• International Journal of Highway Engineering
• /
• v.12 no.3
• /
• pp.147-154
• /
• 2010

In post-tensioned concrete pavement(PTCP), one of the most important design variables is the initial joint width, in addition to the tensioning spacing. The joint width between PTCP slabs directly affects noise and ride quality. If the joint width is too wide, noise increases and ride quality decreases. If the initial joint width is too narrow, on the other hand, under high temperature, PTCP slabs can blow up, or failures near the joint can occur due to excessive compressive stresses. This study was conducted to determine the optimal initial joint width of PTCP and to investigate the joint width behavior under temperature changes. The experiments were performed using one-year-old PTCP slabs. The concrete temperatures were measured using the temperature measurement sensors installed at various depths. The joint widths were measured using vernier-calipers at different times of a day and the relationship between the joint width and temperature was analyzed. From this study, the design methodology to determine the optimal initial joint width of PTCP could be proposed.

• International Journal of Highway Engineering
• /
• v.13 no.1
• /
• pp.223-228
• /
• 2011

The initial joint width design of the terminal joint between post-tensioned concrete pavement (PTCP) and jointed concrete pavement (JCP) was studied in this research. The joint width between PTCP and JCP directly affects noise and ride quality. If the initial joint width is very large, noise increases and ride quality decreases. If the initial joint width is very small, on the other hand, under high temperatures, PTCP slabs can blow up, or failures near the joint can occur due to excessive compressive stresses. The terminal joint width behavior between PTCP and JCP near Jumunjin at Donghae expressway under temperature changes was measured in August and November 2010 and the data was analyzed. From this study, the design methodology of the optimal initial terminal joint width was proposed.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4D
• /
• pp.593-600
• /
• 2006

Joint opening of jointed concrete pavement is caused by change in temperature and humidity of adjoined slab. The magnitude of joint opening influences on the load-transfer-efficiency and the behavior of sealant. If temperature or humidity decreases, joint opening increases. Generally maximum joint opening of a given joint is predicted by using AASHTO equation. While different magnitudes of joint opening at the individual joints have been observed in a given pavement section, AASHTO equation is limited to predict average joint opening in a given pavement section. Therefore the AASHTO equation may underestimate maximum joint for the half of joint in a given pavement section. Joints showing larger opening than the designed may experience early joint sealant failure, early faulting. Also unexpected spalling may be followed due to invasion of fine aggregate into the joints after sealant pop-off. In this study, the variation of the joint opening in a given pavement section was investigated based on the LTPP SMP data. Factors affecting on the variation are explored. Finally a probabilistic joint opening model is developed. This model can account for the reliability of the magnitude of joint opening so that the designer can select the ratio of underestimated joint opening.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.137-137
• /
• 2019

돌출줄눈은 산지하천의 만곡부의 빠른 유속을 감소시키기 위하여 활용된다. 본 연구에서는 친환경 디자인의 나무줄기 돌출줄눈(Tree Trunk Rip, TTR)과 사다리꼴 돌출줄눈(Trapezoid Rip, TR)의 흐름저항을 비교 분석하기 위하여 개수로 수리실험을 수행하였다. 실험은 길이 9m, 폭이 0.6m이며 경사가 0.0035로 고정된 개수로의 한쪽 측벽에 돌출줄눈을 설치하여 진행하였다. 사다리 꼴 돌출줄눈의 형상은 밑변 각이 $63^{\circ}$이며 무차원 설치간격 ${\lambda}_{nv}$가 6, 9, 12인 경우이다. 나무줄기 돌출줄눈의 기본 형상은 사다리꼴이고 표면은 나무껍질 무늬이며 ${\lambda}_{nv}$가 약 10이다. 나무줄기 돌출줄눈의 간격은 사다리꼴 돌출줄눈의 최적 설치 간격 9~12배 범위에 해당되고 평균 마찰계수는 사다리꼴 돌출줄눈의 9~12배의 평균 마찰계수 범위에 포함되었다. 사다리꼴 돌출줄눈의 ${\lambda}_{nv}$가 9, 12일 때의 전체 저항에 대한 형상저항의 비는 평균 $69.4{\pm}5.8%$였으며 나무줄기 돌출줄눈은 $70.2{\pm}2.1%$로 사다리꼴 돌출줄눈과 유사하다. 산지하천 흐름저항을 위한 돌출줄눈 설치에 있어 친환경적 디자인을 고려한 나무줄기가 사다리꼴 돌출줄눈보다 활용도가 클 것으로 기대된다.

• International Journal of Highway Engineering
• /
• v.3 no.1 s.7
• /
• pp.165-176
• /
• 2001

Joints in jointed concrete Pavement are designed to control against randomly occurred cracks within slabs, which may be caused by temperature or moisture variation. The advantage of these artificial cracks (joints) over naturally occurred cracks are easy access of protections, such as installation of joint seal and load transfer mechanism. The potential benefits of joint seals are to prevent infiltration of surface water through the joint into underlying soil and intrusion of incompressible materials (debris, fine size aggregate) in to the joint, which may prevent weakening of underlying soils and spallings due to excessive compressive stress, respectively. For the adequate design of joint seal, horizontal variation of joint widths (horizontal joint movements) are essential inputs. Based on long-term in-situ joint movement data of sixteen jointed concrete pavement sections in Long Term Performance Pavement Seasonal Monitoring Program (LTPP SMP), it was indicated that considerable Portion of joints showed no horizontal movements with change in temperature. This Phenomenon is called 'Joint Freezing'. Possible cause for joint freezing is that designed penetrated cracks do not occur at a joint. In this study, a model for the prediction of the ratio of freezing joints in a particular pavement sections is proposed. In addition, possible effects of joint freezing against pavement performance are addressed.

• International Journal of Highway Engineering
• /
• v.7 no.4 s.26
• /
• pp.69-77
• /
• 2005

Joint spacing is a potent influence in increasing the long term performance of jointed concrete pavement slabs through the control of tensile stress, sealant failure and Load Transfer Efficiency (LTE). Internal Joint Spacing is an empirical and fixed method therefore this study will present the optimum joint spacing considerations depending on various climactic conditions. Calculating the optimum joint spacing eliminates random cracking due to the effect of the environmental loads such as the early behavior of drying shrinkage and heat hydration. Optimum joint spacing is calculated so as not to cause pavement distress by the deterioration of LTE by long term pavement movement. This study shows that the provisional joint spacing is 6-8m. Pavement Distress Prediction Models show that pavement distress has no effect on joint spacing of 8m.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.700-700
• /
• 2012

산지유역은 하천을 따라서 도로가 발달되어 있어서 대부분의 도로가 홍수시 하천의 영향을 많이 받는다. 산지하천은 경사가 급하고 만곡수충부가 많이 발달되어 있기 때문에 홍수시 유속이 빠르고 만곡수충부의 편수위가 매우 크다. 이는 만곡부 호안 파괴와 도로 유실의 피해를 일으키는 경우가 많다. 따라서 대부분의 산지하천 만곡수충부에는 홍수피해 방지를 위해 콘크리트 옹벽호안으로 되어 있다. 그러나 콘크리트 옹벽은 조도가 작기 때문에 유속이 더 빠르게 되고 편수위를 한층 증대시킬 수 있다. 산지하천 만곡수충부의 편수위를 줄이기 위해서는 접근유속을 줄여야 하나 산지하천 특성으로 볼 때 접근유속 저감을 위한 공학적 방법은 제한적이다. 따라서 만곡수충부의 유속을 줄이는 방법으로 콘크리트 옹벽호안의 조도계수를 증대시키는 것이 효과적일 수 있다. 본 연구에서는 개수로 측벽에 수직돌출줄눈이 설치되었을 때 흐름에 미치는 수리효과를 개수로 수리실험으로 파악하고자 한 것이다. 실험결과 돌출줄눈의 간격이 수직돌출줄눈의 무차원 폭이 9일 때 평균유속이 가장 작게 나타났다. 이는 돌출줄눈의 간격이 개수로 내부흐름의 유속분포, 최대유속발생 위치, 유수단 면적의 크기에 영향이 미치기 때문이다. 따라서 개수로 측벽 수직돌출줄눈의 간격을 조절함으로써 개수로 유수저항의 크기를 조절할 수 있다.

• 한국방재학회:학술대회논문집
• /
• 2007.02a
• /
• pp.340-343
• /
• 2007

The temperature variation of concrete pavement at early-age significantly affects the initiation and movement of joint cracks. For this analysis, we have built on IIA(Incheon International Airport) concrete pavement construction zone, and we measured the temperature and movement of the concrete slabs by using thermocouples, moisture sensors, V/W strain gages, and Demac discs. The analysis results showed that pavement's temperature significantly affected the joint movement. The widths of the joint cracks increased at evening and early in the morning when the temperature dropped but, those decreased in the day time when the temperature rose because of the effect of thermal expansion of the concrete slabs. The movements of the joints where the cracks never developed showed opposite trend to the cracked joints.

• International Journal of Highway Engineering
• /
• v.13 no.4
• /
• pp.51-59
• /
• 2011

Tensile stress occurs and random crack develops in concrete pavement slab when it contracts by variation of temperature and humidity. The tensile stress decreases and the random crack is minimized by sawcutting the slab and inducing the crack with regular spacing. The random crack, joint damage, decrease of load transfer efficiency are caused by too wide joint spacing while too narrow joint spacing leads to increase of construction cost and decrease of comfort. A mechanistic-empirical joint spacing design method for the concrete pavement was developed in this study. Structurally and environmentally weakest sections were found among the sections showing good performance, and design strengths were determined by finite element analysis on the sections. The joint width for which the load transfer efficiency is suddenly lowered was determined as allowable joint with referring to existing research results. The maximum joint spacing for which the maximum tensile stress calculated by the finite element analysis did not exceed the design strength were found. And the maximum joint width expected by the maximum joint spacing were compared to the allowable joint width. The new method developed in this study was applied to two zones of Hamyang-Woolsan Expressway being designed. The same joint spacing as a test section constructed by 8.0m of joint spacing wider than usual was calculated by the design method. Very low cracking measured at 6 years after opening of the test section verified the design method developed in this study.

• Journal of Korea Water Resources Association
• /
• v.46 no.9
• /
• pp.947-956
• /
• 2013

Most of flood protection walls built on the impingement in mountain rivers have been made of concrete. It may cause flood disasters because the smooth wall surface could increase flow velocity. In this study the hydraulic experiments was carried out to evaluate the effect of one side wall with rectangular vertical ribs on flow resistance in open channel. The ratio of the pitch between vertical ribs to its depth, ${\lambda}_{nv}$, was designed so that it include the so-called d type and k type roughness. The range of Froude number, $F_r$, based on hydraulic radius is 0.81~1.12. Flow resistance in the open channel with a rib sidewall depends on the interval length of each ribs and the flow discharge. Maximum flow resistance occurred when ${\lambda}_{nv}$ is 9. In the d type roughness which ${\lambda}_{nv}$ is less than 3, the flow resistance decreases with increase of flow discharge. In the k type roughness which ${\lambda}_{nv}$ is greater than 3, the flow resistance increases with increase of flow discharge. The increments of flow resistance are especially great when ${\lambda}_{nv}$ are 9 and 12. The resistance due to vertical rib is mostly by the shape resistance and the vertical rib on one sidewall of open channel affects on the flow resistance so that the equivalent roughness heights of vertical rib may occur in scale of flow depth. Therefore the vertical ribs may be used to reduce the flow velocity and to move the location of maximum flow velocity from the rib sidewall to the centerward in a cross section of channels.