International Journal of Structural Engineering (5 papers in press)

Regular Issues

• Experimental and analytical study on reinforced concrete deep beams  
  by Asghar Amani Dashlejeh, Abolfazl Arabzadeh 
  Abstract: A new simple Strut-and-Tie Model was presented in this paper to study the behavior of reinforced concrete deep beams. This model was obtained based on bottle-shaped struts that can predict flexural, bearing, and shear modes of the failure. Also, the effect of web reinforcements was considered. The proposed model was verified by laboratory test results that obtained from five deep beams with the shear span-to-depth ratio of two and some other experimental results existing in the literature. Comparison of the results of the proposed model with relations from ACI 318 and AASHTO-LRFD codes and some other relations showed that the proposed model is efficiently capable of accurately predicting the ultimate load of simply supported deep beams. Also, comparison of experimental results demonstrated that the flexural capacity of deep beams obtained from the Strut-and-Tie Model is conservative.
  Keywords: Deep beam; Strut and Tie Model; Reinforced concrete; Shear load.
  
  
• Presentation of a new membrane strain based finite element for static and dynamic analysis  
  by Lemmouchi BOUZIDI, Lamine BELOUNAR, Khelifa GUERRAICHE 
  Abstract: A numerical solution using a strain-based quadrilateral finite element is presented to analyse static and dynamic behaviours for membrane structures. The proposed quadrilateral element which possesses two degrees of freedom (u and v) at the four corner nodes as well as at the central node is based on assumed strains. All the three components of strains have linear variation satisfying the compatibility equation. The validity of the developed element is first applied to several selected static examples. This element is further applied to analyse both free and forced vibrations.
  Keywords: membrane; rectangular element; strain approach; finite element; vibration analysis.
  
  
• FLUID - STRUCTURE- SOIL INTERACTION EFFECT ON DYNAMIC BEHAVIOUR OF CIRCULAR WATER TANKS  
  by ASHA JOSEPH, GLORY JOSEPH 
  Abstract: To investigate the seismic behaviour of concrete tanks on different soil conditions, fluid structure- soil interaction system is simulated using finite element analysis software ANSYS. The influence of soil properties on tanks dynamic behaviour is studied by performing modal and transient analyses of cylindrical tanks resting on different soil conditions. Considering four different soil properties, comparisons are made on response parameters such as displacement in radial direction at top of tank wall, maximum hoop force, bending moment and base shear. The effect of frequency content of earthquake on seismic behaviour circular concrete tank is investigated by conducting time history analyses of the tanks under three different earthquakes. All the analyses were performed for half fill and full fill condition. Transient analyses show that the soil property, frequency content of earthquake and water fill condition have significant effect on seismic response of the water tanks.
  Keywords: cylindrical water tank; fluid – structure interaction; soil- structure interaction; water fill condition; frequency content of earthquake; time history analysis; finite element analysis.
  
  
• Evaluation of a Multimode Pushover Procedure for Asymmetric and Non-regular in Plan Reinforced Concrete Buildings under Biaxial Seismic Excitation  
  by Grigorios Manoukas 
  Abstract: In the present paper a recently developed multimode pushover procedure is evaluated for non-regular in plan systems. The procedure is applicable to asymmetric in plan buildings under concurrent action of two horizontal seismic components and its main advantage is that it does not require independent analysis in two orthogonal directions. Thus, the use of simplified directional combination formulae, which is not valid in the nonlinear range, is avoided. The preliminary evaluation of the proposed methodology led to quite satisfactory results. However, the studies conducted up to date are limited to regular buildings. Hence, in the present study the procedure is applied to four asymmetric and non-regular in plan reinforced concrete buildings. The values of selected response quantities are compared to those resulting from a conventional pushover analysis variant as well as from nonlinear dynamic analysis. The whole evaluation study leads to the derivation of useful conclusions.
  Keywords: nonlinear static procedure; multimode pushover analysis; equivalent single degree of freedom systems; reinforced concrete buildings; asymmetric buildings; non-regular buildings; biaxial seismic excitation; multidirectional seismic effects; directional combination; nonlinear dynamic analysis.
  
  
• Multi-objective optimization of steel moment frames subjected to blast  
  by Nima Khaledy, Alireza Habibi, Parham Memarzadeh 
  Abstract: In recent decades, terrorist attacks have been increased all over the world. For this reason, the design of blast resistant structures is very crucial. On the other hand, for decades the optimum design of structures has been an interesting subject for structural engineers and researchers as it can provide cost and behavioural efficiencies. In the current research, the optimum design of steel moment frames under blast loading has been studied. Towards that end, first, a damage index is developed based on the maximum plastic strain in the members. Then, according to the damage index, a multi-objective optimization methodology is proposed to minimize the structural weight and the damage index. The method utilizes explicit nonlinear dynamic finite element analysis as the structural analysis method and NSGA-II optimization algorithm as the optimization technique. At the final point, based on the proposed method a framework is developed, and two numerical examples are studied. Results of this research show that the developed method is effective in achieving optimal designs with desired cost and damage.
  Keywords: Blast loading; Plastic strain; Damage Index; Multi-objective; NSGA-II.