Asian journal of civil engineering
Volume:17 Issue: 6, Oct 2016

This paper investigated the effects of hybrid fiber reinforced high-strength concrete in Exterior beam –column joint specimens. One specimen detailed as per IS 13920, second specimen detailed as per IS 456 code provisions, this two specimens were cast with high strength concrete of Grade M60 and treated as control specimens. Six specimens detailed as per IS 456 but the top & bottom bars of beam were bent-up within the joint core, and maintained the uniform spacing of stirrups for column and beam, those specimens were cast by using the steel fibers, polyolefin fibers were added into the same grade of concrete with various volume fractions. All the specimens were tested by cyclic load, from this test ultimate load, Load deflection behavior, deflection ductility, stiffness were studied and compared the results with control specimens. The hybrid fiber reinforced high strength concrete specimens were gave better performances.

This paper peresents the 2–D discrete wavelet–based crack detection using static and dynamic responses in plate structures. Over the last few decades, the wavelet–based techniques of damage identification methods have been presented and developed in civil and mechanical structures. The techniques are based on a comparison between the current structural responses as damaged structure and those of the previous baseline state, which is considered to be the health structure. To impliment the damage detection of plate structures, in this study the displacement, rotation and stress as the static responses and the mode shapes as the dynamic responses are considered in the crack detection procedure. The numerical results show that the wavelet–based crack detection is sensitive to number of cracks in plate structure. In other words, the existence of a crack can be potentially identified using each of the static or dynamic responses of plate structures. Moreover, if multi–cracks exists in plate structure, both static and dynamic responses of plate structure should be utilized in the damage detection procedure.

In this investigation, broiler hen egg was used as Natural admixture (NAD) to study the effect on mechanical properties of Conventional Concrete (CC) and Class C Fly Ash (FA) blended concrete. Cement was replaced by fly ash at various levels of 0%, 25%, 35% and 45% and broiler hen egg mixed sample (white albumen and yellow yolk) was added to concrete at different replacement dosages of 0%, 0.25%, 0.5%, 1.00%, 1.5% and 2.0% to water content and liquid to binder ratio was maintained at 0.5. For all replacement levels of NAD and FA, the mechaincal properites viz unit weight, compressive strength, splitting tensile strength and modulus of elasticity of CC and Class C fly ash (FA) were studied at 7, 28 and 56 days. From the results, it was concluded that 0.25% of NAD dosage was considered as optimum dosage for both CC and class C fly ash blended concrete.

The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation. Many causes are involved in this behavior such as columns and piers nonlinear deformation patterns. The columns material i.e. (concrete or steel) shall influence the pattern of the seismic behavior of the whole bridge. The objective of this study is to evaluate the effects of column material on earthquake performance of reinforced concrete deck bridges. Strength and stiffness modification factors are proposed to modify force-deformation behaviors of damaged columns. Maximum nonlinear displacement is sensitive to the increase in the number of spans and the earthquake angle of incident; therefore, as the number of spans increases, the deck displacement and rotation responses will be deducted for concrete piers but there is no decrease in steel piers.

In this paper the principal goal is to model cracked structures under dynamic loads by using a new method called the extended finite element method (X-FEM). Then arriving to the evaluation of dynamic stress intensity factor DSIF, which is calculated using two dynamic methods; the first is the modal analysis and the second that is the spectral modal. This latter represents our originality in this study where we want to present its simplicity in the calculation of DSIFs compared to the modal analysis. J integral and Displacement Jump techniques are used to evaluate the modal DSIF and the spectral DSIF.The present study is validated by an example taken from the literature. Next, a case study of a civil engineering structure is carried out in the aim to study the order of crack effect, its size, and its position on the DSIFs and on the dynamic behavior of a concrete structure subjected to seismic excitation. In addition, in order to see the effect of the seismic excitation intensity and the soil support structure, comparison between the spectral stresses intensity factors are tested.

In this paper, an explicit time integration method to determine the linear response of arbitrary structures subjected to dynamic loading is proposed. The total time of dynamic loading is divided into several time steps. For each two time steps, in modeling the acceleration over time domain, a second order polynomial with three unknown parameters is assumed. Validity and effectiveness of the proposed method is demonstrated through two examples where the results of this method are compared with those numerical methods. In this method, over two steps, six unknown responses (three responses for each time step) consisting of two displacements, two velocities and two accelerations are computed. This property reduces the computational cost of the proposed method as compared to Central difference, Houbolt, Newmark (linear and average), Wilson Ѳ etc. Furthermore, accuracy of the results obtained from the proposed method is better than other methods for single and multi-degree of freedom systems. Hence, as advantages of the proposed method, this method has appropriate convergence, accuracy and low computational time. Therefore, the novelty of this work is that for very small values of ∆t, this method is more precise and less time consuming rather than other existed methods. This is a useful instrument for the analysis of dynamic systems with very small values of ∆t under earthquake loading.

This paper presents the results of Adaptive Neuro-Fuzzy Inference System (ANFIS) based model for Reinforced circular columns strengthened with Carbon fibre reinforced polymer (CFRP) sheets. The main objective of this paper is to propose ANFIS based model for predicting the performance characteristics of CFRP strengthened RC columns and to compare it with the experimental results. ANFIS uses neural network for computing the numerical results of functions and fuzzy logic for making decisions based on the resulting values. The ANFIS predicted results show good agreement with the experimental test results.

Concrete material suffers from a relatively low tensile strength and limited deformation capacity. Such defects of the concrete are very fragile and sensitive to shrinkage cracking materials. The Self- Compacting Concrete (SCC) are highly fluid concretes whose implementation without vibration. This material replaces traditional vibrated concrete mainly seen techno-economic interest it presents. The SCC has several advantages which are at the origin of their development crunching. The research is therefore to conduct a comparison in terms of rheological and mechanical performance between different formulations to find the optimal dosage for rubber granulates. Through this research, we demonstrated that it is possible to make different settings SCC composition having good rheological and mechanical properties. This study also showed that the substitution of natural aggregates (NA) by rubber aggregates (RA) in the composition of the SCC, contributes to a slight variation of workability in the fresh state parameters still remaining in the field of SCC required by the AFGC recommendations. The experimental results show that the compressive strengths of SCC decreased slightly by substituting NA by RA. Finally, the decrease in free shrinkage is proportional to the percentage of RA incorporated into the composition of concrete. This reduction is mainly due to the improvement of the deformability of these materials.

This paper investigates discrete design optimization of reinforcement concrete frames using the recently developed meta-heuristic called Enhanced Colliding Bodies Optimization (ECBO) and the Non-dominated Sorting Enhanced Colliding Bodies Optimization (NSECBO) algorithm. The objective function of algorithms consists of construction material costs of reinforced concrete structural elements and carbon dioxide (CO2) emissions through different phases of a building life cycle that meets the standards and requirements of the American Concrete Institute’s Building Code. The proposed method uses predetermined section database (DB) for design variables that are taken as the area of steel and the geometry of cross-sections of beams and columns. A number of benchmark test problems are optimized to verify the good performance of this methodology. The use of ECBO algorithm for designing reinforced concrete frames indicates an improvement in the computational efficiency over the designs performed by Big Bang-Big Crunch (BB-BC) algorithm. The analysis also reveals that the two objective functions are quite relevant and designs focused on mitigating CO2 emissions could be achieved at an acceptable cost increment in practice. Pareto results of the NSECBO algorithm indicate that both objective yield similar solutions.