2018-12-10T10:51:35Z
http://www.qjseg.ir/?_action=export&rf=summon&issue=132
Journal of Structural Engineering and Geo-Techniques
2014
4
4
Evaluation of Autogenous Shrinkage in High-Performance Concrete
Jamal
Ahmadi
Reza
Naghdi2
Recent tendencies in concrete technology have been towards to high- performance concrete with a low water-cement ratio. However, high performance concretes have some problems. One of the problems is early-age cracking due to autogenous shrinkage.
This study presents the results of an experimental investigation carried out to evaluate the autogenous shrinkage of high-strength concrete. According to this, effects of water/binder ratio, cement content, fine to coarse aggregate ratio and silica fume content were evaluated. From the results of this investigation, it can be concluded that the autogenous shrinkage strain of high strength concrete increases with reduction of w/b ratio. The results show also that the variation of cement content and fine to coarse aggregate ratio had only a limited effect on the autogenous shrinkage.
Autogenous Shrinkage
High-Performance Concrete
silica fume
High-Strength Concrete
2014
12
30
1
4
http://www.qjseg.ir/article_768_7458af1790c6f0fbde6eec9e28301953.pdf
Journal of Structural Engineering and Geo-Techniques
2014
4
4
Application of Fuzzy Modeling to Earthquake Engineering: Seismic Performance of Cylindrical Tanks
Milad
Ahmadi Brace
The fuzzy logic concept provides a natural way of dealing with problems in which the source of imprecision is an absence of sharply defined criteria rather than the presence of random variables. The fuzzy approach considers cases where uncertainties play a role in the control mechanism of the concerned phenomena. Fuzzy modeling includes fuzzification, fuzzy analysis and defuzzification. In this paper, the basic of fuzzy theory and all three steps are discussed and a tangible example which includes the application of fuzzy modeling in dealing with uncertainty in data to produce fragility curves is demonstrated step by step. The results are compared to other results of recent studies.
Seimic
Performance
Tank
Fuzzy
Dmage
2014
12
30
5
9
Journal of Structural Engineering and Geo-Techniques
2014
4
4
An Experimental Study on Effect of Waste Tire Rubber on the Fresh and Hardened Behavior of Self-compacting Concrete
Mohammad saleh
Moghaddam
Saman
RahatDahmardeh
mohammad hassan
Moghaddam
The development of environmentally accepted methods of used tire disposal is one of the greatest challenges that waste management experts face today. Use of waste rubber particles as aggregate in self-compacting concrete is a suitable solution for the environmental hazards of waste tires being produced on a large scale. The aim of this work is to investigate the influence of the size of waste rubber particles and the waste replacement volume on the fresh and hardened properties of self-compacting waste rubberized concrete (SCWRC). Tire rubber particles were used in two groups to replace 5%, 10%, 15% and 20% of fine (GRSCC) and coarse (CRSCC) aggregate, separately. The water to cement ratio used in the concrete mixes was 0.42. The experimental results showed that the workability, water absorption and mechanical properties such as compressive and flexural strengths and ultrasonic pulse velocity of SCWRC reduced with the increase of rubbercontent.
self-compacting concrete
Waste rubber
workability
Mechanical properties
2014
12
30
11
16
Journal of Structural Engineering and Geo-Techniques
2014
4
4
EffectofMetakaolin and Nano-SiO2onshort and Long-term shrinkageofself-compactingcement sandmortar
Hassan
Soltanshahi
The use of cementitious products isincreasing in the world,Thusreplacement part of cement with pozzolanic materials reduced energy consumption and preserve natural resources and the environment and also improve the mechanical properties and durability of the cement mortar.Furthermore Nano technology has promptedto tremendous developments in technology of building materials in recent yearsso use of nano-silica has considered by many researchers.On the other hand the use of self-compacting mortar due to high performance and flow ability has increased remarkable in recent years. One of the major issues affecting on durability of cement products is shrinkage of cement mortar.Because of the importance of self-compacting mortar and role of additives pozzolanic, particularly at the nanoscale, in this laboratory study the binary blend of Metakaolinpozzolan and Nano-SiO<sub>2</sub>as replacement part of the cement have been used. The rate of shrinkage of self-compacting mortar has been investigated<strong>.</strong>Therefore Metakaolin with percent by weight 10, 15 and 20 and Nano-SiO<sub>2</sub>with percent by weight 1% and 2% were replaced cement. The results show that using metakaolin,Nano-SiO<sub>2</sub> and combination of them reduce the rate of shrinkage of self-compacting cement mortar.
Pozzolan
Metakaolin
Nano silica
Self-compactingMortar
Shrinkage
2014
12
30
17
22
Journal of Structural Engineering and Geo-Techniques
2014
4
4
A Comparison of Different Non-linear Numerical Models for Pier Shaft Interaction Analysis for study of the Seismic Performance of Bridges
Shahriar
TavousiTafreshi
Amin
Ghafooripour
Seyed shahrum
Jafari
The AASHTO code of practice for design of bridges shows that the ductility level for foundation is given equal to one. Bridges are classified in three classes. For class of essential and normal bridges a question for not to use ductility level due to the importance of bridges’ costs is become an important item in different countries particularly in Middle east.
This paper aimed to study on performance of bridges based on the effect of soil non-linear behavior. A comparison between Finite Difference (F.D), Finite Element (F.E) methods and close form solutions has been carried out on single and group piles under lateral loads in multilayered soils. Winkler model with non-linear springs, FLAC-3D, ANSYS5.4 and ABAQUS software were used for verifications. The Lagrangian method was considered in FLAC-3D and the Drucker-Prager was used in ANSYS. Pile behavior in sandy soils, uniform clayey soils, clayey deposits including sandy lenses, and Sand deposits with thin clay layers were analyzed. Verification between traditional close form solution methods with those analysis methods were carried out.
Results show the effectiveness of foundation ductility in compare with the expected ductility levels and structural performance for superstructure. The ductility level of substructure due to the pile soil interaction has found equal to 3.5 to 4.5 for different soil types. It show in “Pile and Deck (pier shaft)” model in bridges for the normal and essential bridges classes the use of ductility should be taken into account in accordance with soil-structure performance.
In conclusion the paper shows that for the pier shaft system it would be possible to use ductility level for foundations for normal and essential class of bridges and for those countries that they use the structural ductility for design of all components of structure including piles, the level of performance should be precisely investigated and using of structural ductility level is under question for design of pier shaft models.
Non-linear
Pier Shaft
Seismic
Bridges
2014
12
30
23
36
Journal of Structural Engineering and Geo-Techniques
2014
4
4
Determining the Likelihood of Damage in Concrete and its Physical Structure
leila
Shahryari
Applying renormalization group theory to evaluate the safety of overall structure, local damage probability must be obtained at first. According to the results of unit detection test and numerical simulation, the methods how to determine local damage probability was presented in the paper. For small unit, meaning the unit size is far less than the maximum primitive cell or the structure size, if the unit is damaged by detection test, the local damage probability of it is defined as 1. Otherwise it is defined as 0. For large unit, the local damage probability is expressed by the ratio of volume summation of all damages to volume of the unit. The process of local damage probability to be obtained was also introduced. Based on the results of numerical simulation, the local damage probability how to be obtained was mainly expounded. Concrete strength was assumed to obey two parameter Waybill distributions. Therefore, damage probability based on stress of concrete structure may be developed to obey it. The steps of obtaining local damage probability are stated. Furthermore, determination of parameters was introduced in similar structure.
Local damage
Probability
Detection
Numerical simulation
Weibull distribution
Renormalization group theory6 words separated by comma
2014
12
30
37
39