Influence of changing environment conditions on the development of shrinkage strain and the expansion coefficient of large concrete specimens

2019 ◽  
Author(s):  
Dominik Suza ◽  
Johann Kollegger ◽  
Harald S. Müller
Keyword(s):  
Shrinkage Strain ◽  
Theoretical Models ◽  
Test Results ◽  
Current Standard ◽  
Operating Life ◽  
Changing Environment ◽  
Temperature And Humidity ◽  
Bridge Structures ◽  
Standard Models ◽  
Creep And Shrinkage

<p>The standard creep and shrinkage strain measurements of concrete are usually conducted in a laboratory with constant temperature and humidity with a low variation. The creep and shrinkage measurements are conducted over a few months with the expectation that small concrete specimens can sufficiently describe the evolution of the rheology effects on a large multi-span bridge in the course of its operating life.</p><p>The monitoring of real bridge structures shows the actual progression of the deflections and concrete strains. Unfortunately the evaluation and interpretation of the measured values is complicated. The idea of the scientific Creep &amp; Shrinkage project was to combine the two described situations (laboratory experiments and monitoring of real bridge structures) creating an experimental setup which would benefit from the advantages of both approaches.</p><p>In order to achieve conformity of the measured test results with those of theoretical models (MC 2010, EC) it was necessary to upgrade the current models to include the effects of changing temperature and humidity. Within this paper the upgrade of the current standard models to include changing environment conditions will be elaborated, in addition to an explanation of the method used to separate shrinkage strains from the temperature strains from the measured data. The measured concrete expansion coefficients will also be discussed.</p>

Shear Assessment of Concrete Bridge Deck Slabs

2017 ◽  
Vol 738 ◽  
pp. 110-119 ◽  
Author(s):  
Radoslav Vida ◽  
Jaroslav Halvonik
Keyword(s):  
Current Model ◽  
Shear Capacity ◽  
Concrete Bridge ◽  
Current Standard ◽  
Concrete Members ◽  
Deck Slabs ◽  
Bridge Structures ◽  
Bridge Deck Slabs ◽  
Concrete Bridge Deck ◽  
New Generation

The transitions from old STN standards to Eurocode standards brought several problems into bridge design and assessment. Shear reinforcement is now often required even in concrete members, which were previously allowed to be built without it. Moreover, assessment of existing reinforced concrete bridge structures often shows their insufficiency in shear capacity, which means that they should be strengthened or replaced. Work on new generation of Eurocodes is currently in progress and current model for shear assessment should be replaced by a new (and more precise) one. This paper deals with the problem of shear assessment of concrete bridge according to current standard and also according to the new shear models that are under consideration.

Drying Shrinkage of Concrete Affected by Content of Stone Powder in Proto-Machine-Made Sand

2010 ◽  
Vol 152-153 ◽  
pp. 1176-1179 ◽  
Author(s):  
Feng Lan Li ◽  
Qian Zhu
Keyword(s):  
Compressive Strength ◽  
Standard Method ◽  
Structural Engineering ◽  
Drying Shrinkage ◽  
Shrinkage Strain ◽  
Test Results ◽  
Similar Test ◽  
Mix Proportion ◽  
Compressive Strength Of Concrete ◽  
Main Factor

To improve the application of the new proto-machine-made sand in structural engineering, tests are carried out to study the drying shrinkage of concrete affected by stone powder in proto- machine-made sand. The target cubic compressive strength of concrete is 55 MPa, the main factor varied in mix proportion of concrete is the contents of stone powder by mass of proto-machine-made sand from 3 % to 16 %. The drying shrinkage strains of concrete are measured by the standard method at the ages of 1 d, 3 d, 7 d, 14 d, 28 d, 60 d, 90 d, 120 d, 150 d and 180 d. Based on test results, the drying shrinkage of concrete affected by the contents of stone powder in proto-machine-made sand is analyzed and compared with that of similar test of concrete with traditional machine-made sand, which shows that there is the optimum content of stone powder resulting in the lower drying shrinkage of concrete. The formula for predicting drying shrinkage strain of concrete is proposed.

Experimental Study of High Temperature Performance of Steel Suspension Bridge Wires

2019 ◽  
Author(s):  
Jumari A. Robinson ◽  
Adrian Brügger ◽  
Raimondo Betti
Keyword(s):  
Elastic Modulus ◽  
High Temperature ◽  
High Strength Steel ◽  
Cold Working ◽  
High Strength ◽  
Suspension Bridge ◽  
Theoretical Models ◽  
Test Results ◽  
Single Wire ◽  
Steel Wires

<p>The performance of suspension bridges exposed to fire hazards is severely under-studied – so much so that no experimental data exists to quantify the safety of a suspension bridge during or after a major fire event. Bridge performance and safety rely on the integrity of the main cable and its constituent high-strength steel wires. Due to the current lack of experimental high temperature data for wires, the theoretical models use properties and coefficients from data for other types of structural steel. No other structural steel undergoes the amount of cold-working that bridge wire does, and plastic strains from cold-working can be relieved at high temperature, drastically weakening the steel. As such, this work determines the elastic modulus, ultimate strength, and general thermo-mechanical profile of the high-strength steel wires in a range of elevated temperature environments. Specifically, these tests are conducted on a bundle of 61-wires (transient), and at the single wire level (steady-state) at a temperature range of approximately 20-700°C. The test results show an alarmingly high reduction in the elastic modulus and ultimate strength with increased temperature. The degradation shown by experiments is higher than predicted by current theoretical models, indicating that use of high-temperature properties of other types of steel is not sufficient. The test results also show scaling agreement between the single wire and the 61-wire bundle, implying that a full material work up at the single- wire level will accurately inform the failure characterization of the full cable.</p>

scholarly journals Astrometric Tests of Galactic Evolution

1995 ◽  
Vol 166 ◽  
pp. 251-258
Author(s):  
Gerard Gilmore
Keyword(s):  
Phase Space ◽  
Three Dimensional ◽  
Galactic Evolution ◽  
Critical Test ◽  
Current Standard ◽  
High Quality ◽  
Stellar Velocity ◽  
Formation And Evolution ◽  
Standard Models

There are many fundamental aspects of Galactic structure and evolution which can be studied best or exclusively with high quality three dimensional kinematics. Amongst these we note as examples determination of the orientation of the stellar velocity ellipsoid, and the detection of structure in velocity-position phase space. The first of these is the primary limitation at present to reliable and accurate measurement of the Galactic gravitational potential. The second is a critical test of current standard models of Galactic formation and evolution.

scholarly journals Evolutionary dynamics drives role specialization in a community of players

2020 ◽  
Vol 17 (168) ◽  
pp. 20200174 ◽  
Author(s):  
Danyang Jia ◽  
Xinyu Wang ◽  
Zhao Song ◽  
Ivan Romić ◽  
Xuelong Li ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Experimental Studies ◽  
Current Standard ◽  
Complex Processes ◽  
Spatial Games ◽  
Powerful Means ◽  
New Type ◽  
Standard Models ◽  
Natural Fact ◽  
Role Specialization

The progression of game theory from classical to evolutionary and spatial games provided a powerful means to study cooperation, and enabled a better understanding of general cooperation-promoting mechanisms. However, current standard models assume that at any given point players must choose either cooperation or defection, meaning that regardless of the spatial structure in which they exist, they cannot differentiate between their neighbours and adjust their behaviour accordingly. This is at odds with interactions among organisms in nature who are well capable of behaving differently towards different members of their communities. We account for this natural fact by introducing a new type of player—dubbed link players—who can adjust their behaviour to each individual neighbour. This is in contrast to more common node players whose behaviour affects all neighbours in the same way. We proceed to study cooperation in pure and mixed populations, showing that cooperation peaks at moderately low densities of link players. In such conditions, players naturally specialize in different roles. Node players tend to be either cooperators or defectors, while link players form social insulation between cooperative and defecting clusters by acting both as cooperators and defectors. Such fairly complex processes emerging from a simple model reflect some of the complexities observed in experimental studies on social behaviour in microbes and pave a way for the development of richer game models.

Study on Durability of High Bending Strength Pavement Concrete

2012 ◽  
Vol 594-597 ◽  
pp. 1372-1376
Author(s):  
Wei Hong Guo
Keyword(s):  
Wear Resistance ◽  
Bending Strength ◽  
Drying Shrinkage ◽  
Fatigue Property ◽  
Plain Concrete ◽  
Shrinkage Strain ◽  
Test Results ◽  
Concrete Material ◽  
Shrinkage Coefficient ◽  
Pavement Concrete

In order to explore the durability of high bending strength pavement concrete, adding silica flour, fibrous reticulum, SD emulsion and HG emulsion separately in concrete mixture, the shrinkage characteristic, wear resistance and fatigue property of different high bending strength pavement concrete are tested, and contrastive analysis with the plain concrete material is researched. The test results show that the early contraction of HBSPC is bigger, but the total drying shrinkage strain is smaller than plain concrete, and the drying shrinkage stable stage of HBSPC is shorter than plain concrete. The temperature shrinkage of HBSPC and plain concrete is uniform basically, the temperature shrinkage coefficient of HBSPC is lower than the plain concrete in the negative warm area and warm area, but it is higher in 0 °C neighbor. The mixtures of the material enhance the wear resistance and fatigue property of concrete.

Shrinkage tests of two full-scale composite trusses

1992 ◽  
Vol 19 (2) ◽  
pp. 296-309 ◽  
Author(s):  
D. J. Laurie Kennedy ◽  
Anita Brattland
Keyword(s):  
Concrete Beams ◽  
Concrete Slab ◽  
Shrinkage Strain ◽  
Steel Beam ◽  
Restrained Shrinkage ◽  
Test Results ◽  
Linear Strain ◽  
Shrinkage Behaviour ◽  
Composite Section ◽  
Composite Steel

The shrinkage behaviour of two composite trusses with a span of 11.5 m was studied. Shrinkage measurements to determine the effects of slab shrinkage on truss deflections and member strains were recorded over periods of 65 and 85 days. A method is developed to compute shrinkage deflections, based on equilibrium of the shrinkage-induced forces at midspan, which gives excellent agreement with the test results. This method assumes a linear strain distribution through the depth and is based on the free shrinkage strain of the concrete and the average stress–strain characteristics of the concrete in tension under restrained shrinkage conditions as it drys, creeps, and eventually may crack as it is gradually loaded from the green state. The method is extended to composite steel-beam concrete-slab members. It is equivalent to Branson's "composite section method" provided that the correct values for the shrinkage strain and the effective modulus of elasticity of the concrete in tension are used in the latter. Key words: behaviour, composite steel–concrete beams, trusses, shrinkage deflections.

scholarly journals Flexural Elastic Buckling Stress of Batten Type Light Gauge Built-Up Member

2017 ◽  
Vol 25 (2) ◽  
pp. 161-172 ◽  
Author(s):  
Kazuya Mitsui ◽  
Atsushi Sato
Keyword(s):  
Slenderness Ratio ◽  
Shear Wall ◽  
Elastic Buckling ◽  
Test Results ◽  
Current Standard ◽  
Buckling Strength ◽  
Buckling Stress ◽  
Strength Based ◽  
Energy Equilibrium ◽  
Compression Member

Abstract In Japan, built-up member composed with light gauge is used for studs of shear wall. Flexural buckling stress of built-up compression member is evaluated by effective slenderness ratio. The effective slenderness ratio of light gauge built-up compression member is proposed for heavy sections; however, it is not verified that it can be adopted in light gauge. In this paper, full scale testing of light gauge built-up members are conducted. From the test results, it is shown that current Standard overestimates the buckling strength. Based on energy equilibrium theory, modified effective slenderness ratio for light gauge built-up member is derived. The validity of the modified effective slenderness ratio is shown with test results.

scholarly journals Use of Fiber Brag Gating Sensors in civil engineering applications

2021 ◽  
Author(s):  
Zahra Yazdizadeh
Keyword(s):  
High Performance ◽  
Civil Engineering ◽  
Prediction Models ◽  
High Performance Concrete ◽  
Shrinkage Strain ◽  
Second Phase ◽  
Engineering Applications ◽  
Fbg Sensors ◽  
Important Time ◽  
Creep And Shrinkage

This research presents an overview of development and application of Fiber Bragg Grating sensors (FBG) technology in civil engineering applications. The primary focus of this research is the use of FBGs to investigate two most important time-dependent properties of concrete namely: creep strain and shrinkage strain. The first phase of this investigation is focused on using FBG sensors to measure the concrete strains in unreinforced concrete beams and cylinders to determine modulus of elasticity, the modulus of rapture and fracture energy of concrete. The second phase of this research is designed to investigate the creep and shrinkage using FBG sensors. Normal strength concrete (NC), High performance concrete (HPC) and ultra-high performance (UHPC) specimens’ are used to measure creep and shrinkage strains and to compare the values with typical prediction models. The measured creep and shrinkage strains are compared to four different models to determine which model is the most accurate.

scholarly journals Design of Prototype System for Temperature and Humidity Control in Flour Storage

2017 ◽  
Vol 5 (2) ◽  
pp. 59-64
Author(s):  
Annisau Saidah
Keyword(s):  
Wheat Flour ◽  
Load Cell ◽  
Sensor Data ◽  
Prototype System ◽  
Mold Growth ◽  
Test Results ◽  
Linear Formula ◽  
Temperature And Humidity ◽  
Cell Test ◽  
First In First Out

Storage of wheat flour requires good temperature and humidity to avoid mold growth that can damage the nutrients in wheat flour. The temperatures and humidity required for proper storage are above temperatures and humidity below 60% RH. The method used in flour storage is FIFO (First In First Out) using a Load cell sensor as a marker for flour input. The incoming flour will input the time, location and amount of flour, so that it can be easily determined which flour will come out first. To facilitate monitoring of temperature, humidity and stock amount in flour storage in this study, sending monitoring data wirelessly using an internet network that can be accessed anywhere. The test results of this study show that the DHT22 sensor can measure temperature and humidity well, which has a RE (Relative Error) value of 0.5% temperature and 3.9% humidity compared to the HTC-1 measuring instrument. The load cell test compared to digital scales has an accurate value using a linear formula. In the QoS test, sending sensor data to the web server has a good value according to the ITU-T standard, namely delay <150ms

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