Theoretical bearing capacity of clay under shallow footings: verifying whether it is realistic

1988 ◽  
Vol 25 (1) ◽  
pp. 62-75
Author(s):  
Robert P. Chapuis ◽  
Vincent Silvestri ◽  
Michel Soulié
Keyword(s):  
Bearing Capacity ◽  
Major Influence ◽  
Clay Material ◽  
Short Term ◽  
Rigid Plastic ◽  
Long Term Conditions ◽  
True Value ◽  
Load Tests ◽  
Failure Conditions

Traditionally, the bearing capacity and the settlement of footings on clay are determined independently by theoretical analyses: the bearing capacity for short-term conditions and the settlement for long-term conditions. Bearing capacity methods usually assume that the clay has a rigid-plastic behaviour and they neglect prefailure deformations. Conventional settlement methods ignore failure conditions. However, field load tests give load–settlement curves in which it is impossible to dissociate settlement and bearing capacity.This paper examines whether the calculated theoretical qult is realistic. A long-term load–settlement curve can be easily calculated using an oedometric equation. The curve of soed/B versus load is a good approximation of the true long-term settlement curve and can be used to determine whether the (short-term) bearing capacity qu is realistic: if soed/B has a high value for a load smaller than the computed qu, it means that this qu is not a valid evaluation of the bearing capacity, the true value of which remains unknown. To establish when conventional analyses give erroneous bearing capacities four cases are analyzed, encompassing the influence of the compressibility of the clay material and the influence of downward groundwater gradients on the compressibility. The results show that groundwater conditions have a major influence upon the bearing capacity of highly compressible, slightly overconsolidated clays but practically no influence upon the bearing capacity of clays of low compressibility. Key words: shallow foundations, clay, deformability, bearing capacity, settlement.

scholarly journals Stability analysis of roadway embankments supported by stone columns with the presence of water table under short-term and long-term conditions

2018 ◽  
Vol 162 ◽  
pp. 01013 ◽  
Author(s):  
Shaymaa Tareq Kadhim ◽  
Ziad Bashar Fouad
Keyword(s):  
Water Table ◽  
Factor Of Safety ◽  
Soft Soil ◽  
Stone Columns ◽  
Stone Column ◽  
Stability Factor ◽  
Short Term ◽  
Long Term Conditions ◽  
The Stability

Use of stone column technique to improve soft foundation soils under roadway embankments has proven to increase the bearing capacity and reduce the potential settlement. The potential contribution of stone columns to the stability of roadway embankments against general (i.e. deep-seated) failure needs to be thoroughly investigated. Therefore, a two-dimensional finite difference model implemented by FLAC/SLOPE 7.0 software, was employed in this study to assess the stability of a roadway embankment fill built on a soft soil deposit improved by stone column technique. The stability factor of safety was obtained numerically under both short-term and long-term conditions with the presence of water table. Two methods were adopted to convert the three-dimensional model into plane strain condition: column wall and equivalent improved ground methods. The effect of various parameters was studied to evaluate their influence on the factor of safety against embankment instability. For instance, the column diameter, columns’ spacing, soft soil properties for short-term and long-term conditions, and the height and friction angle of the embankment fill. The results of this study are developed in several design charts.

Immigrant Usage Patterns of Natural Health Products: Role in Pharmacoeconomics

2020 ◽  
Vol 16 (1) ◽  
pp. 45-55
Author(s):  
Dalya Abdulla
Keyword(s):  
English Language ◽  
Prescription Medication ◽  
Natural Health Products ◽  
Prescription Medications ◽  
Natural Health ◽  
Short Term ◽  
Long Term Conditions ◽  
Health Products ◽  
Usage Patterns

Background: Understanding patterns and drivers for natural health product (NHP) usage among immigrants is essential in the provision of appropriate health care; many studies have elucidated NHP utilization among immigrants; however, few have considered impacts of concurrent NHP and prescription medication usage. Objective: The study aims to determine new immigrant NHP usage patterns (including concurrent usage with prescription medications) and to discern economic impacts driving concurrent usage. Methods: A survey questionnaire was administered to local new immigrants during English Language Training classes. Results: Most participants understood the NHP definition and would take an NHP for the same disease or condition they would normally take a prescription medication for. Many participants agreed that NHPs are not safe however were unable to provide robust examples of unsafe NHP usage. With regard to purchases of medicines for short and long term illnesses, a high percentage of participants would purchase the prescription medication for a short term illness over the NHP; however this percentage decreases in the event of a long term illness, with more participants relying on NHPs to remedy their long term illness symptoms. Conclusion: Pharmacoeconomics tends to be a major driver for immigrant utilization of NHPs, and is a stronger influencer of use compared to ethnicity or parenteral usage of such products. This pharmacoeconomic correlation in the preference to use NHPs over prescription medications tends to be more observable for chronic and long term conditions (compared to short term illnesses).

scholarly journals Short-term and long-term longitudinal load tests of wooden rods

2020 ◽  
Vol 939 ◽  
pp. 012080
Author(s):  
K A Varenik ◽  
A S Varenik ◽  
A V Kirillov ◽  
M V Shuvalov
Keyword(s):  
Short Term ◽  
Longitudinal Load ◽  
Load Tests

Wooden Trusses With Nodal Joints On Glued Flat Rods

2020 ◽  
pp. 9-15
Keyword(s):  
Bearing Capacity ◽  
Test Procedure ◽  
Experimental Studies ◽  
Operational Reliability ◽  
Design Solution ◽  
Short Term ◽  
High Degree ◽  
Wooden Structures ◽  
Node Type

Wooden trusses are widely used in construction and differ in a variety of structural forms. In general, their bearing capacity and stiffness are determined by the design solution of the node joints. In order to accept significant loads and reduce the overall deformation of trusses, it is necessary to develop new types of nodes that would also be characterized by low labor intensity of manufacturing and a high degree of operational reliability. Proposed by the authors nodes of wooden trusses based on steel glued flat rods are met the above requirements. The article describes the results of experimental studies of a wooden truss with nodal joints on glued flat rods under the short-term loads. The layout principles of the proposed node type are given; test procedure of experimental structures and results of experimental studies are presented: features of operation of steel connecting plates glued into wood in the nodes are revealed. It is shown that the adopted design solution of nodes refers to the joints of wooden structures of a rigid type and provides sufficient load-bearing capacity of the trusses and their increased rigidity. The nature of the destruction and the value of the destructive load confirmed the operational reliability of the proposed type of wooden trusses, including under the action of long-term loads. The analysis of the results revealed the directions of further improvement of wooden trusses nodes with steel glued flat rods.

scholarly journals Influence of long-term compressive stresses on strength of concrete and steel-fiber concrete prismatic element

2018 ◽  
Vol 230 ◽  
pp. 02020
Author(s):  
Stepan Neutov ◽  
Maryna Sydorchuk ◽  
Oleksii Shyliaiev
Keyword(s):  
Bearing Capacity ◽  
Steel Fiber ◽  
Rupture Strength ◽  
Load Level ◽  
Short Term ◽  
Fiber Concrete ◽  
Steel Fiber Concrete ◽  
Long Acting ◽  
Acting Load

The strength and deformation characteristics of concrete and steel-fiber concrete on prisms and cubes are determined. Short-term and long-term tests of the samples were carried out taking into account the recommendations of the regulatory documents for the testing of concrete. Loading of samples with a long load was carried out in force installations (stands) consisting of four metal rods to which rigid loading plates were fixed at certain levels with threaded connections. To cover the entire operational spectrum of the stress state of real reinforced concrete elements, levels of 0.3; 0.4; 0.5; 0.67 and 0.8 from the short-term destructive load were adopted as long-term loading levels. All samples, which were more than a year under the action of a long-acting load, increased their bearing capacity. Prisms from steel-fiber concrete, which were under the influence of a long-acting load during 370 days, increased the bearing capacity, depending on the level of load, by 30-50%. The higher load level, the higher the creep rupture strength. When the loading was repeated before the destruction, the deformations of steel-fiberconcrete prisms changed linearly.

Comparison of Short-Term and Long-Term Variability in Nasalance Scores

2008 ◽  
Vol 45 (5) ◽  
pp. 495-500 ◽  
Author(s):  
Kerry E. Lewis ◽  
Thomas Watterson ◽  
Ann Blanton
Keyword(s):  
Outcome Measures ◽  
Short Term ◽  
Long Term Conditions ◽  
Difference Scores ◽  
Term Variation ◽  
Subject Performance ◽  
Normal Speech ◽  
Over Time ◽  
Short Term Variability

Objective: To evaluate long-term nasalance score variability while accounting for short-term variation associated with subject performance and headgear change variability. Stimuli: Turtle and Mouse Passages. Design: Short-term immediate test-retest nasalance score variability was assessed with no headgear change (NCHG) and with change of headgear (CHG). Long-term variability was assessed with scores obtained in the morning and afternoon of the same day, 1 day apart, and 1 week apart. Scores from the long-term conditions necessarily reflect variability associated with headgear change plus variability, which may be attributed to time. Participants: Twenty-six adults (19 to 70 years of age) with normal speech and resonance. Main Outcome Measures: Forty-six nasalance scores per subject. Results: Mean nasalance difference scores across conditions were compared. Three contrasts were significantly different, each involving comparison of nasalance difference scores in the NCHG condition to difference scores from a CHG condition. Overall, long-term variability was slightly greater than short-term variability. For the Turtle Passage, in the short-term CHG condition, 92% of repeated scores were within five points. In the long-term conditions, 83% to 89% of scores were within five points. For the Mouse Passage, 88% of repeated scores in the CHG condition were within five points. In the long-term conditions, 81% to 83% of scores were within five points. Conclusions: Nasalance scores obtained over time showed slightly greater variability than scores obtained in immediate test-retest conditions; however, variability did not increase as the length of time between measures increased.

scholarly journals INVESTIGATIONS IN THE STRENGTH OF PRESTRESSED MULTILAYERED BEAMS UNDER THE ACTION OF LONG-TERM SHEAR/MEDINIŲ IŠ ANKSTO ĮTEMPTŲJŲ DAUGIASLUOKSNIŲ SIJŲ STIPRUMAS VEIKIANT ILGALAIKĖMS SKERSINĖMS JĖGOMS

1998 ◽  
Vol 4 (2) ◽  
pp. 109-116
Author(s):  
Rimantas Čechavičius
Keyword(s):  
Bearing Capacity ◽  
Relative Strength ◽  
Short Term ◽  
Load Bearing Capacity ◽  
Plastic Deformations ◽  
Load Bearing ◽  
Micro Cracks ◽  
Sawn Timber ◽  
Relationship Of

The results of long-term experiments are presented in the paper. As a result of the experiments, invention SU 1025831 was developed under the name “The method of manufacture of a timber load-bearing element” (E 04 C 3/12, priority since July 11, 1981). The objective of the experiments performed was to check the method of increase of load bearing capacity of glulam beams under the influence of long-term shear. 14 beams were tested: nine of them were multilayered and 5 made of board-package and square-sawn timber. All the beams failed because of the action of shear forces. Two beams were tested by static short loading, the rest twelve by long-term loading. Three beams, that have not failed because of the action of long-term loading, then were tested by short-term loading. From the tests of multilayered, glulam and solid square-sawn timber beams the decrease of the relative strength wood split alongside fibres under the action of long-term shear is bigger than that given in literature in case of standard experiments. Relationship of the level of decrease of this strength with the duration of long-term loading may be calculated according to the equation (2). The influence of long-term loading on the load-bearing capacity of these beams depends on the intensity of actions: if such a load does not cause the plastic deformations in the beam, their load-bearing capacity does not decrease and vice versa—the appearance of plastic deformations and micro-cracks means the decrease of load bearing capacity of the beam under a short-term shear. A short description of invention SU 1025831 is also presented in the paper. The invention is devoted to the perfection of the former invention No 954237. The latter one suggested an increase of load-bearing capacity of glulam elements under a short-term shear. Under a long-term load, or in case of fire, when the temperature and moisture around is changing, the strength of prestressed joint of these beams may not be fully guaranteed because of the influence of inner stresses and possible micro-cracking. With the purpose to increase the strength of beams under a long-term shear the author offers additionally to install pivots (Fig 6, 3) after giving prestress and full polymerisation. This method does not only increase the load-bearing capacity of multilayered elements under a long-term shear, but also ensures a higher reliability and fire resistance of such structures.

Large-Strain Performance Research of XPS Board under Long-Term Load for Controlling Foundation Differential Settlement

2014 ◽  
Vol 501-504 ◽  
pp. 527-532
Author(s):  
Xiao Lei Han ◽  
Bo Kang Ma ◽  
Jia Pu Huang ◽  
Wei Mei Kong ◽  
Wei Feng Li ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Large Strain ◽  
Differential Settlement ◽  
Compression Tests ◽  
Short Term ◽  
Strain Property ◽  
New Methods ◽  
Deformation Features ◽  
Performance Research

Differential settlement may occur in structure foundations for the differences between vertical loads in different parts of the superstructures, or the differences between deformation features of the foundation soils. Then it is of great significance to develop new methods for controlling foundation differential settlement by using special materials, of which the deformation features can be controlled. Through the compression tests, settlement controllable materials can be selected by comparing the bearing capacity and deformation features of different materials experimented in the tests. According to the results of the compression tests in short term and long term, this article analyzed the bearing capacity and deformation features of different materials through the stress-strain curves. The research shows that XPS (Extruded Polystyrene) boards are of high bearing capacity, large strain property and long-term property stability, and are well suited to be used in civil engineering by controlling the differential settlement of the structure foundation.

scholarly journals Experimental Study on Flexural Performance of Regulated Reinforced Glulam Beam after Long-Term Loading

2021 ◽  
Vol 13 (10) ◽  
pp. 5556
Author(s):  
Nan Guo ◽  
Chao Yang ◽  
Ling Li ◽  
Guodong Li ◽  
Yan Zhao
Keyword(s):  
Bearing Capacity ◽  
Comparative Test ◽  
Tensile Failure ◽  
Compressive Failure ◽  
Initial Value ◽  
Short Term ◽  
Glulam Beam ◽  
Flexural Performance ◽  
Creep Characteristics

Due to wood creep characteristics, the failure mode, bearing capacity, stiffness, and deformation of its components are doomed to be impacted by long-term loading. This paper conducted a comparative test on creep beams, regulated beams, and short-term beams based on the former long-term loading research. The results demonstrated that the glulam beam experienced tensile failure of the beam-bottom, while the horizontal joint failure and the local compressive failure of the beam-end happened in the reinforced glulam beam and the prestressed glulam beam. The bearing capacity of the creep beams decreased compared with that of the short-term beams; the decline in the bearing capacity of the ordinary glulam beams, the reinforced glulam beams, and the prestressed glulam beams ranged from 4.22% to 9.83%, from 2.64% to 13.23%, and from 2.90% to 9.16%, respectively. However, the bearing capacity of the regulated beam with the deformation restored to the initial value of the load increased by 4.62–14.08%. The prestressed regulation changed the distribution of the stress on the beam and thus enhanced its bearing capacity. The findings of this work could be used as a frame of reference for similar components in engineering applications.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Sign in / Sign up

Export Citation Format

Share Document