Experimental Study of Effect of Part Replacement of Concrete Mix Ingredients on Specific Heat of Concrete

Vol.1 No.3
 

Year: 2012

 
Issue: Sep-Nov

Title : Experimental Study of Effect of Part Replacement of Concrete Mix Ingredients on Specific Heat of Concrete  

Author Name : Navneet Raheja, Nitin Gupta

  

Synopsis :

With the rise in global warming and increasing environmental imbalances, it is becoming essential to find a viable alternative to replace the conventional concrete mix ingredients. The aim of this research was to check the use of waste material as the concrete ingredients and check the impact of same with regards to strength and specific heat of concrete. This paper presents the mix design analysis, compressive strength results and specific heat results for concrete mixes prepared with part replacement of various different materials. The results and conclusion are noted at the end of the paper for future studies.

Stress Strain Behavior of Steel Fibre Based Concrete In Compression

Vol.1 No.3

Year: 2012

 
Issue: Sep-Nov

Title : Stress Strain Behavior of Steel Fibre Based Concrete In Compression  

Author Name : Tantary M. A, Upadhyay A , Prasad J  

Synopsis : 

Steel fibre based concrete is now being increasingly used in different structural applications, including buildings, bridges, pavements etc. complete stress strain curve of the material is therefore essentially needed for the analysis and design of structures. In this study an experimental investigation was carried out to generate the complete stress strain curve for fibre concrete, containing crimped steel fibres. Four types of crimped steel fibres with aspect ratio of 33.5, 36, 45 and 80 respectively, were used in four different volume fractions (0.5, 1.0, 1.5, 2.0 %) in four different concrete mixes. The vital parameters of fibre concrete namely peak stress, strain at peak stress, toughness and the nature of stress strain curve was studied. A simple analytical model was proposed for stress- strain diagram of steel fibre concrete in uni-axial compression. The model was compared with experimental results and a good agreement was noticed between the two.

Computational Benchmarks in Simulation of Cyclic Performance of Steel Connections Using Three Dimensional Nonlinear Finite Element Method

Vol.1 No.3

Year: 2012

 
Issue: Sep-Nov

Title : Computational Benchmarks in Simulation of Cyclic Performance of Steel Connections Using Three Dimensional Nonlinear Finite Element Method  

Author Name : Mohammad Razavi, Roozbeh Kiamanesh, Ali Abolmaali  

Synopsis : 

The presented manuscript is intended to introduce accurate computational benchmarks to predict the hysteresis behavior of beam-column steel connections by means of a 3D non-linear finite element analysis.In this study, element type, inelastic material behavior,bolts pre-tensioning, and contact properties between different components of connections are discussed. Incremental nonlinear analysis takes into account all three types of nonlinearities including material, geometry, and contact properties in predicting moment-rotation hysteresis loops. A series of full-scale structural tests are performed to validate the results obtained from the finite element analyses. This study shows that cost efficient numerical analysis simulation is capable of replacing full-scale tests for steel connections.

Progressive Collapse Level of Analysis Capacity Evaluation of a Retrofit Scheme

Vol.1 No.3

Year: 2012

 
Issue: Sep-Nov

Title : Progressive Collapse Level of Analysis Capacity Evaluation of a Retrofit Scheme

Author Name: James M. Portea, Jeffrey Laman

Synopsis:

The General Services Administration, Department of Defense, and the National Institute of Standards and Technology have all published and continuously maintained new building design guidelines to lower potential for progressive collapse. In addition, the analysis procedures prescribed by these guides cover a range of options or levels; however, the progressive collapse guidelines focus primarily on new construction. Therefore, research is needed to identify and investigate the effectiveness of novel retrofit methods for mitigating progressive collapse of existing buildings through the available analysis levels. The primary objective of the current study was to investigate and compare the outcomes of four levels of analysis: linear-elastic static analysis (3D); nonlinear static analysis; and dynamic nonlinear analysis (2D and 3D) and to establish an analysis methodology for investigating steel buildings retrofit concepts. The retrofit scheme investigated was devised to improve the progressive collapse resistance of a 5-story steel building subjected to sudden, exterior column loss. Results showed that an a-value of 2 generally leads to highly conservative estimates in the results from 5-story models that did not fail at the progressive collapse design load combination. For the 5-story models that failed at the recommended static load combination, the ratio of peak dynamic end moments to static end moments are only comparable because the full static load was not reached before failure, thus also pointing to a conservative a-value. An assessment of the dynamic amplification factor yielded values of 1.4 to 1.6. A less conservative a-value cannot be specified based on the results of this study alone, but the analysis results indicate that for certain buildings, predictions on performance after column loss that are based on a static analysis with an a-value of 2 may be overly conservative. Although the retrofit did not significantly improve the performance of the 5-story building with moment frames in two directions, the retrofit increased the load-carrying capacity of the model without a moment frame orthogonal to the exterior bay. In this case, the retrofit was more effective because the interior beams on each floor, which would otherwise rotate freely if the cables were not in place, participate in resisting some of the floor loads.

An acoustic emission methodology for protecting the structural integrity of composite pressure vessels using neural networks

Vol.1 No.3

Year: 2012

 
Issue: Sep-Nov

Title: An acoustic emission methodology for protecting the structural integrity of composite pressure vessels using neural networks

 

Author Name: Sasikumar.T Thangaswamy, S.Rajendra Boopathy , K.M.Usha , E.S.Vasudev , S. Albert Singh

Synopsis:

Prior prediction of burst pressure of the composite pressure vessels well before its failure would be a complimentary method in the area of composite characterization. In this proposed research, an attempt was made to predict the failure pressure of  the composite pressure vessels. A series of five identical GFRP (Glass Fiber Reinforced Plastics) pressure vessels were monitored with an acoustic emission (AE) system, while proof testing them up to 50% of their theoretical burst pressure. Back propagation neural network models were generated for the prior prediction of burst pressure of the composite pressure vessels. Three different networks were developed with the peak amplitude distribution data of acoustic emission collected up to 30%, 40% and 50% of the theoretical burst pressures. Amplitude frequencies of AE data recorded from three bottles in the training set and their corresponding burst pressures were used to train the networks. Only the amplitude frequencies of the remaining two bottles were given as input to get the output burst pressures from the trained networks. The neurons present in the multi-hidden layers of the networks were able to map the patterns of failure present in the AE data. The results of three independent networks were compared, and it was found that the network trained with more AE data had better prediction performance. Prior prediction of burst pressures of the composite pressure vessels at low proof testing level may serve to avoid significant fiber failures and the associated structural integrity degradation.

Computational Benchmarks in Simulation of Cyclic Performance of Steel Connections Using Three Dimensional Nonlinear Finite Element Method

Vol.1 No.3

Year: 2012

 
Issue: Sep-Nov

Title : Computational Benchmarks in Simulation of Cyclic Performance of Steel Connections Using Three Dimensional Nonlinear Finite Element Method  

Author Name : Mohammad Razavi, Roozbeh Kiamanesh, Ali Abolmaali  

Synopsis : 

The presented manuscript is intended to introduce accurate computational benchmarks to predict the hysteresis behavior of beam-column steel connections by means of a 3D non-linear finite element analysis.In this study, element type, inelastic material behavior,bolts pre-tensioning, and contact properties between different components of connections are discussed. Incremental nonlinear analysis takes into account all three types of nonlinearities including material, geometry, and contact properties in predicting moment-rotation hysteresis loops. A series of full-scale structural tests are performed to validate the results obtained from the finite element analyses. This study shows that cost efficient numerical analysis simulation is capable of replacing full-scale tests for steel connections.