Results of Experimental Studies of Piles on Horizontal Loads

Постановка задачи. Рассматриваются и сравниваются результаты лабораторных испытаний горизонтально нагруженной сваи, укрепленной стальной сеткой, расположенной в грунте, и отдельно стоящей сваи без сетки. Результаты. Производится сравнительная оценка перемещений и несущей способности сваи на горизонтальную нагрузку при лабораторном эксперименте. Для сопоставления результатов различных испытаний в лабораторных условиях были выполнены опыты в лотке с песком при одних и тех же диаметре и длине сваи. Эксперименты были проведены на моделях в Центре коллективного пользования им. проф. Ю. М. Борисова г. Воронежа. Выводы. Данные лабораторных экспериментов показали, что применение свай, укрепленных стальной сеткой, позволяет существенно повысить несущую способность свайных фундаментов и снизить горизонтальные и угловые перемещения по сравнению с отдельно стоящими сваями при одной и той же нагрузке. Statement of the problem. The results of laboratory tests of a horizontally loaded pile reinforced with a steel grid located in the ground and a free-standing pile without a grid are considered and compared. Results. A comparative assessment of the load-bearing capacity of the pile for a horizontal load is made during a laboratory experiment. To compare the results of various tests in the laboratory, experiments were performed in a tray with sand at the same diameter and length of the pile. The experiments were carried out on models at the center for collective use named after Prof. Yu. M. Barisov (Voronezh). Conclusions. The data of laboratory experiments have shown that the use of piles reinforced with steel mesh can significantly increase the load-bearing capacity of pile foundations and reduce horizontal movements compared to free-standing piles at the same load.

Effects of the Installation Method, Loading Condition, and Failure Mechanism on the Behavior of Suction Piles under Monotonic Horizontal Loading

A suction pile is a promising option when floating offshore structures are deployed at deep and distant locations. A suction pile is typically used for the foundation system of a mooring system subjected to horizontal loading with a load inclination. In this study, the effects of installation method, loading position, and load inclination on the behavior of a suction pile under monotonic horizontal loading were evaluated via large-scale soil chamber testing. A series of horizontal load tests were performed by varying the loading position at pile embedded lengths of 1/4, 1/2, 2/3, and 3/4. A horizontal load test with a load inclination of 20° was conducted and compared with that of a load inclination of 0°. The failure mechanism of the suction piles under monotonic horizontal loading was assessed via particle image velocimetry (PIV) analysis. The movement of the suction pile during monotonic horizontal loading was elucidated in terms of the horizontal displacement, vertical displacement, and rotation angle. The results of this study show apparent differences between jacking and suction-installed piles and piles under different loading conditions. The PIV analysis shows that the rotational behavior under monotonic horizontal loading can be a critical point to affect the horizontal resistance of the suction pile.

Experimental dynamic analysis of the arch road bridge

The paper presents an experimental dynamic analysis of the existing road bridge across the Labe river at Valy village in the Czech Republic. The observed structure is a bridge with 6 spans 23.1 m, 31.5 m, 84.0 m, 31.5 m and 23.1 m long. The horizontal load-bearing structure is a composite structure with two main steel girders and a lower reinforced concrete deck. The load-bearing structure is reinforced in the main span by the arch, this structural system is also called the Langer beam. The experiment was realized in three stages. The first one was performed in May 2020 before its opening, the second stage of the described experiment was realized in August 2020 and the third one was carried out in April 2021. The main purpose of the first stage was to determine in detail the natural frequencies and mode shapes of the whole bridge horizontal load-bearing structure also including the arch. The electrodynamic shaker, that was located on the bridge deck in the quarter of the main bridge span, was used for excitation of the bridge vibration. The measured characteristics of the natural vibration were compared with the calculated ones. Based on this comparison, the theoretical bridge model was verified. Basic objective of the second experiment stage was to verify new approach to dynamic response measurement – radar interferometry realized by two synchronized radars. The vibrations of the bridge caused by the standard road traffic and also by pedestrians were observed concurrently by both radar interferometry and classical approach realized by high sensitive piezoelectric accelerometers. The experiment was focused on the main span of the bridge only and the levels of forced vibration were observed primarily. However, the fundamental natural frequencies were also evaluated. The third stage was carried out by classical approach only. Again, the bridge vibration caused by the usual road traffic and pedestrians were measured in the main bridge span only because this section of the bridge was the most dynamically sensitive. Again, the levels of forced vibration were observed and the fundamental natural frequencies were determined. The evaluated natural frequencies from all three experiment stages were consequently compared.

Comparative analysis of Wall Belt Systems, Shear Core Outrigger Systems and Truss Belt Systems on Residential Apartment

The outrigger structural system is one of the horizontal load resisting systems. In this system the belt truss ties all the external columns on the periphery of the structure and the outriggers connect these belt trusses to the central core of the structure thus restraining the exterior columns from rotation. The shear wall was implemented to oppose lateral loads. To complete these characteristic the Outrigger & wall belt system used in the structure. In this project a G+10 Storey structure has analysed using seven different cases named as RA1 to RA7-OTB. 1 to 7 indicates single outrigger system, shear core outrigger system truss belt support system with optimized trusses, at various locations under seismic zone III. The built up area used for various case as 315 sq. m. After performing result analysis, the comparative analysis of all the cases shows that the most efficient case for the above study is Case RA4. Here for efficiency of the project, two types of optimized truss belt support which has performed well and observed as most optimized and correspondingly minimum in all the cases. Keywords: Truss wall belt support, core wall belt support, outrigger, wall belt, CSI-ETABS, multi-storey

Analysis of Soil Resistance under Horizontal Load of Rigid Antislide Pile

In order to study the bearing characteristics and failure mechanism of the rigid antislide pile under horizontal load, the stress of rigid antislide pile under transverse axial large displacement load is analyzed by using elastic-plastic theory, finite element analysis, and model test. The theoretical formula of the proximal plastic earth pressure near the pile with the depth of soil under the horizontal force is obtained. The results show that the standard is insensitive to the variation of soil parameters and the influence of soil parameters on allowable soil resistance in front of pile should be considered. With the increase of the horizontal force of the pile top, the soil near the pile is destroyed in this process gradually, which is the decline of the cross section of the maximum soil resistance of the pile. When the horizontal displacement of pile top is 20 mm and 70 mm, the soil resistance value and the ultimate soil resistance value in front of the pile can be selected, respectively. The plastic zone develops to the front and bottom of the pile at the same speed, at an angle of 45° with the direction of gravity. When the displacement reaches 34 mm, the plastic zone develops to the deeper depth obviously. The results can provide a theoretical basis for the design and application of antislide piles during the process of slope protections.

DETERMINATION OF THE MOVEMENTS OF THE COMBINED FLOORING USING PROFILED FLOORING FROM HORIZONTAL LOADS

Combined steel-reinforced concrete floors using profiled flooring are the most common solution in buildings with a steel frame. Flexible stops ensure the joint work of the frame and the flooring disks. Deformations of the combined flooring, and therefore of the frame in the horizontal plane, can occur due to the possible appearance of uneven force effects that cause a shift. At the same time, the magnitude of these deformations is influenced by both the level of force influences and the shear stiffness of the flooring disk, as well as the malleability of the flexible stops connecting the latter to the supporting frame. The paper proposes a method for determining the deformations of the flooring disk and the supporting frame from a horizontal load. The problem is considered in which a square floor slab is based on a contour on the crossbars of the frame, but its fixing with flexible stops is provided on two parallel sides. A formula for determining the movements of the frame from the horizontal load is proposed. The displacement of the flooring disk is analytically determined, it is noted how the malleability of flexible stops affects the determination of the final result. Using the example of a numerical experiment, the possibility of using the proposed method is demonstrated. The movement in the flooring disks will allow to assess the rigidity of the frame from horizontal loads without focusing on the deformation of each component of the steel-reinforced concrete slab. In addition, it will help to use materials and resources more efficiently by optimizing design solutions.

Interaction peculiarities of a single unit bored pile with the surrounding rock mass under the horizontal load effect

Interaction peculiarities of a single unit bored pile with the surrounding rock mass under the horizontal load effect, as well as loss mechanism of piles bearing capacity, are considered. The article presents the numerical modeling results and a method developed on their basis for calculating piles in rocky soils under the horizontal load effect under the spatial elastic-plastic problem conditions, with the account of the contact behavior between the pile and the rock mass. The study of the single unit bored pile interaction and the surrounding rock mass under the horizontal and moment loads effect was carried out based on the numerical models’ analysis of the piles and the surrounding rock mass in a spatial setting using the finite element method. The use of regression analysis methods made it possible, to obtain parametric equations, based on the numerical modeling obtained results, that connected the studied response functions (bearing capacity and horizontal displacement of the pile) from preselected independent factors reflecting the geomechanical properties of the body and the design piles peculiarities. The developed calculation method allows at the preliminary design stage to estimate the horizontal pile displacement value, as well as its bearing capacity. Also, using the proposed technique, it is possible to make a piles load test schedule, which can be used in the field observation preparation at the design stage. The relevance of the topic is due to the fact that in modern construction practice, bored piles are used to transfer to the foundation significant loads, on the rock foundation from structures for various purposes, including transport (bridges and overpasses piers’ foundations, etc.).