Search

The aim of this paper is to show the influence of the subgrade reaction coefficient modelling on the simple 3D frame subjected to horizontal symmetrical static load. Since the work represents a continuation of the research on this topic, it was decided that the construction, in this case too, was built on the square foundations on granular soil. Different values of subgrade reaction coefficient obtained for the square foundation are the consequence of using different expressions defined by individual authors. Thus, one diagram shows each author's relation between the width of the foundations and the value of the subgrade reaction coefficient. The response of the characteristic structural framework additionally loaded with horizontal static force is then described further in the paper. [ABSTRACT FROM AUTHOR]

• Nature of building failure and description of the problem. • Type of settlement encountered. • Method of underpinning adopted. • Settlement Analysis and solution to the existing problem. • Panorama of distressed and underpinned building. Many existing foundations, particularly those that are old and dilapidated, are no longer strong enough to support the pressures they bear or support new loads applied to them. In order to boost the load bearing capacity, a unique underpinning technique is required. Underpinning technique provides secure, efficient, and reliable solutions to foundation and geotechnical problems affecting the foundations of buildings. However, the practice of underpinning is not common in Nigeria. This paper presents a case study on the settlement failure of a two-storey residential building in Lagos, Nigeria. The residential building encountered excessive differential settlement due to the variation in the soil strata in in 06°26′12″N Long: 3°30′44″E area of Lagos state. Some portion of the building was laid on weak and loose clayey sand which showed signs of foundation distress and led to the eventual choice of an underpinning technique adopted to extend the foundation depth to a stable stratum, to salvage the failed areas of the foundation in order to strengthen the bearing capacity and to minimize settlement. Underpinning was done because the original raft foundation was inadequate for vertical and lateral loads. The procedure used for underpinning was summarized. The measured settlement points of the underpinned foundations after six-year service life were less than 0.333 mm. This result meant that every point (from points 1–10) measurements were below the settlement limit which guaranteed the bearing resistance of the building. The result showed that the underpinning technique salvaged the areas that initially settled and showed distress signs. [ABSTRACT FROM AUTHOR]

Abstract Load and Resistance Factor Design (LRFD) optimization is concerned with calibrating load and resistance factors against a pre-defined target safety level. The uncertainty in soil properties, the incomplete understanding of soil-structure interaction and the lack of statistical information slowed the development in the field of foundation optimization. A unified target reliability index is proposed for the design of a single pile, a non-redundant pile group, and a redundant pile group foundation. Resistance factors for axially loaded drilled and driven piles based on the statistical results of over 4000 pile load tests were calibrated using the proposed approach. [ABSTRACT FROM AUTHOR]

In conventional analysis, superstructures are generally analysed considering their bases as either totally fixed or hinged. But in reality the superstructure, is connected to compressible soil-foundation system. Hence, there is a need of considering the compressibility of soil and flexibility of foundation for the analysis of superstructure. The effect of Soil-Structure Interaction (SSI) on a G+3 storey building frame with 2 bay resting on pile foundation is studied in the present paper wherein the pile foundations are embedded in Cohesive Soil. A FORTRAN 90 code is developed using three dimensional finite element method for the analysis to be more realistic. An uncoupled analysis is employed to demonstrate the effect of SSI. The results obtained by considering the effect of SSI are compared to that of building with fixed supports (neglecting underlying soil and foundation). A parametric study is conducted by varying pile length, pile diameter, pile spacing and configuration of the piles in the pile group along with the modulus of elasticity of soil. The effect of change in these parameters is observed by analysing the top displacements of the building frame as well as bending moments in both beams and columns. It is observed that these values have increased by a considerable factor when SSI is taken into consideration for the analysis. [ABSTRACT FROM AUTHOR]

Due to the low tensile strength of masonry perpendicular to the bed joint, masonry wall panels have non-linear material properties. Assuming simple elastic constitutive laws, this article presents two modelling variants, which consider the lack of tensile strength in a simple manner. Both variants are investigated for their advantages and disadvantages. In a second part of the article, the application of the methods will be illustrated through the example of a four-storey building. [ABSTRACT FROM AUTHOR]

The recent earthquakes in Italy demonstrated the extreme vulnerability of historical and cultural structures. Masonry vaults, which represent artistically valuable elements of these constructions, have been recognised among the most vulnerable elements. Traditional vault retrofit methods, such as buttresses or ties, are still widely adopted. These retrofit methods prevent differential displacements between vault supports (e.g., abutments, masonry piers and loadbearing walls). However, the pier differential displacement is not the only vulnerability source for vaults, and in many cases, further retrofit interventions are needed. Innovative retrofit methods based on inorganic matrixes, such as IMG, are aimed to prevent hinge mechanism failures. Such methods are suitable to be applied on vaults already retrofitted using traditional methods. The knowledge of the seismic behaviour of a vault, once the differential displacement between the supports is prevented, can be crucial to the assessment of potential further vulnerabilities of vaults already retrofitted with traditional methods. However, a deep knowledge of vault seismic behaviour is still lacking from an experimental point of view. Indeed, to date, few dynamic experimental studies have been conducted. Therefore, to investigate the seismic behaviour of masonry barrel vaults, several shaking table tests were performed on a full-scale specimen before and after the retrofit interventions. The tests investigated the main seismic properties of the tested structure and clarified the cracking mechanisms and capacity improvement due to the retrofit interventions. A comprehensive overview of the main results of the experimental tests has been presented. [ABSTRACT FROM AUTHOR]

This paper describes a systematic approach of inspection, diagnosis, and repair for masonry walls and their claddings, aiming at facilitating the inspection process and deciding on the repair of these elements. It also helps to combat their degradation. Based on a visual analysis, the inspector is able to identify anomalies and use the proposed system tools to establish correlations with its source, delineate an accurate diagnosis, and determine the best repair technique. The tools that allow a faster and simpler inspection and decision are presented here. The nature of the anomalies, their related causes and appropriate repair techniques are classified, listed, and then related through correlation matrices to create a database. This equips the inspectors with the information they need about the pathology in masonry walls, as well as its classification through suitable terminology, so that a statistical analysis can be performed to find the chief causes of the anomalies. The system was developed under a strategy of proactive maintenance, and it represents an innovation that is as useful to rehabilitation in southern Europe as it is in other regions where masonry walls are a widely used technique. [ABSTRACT FROM AUTHOR]

Masonry structure is the main form of Chinese urban and rural housing construction structure. And heavy casualties and huge economic losses are caused by the damages of masonry structures in the previous destructive earthquake. So the failure modes of masonry structures are analyzed in the paper. ABAQUS software was used; and the Xuankou High School Student Dormitory of masonry structure in Yingxiu town, severely damaged under the Wenchuan earthquake, was taken for example. The influence of the stiffness ratio of pier between windows and spandrel on the failure modes of masonry structures is discussed. The results show that the failure modes in the earthquake could be changed by controlling the stiffness ratio. Suitable stiffness ratio helps proper design of masonry structures. [ABSTRACT FROM AUTHOR]

This article deals with the production of veneer walls as specified in DIN EN 1996-2/NA [3]. Against this background of the extensive revision of the section for veneer walls an exposition in accordance with the previous requirements as specified in DIN 1053-1 can hardly be recommended. The necessity for a basic revision of the section for veneer wall construction has already been discussed in detail and justified in several technical articles published in previous years, see [4] to [7]. With many changes and corrections in the section for veneer walls in the National Annex of DIN EN 1996-2 [8] it is certainly not a question of new rules for this method of building, but an adjustment of the requirements in the previous standard on the basis of the practical experience gained over several years. The new requirements for the execution of cavity facing masonry enable a simple and economic implementation of this external wall construction. [ABSTRACT FROM AUTHOR]

In the recent past, the masonry industry has developed many different solutions for optimising the heat protection of buildings. This took place for the building materials, geometric design, but also by development of multiple layered stones in which the components masonry unit, insulation and outer shell have been integrated into a block. [ABSTRACT FROM AUTHOR]

Seismic performance of rocking soil-structure systems subjected to near-fault pulses is investigated considering foundation uplifting and soil plasticity. An extensive parametric study is conducted including medium-to-high-rise buildings with different aspect ratios based on shallow raft foundation at stiff-to-rock sites. Mathematical directivity and fling pulses are used as input ground motion. The superstructure is assumed to have three different boundary conditions: (a) fixed-base, (b) linear soil-structure interaction (SSI), and (c) nonlinear SSI. Evidently, the prevailing pulse period Tpis a key parameter governing nonlinear SSI effects. The normalized acceleration response spectra reveal that despite beneficial effects of foundation uplifting and soil yielding in most cases, there are some minor regions in which the response accelerations are amplified. In addition, more slender buildings significantly benefit from uplifting and soil yielding when subjected to short- and medium-period directivity pulses compared to squat structures. However, response amplifications with respect to fixed-base structures are considerable in case of slender structures subjected to medium- or long-period directivity pulses. So that neglecting the SSI effects on seismic performance of rocking structures with shallow foundations, as mostly assumed in common practice, may give rise to inaccurate estimations of force demands against near-fault pulselike ground motions. Furthermore, the envelope of residual foundation tilting θris limited to 0.015 rad, in case of directivity pulses. [ABSTRACT FROM AUTHOR]

Ground movements observed during foundation installation and basement construction of a residential 53-story RC tower are presented. The One Museum Park West building is located in Chicago, Illinois, and was developed using a combination of bottom-up methods, used for the construction of a central concrete core of the building, and top-down methods to build five levels of basements. The excavation extended 13-15 m below grade and was made through soft to medium-stiff clays. The building was supported by drilled shafts and a perimeter wall formed by secant piles that transitioned to tangent piles below the bottom of the cut. The system was laterally braced with RC floor slabs structurally connected to the secant pile walls and the RC core. Field performance data were collected by means of settlement points and inclinometers located close to the walls on two sides of the excavation. The construction sequence and attendant ground movements during each main activity are summarized. As much as 160 mm of settlement was recorded in the adjacent streets throughout construction. Wall and foundation installation accounted for approximately 35% of the total settlements during construction, whereas top-down construction of the basement resulted in approximately 40% of the total settlements. These data emphasize the importance of considering all construction activities when making predictions of ground movements adjacent to deep supported excavations. [ABSTRACT FROM AUTHOR]

Abstract: The subject of the solution consists in the design and evaluation of vibro-isolation of the multifunctional reinforced concrete frame structure of a building over the tunnel metro structure, based on analysing its 3D calculation model. Measured vibrations in accelerations from passing metro trains were used as non-periodic excitation of the object on the level of its foundation slab. Results of the dynamic calculation are used to document the nature of the building structure response, and of the reduction/amplification of the vibrations at selected points of individual storeys during the pass of metro trains, including the frequency characteristics of the response. The comparison of the building response without and with vibro-isolation is used to demonstrate the efficiency of using a rubber layer in the footing bottom for reducing the transfer of vibrations from the metro to the building. Measurement of the vibrations when the construction had been finished allowed to compare the vibration prognosis to vibrations actually measured in the finished structure. [Copyright &y& Elsevier]

Nachrichten: Deutscher Bautechnik-Tag 2015 in Düsseldorf: Call for Papers. / Die neue Fassung der DIN EN 1997-1:2014-03 (Eurocode 7-1) wird nicht bauaufsichtlich eingeführt! (Dr.-Ing. B. Schuppener) Persönliches: Professor Dr.-Ing. habil. Fritz-Ferdinand Zitscher verstorben. ( Georg Heerten) Firmen und Verbände: Bundesstiftung Baukultur und Förderverein starten gemeinsame Aktion 'Die Bundesstiftung Baukultur stärken. / DWA übernimmt Programm des F. Hirthammer Verlags. Auslobung: Karl-Imhoff-Preis der DWA ausgeschrieben. / Neue Runde im Wettbewerb 'Auf IT gebaut - Bauberufe mit Zukunft'. [ABSTRACT FROM AUTHOR]

Studies concerned with evaluation and rehabilitation of historical masonry structures consider structural analysis in order to better understand the seismic behaviour of these buildings, to define the causes for present damage and to asses the safety level for a large variety of actions. Structural analysis such as linear, plastic or nonlinear analysis contributes to all the stages and activites related to the evaluation and rehabilitation process. This paper follows a description of the modelling methods of masonry structures taking into consideration different modelling strategies in correlation with the complexity of the analysed elements and the expected type of results. Advantages and disavantages of different modelling techniques and the applicability of these methods in the field of old masonry structures assessment are presented. [ABSTRACT FROM AUTHOR]

A design is examined, and results of experimental-theoretical investigations cited for a conical cast-in-place pile, and recommendations are given for its use. [ABSTRACT FROM AUTHOR]

Laws governing development of additional settlements of buildings constructed in the 1960s and 70s on shallow strip foundations when the bed is loaded by the weight of a newly constructed entity in a dense urban setting are examined. [ABSTRACT FROM AUTHOR]

Results of investigations conducted to determine geometric characteristics of foundations with use of geophysical procedures are examined. The effectiveness of hole methods of electrometry is demonstrated in examples of numerical and physical modeling and experimental observations. Means are proposed for refinement of the procedure for complex geologic conditions. [ABSTRACT FROM AUTHOR]

Für die Analyse gemauerter Bogentragwerke aus Natursteinen ist ein umfassender Kenntnisstand des Bestandes erforderlich. Das bedarf einer strukturierten Zusammenarbeit aller Fachdisziplinen, die sich mit der Erkundung und Beurteilung von Natursteinbauwerk beschäftigen. Bei der statischen Analyse sind die im 19. Jahrhundert entwickelten grafischen Verfahren hilfreich. Ihre Ergebnisse dienen als Eingangsgröße für elektronisch gestützte Modelle und deren Plausibilitätskontrolle. Aufgrund der potentiellen Kinematik von gemauerten Bogentragwerken kann ihre Traglast nur nichtlinear, also ohne Superposition der Lastfallergebnisse, ermittelt werden. Ist eine Stabilisierung eines gemauerten Bogentragwerks unumgänglich, so sollte ein biegesteifer Überbau in Betracht gezogen werden. Die Verstärkung von Bögen mit einer aufbetonierten Schale sollte vermieden werden. Retrofitting of masonry arch structures under high loads. For the analysis of masonry arch structures made of natural stone, a comprehensive knowledge of the existing structure is required. It needs a structured cooperation between all scientific disciplines that deal with the exploration and evaluation of natural stone buildings. The graphic methods developed in the 19th Century, are helpful. The results will serve as input for electronically supported models and their validation. Because of the potential kinematics of masonry arch structures, the collapse load can only be determined non-linear, which means without superposition of the load case results. If a stabilisation of a masonry arch structure is inevitable, a more rigid superstructure should be considered. It should be avoided to reinforce the arch structure with a skin of ferroconcrete. [ABSTRACT FROM AUTHOR]

Certain positions of standard documents relating to design of beds and foundation on soils prone to slump-type settlement are analyzed, and suggestions are given for improvement of the in-service reliability of the buildings and structures. [ABSTRACT FROM AUTHOR]

Basic positions of the Instructions for analysis and design of seismically isolated buildings and structures in regions of Turkmenistan with a seven-point and higher seismicity are discussed. The instructions are based primarily on multilevel design using the design and maximum earthquakes. Particular attention is focused on seismically isolating foundations on soft soils. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyse a colums raft foundation system. The soil, on which it is located the structure, belongs to difficult foundation earth and is characterized by a contractile clay with the presence of underground water. Using geotechnical calculation programs has been evaluated the behaviour of piles with large diameter (columns) based on three modelling types of slab design and considering loaded only with axial force, because, especially in this case, the foundation have to ensure safety for entire building. We analyse a single column with the bigger load provided from the slab, proposing also a reinforcement solution. The interest for analysing the columns is to know that the interaction between foundation system and foundation environment is very important. To accomplish these conditions mentioned before it is necessary to ensure the column strength. This research also wants to determine the quantity of materials (concrete and steel) in columns. The final task of the analyse is to design a resistance and safety foundation system. [ABSTRACT FROM AUTHOR]

Stone masonry is one of the oldest building techniques used worldwide and it is known to exhibit poor behaviour under seismic excitations. In this context, this work aims at assessing the in-plane behaviour of an existing double-leaf stone masonry pier by experimental testing. Additionally, a detailed 3D finite element numerical analysis based on micro-modelling of the original pier is presented (fully describing the geometry and division of each individual elements, namely infill, blocks and joints) aiming at simulating the experimental test results. This numerical strategy can be seen as an alternative way of analysing this type of constructions, particularly useful for laboratory studies, and suitable for the calibration of simplified numerical models. As part of a wider research activity, this work is further complemented with the presentation of an effective retrofit/strengthening technique (reinforced connected plaster) to achieve a significant improvement of its in-plane cyclic response which is experimentally verified in the results presented herein. [ABSTRACT FROM AUTHOR]

Masonry structures can be considered as the simplest type of structures concerning its assemblage but, at the same time, it is one of the most complex construction materials in terms of mechanical properties and correct behaviour assessment. In this context, the work herein presented aims at describing an experimental testing campaign recently carried out in order to characterize the out-of-plane behaviour of traditional masonry constructions. Taking advantage of the existence of a traditional two-storey masonry building abandoned after the 1998 Azores earthquake, several in-situ tests were defined and performed with the application of quasi-static cyclic loads at the building top level in the out-of-plane direction. In addition, the efficiency of retrofitting and/or strengthening techniques applied during the 1998 Azores reconstruction process was also experimentally evaluated. Finally, an overall discussion of these techniques is presented, resorting also to previous tests' results carried out by the same authors, aiming at inferring and suggesting quantifications of strengthening techniques' contributions for future interventions on existing buildings. For this purpose, simple analytical mechanical approaches were adopted in order to provide numerical estimates of strength that were found in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

O. A. Savinov's fundamental role of in the development of methods for analysis and design of foundations under machinery inducing dynamic loads and methods for earthquake-resistant construction is examined. His proposed dynamic models of soil beds and their further development are discussed. [ABSTRACT FROM AUTHOR]

Information on the organization and execution of work involving application of jet technology to soil stabilization during reinforcement of the foundations of historical buildings on land occupied by the State Museum and Reservation "Tsitsyno" is presented. [ABSTRACT FROM AUTHOR]

A computational model of foundation-bed deformation, which is based on the method of layer-by-layer summation with consideration of the components of the deviator S and spherical σ tensors, and the relationship between which is different at different points of the bed, is presented. Nonlinear dilatational strain of the soil over time is examined with consideration given to the change in degree of consolidation of the bearing layer of soil in the foundation bed owing to dilatancy. [ABSTRACT FROM AUTHOR]

A viscoelastoplastic hardening model, developed by the author, which dwells upon the notion concerning the work of weak clayey soils, is presented. Use of the model makes it possible to examine the problem of the interaction of buildings on different types of foundations, and also the effect of deep pits on the surrounding development. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the applicability of global ductility in the conventional design procedure of structure–foundation systems under earthquake excitation. For a bilinear elastoplastic model, an equivalent ductility factor for the combined structure and foundation is derived, which can be used in conjunction with the enlarged period and increased damping due to soil–structure interaction (SSI) to determine the design strength. A geometric transformation rule for predicting the ductility demand developed in the structure alone from that experienced by the interacting system is also derived, without the need of computing the rigid-body motion of the foundation. To validate this practical approach for assessing both inelastic strengths as well as ductility demands, a number of numerical results for different system parameters and earthquake excitations are provided. The effects of principal parameters involved are also examined. [Copyright &y& Elsevier]

Strengthening of the foundations of a building in a commercial complex in Ufa with piles injected in predrilled holes in connection with a change in the design of the building while under construction is described. Structural solutions adopted on the basis of monitoring of bed deformations are substantiated. [ABSTRACT FROM AUTHOR]

The possibility of converting from the stress state of a bed under a rectangular foundation to the stress state of a bed under a strip of semi-infinite length is demonstrated. A simpler solution, which defines the stress components under a flexible rectangular foundation, is obtained. These solutions are analyzed. [ABSTRACT FROM AUTHOR]

Basic positions of A. M. Dzagov's paper "Determination of characteristics of the proneness of loess soils to slump-type settlement," which was published in the No. 6 issue of 2009, are discussed. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the results of the forensic analysis carried out on a set of buildings located on the same block in the center of Gijón (NW of Spain). The foundations of these buildings were laid between the years 1944 and 1945, using wooden piles. These wooden piles may have been affected by a subsequent reduction in the groundwater table, caused by the depletion of water that occurred during the construction of the basement of a building located on the adjacent block. Evidence of the first major damage to the building appeared upon initiating construction of the aforementioned basement. The situation was worsened by debris falling from one of the damaged buildings onto a public street below. Within a week, after the city authorities had reviewed the technical reports, they decided to proceed with the eviction of more than forty families in the affected buildings, thus triggering considerable social alarm throughout the region. This article provides a detailed description of the problem, analyzes the damage caused to the buildings, and based on such analysis and description, this article seeks to establish the different hypotheses in an effort to reveal what caused the problem. The focus of this analysis is to present the rotting of the head of the wooden piles of the foundation as the main cause responsible for the ruin of the affected buildings. The rotting was caused as a result of artificially lowering the groundwater table, which occurred during the construction of a building located in the vicinity. This study also analyzes the land subsidence and negative friction experienced by the piles as a result of artificially lowering the groundwater table. [Copyright &y& Elsevier]

Abstract: The paper presents a new macroelement model for shallow foundations. The model is defined through a non-linear constitutive law written in terms of some generalized force and displacement parameters. The linear part of this constitutive law comes from the dynamic impedances of the foundation. The non-linear part comprises of two mechanisms. One is due to the irreversible elastoplastic soil behavior. It is described with a bounding surface hypoplastic model, adapted for the description of the cyclic soil response. An original feature of the formulation is that the bounding surface is considered independently of the surface of ultimate loads of the system. The second mechanism concerns the detachment that can take place at the soil–footing interface (foundation uplift). It is totally reversible and non-dissipative and can thus be described by a phenomenological non-linear elastic model. The macroelement model is qualitatively validated by application to soil–structure interaction analyses of simple real structures and by comparison with results from more sophisticated methods of analysis. [Copyright &y& Elsevier]

This paper presents a fundamentally new approach for the manufacturing and the possible applications of lab on a chip devices, mainly in the form of disposable fluidic microchips for life sciences applications. The new technology approach is based on a novel microscale thermoforming of thin polymer films as core process. The flexibility not only of the semi-finished but partly also of the finished products in the form of film chips could enable future reel to reel processes in production but also in application. The central so-called ‘microthermoforming’ process can be surrounded by pairs of associated pre- and postprocesses for micro- and nanopatterned surface and bulk modification or functionalisation of the formed films. This new approach of microscale thermoforming of thin polymer film substrates overlaid with a split local modification of the films is called ‘SMART’, which stands for ‘substrate modification and replication by thermoforming’. In the process, still on the unformed, plane film, the material modifications of the preprocess define the locations where later, then on the spatially formed film, the postprocess generates the final local modifications. So, one can obtain highly resolved modification patterns also on hardly accessible side walls and even behind undercuts. As a first application of the new technology, we present a flexible chip-sized scaffold for three dimensional cell cultivation in the form of a microcontainer array. The spatially warped container walls have been provided with micropores, cell adhesion micropatterns and thin film microelectrodes. [ABSTRACT FROM AUTHOR]

Problems associated with the design of various types of foundations supporting cellular-communication towers are examined as a function of the type and properties of the bed soils, and the hydrological and geologic-engineering conditions at the construction sites. [ABSTRACT FROM AUTHOR]

Problems associated with the design of foundations of buildings and structures in karst-prone regions are examined. Basic analytical positions are formulated for the design of these foundations. Methods are proposed for evaluation of the deformation characteristics of the bed in designing foundations subject to the formation of a karst-induced collapse. [ABSTRACT FROM AUTHOR]

This paper explores the enhancement of catalyst performance by inducing convection inside a macroporous catalyst carrier. The catalyst carrier used was an acicular mullite monolith with highly permeable microstructured walls. The monolith walls were coated with colloidal silica and impregnated with Pd. After performing the proper preparation steps, the high permeability of the walls was preserved and the catalyst was uniformly distributed with a low effective diffusion length. The catalyst performance of the selective hydrogenation of 3-methyl-1-pentyn-3-ol was investigated in a monolithic stirrer reactor, under internal diffusion-limited conditions, using different silica-supported palladium monoliths. At 2.3 bar H2, 20 mol/m3alkyne, and 25 °C, using equal catalyst loadings, the activity per unit monolith volume was 100% greater and the maximum yield of the alkene was 9% greater for the mullite monolith than for the eggshell-coated monolith with impermeable walls. This confirms that internal diffusional limitations were reduced. Pressure pulses of passing gas bubbles inside the monolith channels induced a convective enhancement, thereby making mass transfer limitations inside the highly permeable walls absent. [ABSTRACT FROM AUTHOR]

Recommendations for consideration (usually not previously brought to attention) of characteristic features of the resistance of large-diameter cast-in-place piles during their loading, which is important in analyzing their settlements, are provided on the basis of codification of test results of the indicated piles. [ABSTRACT FROM AUTHOR]

A method of analyzing the strengthening of foundation beds with crushed-stone piles is discussed. [ABSTRACT FROM AUTHOR]

The history of the development of methodical and regulatory documents relative to construction in karst-prone areas is cited. The basic content of existing regulatory documents is presented, and attention is focused on some of their deficiencies. Specific approaches to the development of a standard for construction in karst-prone areas are proposed. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents experimental results on the mixing process in a coaxial jet mixer in two mixing regimes. In the first mixing regime, a recirculation zone develops just behind a nozzle near mixer walls, while in the second regime a jet is mixed with the co-flow without developing a recirculation zone. In the both regimes, the mixing process is studied at Re d =10000. Behind the nozzle over the range 0.1< x/D <9.1, a velocity field in mixer cross-sections is measured by a one-component laser Doppler velocity meter and a scalar field is detected by the laser image fluorescence (LIF) method. A transverse autocorrelation function, integral length scales and probability density functions (PDF) are calculated using instantaneous distributions of a scalar and its fluctuations. It is shown that the scalar field acquires a homogeneous state faster than the velocity one. A quasi-uniform scalar distribution over the mixer cross-section is completed at the distance x/D =5.1 in the first mixing regime, while this distribution has not been yet attained in the second. Analysis of the turbulent statistical moments and the autocorrelation function reveals how unsteady vortex structures exert a dramatic influence on the mixing. When the recirculation zone has developed, long-period antiphase oscillations exist near the mixer walls. [Copyright &y& Elsevier]

In shallow foundation design, the key improvements offered by LRFD over the traditional working stress design (WSD) are the ability to provide a more consistent level of reliability between different designs and the possibility of accounting for load and resistance uncertainties separately. In the development of LRFD, a framework for the objective, logical assessment of resistance factors is needed. Additionally, in order for LRFD to fulfill its promise for designs with more consistent reliability, the methods used to execute a design must be consistent with the methods assumed in the development of the LRFD factors. In this paper, a methodology for the estimation of soil parameters for use in design equations is proposed that should allow for more statistical consistency in design inputs than is possible in traditional methods. Resistance factors for ultimate bearing capacity are computed using reliability analysis for shallow foundations both in sand and in clay, with input parameters obtained from both the cone penetration test and the standard penetration test, and for both ASCE-7 2000 and AASHTO 1998 load factors. Resistance factor values are dependent upon the values of load factors used. Thus, a method to adjust the resistance factors to account for code-specified load factors is also presented. [ABSTRACT FROM AUTHOR]

LRFD shows promise as a viable alternative to the present working stress design (WSD) approach to shallow foundation design. The key improvements of LRFD over the traditional WSD are the ability to provide a more consistent level of reliability and the possibility of accounting for load and resistance uncertainties separately. For LRFD to gain acceptance in geotechnical engineering, a framework for the objective assessment of resistance factors is needed. Such a framework, based on reliability analysis, is proposed in this paper. Probability density functions (PDFs), representing design variable uncertainties, are required for analysis. A systematic approach to the selection of PDFs is presented. A procedure such as that proposed provides a rational probabilistic basis for the development of LRFD methods in geotechnical engineering. [ABSTRACT FROM AUTHOR]

An attempt is made to establish an analytically based estimate of the influence zone surrounding the tip of a loaded pile in sand. In the framework of the cavity expansion theory and a confined local failure mechanism, explicit expressions are derived in which the sizes of the upward and downward influence zones are properly linked with the angle of shearing resistance, the stiffness, the volumetric strain, and the mean effective stress of the sand at the pile tip. Based on a series of parametric analyses, the mean range of the influence zone is suggested. For piles in clean sand, the influence zone above the pile tip is between 1.5 and 2.5D and the zone below the tip ranges from 3.5 to 5.5D, where D is pile diameter. For piles in more compressible silty sand, the influence zone extends between 0.5 and 1.5D above the pile tip and between 1.5 and 3D below the tip. Because of its analytical nature, the present study may provide a meaningful insight into the current empirical interpretations. [ABSTRACT FROM AUTHOR]