linear soil structure interaction of shear wall system with super element

Shear wall is commonly employed as a principal element to resist lateral loads due to wind or earthquake forces. An accurate model for shear wall system needs to consider the effect of all components for analyses i.e. shear wall, foundation and subsoil. This investigation presents modeling of shear wall structure - foundation and soil system using the super element, finite and infinite elements after considering soil nonlinearity. A finite element program has been written based on the proposed physical and material model for the analysis of the system. The applicability of the proposed idealization has been shown by analyzing a shear wall structure under static loading. In order to explore the efficiency of using super elements, an attempt has also been made to model the shear wall building using fully conventional finite element discretization. Furthermore the paper investigates the necessity of including soil structure interaction in analyzing shear wall structures. The results obtained from the analysis of shear wall model considering five different types of soil for the soil media show that the influence of soil interaction is very significant in the displacement as well as stresses induced in shear wall. Furthermore this investigation highlighted the effect of considering nonlinearity of soil in total displacement and stresses in shear wall system

Vibration analysis of nonlinear conical spring bracing system subjected to seismic load

In this study, an attempt has been made to assess the impact of proposed nonlinear conical spring bracing (NCSB) system on seismic response subjected to earthquake. The developed system includes of two telescopic conical spring springs that operate in axial compression. Due to shape of spring, the proposed system can performed as a nonlinear stiffness element that provide more lateral stability to structural frame. The action of NCSB does not control the low and moderate vibration due to earthquake but it acts for severe vibration whereas the frame displacement pass the allowable boundary. This inconstant performance avoids excessive effects of conventional bracing system if they attached as retrofitting components to moment resistant steel frame. by other words, due to the aforementioned characteristics of NCSB system, the inherent ductility of steel frame is not scarified and earthquake energy can be dissipate due to frame ductility, but, NCSB system provided more stability of structures and prevent large story drift. In this study, pushover and time history analyses has been conducted to evaluate the seismic performance of introduced device. The results from pushover disclose a considerable enhancement of structural capacity and ductility. Besides, the application on NCSB device changed the location of plastic hinge formation in structural elements. Furthermore, time history results proved the efficiency of NCSB device on reducing the maximum displacement

Static and dynamic analysis of rockfill dam using finite-infinite element method

In this paper, the dam body and the underneath soil were modeled using coupled finite-infinite elements under plane strain conditions. Initially, static stresses developed in the dam-foundation system due to gravity and hydrostatic loads are evaluated. Elasto-plastic seismic analysis of the dam-foundation system is next carried out by adopting the Drucker-Prager criterion for the material nonlinearity. The equation of motion is solved by New mark incremental time integration technique. The study focuses on the structural behaviour of the dam-foundation system under earthquake excitations. The behaviour in terms of displacement contours, stress distributions and the failure mode are presented

Seismic Response Evaluation of Reinforced Structure with Embedded Viscous Damper in Shear Wall.

Recently implementation of viscous damper devices as seismic energy dissipation attracts a lot of civil engineer interested due to effect of dampers in diminishing of earthquake loading. Furthermore along lateral load resistance systems, shear wall has better resistance performance by providing enough stiffness to the structure. But the overall weight of building is dramatically increased whenever shear walls are used as lateral resistance system. So, in present study an attempt has been made to evaluate seismic response of reinforced concrete structure which is equipped with viscous damper inside of shear walls. So, seismic response assessment carried out by aid of time history analysis and the results emerged in terms of average story displacement, axial force, moment and torsion in critical elements. Various models with different shear wall arrangement and embedded viscous damper layouts were subjected to earthquake excitation and response investigated. The results indicated that the best performance achieved when the viscous damper located at the top of the shear wall frame structure with the highest reduction percentage of axial forces, moment at the base of the shear wall, torsion and base shear values