Action Of Horizontal Forces Research Articles

TRANSFER OF LOADS FROM THREE HETEROGENEOUS ELASTIC STRINGERS TO AN INFINITE SHEET THROUGH ADHESIVE LAYERS

This paper considers the problem for an elastic infinite plate (sheet), which on parallel finite parts of its upper surface is strengthened by three finite stringers, two of which are located on the same line, having different elastic properties. The stringers are deformed under the action of horizontal forces. The interaction between infinite sheet and stringers takes place through thin elastic adhesive layers having other physical-mechanical properties and geometric configuration. The problem of determining unknown shear stresses acting between the infinite sheet and stringers is reduced to a system of Fredholm integral equations of second kind with respect to unknown functions, which are specified on three finite intervals. It is shown that in the certain domain of the change of the characteristic parameters of the problem this system of integral equations can be solved by the method of successive approximations. Particular cases are considered, the character and behaviour of unknown shear stresses are investigated. Further, for various values of changing characteristic parameters of the problem the multiple numerical results and its analysis are presented.

ON A PROBLEM FOR AN ELASTIC INFINITE SHEET STRENGTHENED BY TWO PARALLEL STRINGERS WITH FINITE LENGTHS THROUGH ADHESIVE SHEAR LAYERS

The article considers the problem for an elastic infinite sheet (plate), which is strengthened on two parallel finite parts of its upper surface by two parallel finite stringers with different elastic properties. The parallel stringers are located asymmetrically with respect to the horizontal axis of the sheet and deform under the action of horizontal forces. The interaction between the infinite sheet and stringers takes place through thin elastic adhesive layers. The problem of determining unknown shear stresses acting between the infinite sheet and stringers is reduced to a system of Fredholm integral equations of second kind with respect to unknown functions, which are specified on two parallel finite intervals. It is shown that in the certain domain of the change of the characteristic parameters of the problem this system of integral equations in Banach space can be solved by the method of successive approximations. Particular cases are considered, the character and behaviour of unknown shear stresses are investigated.

Experimental Study on Effect of Disc Spacing on Soil Failure State of Expanded Pile under the Action of Horizontal Force and Application in Oceanographic Engineering

Qian, Y.; Fang, B.; Jin, Y., and Wang, R., 2020. Experimental study on effect of disc spacing on soil failure state of expanded pile under the action of horizontal force and application in oceanographic engineering. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 283–287. Coconut Creek (Florida), ISSN 0749-0208.In oceanographic engineering, concrete expanded piles represent a new type of pile foundation. This article observes small-scale half-section model pile of undisturbed soil, analyzes horizontal displacement of pile top and failure state of soil around piles under the action of horizontal force, and then further determines the effect of disc spacing on horizontal bearing capacity of concrete expanded piles. The test program, process, and test precautions are elaborated in the article, and the new findings of the test results, which provide a reliable theoretical basis for their application in oceanographic engineering, are presented.

Experimental Study on Effect of Disc Form on Soil Failure State of Expanded Piles under Horizontal Force

In this paper, test method of half-section small-scale model with indoor undisturbed soil is used to study the effect of difference disc forms on bearing mechanism of concrete disc piles and soil failure state around piles under horizontal force. The model piles with different disc cross-section forms were designed under the condition of undisturbed soil, and loading test was carried out to analyze soil failure state around the pile. The results show that: under the action of horizontal force, soil around the pile is cracked along the midline; asymmetric bearing disc is more reasonable than symmetrical bearing disc. The minimum load difference between the disc end fillet and the disc tip fillet is less than 5%. The curved end of bearing disc has little effect on the horizontal bearing capacity of concrete expanded disc pile.

TRANSFER OF LOADS FROM A FINITE NUMBER OF ELASTIC OVERLAYS WITH FINITE LENGTHS TO AN ELASTIC STRIP THROUGH ADHESIVE SHEAR LAYERS

This article deals with the problem of an elastic infinite strip, which is strengthened along its free boundary by a finite number of finite overlays with different elastic characteristics and small constant thicknesses. The interaction between the strip and the overlays is mediated by adhesive shear layers. The overlays are deformed under the action of horizontal forces. The problem of determination of unknown stresses acting between the strip and overlays are reduced to a system of Fredholm integral equations of the second kind for a finite number of unknown functions defined on different finite intervals. It is shown that in the certain domain of variation of the characteristic parameter of the problem this system of integral equations in Banach space may be solved by the method of successive approximations. Particular cases are discussed and the character and behaviour of unknown shear stresses are investigated.

Evaluation of structural capacity of triangular and hexagonal reinforced concrete free-form shells

This paper presents a study of the structural capacity of reinforced concrete free-form shells, with hexagonal and triangular plants supported on corners. Initially, it presents the computational models for free-form shells generation and the parameters used in a linear static analysis. From the results of this analysis, the conditions of minimum thickness in which the structural behavior of the shells agrees with the membrane theory of thin shells are defined. Then, these shells are submitted to nonlinear pushover analysis, considering the plasticity and the accumulation of damage in each load increase. To determine the capacity of these shells, the parametric analysis is performed with the variation of the mechanical properties and the directions of the application of the horizontal force, taking the structure to the failure point. The results present the elastic-plastic behavior of shell structures under the action of horizontal forces. Therefore, this study aims to broaden the knowledge on the performance of the free-form shells under the action of external horizontal loading, such as structures under seismic action.

Collapse State of Multi-Storey Masonry Walls Reinforced by Steel Ties Subjected to In-Plane Horizontal Loads

The determination of the seismic strength of masonry building is strictly connected to the in-plane strength of masonry walls under the action of horizontal forces. Simplified criteria are currently available in literature, based on modelling of the structure as loaded by dead loads and by a gradually increasing distribution of horizontal forces, proportional to the mass of the building. According to this approach, called push-over method, the seismic strength of the building corresponds to the intensity of these gradually increasing horizontal loads, leading the building to the failure condition. This paper moves in the framework of the Limit Analysis, based on the Heyman’s masonry model (1966), rigid in compression with no tensile strength. The resistant model refers to a multi-storey wall with openings arranged in regular patterns, along both vertical and horizontal directions, reinforced at floor levels by steel ties. The in-plane failure of the regular multi-storey walls can occur with the development of various kinematically admissible mechanisms, characterized by the attainment of the yielding state in the steel ties. The proposed methodology consists in the definition of the mechanism along which the failure effectively occurs and in a subsequent check of the statical admissibility of the internal stress state at the limit load. Only in this case, the corresponding kinematical multiplier is the effective collapse multiplier. The presence of the panels situated above the openings strongly conditions the in-plane failure of the wall, acting as diagonal struts, causing different horizontal displacements between the piers at the floor levels and consequently engaging the horizontal ties in the mechanism. In order to ensure the development of the global failure, avoiding local brittle failures, steel strengths of the ties have thus to be suitably defined. Finally, a parametric investigation is carried out considering different geometries of masonry walls and varying the position of the piers self-weights and the horizontal forces distribution, constant or proportional to the height of the masses from the foundation level.

Rocking in Presence of Cracking of Masonry Wall Piers

The wall pier represents the vertical element of multi-storey walls with openings, the main resistant structural components of a masonry building. Structural systems of wall piers and spandrels are required to sustain the in-plane seismic actions acting on the wall, opposing with their weights to the action of horizontal forces. The behavior of masonry constructions results to be very far from the one characterizing ductile structures, because of the lack of energy dissipation during the deformation. A strength resource of masonry structures, properly reinforced in order to avoid early local failures, consists in exhibiting rocking behavior, until a failure condition is attained. An investigation on the dynamic behavior of masonry wall piers is carried out by following Housner’s studies and properly introducing the effect of diagonal cracks, shown by typical post-earthquake cracking patterns. As a consequence, the system is characterized by the detachment of a lower triangular region that becomes ineffective during the development of the mechanism and does not oppose with its weight to the overturning. Finally, it is shown that the occurrence of diagonal cracks can be prevented by the execution of suitable retrofit interventions.

CHARACTERISATION OF BREAKING WAVES ON THE EDDYSTONE LIGHTHOUSE: A LABORATORY INVESTIGATION ON WAVE PRESSURE

Commonly, rock lighthouses are erected on the top of steep reefs and in limited water depths. The effect of these environmental conditions on wave loading requires deeper understanding. This paper investigates wave loading at small scale for a particular case study: the Eddystone lighthouse (UK). Load characteristics due to breaking waves are obtained by the use of pressure transducers and the test program is designed to generate a comprehensive data set covering a broader range of wave conditions. Although the magnitude of wave pressures is rather random from wave to wave of the same train of regular waves, the pressure impulsivity tends to decrease with increasing relative breaking distance. Four breaker types are described and particular attention is given to time histories of the line of action of horizontal force and vertical spatial distributions. Estimation of overall forces, obtained by pressure integration, indicates that the wave loading is strongly affected by the limited water depth condition. In fact, only small plunging waves are able to break at the structure; thus, they cause small forces despite the small breaking distances. Finally, the occurrence of the breakers is investigated on a dimensionless plane given by the combination of the Iribarren number and momentum flux of Hughes.

Instability in students' use of intuitive and Newtonian models to predict motion: the critical effect of the parameters involved

This study reports how children switch from intuitive to scientific models of explanation of motion when the numerical conditions in the presented problem are changed. Previous studies have suggested that student knowledge of mechanics may be compartmentalized: their everyday intuition serves in everyday contexts and their scientific model is activated, if ever, in academic contexts. In this study we investigate a case where significant numbers of students appear to draw on different models of motion in what is essentially the same, academic context, i.e. the prediction of the motion of a block on a smooth surface under the action of horizontal forces. Many students exhibit combinations of Aristotelian-like intuitions and Newtonian conceptions depending on the magnitudes of the quantities involved. The students' experience of being taught Newtonian theory in mathematics and physics has small but significant effects on the explanations they offer. The notion of anchoring and bridging is re-examined as a te...

Instability in students' use of intuitive and Newtonian models to predict motion: the critical effect of the parameters involved

This study reports how children switch from intuitive to scientific models of explanation of motion when the numerical conditions in the presented problem are changed. Previous studies have suggested that student knowledge of mechanics may be compartmentalized: their everyday intuition serves in everyday contexts and their scientific model is activated, if ever, in academic contexts. In this study we investigate a case where significant numbers of students appear to draw on different models of motion in what is essentially the same, academic context, i.e. the prediction of the motion of a block on a smooth surface under the action of horizontal forces. Many students exhibit combinations of Aristotelian-like intuitions and Newtonian conceptions depending on the magnitudes of the quantities involved. The students' experience of being taught Newtonian theory in mathematics and physics has small but significant effects on the explanations they offer. The notion of anchoring and bridging is re-examined as a teaching strategy in such situtions.

Three-Dimensional Interaction of Walls and Frames

The three-dimensional interaction of several plane walls, open section walls, and plane frames is studied under the action of horizontal forces. Walls are taken to have infinite shear rigidity while warping effects are considered. Frames are treated as vertical cantilever beams with infinite bending moment rigidities but finite shear stiffnesses. The floor slabs are replaced by an infinite number of diaphragms with no transverse stiffness but infinite in-plane rigidity. The stiffnesses of the walls and frames are assumed constant throughout the height of the building. A system of three differential equations of the third order solves the problem in a way similar to the displacement method. The method is useful in providing a general view of the macroscopic behavior of the structure through the use of a small number of elastic parameters.