This paper presents the static and fatigue tests of hybrid(bonded/bolted)glass fiber reinforced polymer(GFRP)joints.Nine specimens of single-lap hybrid GFRP joints have been fabricated to study the static and fatigue ...This paper presents the static and fatigue tests of hybrid(bonded/bolted)glass fiber reinforced polymer(GFRP)joints.Nine specimens of single-lap hybrid GFRP joints have been fabricated to study the static and fatigue behaviors in the experimental campaign.The static tests of uniaxial tension loading are first conducted,from which the static ultimate bearing capacities of the joints are obtained.High-cycle fatigue tests are subsequently carried out so that the fatigue failure mode,fatigue life,and stiffness degradation of joints can be obtained.The measuring techniques including acoustic emission monitoring and three-dimensional digital image correlation have been employed in the tests to record the damage development process.The results revealed that the static strength and fatigue behavior of such thick hybrid GFRP joints were controlled by the bolted connections.The four stages of fatigue failure process are obtained from tests and acoustic emission signals analysis:cumulative damage of adhesive layer,damage of the adhesive layer,cumulative damage of GFRP plate,and damage of GFRP plate.The fatigue life and stiffness degradation can be improved by more bolts.The S-N(fatigue stress versus life)curves for the fatigue design of the single-lap hybrid GFRP joints under uniaxial tension loading are also proposed.展开更多
The infrastructure in the urban core area is becoming increasingly dense,leading to restrictions on intensive development;however,there is a lack of adequate research on the structural mechanics of quasi-rectangular p...The infrastructure in the urban core area is becoming increasingly dense,leading to restrictions on intensive development;however,there is a lack of adequate research on the structural mechanics of quasi-rectangular pipe jacking tunnels.This paper presents an experimental investigation that was conducted to analyze the impact of ground surcharge on the structural behavior of a quasi-rectangular tunnel located at Jing’an Temple station of Shanghai Rail Transit Line 14.The experimental setup included a scaled-down model of a quasi-rectangular tunnel,which was considered to be typical of underground structures.A series of tests were carried out by applying varying surcharge loads and eccentricities on the ground surface located above the tunnel.The tunnel structure’s response was monitored and analyzed through the use of earth pressure gauges,displacement sensors,and strain gauges.The experimental results revealed that ground surcharge on existing tunnels is mainly influenced by eccentricity and depth,with distinct effects at zero eccentricity and increasing eccentricity.Shallow tunnel burial depths intensify the impact of ground surcharge on the tunnel structure.展开更多
An extensive experimental-mechanistic study was conducted to reveal the relationship between the light weight deflectometer(LWD)measured deflections and the degree of compaction of pavement base materials.Both laborat...An extensive experimental-mechanistic study was conducted to reveal the relationship between the light weight deflectometer(LWD)measured deflections and the degree of compaction of pavement base materials.Both laboratory experiments and test pits experiments were performed with different types of pavement base materials.The modulus based maximum allowable LWD deflections under different structural and compaction conditions were developed for the most commonly used pavement base aggregate in Indiana.The maximum allowable deflections are based on the equivalent subgrade modulus and the thickness of the layer to be compacted.It is emphasized that the LWD deflections must be measured as soon as the material is compacted or before the moisture content decreases beyond a specified range.Therefore,the maximum allowable deflections are specified in terms of the difference between the actual moisture content and the optimum moisture content.The maximum allowable deflection values provide a sound basis for compaction quality control using LWD devices.展开更多
基金the National Natural Science Foundation of China(No.51978400)。
文摘This paper presents the static and fatigue tests of hybrid(bonded/bolted)glass fiber reinforced polymer(GFRP)joints.Nine specimens of single-lap hybrid GFRP joints have been fabricated to study the static and fatigue behaviors in the experimental campaign.The static tests of uniaxial tension loading are first conducted,from which the static ultimate bearing capacities of the joints are obtained.High-cycle fatigue tests are subsequently carried out so that the fatigue failure mode,fatigue life,and stiffness degradation of joints can be obtained.The measuring techniques including acoustic emission monitoring and three-dimensional digital image correlation have been employed in the tests to record the damage development process.The results revealed that the static strength and fatigue behavior of such thick hybrid GFRP joints were controlled by the bolted connections.The four stages of fatigue failure process are obtained from tests and acoustic emission signals analysis:cumulative damage of adhesive layer,damage of the adhesive layer,cumulative damage of GFRP plate,and damage of GFRP plate.The fatigue life and stiffness degradation can be improved by more bolts.The S-N(fatigue stress versus life)curves for the fatigue design of the single-lap hybrid GFRP joints under uniaxial tension loading are also proposed.
基金Financial support,jointly provided by the Ministry of Science and Technology of China(No.2021YFE0114100)the Federal Ministry of Education,Science,and Research(BMBWF)of Austria(No.CN11/2021)for the project“Intense Upgrades of the New Austrian Tunnelling Method(NATM)and Demonstration of its Applicability to High-Quality Urban Development”,is gratefully acknowledged+2 种基金the National Natural Science Foundation of China(Grant No.U1934210)the Science and Technology Commission of Shanghai Municipality(Nos.21DZ1203505,22DZ1203005,21DZ1202803,and 21DZ1202806)the Shanghai Rising-Star Program(No.22QB1405000)for their financial support of this work.
文摘The infrastructure in the urban core area is becoming increasingly dense,leading to restrictions on intensive development;however,there is a lack of adequate research on the structural mechanics of quasi-rectangular pipe jacking tunnels.This paper presents an experimental investigation that was conducted to analyze the impact of ground surcharge on the structural behavior of a quasi-rectangular tunnel located at Jing’an Temple station of Shanghai Rail Transit Line 14.The experimental setup included a scaled-down model of a quasi-rectangular tunnel,which was considered to be typical of underground structures.A series of tests were carried out by applying varying surcharge loads and eccentricities on the ground surface located above the tunnel.The tunnel structure’s response was monitored and analyzed through the use of earth pressure gauges,displacement sensors,and strain gauges.The experimental results revealed that ground surcharge on existing tunnels is mainly influenced by eccentricity and depth,with distinct effects at zero eccentricity and increasing eccentricity.Shallow tunnel burial depths intensify the impact of ground surcharge on the tunnel structure.
基金supported in part by the Joint Transportation Research Program administered by the Indiana Department of Transportation and Purdue University。
文摘An extensive experimental-mechanistic study was conducted to reveal the relationship between the light weight deflectometer(LWD)measured deflections and the degree of compaction of pavement base materials.Both laboratory experiments and test pits experiments were performed with different types of pavement base materials.The modulus based maximum allowable LWD deflections under different structural and compaction conditions were developed for the most commonly used pavement base aggregate in Indiana.The maximum allowable deflections are based on the equivalent subgrade modulus and the thickness of the layer to be compacted.It is emphasized that the LWD deflections must be measured as soon as the material is compacted or before the moisture content decreases beyond a specified range.Therefore,the maximum allowable deflections are specified in terms of the difference between the actual moisture content and the optimum moisture content.The maximum allowable deflection values provide a sound basis for compaction quality control using LWD devices.
