Abstract
This paper develops a comparatively time-efficient methodology for performing seismic fragility analysis of the
reinforced concrete (RC) buildings in the presence of uncertainty sources. It aims to appraise the effectiveness of any variation in the material's mechanical properties as epistemic uncertainty, and the record-to-record variation as aleatory uncertainty in structural response. In this respect, the fuzzy set theory, a well-known a-cut approach, and the Genetic Algorithm (GA) assess the median of collapse fragility curves as a fuzzy response. GA is requisite for searching the maxima and minima of the objective function (median fragility herein) in each membership degree, a. As this is a complicated and time-consuming process, the authors propose utilizing the Gene Expression Programming-based (GEP-based) equation for reducing the computational
analysis time of the case study building significantly. The results indicate that the proposed structural analysis algorithm on the derived GEP model is able to compute the fuzzy median fragility about 33.3% faster, with errors less than 1%.
Key Words
fuzzy set theory; gene expression programming; genetic algorithm; seismic fragility curve; uncertainty
Address
Elaheh Ebrahimi, Gholamreza Abdollahzadeh: Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
Ehsan Jahani: Department of Civil Engineering, University of Mazandaran, Babolsar, Iran
Abstract
To solve the problem of detecting structural damage, a two-stage method using the Kalman filter and Particle Swarm Optimization (PSO) is proposed. In this method, the first PSO population is enhanced using the Kalman filter method based on dynamic responses. Due to noise in the sensor responses and errors in the damage detection process, the accuracy of the damage detection process is reduced. This method proposes a novel approach for solve this problem by integrating the Kalman filter and sensitivity analysis. In the Kalman filter, an approximate damage equation is considered as the equation of state and the damage detection equation based on sensitivity analysis is considered as the observation equation. The first population of PSO are the random damage scenarios. These damage scenarios are estimated using a step of the Kalman filter. The results of this stage are then used to detect the exact location of the damage and its severity with the PSO algorithm. The efficiency of the proposed method is investigated using three numerical examples: a 31-element planer truss, a 52-element space dome, and a 56-element space truss. In these examples, damage is detected for several scenarios in two states: using the no noise responses and using the noisy responses. The results show that the precision and efficiency of the proposed method are appropriate in structural damage detection.
Abstract
A numerical approach for dynamic stability analysis of sandwich plates has been provided using Chebyshev-Ritz-
Bolotin approach. The sandwich plate with porous core has been formulated according to a higher-order plate. All of material properties are assumed to be dependent of porosity factor which determines the amount or volume of pores. The sandwich plate has also been assumed to be under periodic in-plane loading of compressive type. It will be shown that stability boundaries of the sandwich plate are dependent on static and dynamical load factors, porosity factor, porosity variation and core thickness.
Ahmed Bakoura, Ibrahim Klouche Djedid, Fouad Bourada, Abdelmoumen Anis Bousahla, S.R. Mahmoud, Abdelouahed Tounsi, Mofareh Hassan Ghazwani and Ali Alnujaie
Abstract
A novel three variable refined plate theory (TVRPT) is developed in this article for laminated composite plates for
the first time. The theory takes into account the nonlinear variation of transverse shear deformations, and satisfies the boundary conditions of zero traction on the plate surfaces without considering the "shear correction factor". The important characteristic of this new kinematic is that the unknowns numbers is only 3 as is employed in "classical plate theory" (CPT). The numerical results of the current theory are compared with 3D-elasticity solutions and the calculations of "first order theories" and other higher order models found in the literature.
Key Words
bending; buckling; laminated composite plate
Address
Ahmed Bakoura: Département de Génie Civil, Faculté d'Architecture et de Génie Civil, Université des Sciences et de la Technologie d'Oran, BP 1505 El M'naouer, USTO, Oran, Algeria; Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria
Ibrahim Klouche Djedid: Laboratoire Matériaux et Structures (LMS), Département de Génie Civil, Faculté des Sciences Appliquées, University of Tiaret, Algeria
Fouad Bourada: Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria: Département des Sciences et de la Technologie, Université de Tissemsilt, BP 38004, Ben Hamouda, Algérie
Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
S.R. Mahmoud: GRC Department, Jeddah Community College, King Abdulaziz University. Jeddah 21589, Saudi Arabia
Abdelouahed Tounsi: Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria; YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
Mofareh Hassan Ghazwani: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Kingdom of Saudia Arabia
Ali Alnujaie: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Kingdom of Saudia Arabia
Abstract
In past major earthquakes (1994 Northridge, 1995 Kobe, Chi-Chi 1999, Kocaeli 1999), significant damages occurred
in the liquid storage tanks. The basic failure patterns were observed to be the buckling of the tank wall and uplift of the anchorage system. The damages in the industrial facilities and nuclear power plants have caused the spread of toxic substances to the environment and significant fires. Seismic isolation can be used in liquid storage tanks to decouple the structure and decrease the structural demand in the superstructure in case of ground shaking. Previous studies on the use of seismic isolation systems on liquid storage tanks show that an isolation system reduces the impulsive response but might slightly increase the convective one. There is still a lack of understanding of the seismic response of seismically isolated liquid storage tanks considering the fluid-structure interaction. In this study, one broad tank, one medium tank, and one slender tank are selected and designed. Two- and three-dimensional elastomeric bearings are used as seismic isolation systems. The seismic performance of the tanks is then investigated through nonlinear dynamic time-history analyses. The effectiveness of each seismic isolation system on tanks' performance was investigated. Isolator tension forces, modal analysis results, hydrodynamic stresses, strains, sloshing heights and base shear forces of the tanks are compared. The results show that the total base shear is lower in 3Disolators compared to 2D-isolators. Even though the tank wall stresses, and strains are slightly higher in 3D-isolators, they are more efficient to prevent the tension problem.
Key Words
3D isolators; base isolation; tank seismic design
Address
Samet Kiliç, Bülent Akbaş: Department of Civil Engineering, Gebze Technical University, Gebze, Kocaeli, Türkiye
Jay Shen: Department of Civil, Construction and Environmental Engineering, Iowa State University, Iowa, USA
Fabrizio Paolacci: Department of Engineering, Rome Tre University, Rome, Italy
Abstract
Environmental thermal loads such as vertical and lateral temperature gradients are significant factors that must be taken into account when designing the bridge. Different models have been developed and used by countries for simulating thermal gradients in bridge codes. In most of the codes only vertical temperature gradients are considered, such as Iranian Standard Loads for Bridge code (ISLB), which only considers the vertical gradient for bridge design proposes. On the other hand, the vertical gradient profile specified in ISLB, has many lacks due to the diversity of climate in Iran, and only one vertical gradient profile is defined for whole Iran. This paper aims to get the both vertical and lateral gradient loads for the concrete box girder using experimental analysis in the capital of Iran, Tehran. To fulfill this aim, thermocouples are installed in experimental concrete segment and temperatures in different location of the segment are recorded. A three dimensional finite element model of concrete box-girder bridge is constructed to study the effects of thermal loads. Results of investigation proved that the effects of thermal loads are not negligible, and must be considered in design processes. Moreover, a solution for reducing the negative effects of thermal gradients in bridges is proposed. Results of the simulation show that using one layer polyurethane insulation can significantly reduce the thermal gradients and thermal stresses.
Address
Farzad Raeesi: Department of Civil Engineering, University of Tabriz, Tabriz, Iran
Sajad Heydari: School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran
Hedayat Veladi: Department of Civil Engineering, University of Tabriz, Tabriz, Iran
Abstract
Passive vibration control devices like tuned liquid column dampers (TLCD) not only significantly reduce buildings'
vibrations but also can serve as a water storage facility. The recently introduced modified form of TLCD known as tuned liquid column ball damper (TLCBD) suppressed external vibration efficiently compared to traditional TLCD. For excellent performance, the mass ratio of TLCBD should be in the range of 5% to 7%, which does not include the mass of the ball. This additional mass of the ball increases the overall structure mass. Therefore, in this paper, an effort is made to reduce the mass of TLCBD. For this purpose, a new modified version of TLCBD known as tuned liquid column hollow ball damper (TLCHBD) is proposed. The existing mathematical modeling of TLCBD is used for this new damper by updating the numerical values of the mass and mass moment of the ball. Analytically the optimal design parameters are obtained. Numerically the TLCHBD is investigated with a single degree of freedom structure under harmonic and seismic loadings. It is found that TLCHBD performance is similar to TLCBD in both loadings's cases. To validate the numerical results, an experimental study is conducted. The mass of the ball of TLCHBD is reduced by 50% compared to the ball of TLCBD. Both the arrangements are studied with a multi-degree of freedom structure under harmonic and seismic loadings using a shake table. The results of the experimental study confirm the numerical findings. It is found that the performance behavior of both the dampers is almost similar under harmonic and seismic loadings. In short, the TLCHBD is lighter in weight than TLCBD but has a similar vibration suppression ability.
Key Words
harmonic loadings; normalized frequency response; passive control devices; shake table; tuned liquid column ball damper; tuned liquid column hollow ball damper; tunning frequency; vibration controls
Address
Mati Ullah Shah, Muhammad Usman: School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), H-12 Sector Islamabad 44000, Pakistan
In-Ho Kim: Department of Civil Engineering, Kunsan National University, Gunsan 54150, Republic of Korea
Sania Dawood: School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), H-12 Sector Islamabad 44000, Pakistan
Abstract
The shear capacity of beams is an essential parameter in designing beams carrying shear loads. Precise estimation of
the ultimate shear capacity typically requires comprehensive calculation methods. For steel fiber reinforced concrete (SFRC) beams, traditional design methods may not accurately predict the interaction between different parameters affecting ultimate shear capacity. In this study, artificial neural network (ANN) modeling was utilized to predict the ultimate shear capacity of SFRC beams using ten input parameters. The results demonstrated that the ANN with 30 neurons had the best performance based on the values of root mean square error (RMSE) and coefficient of determination (R2) compared to other ANN models with different neurons. Analysis of the ANN model has shown that the clear shear span to depth ratio significantly affects the predicted ultimate shear capacity, followed by the reinforcement steel tensile strength and steel fiber tensile strength. Moreover,
a Genetic Algorithm (GA) was used to optimize the ANN model's input parameters, resulting in the least cost for the SFRC beams. Results have shown that SFRC beams' cost increased with the clear span to depth ratio. Increasing the clear span to depth ratio has increased the depth, height, steel, and fiber ratio needed to support the SFRC beams against shear failures. This study approach is considered among the earliest in the field of SFRC.
Address
Nadia Nassif: Department of Civil and Environmental Engineering, College of Engineering, University of Sharjah, P.O. Box 27272 Sharjah, Sharjah, UAE; Research Institute of Sciences and Engineering, University of Sharjah, Sharjah, UAE
Zaid A. Al-Sadoon, Khaled Hamad, Salah Altoubat: Department of Civil and Environmental Engineering, College of Engineering, University of Sharjah, P.O. Box 27272 Sharjah, Sharjah, UAE
Abstract
The vibrational response of the two bones in a Volleyball player's arm under ball impact is conducted. The two bones in hand, Ulna and Radius, are modeled as two cylindrical shells. The formulations associated with the shells' vibration are obtained using the energy method. Then, the results are extracted with the aid of the two-dimensional form of DQM in conjunction with Runge-Kutta. The results are validated by means of a published paper. Lastly, the role of parameters in determining vibrational frequency as well as deflection is explored through parametric studies. It was shown that the impactor speed and the time of the impact could be essential factors in determining the vibration behavior of the bones. This work can be used in the further investigation of the behavior of bones and physiological structures.
Key Words
dynamic stability, finite element method, mathematical modeling, ulna/radius bone, volleyball ball
Address
Yangping Wang: School of Architectural Engineering, Chongqing Creation Vocational College, Yongchuan 402160, Chongqing, China
Shuze Sun: School of Sports and Health, Linyi University, Linyi 276000, Shandong, China
Abstract
Bonded joints have proven their performance against conventional joining processes such as welding, riveting and
bolting. The single-lap joint is the most widely used to characterize adhesive joints in tensile-shear loadings. However, the high stress concentrations in the adhesive joint due to the non-linearity of the applied loads generate a bending moment in the joint, resulting in high stresses at the adhesive edges. Geometric optimization of the bonded joint to reduce this high stress concentration prompted various researchers to perform geometric modifications of the adhesive and adherends at their free edges. Modifying both edges of the adhesive (spew) and the adherends (bevel) has proven to be an effective solution to reduce stresses at both edges and improve stress transfer at the inner part of the adhesive layer. The majority of research aimed at
improving the geometry of the plate and adhesive edges has not considered the effect of temperature and water absorption in evaluating the strength of the joint. The objective of this work is to analyze, by the finite element method, the stress distribution in an adhesive joint between two 2024-T3 aluminum plates. The effects of the adhesive fillet and adherend bevel on the bonded joint stresses were taken into account. On the other hand, degradation of the mechanical properties of the adhesive following its exposure to moisture and temperature was found. The results clearly showed that the modification of the edges of the adhesive
and of the bonding agent have an important role in the durability of the bond. Although the modification of the adhesive and bonding edges significantly improves the joint strength, the simultaneous exposure of the joint to temperature and moisture generates high stress concentrations in the adhesive joint that, in most cases, can easily reach the failure point of the material even at low applied stresses.
Key Words
adherend bevel; fillet of adhesive; humidity; single-lap joint; temperature
Address
S.M. Medjdoub: Department of Mechanical Engineering, University of Sidi Bel Abbes, BP 89 Cité Ben M'hidi 22000, Sidi Bel Abbes, Algeria
K. Madani: Djillali Liabes University of Sidi Bel Abbes, Sidi Bel Abbes 22000, Algeria
L. Rezgani: Department of Civil Engineering, Taher Moulay University of Saida, Algeria
S. Mallarino: LaSIE, Laboratoire des Sciences de l'Ingénieur pour l'Environnement, La Rochelle University, France
S. Touzain: LaSIE, Laboratoire des Sciences de lIngénieur pour l'Environnement, La Rochelle University, France
R.D.S.G. Campilho: ISEP-School of Engineering, Polytechnic of Porto, R. Dr. António Bernardino de Almeida, 431, 4200-072 Porto, Portugal; INEGI-Institute of Science and Innovation in Mechanical and Industrial Engineering, Rua Dr. Roberto Frias, 400, 4200-465 Porto, Portugal
