The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study...The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study clarifies the relationship between radial pressure and bonding length for the ultimate pullout force and reveals the microscopic failure process of the resin-rock interface in the anchoring system.The results show that the ultimate load increases with the increase of bonding length in three different stages:rapid,slow,and uniform growth.The new mechanical model developed considering radial pressure describes the inverse relationship between radial pressure and the plastic zone on the bonding section,and quantifies the reinforcing effect of confining pressure on the anchoring force.During the pull-out process of the anchor cable,the generation of failure cracks is in the order of orifice,bottom,and middle of the hole.Radial pressure can effectively enhance the ultimate pull-out force,alleviate the oscillation increase of pull-out force,and inhibit resin cracking,but will produce an external crushing zone.It also reveals the synergistic effect between bonding length and radial pressure,and successfully carries out industrial tests of anchor cable support,which ensures the stability of the stope roof and provides an important reference for the design of anchor cable support in deep high-stress mines.展开更多
Rotational isomerism effects on the optical spectra of a push-pull nonlinear optical chro-mophore 2-dicyanomethylen-3-cyano-4-f2-[E-（4-N,N-di（2-acetoxyethyl）-amino）-phenylene-（3,4-dibutyl）-thien-5]-E-vinylg-5,5-...Rotational isomerism effects on the optical spectra of a push-pull nonlinear optical chro-mophore 2-dicyanomethylen-3-cyano-4-f2-[E-（4-N,N-di（2-acetoxyethyl）-amino）-phenylene-（3,4-dibutyl）-thien-5]-E-vinylg-5,5-dimethyl-2,5-dihydrofuran （FTC） in a few solvents have been studied using the time-dependent density functional theory in combination with the polarizable continuum model. It is shown that the maximum absorption peaks of the ro-tamers have difference of nearly 30 nm both in vacuum and in solutions. The population of the rotamers changes a lot in different solvents. Based on the geometries optimized by Hartree-Fock method, the Maxwell-Boltzmann averaged absorption has been calculated and the maximum absorption peak is in good agreement with experiment. It indicates that the bond length alternation can have an important effect on the optical spectra.展开更多
The bond length of ^4HeH^＋ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of ^4HeH^＋ is 0.094±0.003nm. The bond length of ...The bond length of ^4HeH^＋ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of ^4HeH^＋ is 0.094±0.003nm. The bond length of ^4HeH^＋ obtained with our radio frequency （RF） ion source is larger than that obtained with a duoplasmatron ion source at Argonne National Laboratory （ANL）, but the bond lengths of H^＋2 and H^＋3obtained separately by ANL and by us with the two different ion sources are consistent with each other, which implies that there exists an ion source effect on the bond length of ^4HeH^＋. The main reason why the 4^4HeH^＋ bond lengths obtained by the two different ion sources are different is also discussed.展开更多
Metal-organic frameworks(MOFs)have been developed as an ideal platform for exploration of the relationship between intrinsic structure and catalytic activity,but the limited catalytic activity and stability has hamper...Metal-organic frameworks(MOFs)have been developed as an ideal platform for exploration of the relationship between intrinsic structure and catalytic activity,but the limited catalytic activity and stability has hampered their practical use in water splitting.Herein,we develop a bond length adjustment strategy for optimizing naphthalene-based MOFs that synthesized by acid etching Co-naphthalenedicarboxylic acid-based MOFs(donated as AE-CoNDA)to serve as efficient catalyst for water splitting.AE-CoNDA exhibits a low overpotential of 260 mV to reach 10 mA cm^(−2)and a small Tafel slope of 62 mV dec^(−1)with excellent stability over 100 h.After integrated AE-CoNDA onto BiVO_(4),photocurrent density of 4.3 mA cm^(−2)is achieved at 1.23 V.Experimental investigations demonstrate that the stretched Co-O bond length was found to optimize the orbitals hybridization of Co 3d and O 2p,which accounts for the fast kinetics and high activity.Theoretical calculations reveal that the stretched Co-O bond length strengthens the adsorption of oxygen-contained intermediates at the Co active sites for highly efficient water splitting.展开更多
Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp （n=Q, 5）, combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order po...Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp （n=Q, 5）, combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order polynomial fitting technique, the bond length and spectroscopic constants of Hg2 are studied by the coupled cluster theory with spin-orbit coupling. Spin-orbit coupling is included in the post Hartree-Fock procedure, i.e., in the coupled- cluster iteration, to obtain more reliable theoretical results. The results show that our theoretical values agree with the experimental values very well and will be helpful to understand the spectral character of Hg2.展开更多
By using a two-dimensional Monte-Carlo classical ensemble method, we investigate the double ionization（DI） process of the CS_2 molecule with different bond lengths in an 800-nm intense laser field. The double ioniza...By using a two-dimensional Monte-Carlo classical ensemble method, we investigate the double ionization（DI） process of the CS_2 molecule with different bond lengths in an 800-nm intense laser field. The double ionization probability presents a ＂knee＂ structure with equilibrium internuclear distance R = 2.9245 a.u.（a.u. is short for atomic unit）. As the bond length of CS increases, the DI probability is enhanced and the ＂knee＂ structure becomes less obvious. In addition,the momentum distribution of double ionized electrons is also investigated, which shows the momentum mostly distributed in the first and third quadrants with equilibrium internuclear distance R = 2.9245 a.u. As the bond length of CS increases,the electron momentum becomes evenly distributed in the four quadrants. Furthermore, the energy distributions and the corresponding trajectories of the double-ionized electrons versus time are also demonstrated, which show that the bond length of CS in the CS_2 molecule plays a key role in the DI process.展开更多
Silicene,a silicon analog of graphene,holds promise for next-generation electronics due to its tunable bandgap and larger spin-orbit coupling.Despite extensive efforts to synthesize and characterize silicene on metal ...Silicene,a silicon analog of graphene,holds promise for next-generation electronics due to its tunable bandgap and larger spin-orbit coupling.Despite extensive efforts to synthesize and characterize silicene on metal substrates,bondresolved imaging of its atomic structure has remained elusive.Here,we report the fabrication and bond-resolved characterization of silicene on Au(111)substrate.Three silicene phases tuned by surface reconstruction and annealing temperatures are achieved.Using CO-terminated scanning tunneling microscopy(STM)tips,we resolve these silicene phases with atomic precision,determining their bond lengths,local strain,and geometric configurations.Furthermore,we correlate these structural features with their electronic properties,revealing the effect of strain and substrate interactions on the electronic properties of silicene.This work establishes silicene's intrinsic bonding topology and resolves longstanding controversies in silicene research.展开更多
Bond length (or lattice) distortion, crystallite size and crystal boundary structure areall important aspects in the research of nanocrystalline structure. A number of interestingworks have been published concerning t...Bond length (or lattice) distortion, crystallite size and crystal boundary structure areall important aspects in the research of nanocrystalline structure. A number of interestingworks have been published concerning the effect of lattice distortion on the properties ofnanocrystalline, but the studies of the characteristics of bond length or lattice distortionof nanocrystalline have not been specially reported. In this note, a new method analyzingbond length distortion in nanocrystalline by Raman spectroscopy is given on the basis展开更多
Some behavior of graphite at high temperature has been studied using X-ray diffraction and Raman spectrat. Recently a model, which can be used to calculate the bond length of sp<sup>2</sup> in graphite usi...Some behavior of graphite at high temperature has been studied using X-ray diffraction and Raman spectrat. Recently a model, which can be used to calculate the bond length of sp<sup>2</sup> in graphite using the frequency of Raman active mode E<sub>2g</sub>, has been proposed by E. Fitzer. This model is successful at ambient temperature. But is it suitable at high temperature? In this note, the law of bond length changing with temperature for TG64 type graphite is studied by X-ray diffraction and Raman spectra at展开更多
A relationship between the X-H (X = N, O, C, and so on) equilibrium bond length in a Morse oscillator and the X-H stretching overtone frequency shifts is obtained theoretically. We use the equation to discuss the empi...A relationship between the X-H (X = N, O, C, and so on) equilibrium bond length in a Morse oscillator and the X-H stretching overtone frequency shifts is obtained theoretically. We use the equation to discuss the empirical linear relationships that have been proposed for heterocyclics, alkanes and fluorinated benzenes. On the other hand, a unified relationship between the X-H bond angles and the experimental quantities (ω(?) and the coupling strength λ) is also presented for XH2, XH, and XH4 molecules or molecular fragments. Calculations of X-H bond angles for a number of molecules show that the results from our equations are in excellent agreement with the experimental values. Also we can extract the information of relative magnitude of bond coupling force field.展开更多
Until recently the hydrogen molecule structural parameters are calculated with the methods of quantum mechanics. To achieve results close to experimental values, the wave function used is complicated and has no clear ...Until recently the hydrogen molecule structural parameters are calculated with the methods of quantum mechanics. To achieve results close to experimental values, the wave function used is complicated and has no clear physical meaning. Because the distribution of the electron probability density is a statistical rule, the macro time has actually been used in the concept on a electron cloud graph. Here are obtained three formulas with a classical mechanics method on the bond length r e , bond energy D e and force constant k of the ground state hydrogen molecule, which have a clear physical meaning but no artificial parameters, and compared with experimental values, the relative errors are respectively less than 1%, 2% and 4%.展开更多
This study intends to find out the correlation between the cover depth and the bond characteristics of UHPC through pull-out tests of UHPC specimens with different cover depths and bond tests of rebar using flexural m...This study intends to find out the correlation between the cover depth and the bond characteristics of UHPC through pull-out tests of UHPC specimens with different cover depths and bond tests of rebar using flexural members. In this experimental study, specimens are fabricated with the lap-splice length as test variable in relation with the calculation of the lap-splice length for 180- MPa UHPC. Moreover, specimens are also fabricated with the cover depth as test variable to evaluate the effect of the cover depth on the UHPC flexural members. The load-displacement curves are analyzed for each of these test variables to compute the lap-splice length proposed in the K-UHPC structural design guideline and to evaluate the influence of the cover depth on the flexural members. As a result, the stability of the structural behavior can be significantly enhanced by increasing slightly the cover depth specification of the current UHPC Structure Design Guideline from the maximum value between 1.5 times of rebar diameter and 20 mm to the maximum value between 1.5 times of rebar diameter and 25 mm.展开更多
The main reaction products were investigated by analysis of microstructure of alkali-activated ground granulated blast furnace slag （GGBFS） paste. An experimental research was performed on bond performance of alkali...The main reaction products were investigated by analysis of microstructure of alkali-activated ground granulated blast furnace slag （GGBFS） paste. An experimental research was performed on bond performance of alkali-activated GGBFS paste as a construction adhesive after exposure to 20-500℃. Through XRD analysis, a few calcium silicate hydrate, hydrotalcite and tetracalcium aluminate hydrate were determined as end products, and they were filled and packed each other at room temperature. In addition, akermanite dramatically increased at 800 ~C and above. The two key parameters, the ultimate load Pu.T and effective bond length Le, were determined using test data of carbon fiber-reinforced polymer （CFRP）-to-concrete bonded joints at elevated temperature. The experimental results indicate that the ultimate load Pu.T remains relatively stable initially and then decreases with increasing temperature. The effective bond length Le increases with increasing temperature except at 300℃. The proposed temperature-dependent effective bond length formula is shown to closely represent the test data.展开更多
Carbon forms a variety of compounds with single, double, triple and the intermediate resonance bonds with atoms of its own or other kinds. This paper is concerned with graphite, a very useful material, which is a stac...Carbon forms a variety of compounds with single, double, triple and the intermediate resonance bonds with atoms of its own or other kinds. This paper is concerned with graphite, a very useful material, which is a stack of electrically conducting graphene layers held together by weak van der Waals (vdW) bonds. It crystallizes in hexagonal and rhombohedral forms, in which the hexagon inter-planar bond distance is 0.34 nm. Here a new and simple approach accounts for this bond length and shows the coulombic nature of the vdW bond.展开更多
The static O-H bond parameters including O-H bond length, O-H charge difference, O-H Mulliken population and O-H bond stretching force constant (k) for 17 phenols were calculated by ab initio method HF/6-31G**. In com...The static O-H bond parameters including O-H bond length, O-H charge difference, O-H Mulliken population and O-H bond stretching force constant (k) for 17 phenols were calculated by ab initio method HF/6-31G**. In combination with the O-H bond dissociation enthalpies (BDE) of the phenols determined by experiment, it was found that there were poor correlationships between the static O-H bond parameters and O-H BDE. Considering the good correlationship bt tween O-H BDE and logarithm of free radical scavenging rate constant for phenolic antioxidant, it is reasonable to believe that the ineffectiveness of static O-H bond parameters in characterizing antioxidant activity arises from the fact that they cannot measure the O-H BDE.展开更多
Fiber optic sensor has been widely used as a structural health monitoring device by either embedding into or surface bonding onto the structures. The strain of optic fiber induced by the host material is strongly depe...Fiber optic sensor has been widely used as a structural health monitoring device by either embedding into or surface bonding onto the structures. The strain of optic fiber induced by the host material is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the length of bonding. The strains between the fiber optics and host structure are not exact the same. The existence of the protective coating and adhesive layer would affect the strain measured by the surface bonding optic sensor. The analytical expression of the strain in the optic fiber induced by the host material was presented. The results were validated by the finite element method. The theoretical predictions reveal that the strain in the optical fiber is lower than the strain of host material. Parametric study shows that a long bonding length and high modulus of protective coating would increase the percentage of strain transferring into the optical fiber. Experiments were conducted by using Mach-Zehnder interferometer to measure the strain of the surface bonding optic fiber induced by the host structure. Good agreements were observed in comparison with the experimental results and theoretical predictions.展开更多
As a preliminary study for the erection of floating structures using high performance concrete, this paper examines the bond characteristics between concrete and the reinforcing bar. Since the floating structure is co...As a preliminary study for the erection of floating structures using high performance concrete, this paper examines the bond characteristics between concrete and the reinforcing bar. Since the floating structure is constructed in aquatic environment, corrosion of the reinforcing steel is likely to develop more prematurely than in onshore structure in case of concrete cracking. A solution to this corrosion problem could use FRP rebar instead of steel reinforcement. To that goal, an experimental study is conducted on the concrete-FRP bond strength to verify if such FRP rebar develops performance comparable to the conventional steel rebar. A series of tests are performed considering the bond length of ordinary steel rebar and G-FRP rebar as test variable with respect to the strength of concrete, and the results are presented.展开更多
基金Financial supports for this work,provided by the National Natural Science Foundation Project of China(No.52374152)the Guangxi Science and Technology Plan Project of China(No.2022AB31023)the National Basic Research Development Program of China(No.2022YFC2904602)are gratefully acknowledged。
文摘The anchoring capacity of the anchor cable is closely related to the bonding length and radial pressure conditions.Through field pull-out tests,theoretical analysis,numerical simulation,and industrial tests,this study clarifies the relationship between radial pressure and bonding length for the ultimate pullout force and reveals the microscopic failure process of the resin-rock interface in the anchoring system.The results show that the ultimate load increases with the increase of bonding length in three different stages:rapid,slow,and uniform growth.The new mechanical model developed considering radial pressure describes the inverse relationship between radial pressure and the plastic zone on the bonding section,and quantifies the reinforcing effect of confining pressure on the anchoring force.During the pull-out process of the anchor cable,the generation of failure cracks is in the order of orifice,bottom,and middle of the hole.Radial pressure can effectively enhance the ultimate pull-out force,alleviate the oscillation increase of pull-out force,and inhibit resin cracking,but will produce an external crushing zone.It also reveals the synergistic effect between bonding length and radial pressure,and successfully carries out industrial tests of anchor cable support,which ensures the stability of the stope roof and provides an important reference for the design of anchor cable support in deep high-stress mines.
基金ACKNOWLEDGMENTS This work was supported by Young Scientists Fund of the National Natural Science Foundation of China （No.10904085）.
文摘Rotational isomerism effects on the optical spectra of a push-pull nonlinear optical chro-mophore 2-dicyanomethylen-3-cyano-4-f2-[E-（4-N,N-di（2-acetoxyethyl）-amino）-phenylene-（3,4-dibutyl）-thien-5]-E-vinylg-5,5-dimethyl-2,5-dihydrofuran （FTC） in a few solvents have been studied using the time-dependent density functional theory in combination with the polarizable continuum model. It is shown that the maximum absorption peaks of the ro-tamers have difference of nearly 30 nm both in vacuum and in solutions. The population of the rotamers changes a lot in different solvents. Based on the geometries optimized by Hartree-Fock method, the Maxwell-Boltzmann averaged absorption has been calculated and the maximum absorption peak is in good agreement with experiment. It indicates that the bond length alternation can have an important effect on the optical spectra.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10175041 and 10375040）.
文摘The bond length of ^4HeH^＋ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of ^4HeH^＋ is 0.094±0.003nm. The bond length of ^4HeH^＋ obtained with our radio frequency （RF） ion source is larger than that obtained with a duoplasmatron ion source at Argonne National Laboratory （ANL）, but the bond lengths of H^＋2 and H^＋3obtained separately by ANL and by us with the two different ion sources are consistent with each other, which implies that there exists an ion source effect on the bond length of ^4HeH^＋. The main reason why the 4^4HeH^＋ bond lengths obtained by the two different ion sources are different is also discussed.
基金supported by the National Key Research and Development Program of China (2022YFB4002100)the development project of Zhejiang Province's "Jianbing" and "Lingyan" (2023C01226)+4 种基金the National Natural Science Foundation of China (22278364, U22A20432, 22238008, 22211530045, and 22178308)the Fundamental Research Funds for the Central Universities (226-2022-00044 and 226-2022-00055)the Science Foundation of Donghai Laboratory (DH-2022ZY0009)the Startup Foundation for Hundred-Talent Program of Zhejiang UniversityScientific Research Fund of Zhejiang Provincial Education Department.
文摘Metal-organic frameworks(MOFs)have been developed as an ideal platform for exploration of the relationship between intrinsic structure and catalytic activity,but the limited catalytic activity and stability has hampered their practical use in water splitting.Herein,we develop a bond length adjustment strategy for optimizing naphthalene-based MOFs that synthesized by acid etching Co-naphthalenedicarboxylic acid-based MOFs(donated as AE-CoNDA)to serve as efficient catalyst for water splitting.AE-CoNDA exhibits a low overpotential of 260 mV to reach 10 mA cm^(−2)and a small Tafel slope of 62 mV dec^(−1)with excellent stability over 100 h.After integrated AE-CoNDA onto BiVO_(4),photocurrent density of 4.3 mA cm^(−2)is achieved at 1.23 V.Experimental investigations demonstrate that the stretched Co-O bond length was found to optimize the orbitals hybridization of Co 3d and O 2p,which accounts for the fast kinetics and high activity.Theoretical calculations reveal that the stretched Co-O bond length strengthens the adsorption of oxygen-contained intermediates at the Co active sites for highly efficient water splitting.
基金Supported by the Start-Up Funds of Xi’an Polytechnic University under Grant No BS1211the Scientific Research Program Funded by Shaanxi Provincial Education Department under Grant No 2013JK0679
文摘Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp （n=Q, 5）, combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order polynomial fitting technique, the bond length and spectroscopic constants of Hg2 are studied by the coupled cluster theory with spin-orbit coupling. Spin-orbit coupling is included in the post Hartree-Fock procedure, i.e., in the coupled- cluster iteration, to obtain more reliable theoretical results. The results show that our theoretical values agree with the experimental values very well and will be helpful to understand the spectral character of Hg2.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11574117 and11604131)
文摘By using a two-dimensional Monte-Carlo classical ensemble method, we investigate the double ionization（DI） process of the CS_2 molecule with different bond lengths in an 800-nm intense laser field. The double ionization probability presents a ＂knee＂ structure with equilibrium internuclear distance R = 2.9245 a.u.（a.u. is short for atomic unit）. As the bond length of CS increases, the DI probability is enhanced and the ＂knee＂ structure becomes less obvious. In addition,the momentum distribution of double ionized electrons is also investigated, which shows the momentum mostly distributed in the first and third quadrants with equilibrium internuclear distance R = 2.9245 a.u. As the bond length of CS increases,the electron momentum becomes evenly distributed in the four quadrants. Furthermore, the energy distributions and the corresponding trajectories of the double-ionized electrons versus time are also demonstrated, which show that the bond length of CS in the CS_2 molecule plays a key role in the DI process.
基金Project supported by the National Natural Science Foundation of China(Grant No.12474181)the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2021B0301030002 and 2024A1515010656)the Guangdong Science and Technology Project(Grant No.2021QN02X859)。
文摘Silicene,a silicon analog of graphene,holds promise for next-generation electronics due to its tunable bandgap and larger spin-orbit coupling.Despite extensive efforts to synthesize and characterize silicene on metal substrates,bondresolved imaging of its atomic structure has remained elusive.Here,we report the fabrication and bond-resolved characterization of silicene on Au(111)substrate.Three silicene phases tuned by surface reconstruction and annealing temperatures are achieved.Using CO-terminated scanning tunneling microscopy(STM)tips,we resolve these silicene phases with atomic precision,determining their bond lengths,local strain,and geometric configurations.Furthermore,we correlate these structural features with their electronic properties,revealing the effect of strain and substrate interactions on the electronic properties of silicene.This work establishes silicene's intrinsic bonding topology and resolves longstanding controversies in silicene research.
文摘Bond length (or lattice) distortion, crystallite size and crystal boundary structure areall important aspects in the research of nanocrystalline structure. A number of interestingworks have been published concerning the effect of lattice distortion on the properties ofnanocrystalline, but the studies of the characteristics of bond length or lattice distortionof nanocrystalline have not been specially reported. In this note, a new method analyzingbond length distortion in nanocrystalline by Raman spectroscopy is given on the basis
基金Project supported by the National Natural Science Foundation of China
文摘Some behavior of graphite at high temperature has been studied using X-ray diffraction and Raman spectrat. Recently a model, which can be used to calculate the bond length of sp<sup>2</sup> in graphite using the frequency of Raman active mode E<sub>2g</sub>, has been proposed by E. Fitzer. This model is successful at ambient temperature. But is it suitable at high temperature? In this note, the law of bond length changing with temperature for TG64 type graphite is studied by X-ray diffraction and Raman spectra at
基金Project supported by the National Natural Science Foundation of China
文摘A relationship between the X-H (X = N, O, C, and so on) equilibrium bond length in a Morse oscillator and the X-H stretching overtone frequency shifts is obtained theoretically. We use the equation to discuss the empirical linear relationships that have been proposed for heterocyclics, alkanes and fluorinated benzenes. On the other hand, a unified relationship between the X-H bond angles and the experimental quantities (ω(?) and the coupling strength λ) is also presented for XH2, XH, and XH4 molecules or molecular fragments. Calculations of X-H bond angles for a number of molecules show that the results from our equations are in excellent agreement with the experimental values. Also we can extract the information of relative magnitude of bond coupling force field.
文摘Until recently the hydrogen molecule structural parameters are calculated with the methods of quantum mechanics. To achieve results close to experimental values, the wave function used is complicated and has no clear physical meaning. Because the distribution of the electron probability density is a statistical rule, the macro time has actually been used in the concept on a electron cloud graph. Here are obtained three formulas with a classical mechanics method on the bond length r e , bond energy D e and force constant k of the ground state hydrogen molecule, which have a clear physical meaning but no artificial parameters, and compared with experimental values, the relative errors are respectively less than 1%, 2% and 4%.
文摘This study intends to find out the correlation between the cover depth and the bond characteristics of UHPC through pull-out tests of UHPC specimens with different cover depths and bond tests of rebar using flexural members. In this experimental study, specimens are fabricated with the lap-splice length as test variable in relation with the calculation of the lap-splice length for 180- MPa UHPC. Moreover, specimens are also fabricated with the cover depth as test variable to evaluate the effect of the cover depth on the UHPC flexural members. The load-displacement curves are analyzed for each of these test variables to compute the lap-splice length proposed in the K-UHPC structural design guideline and to evaluate the influence of the cover depth on the flexural members. As a result, the stability of the structural behavior can be significantly enhanced by increasing slightly the cover depth specification of the current UHPC Structure Design Guideline from the maximum value between 1.5 times of rebar diameter and 20 mm to the maximum value between 1.5 times of rebar diameter and 25 mm.
基金Funded by the National Natural Science Foundation of China(50178026)the Cheung Kong Scholars Program Foundation of Chinese Ministry of Education(2009-37)
文摘The main reaction products were investigated by analysis of microstructure of alkali-activated ground granulated blast furnace slag （GGBFS） paste. An experimental research was performed on bond performance of alkali-activated GGBFS paste as a construction adhesive after exposure to 20-500℃. Through XRD analysis, a few calcium silicate hydrate, hydrotalcite and tetracalcium aluminate hydrate were determined as end products, and they were filled and packed each other at room temperature. In addition, akermanite dramatically increased at 800 ~C and above. The two key parameters, the ultimate load Pu.T and effective bond length Le, were determined using test data of carbon fiber-reinforced polymer （CFRP）-to-concrete bonded joints at elevated temperature. The experimental results indicate that the ultimate load Pu.T remains relatively stable initially and then decreases with increasing temperature. The effective bond length Le increases with increasing temperature except at 300℃. The proposed temperature-dependent effective bond length formula is shown to closely represent the test data.
文摘Carbon forms a variety of compounds with single, double, triple and the intermediate resonance bonds with atoms of its own or other kinds. This paper is concerned with graphite, a very useful material, which is a stack of electrically conducting graphene layers held together by weak van der Waals (vdW) bonds. It crystallizes in hexagonal and rhombohedral forms, in which the hexagon inter-planar bond distance is 0.34 nm. Here a new and simple approach accounts for this bond length and shows the coulombic nature of the vdW bond.
文摘The static O-H bond parameters including O-H bond length, O-H charge difference, O-H Mulliken population and O-H bond stretching force constant (k) for 17 phenols were calculated by ab initio method HF/6-31G**. In combination with the O-H bond dissociation enthalpies (BDE) of the phenols determined by experiment, it was found that there were poor correlationships between the static O-H bond parameters and O-H BDE. Considering the good correlationship bt tween O-H BDE and logarithm of free radical scavenging rate constant for phenolic antioxidant, it is reasonable to believe that the ineffectiveness of static O-H bond parameters in characterizing antioxidant activity arises from the fact that they cannot measure the O-H BDE.
基金the financial support under grant No.NSC 93-2212-E-155-007 for this work
文摘Fiber optic sensor has been widely used as a structural health monitoring device by either embedding into or surface bonding onto the structures. The strain of optic fiber induced by the host material is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the length of bonding. The strains between the fiber optics and host structure are not exact the same. The existence of the protective coating and adhesive layer would affect the strain measured by the surface bonding optic sensor. The analytical expression of the strain in the optic fiber induced by the host material was presented. The results were validated by the finite element method. The theoretical predictions reveal that the strain in the optical fiber is lower than the strain of host material. Parametric study shows that a long bonding length and high modulus of protective coating would increase the percentage of strain transferring into the optical fiber. Experiments were conducted by using Mach-Zehnder interferometer to measure the strain of the surface bonding optic fiber induced by the host structure. Good agreements were observed in comparison with the experimental results and theoretical predictions.
文摘As a preliminary study for the erection of floating structures using high performance concrete, this paper examines the bond characteristics between concrete and the reinforcing bar. Since the floating structure is constructed in aquatic environment, corrosion of the reinforcing steel is likely to develop more prematurely than in onshore structure in case of concrete cracking. A solution to this corrosion problem could use FRP rebar instead of steel reinforcement. To that goal, an experimental study is conducted on the concrete-FRP bond strength to verify if such FRP rebar develops performance comparable to the conventional steel rebar. A series of tests are performed considering the bond length of ordinary steel rebar and G-FRP rebar as test variable with respect to the strength of concrete, and the results are presented.
