Journal of Civil Engineering Beyond Limits (CEBEL) - ACA Publishing ®

Journal of Civil Engineering Beyond Limits (CEBEL)

ARTICLES Volume 3 - Issue 1 - January 2022

Hao Huang Cheng Wang Weiming Gong Huanan Xu

To investigate the bearing characteristics of diaphragm wall foundation under combined load, the results from elasto-plastic analyses of 3D finite element models (FEM) were presented in this study. The vertical load of the diaphragm wall foundation is borne by inner and outer side resistance, resistance of soil core and the end of wall, respectively. Moreover, the sum of end resistance and soil core resistance accounts for about 75% of the vertical load. The mobilization mechanism and distribution of side resistance of the foundation were also analyzed. It is clarified that the mobilization characteristics of inner and outer side resistance of the wall are completely opposite. Due to the combined load, the horizontal load has an amplification effect on the settlement of the foundation. Additionally, the calculation methods of the Eight-component Winkler spring model and rigid pile displacement were used for determining the vertical load-bearing capacity and the overturning stability. A comparison between results from the FEM and the theoretical calculation methods showed that the results of the numerical simulation properly coincided with that of the displacement solution of theoretical model. The conclusions obtained by the above methods all indicate that the foundation has the characteristics of overall overturning failure under the combined load.

Muhammad Aun Bashir Bassam Khulaif Alharbi

Concrete filled steel tube structures are becoming very popular in the modern civil engineering projects. Studying composite structures is useful, since it is an innovative and contemporary way to build structures. This type of structure has the ability to use respective strength of both steel and concrete due to confinement. Prefabrication of steel tube section is beneficial, and allows rapid installation into main structure. It also reduces the assembly cost and construction time. This paper will present the simple equation to predict the compressive strength of square concrete filled steel tube by using Finite Element Analysis (FEA)based software ABAQUs. In this study, 3D non-linear finite element models of short square composite columns were prepared using ABAQUS. The results were compared with published experimental tests of a concrete filled steel tube short columns. After getting the good agreement with the experimental results, a simple equation for the prediction of compressive strength is presented by considering the width to thickness ratio of steel tube. Results are validated with experimental results. The equation can predict the compressive strength only for the given material strengths and in future, the simple equation can be improved by considering different parameters e.g. material strength, slenderness ratio and end conditions.

Badee Alshameri

The compaction is a mechanism to densify the loose soils. The maximum soil densification can be achieved by optimization of the desirable optimum moisture content (OMC) and maximum dry density (MDD). The maximum dry density and the optimum moisture content were affected by several parameters. The coarse content (CC) is one of these parameters. This paper studied the effect of the coarse content on the compaction parameters (MDD, OMC). Several sand-kaolin mixtures had coarse content ranged from 30 % to 80 % and moisture content ranged from 12% to 20% were used to inspect the relationship between CC, specific gravity (Gs), MDD, OMC, and bulk density. The results presented five empirical correlations with coefficient of determination (R2 ≥ 0.98) between CC, Gs, MDD, OMC and bulk density. The comparison between the current study and previous researchers indicated that both soil type and moisture content have significant effect on the efficiency of the empirical correlation equations between the maximum dry density, specific gravity, and coarse content. The results indicated a linear relationship between coarse content toward maximum dry density and specific gravity where both MDD and Gs increased with an increase CC. In contrary, the results showed non-linear relationship between optimum moisture content and coarse content where OMC decrease with an increase CC.

Marsed Leti Hüseyin Bilgin

Albania has suffered from major earthquakes in the past century that have caused varying levels of damage to buildings. As a result of the number of damaged buildings and loss of life, attention has focused mostly on the poor performance of reinforced concrete and masonry structures in low and mid-rise buildings. This paper presents the results of a reconnaissance visits to the disaster-stricken area in the Durrës region in Albania and covers many zones in the region where historical and modern buildings suffered serious structural damage or collapses during the November 26, 2019, Durrës Earthquake. Special emphasis was placed on masonry and RC buildings, since the damage level was high in these buildings. The consequences of the Durrës earthquake are important for similar masonry and RC building stock in other seismically vulnerable European cities. Regularity of the structural system, quality of the material utilized, the distribution of mass and stiffness through the building, the ratio of openings on masonry walls and diaphragm stiffness have a crucial influence on the structural response. Inappropriate interventions led to serious damage or collapses, resulting in casualties. Examples of numerous damage types, as witnessed during the site visits to the affected region are presented, along with technically explanation of causes for the damages.

Marsed Leti Hüseyin Bilgin

This study covers the application of Static and Dynamic nonlinear analysis to an old moment-frame reinforced concrete building. The case study selected is a template one designed in 1982 without shear walls and built throughout Albanian region in the communism era using old standards (KTP 2-78). For the capacity calculation, Pushover analysis is performed using an inverse triangular load pattern. The demand calculation is conducted using Incremental Dynamic Analysis (IDA) as a method which provides the response behavior of the structure from the elastic range until collapse. For the dynamic analysis is used a set of 18 earthquakes with no marks of directivity. Limit stated are defined for both Pushover and IDA based on the FEMA 356 guidelines. The mathematical model is prepared in the environment of Zeus-NL, a software developed especially for earthquake applications. The parameters defined for the IDA analysis are 5% damped first mode spectral acceleration (Sa(T1,5%)) for the intensity measure (IM) and maximum global drift ratio (ϴmax) for the damage measure (DM). In addition, limit states are selected for the pushover curve as Immediate Occupancy (IO), Life Safety (LS) and Collapse Prevention (CP). Similarly, for the IDA curve the limit states are selected as IO, CP and Global Instability (GI) based on FEMA guidelines. Furthermore, IDA curves are summarized into 16%, 50% and 84% fractiles as suggested in the literature. Additionally, a comparison between Pushover and IDA median (50% fractile) is shown from the same graph to illustrate the correlations between performance levels. Finally, structural performance is interpreted based on the outcomes.