INTERNATIONAL JOURNAL OF ADVANCED STRUCTURAL ENGINEERING
Year:2019 | Volume:11 | Issue:1|Papers Count:11

This work aims to evaluate time-dependent reliability of a pipeline under corrosion impact over its lifetime. A finite element corrosion model was proposed, and an empirical power low model is also used and coupled with a probabilistic model for evaluating reliability index about a limit state function. The failure probability of structure was determinate for deferent corrosion rate (low, moderate and high rates), considering corrosion depth. Form method and Monte Carlo simulation are used for evaluating the structure reliability. The impact of applying both effect of corrosion and residual stress is shown which is appears a significant failure probability of the studied pipeline. The found results are analyzed and discussed.

Footing is an important part of a structure, because its repair is extremely difficult and cumbersome. Therefore, all structural parameters should be carefully considered when designing a footing. An isolated footing needs sufficient depth, when considering the fixed base assumption. Extensive research has previously been conducted to define and formalize the depth of a rigid footing, i. e., the depth required, such that footing behaves as a rigid. Alternatively, working stress method (WSM) and limit state method (LSM) provide a lower depth for low subgrades and a higher depth for high subgrades than that required by rigid condition if a unit width footing is considered for the design. This paper presents a simple approach for calculating the depth to meet the rigid condition under static loading. The proposed calculation method produced a better rigidity than the existing approaches and it correlated well to the finite-element method (FEM) for low subgrades. The reinforcement distribution is function of the bending moment (BM). Steel is uniformly embedded throughout the length or width of conventional footing methods, but this is inappropriate, because the bending moment is not uniform along the length or width of the footing. This paper proposes solutions to this by redefining the placement of steel in the central zone of the footing. The effective zone for reinforcement was based on the FEM results. This simple procedure was developed for calculating the maximum moment using the Diagonal Strip Method (DSM). DSM is a substitute for FEM, and it has been shown to correlate well. The BM at central zone as well as at the edges can be calculated to define the spacing of the reinforcements.

The work presents a finite element modeling of beam resting on a two-parameter layered soil. The behavior of the soil continuum and the beam are assumed to be linear and homogeneous isotropic. Using the strain energy expressions, the shear strain of the beam element and the soil foundation are taken together in the analysis. In this approach, the stiffness matrix of each component is elaborated and integrated in the finite element analysis. First, various examples are elaborated to show the effectiveness of the proposed approach and the ability of the numerical program developed for this concern. Second, the analysis is widened to study the influence of the soil properties on the interface continuum and on the beam responses. Third, a parametric study is carried out to highlight the effect of the position of springs at the interface continuum, the properties of soil, the deepest of the soil foundation and the ballast layer on the response of the interface and the beam itself. Moreover, shear deformations are presented to show the crucial influence on the beam, on the structure and on the interface behaviors. Obtained results show pertinent results corresponding to the interface continuum and the beam responses.

The performance of reinforced concrete (RC) element may be deficient for a variety of causes. Correct actions should be taken to resume the performance of the deficient element to maintain the strength and serviceability of the structure. A deficient RC column element may be identified in the form of spalling of concrete cover. A patching method could be selected to recover the damaged area and, hopefully, regain the strength of the damaged RC column to its original value. This research aims to investigate the suitability of patch repair material to recover the performance of damaged RC column. The investigation is carried out by comparing the behaviour of patched RC columns with the corresponding normal RC column. The eccentric loading has been set up in this investigation to induce compression failure of the RC columns. The simulated area of damage is patched using unsaturated polyester resin mortar (UPR mortar). The results indicate that the mode of failure is not induced at the patched sections. The presence of patching causes a redistribution of stress at the patched section in such a way, so a higher stress transfer occurs in the undamaged zone and in the longitudinal reinforcements compared to those of the normal column. The capacity of the patched RC columns is only 71– 92% of the normal RC column.

The focus of this study is to investigate the seismic behavior of outrigger-braced building considering the soil– structure interaction based on finding the best location of outrigger and belt truss system. For this purpose, a central outrigger-braced frame of a steel tall building is considered. A layered soil deposit underlied this frame and the resulting soil– structure system is subjected to seismic excitation. To analyze this system, direct method is employed in OpenSees. Also, elastic and in-elastic analyses are both considered and a comparison is made between current results and the results related to the system with fixed base. The best location of outrigger– belt truss system is determined by considering the maximum roof displacement, base moment and base shear with and without soil– structure interaction. It is shown that considering SSI affects the location of outrigger– belt truss system. Elastic analysis of both systems, namely with fixed base and with soil– structure interaction, showed that locating the belt truss at higher stories caused lower amounts of roof displacement.

The anchorage of the piles on a stiffer soil layer plays an important role to transmit the loads of the superstructure to the soil. Depending on the pile toe condition, three configurations of piles are considered: floating piles, rested, and anchored piles. To study the effect of the pile toe condition on the dynamic response of pile and pile groups, a three-dimensional finite element modeling of the soil– pile– slab dynamic interaction is presented. The soil and piles are represented as continuum solids and the slab by structural elements. Quiet boundaries are placed at the boundaries of the model to avoid wave reflection. The formulation is based on the substructuring method. The dynamic response is obtained in terms of the dynamic impedances. In this study the dynamic response of the floating, rested, and anchored piles are analyzed and the group effect is shown. An analysis of the horizontal and vertical pile foundation impedances is presented and the results are compared with different configurations.

Structures resting on sloping ground are highly vulnerable to earthquakes due to irregularities in plan and elevation. Structures are often analysed under earthquake loadings, without considering the effect of soil– structure interaction (SSI). This practice is not advisable from practical point of view. In this present study, an attempt has been made to study the effect of slope angle variation for the structures resting on sloping ground, considering the base of the structures fixed as well as flexible (SSI). The analysis is performed in equivalent static force method (ESFM), response spectrum method (RSM), time history method (THM), nonlinear static method (NLSM) and nonlinear time history method (NLTHM). Results expose the criticality associated with increment of slope angle, with and without SSI consideration. Importance of considering SSI in seismic analysis is also revealed.

The main objective of this study is strengthening of flat slabs in punching shear with a new model. For this purpose 15 numerical samples include a control and 14 strengthened defined and nonlinearly analyzed up to failure. The strengthening method is new method of grooving in two orthogonal direction (x and y axes of slab plan) and then mounting the external bars (sticking) in one direction and FRP in EBROG (externally bonded reinforcement on groove) method in another direction. The results showed the great efficiency of the method so that the punching shear capacity of strengthened samples increased between 28 and 62% compare to control one. Also the mode of failure changed in strengthened specimens from shear to flexure– shear and the punching critical area was broader and developed from the loading point. In the grooving method the sticking bars yielded in all specimens and the FRP tensile strain was closer to rupture strain compared to EBR.

The aim of the present study is to examine the behaviour of cold-formed steel (CFS) lipped channel built-up I-section with edge and intermediate web stiffeners under bending. Initially, the section dimension of length, width of the flange and depth of the sections are optimized numerically and finally, it is validated with the test results. All the select cross-section dimensions have satisfied the pre-qualified beam dimensions. Numerical analysis is carried out using the software ABAQUS. Totally, four section geometries are tested experimentally. After validation, a total of 75 parametric studies are carried out using the verified finite element model. All the results are compared with the direct strength method specifications for CFS structures and the suitable design modifications are detailed.

Warping and distortion are relevant kinematic features of thin-walled beam structures, which have a non-trivial analysis. On this basis, this paper not only evaluates the possible kinematic transmissions involving high-order warping and distortion, but also presents a procedure to analyze structures using mixed models based on shell and Generalized Beam Theory (GBT) elements. In this mixed beam-shell structure, the traditional shell elements are applied at structural detailing points, such as joints, and GBT elements are used to model the beams/columns. Such a modeling technique uses the benefits of both elements. Shell elements can easily simulate different types of geometry conditions and details, such as stiffeners and holes; meanwhile, for the beams and columns, GBT can provide high performance, accuracy, and an easy modeling approach with clear results. The numerical formulation is based on multi-freedom constraint techniques. Special attention is given to the Master– Slave method, which is developed based on GBT kinematic assumptions. Furthermore, there is a discussion concerning the choice of the master degrees of freedom and its implications in numerical performance. An example of a thin-walled hollow circular cross section illustrates the proposed approach and is compared with fully shell element models.

With the aim of avoiding confusion with any other commercial software having the same name, any future reference to the optimisation software package described in this article should be made as TOSCA-TS.