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Volume 14, Number 3, September 2022

The interaction between blast load and structures, as well as the interaction among structural members may well affect the structural response and damages. Therefore, it is necessary to analyse more realistic reinforced concrete structures in order to gain an extensive knowledge on the possible structural response under blast load effect. Among all the civilian structures, columns are considered to be the most vulnerable to terrorist threat and hence detailed investigation in the dynamic response of these structures is essential. Therefore, current research examines the effect of blast loads on the reinforced concrete columns via development of Pressure- Impulse (P-I) diagrams. In the finite element analysis, the level of damage on each of the aforementioned RC column will be assessed and the response of the RC columns when subjected to explosive loads will also be identified. Numerical models carried out using LS-DYNA were compared with experimental results. It was shown that the model yields a reliable prediction of damage on all RC columns. Validation study is conducted based on the experimental test to investigate the accuracy of finite element models to represent the behaviour of the models. The blast load application in the current research is determined based on the Lagrangian approach. To develop the designated P-I curves, damage assessment criteria are used based on the residual capacity of column. Intensive investigations are implemented to assess the effect of column dimension, concrete and steel properties and reinforcement ratio on the P-I diagram of RC columns. The produced P-I models can be applied by designers to predict the damage of new columns and to assess existing columns subjected to different blast load conditions.

Key Words
blast loads; damage index; Lagrangian method; P-I diagram; RC columns; vulnerability assessment

Multidisciplinary Center for Infrastructure Engineering, Shenyang University of Technology, Shenyang 110870, China.

In this article, vibrational behavior and wave propagation characteristics in (FG) functionally graded plates resting on Kerr foundation with three parameters is studied using a 2D dimensional (HSDT) higher shear deformation theory. The new 2D higher shear deformation theory has only four variables in field's displacement, which means has few numbers of unknowns compared with others theories. The shape function used in this theory satisfies the nullity conditions of the shear stresses on the two surfaces of the FG plate without using shear correction factors. The FG plates are considered to rest on the Kerr layer, which is interconnected with a Pasternak-Kerr shear layer. The FG plate is materially inhomogeneous. The material properties are supposed to vary smoothly according to the thickness of the plate by a Voigt's power mixing law of the volume fraction. The equations of motion due to the dynamics of the plate resting on a three-parameter foundation are derived using the principle of minimization of energies; which are then solved analytically by the Navier technique to find the vibratory characteristics of a simply supported plate, and the wave propagation results are derived by using the dispersion relations. Perceivable numerical results are fulfilled to evaluate the vibratory and the wave propagation characteristics in functionally graded plates and some parameters such wave number, thickness ratio, power index and foundation parameters are discussed in detail.

Key Words
FGM plates; HSDT theory; Kerr foundations; natural frequency; phase velocity

(1) Riadh Bennai, Hassen Ait Atmane:
Department of Civil Engineering, Faculty of Civil Engineering and Architecture, University Hassiba Benbouali of Chlef, Algeria;
(2) Riadh Bennai, Mokhtar Nebab, Fatma Mellal, Hassen Ait Atmane:
Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Hassiba Benbouali University of Chlef, Algeria;
(3) Fatma Mellal:
Department of Technology, Faculty of Science and Technology, Djilali Bounaama University, Khemis Miliana, Algeria;
(4) Mokhtar Nebab:
Department of Civil Engineering, Faculty of Sciences, University of M'Hamed Bougara Boumerdes, Algeria;
(5) Hocine Fourn, Redhwane Ait Atmane, Mourad Benadouda, Abdelouahed Tounsi:
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
(6) Abdelouahed Tounsi:
YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea;
(7) Abdelouahed Tounsi:
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia.

For producing cement and concrete, the construction field has been encouraged by the usage of industrial soil waste (or) secondary materials since it decreases the utilization of natural resources. Simultaneously, for ensuring the quality, the analyses of the strength along with durability properties of that sort of cement and concrete are required. The prediction of strength along with other properties of High-Performance Concrete (HPC) by optimization and machine learning algorithms are focused by already available research methods. However, an error and accuracy issue are possessed. Therefore, the Enhanced Deep Neural Network (EDNN) based strength along with durability prediction of HPC was utilized by this research method. Initially, the data is gathered in the proposed work. Then, the data's pre-processing is done by the elimination of missing data along with normalization. Next, from the pre-processed data, the features are extracted. Hence, the data input to the EDNN algorithm which predicts the strength along with durability properties of the specific mixing input designs. Using the Switched Multi-Objective Jellyfish Optimization (SMOJO) algorithm, the weight value is initialized in the EDNN. The Gaussian radial function is utilized as the activation function. The proposed EDNN's performance is examined with the already available algorithms in the experimental analysis. Based on the RMSE, MAE, MAPE, and R2 metrics, the performance of the proposed EDNN is compared to the existing DNN, CNN, ANN, and SVM methods. Further, according to the metrices, the proposed EDNN performs better. Moreover, the effectiveness of proposed EDNN is examined based on the accuracy, precision, recall, and F-Measure metrics. With the already-existing algorithms i.e., JO, GWO, PSO, and GA, the fitness for the proposed SMOJO algorithm is also examined. The proposed SMOJO algorithm achieves a higher fitness value than the already available algorithm.

Key Words
copper slag; Enhanced Deep Neural Network (EDNN); fibre synergy; High-Performance Concrete (HPC); Switched Multi-Objective Jellyfish Optimization (SMOJO)

Civil Engineering Department, Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, Delhi-110042, India.

As a brittle failure mode, punching-shear failure can be widely found in traditional RC slab-column connections, which may lead to the entire collapse of a flat plate structure. In this paper, a novel RC slab-column connection with inner steel truss was proposed to enhance the punching strength. In the proposed connection, steel trusses, each of which was composed of four steel angles and a series of steel strips, were pre-assembled at the periphery of the column capital and behaved as transverse reinforcements. With the aim of exploring the punching behavior of this novel RC slab-column connection, a static punching test was conducted on two full-scaled RC slab specimens, and the crack patterns, failure modes, load-deflection and load-strain responses were thoroughly analyzed to explore the contribution of the applied inner steel trusses to the overall punching behavior. The test results indicated that all the test specimens suffered the typical punching-shear failure, and the higher punching strength and initial stiffness could be found in the specimen with inner steel trusses. The numerical models of tested specimens were analyzed in ABAQUS. These models were verified by comparing the results of the tests with the results of the analyzes, and subsequently the sensitivity of the punching capacity to different parameters was studied. Based on the test results, a modified critical shear crack theory, which could take the contribution of the steel trusses into account, was put forward to predict the punching strength of this novel RC slab-column connection, and the calculated results agreed well with the test results.

Key Words
critical shear crack theory; punching behavior; punching strength; RC slab-column connection; steel truss

(1) Qingxuan Shi, Ge Ma, Jiangran Guo:
School of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, P.R. China
(2) Qingxuan Shi, Chenchen Ma:
State Key Laboratory of Green Building in Western China, Xi'an, Shaanxi, P.R. China;
(3) Jiangran Guo, Chenchen Ma:
Key Lab of Structural Engineering and Earthquake Resistance of the Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, P.R. China.

Due to seawater's physical and chemical deterioration effects on concrete structures, it is crucial to investigate the durability of these structures in marine environments. In some conditions, concrete structures are exposed to seawater from the first days of construction or because of the lack of potable water, part of the concrete curing stage is done with seawater. In this research, the effects of exposure to seawater after 7 days of curing in standard conditions were evaluated. To improve thedurability of concrete, fly ash has been used as a substitute for a part of the cement in the mixing design. For this purpose, 5, 15, and 30% of the mixing design cement were replaced with type F fly ash, and the samples were examined after curing in seawater. The resistance of concrete against chloride ion penetration based on the rapid chloride penetration test (RCPT), water permeability based on the depth of water penetration under pressure, and water absorption test was done. The changes in the compressive strength of concrete in different curing conditions were also investigated. The results show that the curing in seawater has slightly reduced concrete resistance to chloride ion permeation. In the long-term, samples containing FA cured in seawater had up to 10% less resistance to chloride ion penetration. The amount of reduction in chloride ion penetration resistance was more for samples without FA. Whiles, for both curing conditions in the long-term up to 15%, FA improved the chloride ion penetration resistance up to 40%. Curing in seawater slightly increased the penetration depth of water under pressure in samples containing FA, while this increase was up to 12% for samples without FA. In the long-term the compressive strength of samples cured in seawater is not much different from the compressive strength of samples cured in plain water, while at the age of 28 days, due to seawater salts' accelerating effects the difference is more noticeable.

Key Words
chloride ion; concrete durability; curing; fly ash; permeability; seawater

Faculty of Technology and Mining, Yasouj University, Choram, Iran.

Thermal comfort and energy conservation are critical issues in the building sector. Energy consumption in the building sector should be reduced whilst enhancing the thermal comfort of occupants. Concrete is the most widely used construction material in buildings. Its thermal conductivity (k-value) has a direct effect on thermal comfort perception. This study aims to find the optimum value of replacing the normal aggregate with lightweight expanded clay aggregate (LECA) under high strengths and low thermal conductivity, density and water absorption. The k-value of the LECA concrete and its physical and mechanical properties have varying correlations. Results indicate that the oven-dry density, compressive strength, splitting tensile strength and k-value of concrete decrease when normal coarse aggregates are replaced with LECA. However, water absorption (initial and final) increases. Thermal conductivity and the physical and mechanical properties have a strong correlation. The statistical optimisation of the experimental data shows that the 39% replacement of normal coarse aggregate by LECA is the optimum value for maximising the compressive and splitting tensile strengths whilst maintaining the k-value, density and water absorption at a minimum.

Key Words
density; expanded clay; lightweight aggregate concrete; mechanical properties; thermal conductivity

(1) Zakaria Che Muda:
Faculty of Engineering & Quantity Surveying, INTI-International University, Persiaran Perdana BBN Putra Nilai, 71800 Nilai, Negeri Sembilan, Malaysia;
(2) Payam Shafigh, Norhayati Binti Mahyuddin, Iman Asadi:
Center for Building, Construction & Tropical Architecture (BuCTA), Faculty of Built Environment, Universiti Malaya, 50603 Kuala Lumpur, Malaysia;
(3) Sumra Yousuf:
Department of Building and Architectural Engineering, Faculty of Engineering & Technology, Bahauddin Zakariya University, 60000 Multan, Pakistan.

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