scholarly journals Strengthening Effect of the External Prestressing Method That Simulated a Deterioration Bridge

2021 ◽  
Vol 11 (6) ◽  
pp. 2553
Author(s):  
Sang-Hyun Kim ◽  
Jong-Sup Park ◽  
Woo-Tai Jung ◽  
Jae-Yoon Kang
Keyword(s):  
Compressive Strength ◽  
Strengthening Effect ◽  
Reinforcement Effect ◽  
Loading Test ◽  
Yield Load ◽  
Existing Structures ◽  
External Prestressing ◽  
The Difference ◽  
Existing Structure ◽  
Strengthening Method

Various methods for strengthening existing structures have been developed owing to the increase in human and property damages caused by the deterioration of structures. Among the various reinforcing methods, the external prestressing method increases the usability and safety of a structure by directly applying tension to the weak tensile area that suffers the greatest deflection during the structure usage. The external prestressing method is advantageous in reducing cracks caused by the introduced tension and restoration of the deflection. Since the strengthening method is applied to deterioration bridges, the strengthening effect is affected by the condition of the existing structure. However, studies on the strengthening effect according to the degree of deterioration are insufficient. Therefore, the behavior according to the strengthening status was analyzed, and the strengthening effect was identified in this study by simulating the deteriorated bridge, reducing the compressive strength and reinforcement quantity, and conducting a four-point loading test. As a result of the experiment, a reinforcement effect of 215% crack load, 161% yield load, and the difference in behavior according to the reinforcement parameters were confirmed.

The Shear Resistant Effect of RC Beam Strengthened with SWR External Prestressing under Dead Load Level when Strengthening

2011 ◽  
Vol 243-249 ◽  
pp. 5576-5581
Author(s):  
Tian Lai Yu ◽  
Lei Lei Tian ◽  
Qiang Ma
Keyword(s):  
Steel Wire ◽  
Load Level ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Strengthening Effect ◽  
Dead Load ◽  
Yield Load ◽  
Damage Degree ◽  
External Prestressing ◽  
The Dead

Ability insufficiently in shear is one of common trouble of old RC (reinforced concrete) beams, so scientific and reasonable shear resistant reinforcement method is one of the important research topics in the old bridge reinforcement and rehabilitation fields, and is of great significance in improving old bridge’s mechanical properties and reducing safe accidents. The shear resistant strengthening effect of strengthened beams with SWR (steel wire rope) external prestressing is studied under different dead load level and damage degree when strengthening, through the indoor experiment in shear. The results of the experiment shows: the width of diagonal cracks of the beams strengthened with SWR external prestressing become smaller and the yield load of stirrups is delayed, and the shear capacity is improved compared with basic beam. Both dead load level when strengthening and damage degree of original beams are the important factors influencing the shear resistant reinforcement effect , and with increasing of the dead load level and damage degree when strengthening, the improved amplitude of the yield load of stirrups and the shear bearing capacity are getting decreasing. The dead load level and damage degree when strengthening should be taken into account.

Strengthening Experiment of a Hollow Slab Bridge by External Transverse Prestressing

2011 ◽  
Vol 243-249 ◽  
pp. 1561-1566
Author(s):  
Fu Ming Wang ◽  
Sheng Zhen Kang ◽  
Xiao Long Li ◽  
Ying Chun Cai
Keyword(s):  
Static Load ◽  
Load Test ◽  
Strengthening Effect ◽  
Construction Technology ◽  
Test Results ◽  
Static Load Test ◽  
Hinge Joint ◽  
External Prestressing ◽  
Before And After ◽  
Strengthening Method

For hollow slab bridge, its concrete hinge joint is prone to be damaged under overload vehicles, as weakens the transverse integrity of bridge, leads to single slab bearing and threatens the safety of service. Aiming at the problem, a strengthening experiment of an actual concrete hollow slab bridge, which has experienced a destructive test with its transverse connections seriously damaged, was performed by applying external transverse prestressing to it. The strengthening design and construction technology of external prestressing were introduced. By means of truck static load test, the variation of deflections and strains of the bridge before and after strengthening under different tension force was obtained, and the influence of tension value to strengthening effect was emphatically analyzed. The test results proved the effectiveness of the strengthening method and some improvement suggestions were also presented.

Biomechanical comparison of the Lim/Tsai tendon repair with a modified method using a single looped suture

2017 ◽  
Vol 42 (9) ◽  
pp. 915-919 ◽  
Author(s):  
Min Kai Chang ◽  
Yoke Rung Wong ◽  
Shian Chao Tay
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Mechanical Performance ◽  
Tendon Repair ◽  
Original Method ◽  
Flexor Digitorum Profundus ◽  
Loading Test ◽  
Modified Method ◽  
Cycle Loading ◽  
The Difference

The Lim/Tsai tendon repair technique has been modified clinically to achieve a 6-strand repair using a single looped suture with one extratendinous knot. We compared biomechanical performance of the original and modified methods using 20 porcine flexor digitorum profundus tendons. The ultimate tensile strength, load to 2 mm gap force, mode of failure, and time taken to repair each tendon were recorded during a single cycle loading test in 10 tendons with each repair method. We found that despite having the same number of core strands, the single looped suture modified Lim/Tsai technique possessed significantly greater ultimate tensile strength and load to 2 mm gap force. Also, less repair time was required. We conclude that the modified 6-strand repair using a single looped suture has better mechanical performance than the original method. The difference likely was due to the changes in locations of the knots and subsequent load distribution during tendon loading.

scholarly journals A Comparative Study on the Efficiency of CFRP and GFRP in the Improvement of Compressive Strength, Acoustic Impedance and Bracing of Filled and Hollow Concrete Columns in Different Layers and Ages

2016 ◽  
Vol 9 (5) ◽  
pp. 110 ◽  
Author(s):  
Mohammadreza Zarringol ◽  
Mohammadehsan Zarringol
Keyword(s):  
Compressive Strength ◽  
Comparative Study ◽  
Ultimate Strength ◽  
Acoustic Impedance ◽  
Concrete Columns ◽  
Concrete Surface ◽  
Ultrasonic Waves ◽  
Shear Strengthening ◽  
Surface Strength ◽  
Strengthening Method

<p>FRP technique is growing in popularity as a modern strengthening method. When it comes to FRP, concrete surface strength plays a determining role in the bond between FRP and concrete. This paper aims to compare the efficiency of CFRP and GFRP in the improvement of compressive strength, acoustic impedance and bracing of filled and hollow concrete columns in different layers and ages. In doing so, we carried out various tests on 18 samples in the ages of 3, 7, 14, 28, 42 and 90 days. According to the results, the strength of un-braced carbon and glass increased by 19-40% and 8-43% respectively and the strength of braced carbon and glass increased by 17-25% and 10-82% respectively. The compressive strength increased by 66% in one-layer CFRP hollow column, 96% in two-layer CFRP hollow column, 123% in three-layer CFRP hollow column, 36% in one-layer GFRP hollow column, 63% in two-layer GFRP hollow column, 105% in three-layer GFRP hollow column, 71% in one-layer CFRP filled column, 138% in two-layer CFRP filled column, 154% in three-layer CFRP filled column, 45% in one-layer GFRP filled column, 79% in two-layer GFRP filled column, and 144% in three-layer GFRP filled column. The ultimate strength of the beams with flexural-shear strengthening was higher than other beams. Also, the increased percentage of fiber resulted in the increased speed of ultrasonic waves. </p>

Strengthening of steel decks for cable-stayed bridge using ultra-high performance concrete: A case study

2020 ◽  
Vol 23 (16) ◽  
pp. 3373-3384
Author(s):  
Lei Wang ◽  
Xiaochao Su ◽  
Yafei Ma ◽  
Ming Deng ◽  
Jianren Zhang ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Fatigue Cracking ◽  
Strengthening Effect ◽  
Steel Bridge ◽  
Ultra High Performance Concrete ◽  
Cable Stayed Bridge ◽  
Local Stresses ◽  
Orthotropic Steel Decks ◽  
Strengthening Method

Fatigue cracking induced by vehicle load is a prevalent problem in orthotropic steel decks. In addition, pavement debonding in steel bridge decks is another familiar issue resulting from low slip resistance in the faying surface between the steel and asphalt concrete. The present study proposed a strengthening method that uses ultra-high performance concrete to stiffen a repeatedly maintained cable-stayed bridge in order to help address these two problems. The existing issues of the real bridge and the corresponding causes were investigated. Following this, an ultra-high performance concrete paving system was designed to improve the stiffness of the orthotropic steel decks. For this paving system, a 45-mm ultra-high performance concrete layer was connected to the deck by welded shear studs. The local stresses at the typical vulnerable fatigue cracking points were determined by means of a finite element model and of a field loading test to evaluate the strengthening effect. The results showed that this strengthening method can prevent the propagation of fatigue cracks. The local stresses of the U-ribs and diaphragms were reduced by 45.4% and 40.0%, respectively. The repaired bridge has sufficient resistance against fatigue cracking based on the in situ observations.

scholarly journals PEMANFAATAN LIMBAH FLY ASH DARI PEMBAKARAN BATUBARA PADA PEMBUATAN SEMEN PCC (PORTLAND COMPOSITE CEMENT) DI PT SEMEN XYZ LAMPUNG

2020 ◽  
Vol 4 (2) ◽  
Author(s):  
Dwi Septiyana Sari ◽  
◽  
Susanti Sundari
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Raw Materials ◽  
Testing Machine ◽  
Technical Aspect ◽  
Raw Material ◽  
Physical Test ◽  
Composite Cement ◽  
The Difference ◽  
The Cost

Abstract This study discusses the use of fly ash waste from coal burning on the manufacture of PCC (Portland composite cement) at PT. XYZ Lampung. The purpose of this research is to look at the technical studies and the efficiency of raw materials in the use of fly ash in cement making, in this case PCC cement (Portland Composite Cement). The steps taken in analyzing the data in this study were viewed from a technical aspect by means of a physical test, namely the cement compressive strength test at the age of 3 days, 7 days, and 28 days using the Compression Testing Machine. This test was conducted to see the comparison of the compressive strength of PCC cement using limestone and fly ash as raw materials, then calculate the difference in raw material costs in the year before and after the replacement of limestone with fly ash. The results showed that cement with the addition of fly ash after 3 days, 7 days and 28 days had an increased compressive strength value, which increased 21.69%, 16.07% and 8.05% respectively of the compressive strength of cement using limestone. The use of fly ash as a substitute for limestone has an effect on the cost of raw materials, where the difference between the cost of raw materials in 2019 and the cost of raw materials in 2018 is Rp. 39,440,952,074.

scholarly journals Cyclic Shear Performance of Reinforced Concrete Columns Strengthened by External Steel Rods

2021 ◽  
Vol 13 (23) ◽  
pp. 13224
Author(s):  
Hyeong-Gook Kim ◽  
Yong-Jun Lee ◽  
Kil-Hee Kim
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Analytical Approach ◽  
Concrete Columns ◽  
Loading Test ◽  
Rc Structures ◽  
Cyclic Shear ◽  
Flexural Failure ◽  
Shear Performance ◽  
Strengthening Method

This study presents a strengthening method for reinforced concrete (RC) columns. The proposed method, which consists of a pair of steel rods, two reverse-threaded couplers, and four corner blocks, is feasible and straightforward. A quasi-static cyclic loading test was performed on the columns externally strengthened by the steel rods. It was found that the corner blocks and the external steel rods with a low prestress level effectively confined the concrete on the compression side of plastic hinges, which eventually induced flexural failure with a ductility higher than three in the strengthened columns. In addition, an analytical approach to predict the shear strength and ultimate flexural strength of the externally strengthened columns was applied. The comparison of analytical and experimental results showed that the analytical approach provided highly accurate predictions on the maximum strength and the failure mode of the externally strengthened columns. It is expected that the application of the proposed method will improve the seismic performance of damaged or deteriorated RC structures, thereby increasing their lifespan expectancy and sustainability.

scholarly journals Estimation of the characteristic compressive strength value of concrete based on the current code recommendations

2013 ◽  
Vol 12 (3) ◽  
pp. 193-200
Author(s):  
Izabela Skrzypczak
Keyword(s):  
Compressive Strength ◽  
Statistical Method ◽  
Test Results ◽  
Empirical Relationships ◽  
Existing Structures ◽  
Characteristic Strength ◽  
Characteristic Values ◽  
Current Code

The use of cores is an integral part of the assessment of existing structures that are modernized, redesigned or have been damaged. Evaluation of the test results and the estimation of characteristic values of compressive strength can be performed according to the statistical method proposed by the Annex D of the PN-EN 1990 [1] standard, and  also according to the PN-EN 13791 [2]. The procedures recommended in these both documents are different which can lead to various assessments of the characteristic values. The author has been verified whether the empirical relationships, defined in PN-EN 13791 [2], lead to obtaining larger values of characteristic strength and, consequently, to  estimation at the unsafe region. The characteristic compressive strength was of determined in accordance with the recommendations of  the PN-EN 13791 code [2] and the PN-EN 1990 - Annex D [1].

scholarly journals The Analysis, Discussion and Suggestions for the Mesh Reinforcement Technique of Polymer Mortar Wire Rope

2012 ◽  
Vol 5 ◽  
pp. 271-276
Author(s):  
Shu Ren Zhang ◽  
Zhong Long Li
Keyword(s):  
Engineering Application ◽  
Wire Rope ◽  
Practical Significance ◽  
Strengthening Effect ◽  
Technical Standards ◽  
Healthy Development ◽  
Mesh Reinforcement ◽  
Polymer Mortar ◽  
The Difference ◽  
Correct Understanding

The mesh reinforcement technique of polymer mortar wire rope is a new reinforcement technique used more in the domestic fittest reinforcement project recent years. Recently, there is no unified technical standards, the detailed practice is not same in practical work. There are big differences among the reinforcement effects. The key issue of wire rope is whether add prestressed or not. If add, how much should be prestressed? The difference of the actual practice and reinforcement effect reflects the understanding gap polymer mortar wire rope of mesh reinforcement technique action principle of the designer. A correct understanding of polymer mortar wire rope of mesh reinforcement technique the mechanism and the objective analysis strengthening effect and actively explore research in engineering application problems have a practical significance to promote the healthy development of the structure strengthening technology.

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