DYNAMIC SOIL-STRUCTURE INTERACTION ANALYSIS: DETECTING THE RELIABILITY OF MODELLING THE PILES AS A PLATE ELEMENT FOR A MULTISTORY BUILDING RESTING ON DEEP FOUNDATION

The assessment of seismic responses of buildings in dynamic-soil-pile-structure interaction problems has been one of the main interests among researchers in recent decades. Simulating such problems is usually done by two-dimensional models to overcome the difficulties encountered in 3D models. Commonly, piles were represented by plate elements of infinite length, disregarding the soil flowing between piles. Recently, Plaxis – a finite element software- implemented a new feature known as “the embedded pile row” that allows the definition of piles\u27 out of plane spacing in a 2D model. Many researchers proved its validity in accurately simulating the real 3D pile’s behavior. The objective of this paper is to detect the reliability of modeling the piles as plate elements, by comparing the performance of the structural-pile system with the plate feature to that with the embedded pile row feature. A series of 2D finite element models are generated while varying the soil type, the earthquake frequency content, and the out-of-plane piles\u27 spacing. This paper demonstrated that the building response with piles modeled as plate elements is just adequate when the surrounding soil is dense. Yet, regarding the pile response, the plate feature is unable to capture the real behavior for all soil types

Comparative study of modeling methods used to simulate initial stresses in prestressed beams towards manual analysis

Numerical modeling of the prestressing element that generates prestressed effect in beams has always been considered a big challenge. This research compares two methods of modeling; In the first method we used initial stresses predefined stress and in the second method we used the temperature strain. Concrete damage plasticity model (CDP) was used to model the non-linear behavior of concrete material and an elasto-plastic behavior was applied to ordinary and prestressed reinforcement. Truss elements were used to model ordinary and prestressed reinforcement embedded inside the concrete. As a result, Initial Temperature load method showed less error in bottom and top stresses and cambering of beam in comparison with the basic concept method, than predefined method

Numerical study for the effect of hairpin shaped shear reinforcement on one-way shear capacity of reinforced concrete beams

This study investigates the effectiveness of using Hairpin shaped stirrups to increase the shear capacity of beams and slabs. The hairpin system consists of inverted U-shape stirrups welded to flexural corner rebar. Previous research works proved the increase of the hairpin system in increasing the two-way shear capacity compared to conventional punching reinforcement. However, the system’s ability to increase the shear capacity of beams has not been explored. This paper presents the results of Finite Element simulation of two beams performed using ABAQUS Software; one beam is reinforced with conventional shear stirrups, and the other is reinforced with hairpin stirrups. The load capacity, deflection and damage pattern of the two beams were compared. Results showed that beams reinforced with hairpin stirrups have higher load capacity and ductility compared to beams with conventional stirrups. However, the reinforcement type had little effect on the shear damage pattern

Seismic assessment and rehabilitation of a historical masonry mosque

In order to assess the structural behaviour and to evaluate the seismic vulnerability of old masonry structures located in Lebanon, a historical masonry mosque was analysed under earthquake loading. A numerical model developed by the finite element method using Abaqus software was elaborated on the basis of previously published experimental studies. It was concluded that the numerical model can predict maximum stresses with reasonable accuracy, allowing control of a full scale wall model. This analysis shows that the stresses generated in the joints between the blocks exceed the ultimate shear stress of the mortar, resulting in cracks in the joints. The choice of an adequate structural rehabilitation method was limited because the mosque is of archaeological importance and its original appearance should not be modified. Therefore, a seismic retrofit solution using internal or external post tensioned tendons was recommended

Numerical study for the effect of hairpin shaped shear reinforcement on one-way shear capacity of reinforced concrete beams

This study investigates the effectiveness of using Hairpin shaped stirrups to increase the shear capacity of beams and slabs. The hairpin system consists of inverted U-shape stirrups welded to flexural corner rebar. Previous research works proved the increase of the hairpin system in increasing the two-way shear capacity compared to conventional punching reinforcement. However, the system’s ability to increase the shear capacity of beams has not been explored. This paper presents the results of Finite Element simulation of two beams performed using ABAQUS Software; one beam is reinforced with conventional shear stirrups, and the other is reinforced with hairpin stirrups. The load capacity, deflection and damage pattern of the two beams were compared. Results showed that beams reinforced with hairpin stirrups have higher load capacity and ductility compared to beams with conventional stirrups. However, the reinforcement type had little effect on the shear damage pattern

Seismic assessment and rehabilitation of a historical masonry mosque

In order to assess the structural behaviour and to evaluate the seismic vulnerability of old masonry structures located in Lebanon, a historical masonry mosque was analysed under earthquake loading. A numerical model developed by the finite element method using Abaqus software was elaborated on the basis of previously published experimental studies. It was concluded that the numerical model can predict maximum stresses with reasonable accuracy, allowing control of a full scale wall model. This analysis shows that the stresses generated in the joints between the blocks exceed the ultimate shear stress of the mortar, resulting in cracks in the joints. The choice of an adequate structural rehabilitation method was limited because the mosque is of archaeological importance and its original appearance should not be modified. Therefore, a seismic retrofit solution using internal or external post tensioned tendons was recommended

Effect of Successive Impact Loads From a Drop Weight on a Reinforced Concrete Flat Slab

Lebanon is one of the countries which are at high risk of experiencing rock falls. In order to ensure public safety, engineers must take into consideration this risk. In the past years, numerous researches were conducted on the behavior of horizontal structural elements, slabs, of different types under dynamic impact load. Reinforced concrete flat slabs are commonly used slabs in residential buildings. To build a profound understanding of the structural behavior of the slabs under such loadings, it is important to investigate the effect of energy dissipation on the equivalent impact force, mid-span deflection and damage pattern. In this study a sample reinforced concrete slab of 500 x 1000 x 100 mm dimensions is considered. The aim of this paper is to find how these factors vary with the increase in energy as the drop load resembling the real rock fall is left to drop freely from different heights 0.6 m and 1 m