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2004 Vol. 34, No. 10
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2004, 34(10): 1-5,55.
doi: 10.13204/j.gyjz200410001
Abstract:
The nonlinear seismic response analyses of structures are reviewed, which include the analytic model of structure system, the element analytic model and its restoring force model and the solving of dynamic equations.Taking the plane frame model as an example for elastoplastic seismic response analyses of structure under two grades of earthquake input, the nonlinearities of structure are discussed, whose calculated results are also compared with those of the new seismic design code. Finally some advices of nonlinear seismic design of structures are suggested.
The nonlinear seismic response analyses of structures are reviewed, which include the analytic model of structure system, the element analytic model and its restoring force model and the solving of dynamic equations.Taking the plane frame model as an example for elastoplastic seismic response analyses of structure under two grades of earthquake input, the nonlinearities of structure are discussed, whose calculated results are also compared with those of the new seismic design code. Finally some advices of nonlinear seismic design of structures are suggested.
2004, 34(10): 6-9,23.
doi: 10.13204/j.gyjz200410002
Abstract:
Based on comprehensive comparison and analysis of current earthquake-resistance testing methods for structures,the pseudo-dynamic testing method is discussed especially.For large-stiffness and multi-degree of freedom structures,a method based on compound force-displacement control is presented.
Based on comprehensive comparison and analysis of current earthquake-resistance testing methods for structures,the pseudo-dynamic testing method is discussed especially.For large-stiffness and multi-degree of freedom structures,a method based on compound force-displacement control is presented.
2004, 34(10): 10-12,49.
doi: 10.13204/j.gyjz200410003
Abstract:
The optimum parameters of a TMD system can be determined with optimization designing. However, sometimes object functions needed to be optimized are more than one. Although itcs possible to integrate multiobject functions into one object function with weighting method, how to select weighting coefficients is disputable. Besides, there are always errors between the parameters realized in practical engineering and the designed ones which would deteriorate optimization effect.It. s difficult to find out how bad things were from optimum parameters. The concept of effective parametric fields is presented. To design TMD system with effective parametric fields can effectively improve reliability of the TMD system,therefore promote the spread and utilization of TMD shock-absorption technique.
The optimum parameters of a TMD system can be determined with optimization designing. However, sometimes object functions needed to be optimized are more than one. Although itcs possible to integrate multiobject functions into one object function with weighting method, how to select weighting coefficients is disputable. Besides, there are always errors between the parameters realized in practical engineering and the designed ones which would deteriorate optimization effect.It. s difficult to find out how bad things were from optimum parameters. The concept of effective parametric fields is presented. To design TMD system with effective parametric fields can effectively improve reliability of the TMD system,therefore promote the spread and utilization of TMD shock-absorption technique.
2004, 34(10): 13-16,20.
doi: 10.13204/j.gyjz200410004
Abstract:
A super-elastic shape memory alloy(SMA) damper is used in frame structural passive control.A simplified constitutive model of the super－elastic SMA is given.The mechanical model and the vibration equation for the frame structure with SMA dampers are set up.The vibration control effect is verified by time-history analysis of the practical structure under the earthquake.The results show that the super-elastic SMA damper has good effect on structural vibration control.
A super-elastic shape memory alloy(SMA) damper is used in frame structural passive control.A simplified constitutive model of the super－elastic SMA is given.The mechanical model and the vibration equation for the frame structure with SMA dampers are set up.The vibration control effect is verified by time-history analysis of the practical structure under the earthquake.The results show that the super-elastic SMA damper has good effect on structural vibration control.
2004, 34(10): 17-20.
doi: 10.13204/j.gyjz200410005
Abstract:
Through interlaminar shear model with the multi??degree of freedom, the equation of motion was established for base??isolated structure with the rubber bearings, considering the earthquake action in horizontal and vertical directions. The simplified formula for the calculation of the limit ratio of height to width was derived. The influence of vertical earthquake action on the limit ratio was analyzed, in consideration of the factors such as sites and earthquake intensity. The research shows that the influence of vertical earthquake action on the limit ratio of height to width is large in rigid site, which can be increased with an increase in seismic intensity and the peak value of the vertical acceleration. So, the influence of vertical earthquake action on the limit ratio of height to width for base??isolated structure is not ignored in high earthquake intensity zone and rig id site.
Through interlaminar shear model with the multi??degree of freedom, the equation of motion was established for base??isolated structure with the rubber bearings, considering the earthquake action in horizontal and vertical directions. The simplified formula for the calculation of the limit ratio of height to width was derived. The influence of vertical earthquake action on the limit ratio was analyzed, in consideration of the factors such as sites and earthquake intensity. The research shows that the influence of vertical earthquake action on the limit ratio of height to width is large in rigid site, which can be increased with an increase in seismic intensity and the peak value of the vertical acceleration. So, the influence of vertical earthquake action on the limit ratio of height to width for base??isolated structure is not ignored in high earthquake intensity zone and rig id site.
2004, 34(10): 21-23.
doi: 10.13204/j.gyjz200410006
Abstract:
The state of aseismic structure is classified as several sorts according to Code for Seismic Design of Building (GB 50011-2001) and corresponding maintenance strategy is set also. A mathematical model of optimal maintenance strategy based on Markov process for aseismic structure is built. State transition probability matrix and reward matrix are determined according to the different maintenance strategies, then structure limiting state transition probability vector and expected total cost are calculated. By optimization analysis of maintenance strategy for aseismic structure, the optimal maintenance strategy which is the minimal expected total cost can be get. An optimal maintenance strategy is arranged according to the state of structure. All of these provide a scientific basis for decision-making.
The state of aseismic structure is classified as several sorts according to Code for Seismic Design of Building (GB 50011-2001) and corresponding maintenance strategy is set also. A mathematical model of optimal maintenance strategy based on Markov process for aseismic structure is built. State transition probability matrix and reward matrix are determined according to the different maintenance strategies, then structure limiting state transition probability vector and expected total cost are calculated. By optimization analysis of maintenance strategy for aseismic structure, the optimal maintenance strategy which is the minimal expected total cost can be get. An optimal maintenance strategy is arranged according to the state of structure. All of these provide a scientific basis for decision-making.
2004, 34(10): 24-26.
doi: 10.13204/j.gyjz200410007
Abstract:
Buildings are the main feature of a city. Urban environments are mostly relative to buildings. Roofs are the main interface of cities which connect buildings to the air, rainwater and sunlight. The ecological functions of a roof are exhibited in rainwater collecting, roof planting, solar facilities and building unit design etc. A design thought combining a roof's ecological functions is proposed.
Buildings are the main feature of a city. Urban environments are mostly relative to buildings. Roofs are the main interface of cities which connect buildings to the air, rainwater and sunlight. The ecological functions of a roof are exhibited in rainwater collecting, roof planting, solar facilities and building unit design etc. A design thought combining a roof's ecological functions is proposed.
2004, 34(10): 27-29.
doi: 10.13204/j.gyjz200410008
Abstract:
The research on the building epidermis is no longer within the range of two-dimensional hierarchy, whose emphasis is now on the integral building shape embodied in the building epidermis. Therefore, much effort should be given to explore building material and technology as well as the impression of building epidermis in construction modelling and esthetics.
The research on the building epidermis is no longer within the range of two-dimensional hierarchy, whose emphasis is now on the integral building shape embodied in the building epidermis. Therefore, much effort should be given to explore building material and technology as well as the impression of building epidermis in construction modelling and esthetics.
2004, 34(10): 30-32,61.
doi: 10.13204/j.gyjz200410009
Abstract:
At the present most of the temperature stress analyses are conducted at the linear elastic stage of a concrete.A numerical simulation of the cracking process of a beam-slab structure at detemperature is carried out using nonlinear FEM crack model of reinforced concrete, whose results are compared with the observations of actual projects and the calculated ones of a simplified model.It is proved that the stress distribution due to the structures detemperature, and the position and direction of the cracks due to which can all be estimated properly by this model.Which provides a guidance to engineering design and practice.
At the present most of the temperature stress analyses are conducted at the linear elastic stage of a concrete.A numerical simulation of the cracking process of a beam-slab structure at detemperature is carried out using nonlinear FEM crack model of reinforced concrete, whose results are compared with the observations of actual projects and the calculated ones of a simplified model.It is proved that the stress distribution due to the structures detemperature, and the position and direction of the cracks due to which can all be estimated properly by this model.Which provides a guidance to engineering design and practice.
2004, 34(10): 33-35,46.
doi: 10.13204/j.gyjz200410010
Abstract:
Based on a series of loading tests of ful-l scale model DX piles cas-t in- situ, the bearing behaviour and loadtransferring mechanism of tension DX piles are studied. The results show that the tension bearing capacity of DX pile is apparently higher than that of the pile with constant section, and the curve of load-displacement of DX pile is slowly varying. The enlarged disks bear the most of all tension bearing capacity. It is found that the unit frictional resistances of DX pile is also higher than that of the pile with constant section because of squeezed efficiency of disk. Then, the lateral resistance of tension DX pile, tension pile and compression pile with constant sections are compared. The difference of lateral resistance under tensile and compressive loadings is also analyzed.
Based on a series of loading tests of ful-l scale model DX piles cas-t in- situ, the bearing behaviour and loadtransferring mechanism of tension DX piles are studied. The results show that the tension bearing capacity of DX pile is apparently higher than that of the pile with constant section, and the curve of load-displacement of DX pile is slowly varying. The enlarged disks bear the most of all tension bearing capacity. It is found that the unit frictional resistances of DX pile is also higher than that of the pile with constant section because of squeezed efficiency of disk. Then, the lateral resistance of tension DX pile, tension pile and compression pile with constant sections are compared. The difference of lateral resistance under tensile and compressive loadings is also analyzed.
2004, 34(10): 36-39.
doi: 10.13204/j.gyjz200410011
Abstract:
Finite element method can consider not only soil lateral deformation but also rheology during settlement calculation of highway, but the course is more numerous and not easily mastered by common engineering technicians.With a lot of nonlinear finite element method calculations, one settlement general modification formula is brought out, which may cause the e-lgp method to consider lateral deformation, then, based on the fact of secondary compression related to loadings, the absolute time coordinate sy stem is suggested for secondary compression calculation, by the traditional secondary compression calculation formula is rectified.Thus, during the 1-D settlement calculation of highway, the thing that in consideration of rheology and lateral deformation can become reality when combined the above two sides.This thought can cause more accurate results and can be lightly mastered, so it has definite using value in practical engineering.
Finite element method can consider not only soil lateral deformation but also rheology during settlement calculation of highway, but the course is more numerous and not easily mastered by common engineering technicians.With a lot of nonlinear finite element method calculations, one settlement general modification formula is brought out, which may cause the e-lgp method to consider lateral deformation, then, based on the fact of secondary compression related to loadings, the absolute time coordinate sy stem is suggested for secondary compression calculation, by the traditional secondary compression calculation formula is rectified.Thus, during the 1-D settlement calculation of highway, the thing that in consideration of rheology and lateral deformation can become reality when combined the above two sides.This thought can cause more accurate results and can be lightly mastered, so it has definite using value in practical engineering.
2004, 34(10): 40-43.
doi: 10.13204/j.gyjz200410012
Abstract:
According to the stress and displacement variational principles, the mixed variational equations are established,from which the state equation is obtained .Thus, the theory of state space is combined with variational solution .The foundation reaction as non-independent state variable is introduced in the expression of state equation, and the variational solutions are presented for transverse isotropic foundation plates with arbitrary thickness.Numerical results are compared with exact solutions, whose result is satisfactory .
According to the stress and displacement variational principles, the mixed variational equations are established,from which the state equation is obtained .Thus, the theory of state space is combined with variational solution .The foundation reaction as non-independent state variable is introduced in the expression of state equation, and the variational solutions are presented for transverse isotropic foundation plates with arbitrary thickness.Numerical results are compared with exact solutions, whose result is satisfactory .
2004, 34(10): 44-46.
doi: 10.13204/j.gyjz200410013
Abstract:
Based on the Hu Haichang's solution of transverse isotropic body, the transfer matrix of one-layer foundation is studied and applied in the solution of multi layer foundation. In addition, a surface settlement formula of transvers isotropic foundation under the concentrated force is given by an example.
Based on the Hu Haichang's solution of transverse isotropic body, the transfer matrix of one-layer foundation is studied and applied in the solution of multi layer foundation. In addition, a surface settlement formula of transvers isotropic foundation under the concentrated force is given by an example.
2004, 34(10): 47-49.
doi: 10.13204/j.gyjz200410014
Abstract:
Through compressive tests of 126 (150mm150mm300mm) and 63 specimens ( 150mm150mm150mm) of plain and fiber reinforced high-strength concrete, the effects of fiber types and volume fractions on elastic modulus of highstrength concrete, and the relation between elastic modulus and compressive strength were studied. Based on the discussion on the elastic modulus of high-strength concrete, the calculating formula of elastic modulus of fiber reinforced high-strength concrete was put forward, good agreement between the calculated values and the test results was found.
Through compressive tests of 126 (150mm150mm300mm) and 63 specimens ( 150mm150mm150mm) of plain and fiber reinforced high-strength concrete, the effects of fiber types and volume fractions on elastic modulus of highstrength concrete, and the relation between elastic modulus and compressive strength were studied. Based on the discussion on the elastic modulus of high-strength concrete, the calculating formula of elastic modulus of fiber reinforced high-strength concrete was put forward, good agreement between the calculated values and the test results was found.
2004, 34(10): 50-52,43.
doi: 10.13204/j.gyjz200410015
Abstract:
The concrete materials damage, which has been caused by monotonic tensile loading, is analyzed from mesoscopic fracture. The nonlinear performance of the curve is analyzed using a class of mesoscopic springs model. The model can also explain the phenomena such as strain softening and stress drop. With the help of force equilibrium and deformation compatbility, a damage constitutional model of concrete under monotonic tensile loading is put forward. Based on the experiments on the concrete subjected to monotonic tensile loading, the coefficients can be uniquely determined. It is found that the calculated curve has a good agreement with experiment's.
The concrete materials damage, which has been caused by monotonic tensile loading, is analyzed from mesoscopic fracture. The nonlinear performance of the curve is analyzed using a class of mesoscopic springs model. The model can also explain the phenomena such as strain softening and stress drop. With the help of force equilibrium and deformation compatbility, a damage constitutional model of concrete under monotonic tensile loading is put forward. Based on the experiments on the concrete subjected to monotonic tensile loading, the coefficients can be uniquely determined. It is found that the calculated curve has a good agreement with experiment's.
2004, 34(10): 53-55.
doi: 10.13204/j.gyjz200410016
Abstract:
According to the testing data of binding material hydration heat, temperature differences at every setting time and every part of the concrete walls can be estimated approximately by a certain theoretical hypothesis.It is proved that the maximal temperature differences of mass concrete in Xuanwu Lake Tunnel which caused by hydration heat were within 25℃,and they were accorded with the requirements proposed by engineering.
According to the testing data of binding material hydration heat, temperature differences at every setting time and every part of the concrete walls can be estimated approximately by a certain theoretical hypothesis.It is proved that the maximal temperature differences of mass concrete in Xuanwu Lake Tunnel which caused by hydration heat were within 25℃,and they were accorded with the requirements proposed by engineering.
2004, 34(10): 56-58.
doi: 10.13204/j.gyjz200410017
Abstract:
The technique of adding extra- floors spanning existing building has many remarkable aspects on technology,economy and security. In order to extend application of this new structure, the paper introduces its structural system,design-specialities and calculational methods combining with a project example and puts forward some new suggestions to optimize structural design through a comparison of specific schemes.
The technique of adding extra- floors spanning existing building has many remarkable aspects on technology,economy and security. In order to extend application of this new structure, the paper introduces its structural system,design-specialities and calculational methods combining with a project example and puts forward some new suggestions to optimize structural design through a comparison of specific schemes.
2004, 34(10): 59-61.
doi: 10.13204/j.gyjz200410018
Abstract:
The fatigue crack between the web and the upper flange of a welded steel crane beam for heavy duty service was discussed, and based on long??term observation and research, the author classified fatigue crack into support type and intercostal type crack along the horizontal direction. The cause, distributive law and mechanism of the crack were analyzed,and the measures to prevent and remedy crack were presented.
The fatigue crack between the web and the upper flange of a welded steel crane beam for heavy duty service was discussed, and based on long??term observation and research, the author classified fatigue crack into support type and intercostal type crack along the horizontal direction. The cause, distributive law and mechanism of the crack were analyzed,and the measures to prevent and remedy crack were presented.
2004, 34(10): 62-65,84.
doi: 10.13204/j.gyjz200410019
Abstract:
In-plane elastoplastic instability of tapered members under axial loads is studied and a new design method is suggested in which the tapered member is equivalent to a prismatic member with the cross-section at the larger end of the tapered member as compared to the current design code CECS102: 2002 where the smaller end cross section is used. A table for determining the equivalent effective length of tapered member is also given. In addition, the elastoplastic working behaviors are compared between the tapered members and the elastic equivalent prismatic ones, and it is found that the tapered members have a higher ultimate load carrying capacity than that of the elastic equivalent prismatic one.
In-plane elastoplastic instability of tapered members under axial loads is studied and a new design method is suggested in which the tapered member is equivalent to a prismatic member with the cross-section at the larger end of the tapered member as compared to the current design code CECS102: 2002 where the smaller end cross section is used. A table for determining the equivalent effective length of tapered member is also given. In addition, the elastoplastic working behaviors are compared between the tapered members and the elastic equivalent prismatic ones, and it is found that the tapered members have a higher ultimate load carrying capacity than that of the elastic equivalent prismatic one.
2004, 34(10): 66-68.
doi: 10.13204/j.gyjz200410020
Abstract:
The effects of outer diameter of steel tube, ratio of inner diameter to outer diameter, ratio of diameter to thickness and strength of concrete on the axial compressive bearing capacity of the single and double concrete filled steel tube columns are analyzed, some beneficial conclusions are obtained, which may be a reference for design and engineering practice.
The effects of outer diameter of steel tube, ratio of inner diameter to outer diameter, ratio of diameter to thickness and strength of concrete on the axial compressive bearing capacity of the single and double concrete filled steel tube columns are analyzed, some beneficial conclusions are obtained, which may be a reference for design and engineering practice.
2004, 34(10): 69-71,93.
doi: 10.13204/j.gyjz200410021
Abstract:
The beam string structure has been concerned due to its long-span capacity and economization of steel. The conceptual problems of the design of the structure are researched, which include how to regard the corner friction of bottom chord stay, the method of determining the space between stay bars, the limit value of working stress of bottom chord stay and the section of arched beam etc.
The beam string structure has been concerned due to its long-span capacity and economization of steel. The conceptual problems of the design of the structure are researched, which include how to regard the corner friction of bottom chord stay, the method of determining the space between stay bars, the limit value of working stress of bottom chord stay and the section of arched beam etc.
2004, 34(10): 72-76.
doi: 10.13204/j.gyjz200410022
Abstract:
It has been introduced that the work content of manufacture stage for a membrane structure, including the principle of cutting design, cutting method, the membrane material connection, cutting blanking drawing, the shop drawing,the fabrication order and the quality requirements.
It has been introduced that the work content of manufacture stage for a membrane structure, including the principle of cutting design, cutting method, the membrane material connection, cutting blanking drawing, the shop drawing,the fabrication order and the quality requirements.
2004, 34(10): 77-80.
doi: 10.13204/j.gyjz200410023
Abstract:
The design calculation accuracy of structure with energy dissipation devices is studied using complex mode method with the data on 57 natural seismic waves, forcing decoupling method, equivalent damping method based on deformation energy according to Aseismic Design Code of Buildings(GB 50011-2001). The initial calculation accuracies among the different design methods is discovered. This is instructing significance for design of structure with energy dissipation devices.
The design calculation accuracy of structure with energy dissipation devices is studied using complex mode method with the data on 57 natural seismic waves, forcing decoupling method, equivalent damping method based on deformation energy according to Aseismic Design Code of Buildings(GB 50011-2001). The initial calculation accuracies among the different design methods is discovered. This is instructing significance for design of structure with energy dissipation devices.
2004, 34(10): 81-84.
doi: 10.13204/j.gyjz200410024
Abstract:
The results of test made with 21 FRP confined concrete columns in three different sectional shapes show that the strain stress curves of FRP confined concrete columns are similar to each other. But because of effective confine's difference,characteristic values of strain-stress curves are different even though strength of concrete and the content of FRP are the same. Referring to a large test database assembled from domestic and foreign existing studies, an uniform formula of stress-strain relationship is proposed. In order to calculate eigenvalues, methods of confine stiffness j choosen as a primary parameter are given.
The results of test made with 21 FRP confined concrete columns in three different sectional shapes show that the strain stress curves of FRP confined concrete columns are similar to each other. But because of effective confine's difference,characteristic values of strain-stress curves are different even though strength of concrete and the content of FRP are the same. Referring to a large test database assembled from domestic and foreign existing studies, an uniform formula of stress-strain relationship is proposed. In order to calculate eigenvalues, methods of confine stiffness j choosen as a primary parameter are given.
2004, 34(10): 85-87,58.
doi: 10.13204/j.gyjz200410025
Abstract:
The real structural safety of mill building is ensured both by structure itself and human. For groups of mill buildings in service, the initial and most important barrier ensuring the structural safety of them is the maintenance and detection conducted by corporations themselves. Therefore, the human factor should be taken into account in the study and control of the real structural safety.The structural safety controlling mode of mill buildings in service is discussed first in the angle of ergonomics, the minimum and normal objectives of safety control are presented, and the relations between the human factor and the real structural safety is also discussed.To appraise the effects of human factor, the method to assess conditions for monitoring structural safety of industrial buildings is put forward finally.
The real structural safety of mill building is ensured both by structure itself and human. For groups of mill buildings in service, the initial and most important barrier ensuring the structural safety of them is the maintenance and detection conducted by corporations themselves. Therefore, the human factor should be taken into account in the study and control of the real structural safety.The structural safety controlling mode of mill buildings in service is discussed first in the angle of ergonomics, the minimum and normal objectives of safety control are presented, and the relations between the human factor and the real structural safety is also discussed.To appraise the effects of human factor, the method to assess conditions for monitoring structural safety of industrial buildings is put forward finally.
2004, 34(10): 88-90.
doi: 10.13204/j.gyjz200410026
Abstract:
Small-sized concrete hollow block is a new-style material which was widely applied in dwelling house in our country. But the practice bears out that concrete hollow block masonry building is easy to crack on the top wall because of temperature stress. The cause of temperature cracks of block masonry structure was analyzed. Furthermore, an effective technique, by which a prestress can be used to control the temperature cracks of the block masonry wall, was presented.Experimental study indicates that this technique can effectively improve crack-resistance behavior and shear capacity of the wall. The design and construction suggestions and detailing measures of prestressed masonry structure were also proposed.
Small-sized concrete hollow block is a new-style material which was widely applied in dwelling house in our country. But the practice bears out that concrete hollow block masonry building is easy to crack on the top wall because of temperature stress. The cause of temperature cracks of block masonry structure was analyzed. Furthermore, an effective technique, by which a prestress can be used to control the temperature cracks of the block masonry wall, was presented.Experimental study indicates that this technique can effectively improve crack-resistance behavior and shear capacity of the wall. The design and construction suggestions and detailing measures of prestressed masonry structure were also proposed.
2004, 34(10): 91-93.
doi: 10.13204/j.gyjz200410027
Abstract:
After detecting and analyzing a real quality accident of construction joint in the connection of beam and column,the treatment scheme and relevant measures to strengthen them are proposed. Moreover, the common cause of occurrence of accidents is analyzed and the prevention measures are also suggested.
After detecting and analyzing a real quality accident of construction joint in the connection of beam and column,the treatment scheme and relevant measures to strengthen them are proposed. Moreover, the common cause of occurrence of accidents is analyzed and the prevention measures are also suggested.
2004, 34(10): 94-96.
doi: 10.13204/j.gyjz200410028
Abstract:
The technical requirements for huge and medium computer rooms are introduced through analysis of actual cases;and transformation of function in building design as continuing development in the computer field through realistic building design of a computer center is also expounded.The new techniques and methods that should be used in design are proposed.
The technical requirements for huge and medium computer rooms are introduced through analysis of actual cases;and transformation of function in building design as continuing development in the computer field through realistic building design of a computer center is also expounded.The new techniques and methods that should be used in design are proposed.
2004, 34(10): 97-98.
doi: 10.13204/j.gyjz200410029
Abstract:
A meaningful movement is being carried out in the decorative art of architectures, which gives us the guidance of thinking and method of design, and expands the vision of architectural decorative art with a for-reaching influence, thus providing some enlightenment and thinking for our design.
A meaningful movement is being carried out in the decorative art of architectures, which gives us the guidance of thinking and method of design, and expands the vision of architectural decorative art with a for-reaching influence, thus providing some enlightenment and thinking for our design.
