CN108169002A - A kind of reduced scale test model and method for testing steel-concrete composite beam Creep Characteristics - Google Patents

Abstract

The invention discloses a kind of structure testing methods of field of civil engineering.For steel-concrete combination beam full size long duration load test operation difficult problem, a kind of scaled model is invented, the model component is simple, small, the small spatial position such as can be placed under desk；Instrument is using vibrating string extensometer and thousand points of meters with position contrast test, it is ensured that the accuracy of result；Data collection uses Portable data acquisition instrument, can carry out energization acquisition for a long time, also can manually acquire；Result of the test can be compared with written calculation result.The data that experiment is collected can accurately describe mechanical characteristic of the steel-concrete structure under action of long-term load, disclose the long-term Laws of Mechanics of combination beam.

Description

A scaled-scale test model and method for testing the creep characteristics of steel-concrete composite beams

technical field

The patent of the invention belongs to the technical field of civil engineering structure test, and relates to a scale test model and method for testing the creep characteristics of steel-concrete composite beams.

Background technique

Steel-concrete composite beams have significant technical and economic benefits and broad application prospects. During the use of the structure, the concrete in the composite beam will produce creep, and the restraint of this deformation by the steel beam will lead to the redistribution of cross-sectional stress inside the statically indeterminate composite beam, and for the statically indeterminate composite beam, it will also cause creep that changes with time. Change (shrink) the internal force, resulting in a change in the final stress state of the composite beam section, which can be several times the elastic deformation, which is very unfavorable for structures with strict deflection requirements.

However, the effect of creep on the performance of steel-concrete composite beams is very complex, including a considerable number of uncertain factors. Almost all factors affecting creep and their results are random variables. In order to obtain these parameters, it is usually necessary to conduct a full-scale test. Since creep is a long-term mechanical property, it takes a long time, usually lasts for more than one year, and is greatly affected by environmental disturbance and laboratory space. At the same time, the test requires long-term measurement data, while the traditional strain gauge reading requires alternating current, and the observed It is short-term data, which cannot achieve the purpose of obtaining stable, long-term and accurate effective data of specimens. Therefore, it is very difficult to realize the full-scale long-term load test of composite beams.

Contents of the invention

Aiming at the difficulty in operating the full-scale long-term load test of steel-concrete composite beams, a scaled-down model is invented. The comparison test of the sub-meter and the same position ensures the accuracy of the results; the data collection adopts a portable data acquisition instrument, which can be collected by power-on for a long time, and can also be collected manually; the test results can be compared with the results of written calculations.

Description of drawings

Fig. 1 is a schematic diagram of the longitudinal axis direction of the scale model;

Fig. 2 is a schematic diagram of the transverse section size of the scale model;

Fig. 3 is a perspective view of a scale model.

The labels in the figure are: 1 is steel-concrete composite beam; 2 is standard steel loading block; 3 is standard steel pad; 4 is dial gauge; 5 is vibrating wire strain gauge; 6 is dial gauge with gauge ; 7 is a portable data acquisition instrument; 8 triangular support; 9 semi-arc support; 10 ribbed steel bar; 11 steel plate.

Detailed ways

The content of the patent of the present invention is realized through the following technical solutions.

1) In indoor places where human disturbance is relatively small, the operating space covers an area of about 4 square meters to erect support 8 and support 9, and make steel-concrete member 1. The size of member 1 can be reduced in proportion to the actual size, The steel plate-reinforcing bar model is convenient for comparison and analysis of calculation results and test results; a spacer 3 is placed on each support 8 and 9; component 1 is placed on the support with spacer 3 after 7 days of maintenance.

2) On the day when the component is placed on the support (that is, the seventh day of component maintenance), install a vibrating wire strain gauge 5 and a gauge gauge 6 on the upper edge of the component, the lower edge steel plate 11 and the concrete The upper and lower edges; 5 and 6 are installed at the same position for data comparison. Install a dial indicator at the mid-span of the component and at the supports 8 and 9 respectively.

3) On the day of instrument installation (that is, the 7th day of component maintenance), place the standard steel loading block 2 at the third point of the component, and connect the sinusoidal strain gauge 5 with the portable data acquisition instrument 7 for the first The time points for follow-up measurements are: once a day in the first month, every 3 days in the second and third months, and every 7 days in the 4th to 12th months, with a time span of one year. After one year, it can be measured every 10 days.

4) The data at each measuring point can be compared with the results of the vibrating wire strain gauge 5 and the measurement results of the dial gauge with gauge; at the same time, the test results can be compared with the results of the hand calculation.

Claims (2)

1. a kind of experimental rig and test method for measuring composite structure Creep Characteristics, it is characterised in that：Component is simple, volume It is small, it the small spatial position such as can be placed under desk；Instrument is using vibrating string extensometer and thousand points of meters with position contrast test, it is ensured that As a result accuracy；Data collection uses Portable data acquisition instrument, can carry out energization acquisition for a long time, also can manually acquire；Examination Testing result can be compared with written calculation result；The data that experiment is collected can accurately describe steel-concrete structure long-term Mechanical characteristic under load action discloses the long-term Laws of Mechanics of combination beam.

2. experimental rig as described in claim 1 and test method include component making, instrument Installation And Test scheme, specifically Step includes：

1）Bearing 8 and bearing are set up at the relatively small indoor spaces of artificial disturbance, about 4 square metres of operating space floor space 9, steel-concrete component 1 is made, the size of component 1 can be easy for by actual size scaled down, steel plate-reinforcing bar pattern Manual calculation result and comparison of test results are analyzed；One piece of cushion block 3 is respectively put on bearing 8 and 9；Component 1 conserves 7 days and is placed into cushioning block On 3 bearing；

2）The same day of bearing is placed into component（That is the 7th day of component conservation）, by a vibrating string extensometer 5 and a band mark Component top edge, lower edge steel plate 11 and concrete lower edges are separately mounted to away from amesdial 6；5 and 6 are mounted on same position It puts, carries out data comparison.A dial gauge is installed respectively at component span centre and bearing 8,9；

3）In the same day of instrument installation（That is the 7th day of component conservation）, standard steel loading blocks 2 are placed on to the trisection point of component Place, while connect sinusoid strain gauge 5 with Portable data acquisition instrument 7 and carry out measurement in first day, the time point subsequently measured be： It measures once within 1st month, is measured within every 3 days the 2nd, the 3rd month once daily, measure within every 7 days the 4th to 12nd month primary, the time Span is 1 year.It can be measured after 1 year every 10 days primary；

4) data at each measuring point can be carried out with the result of vibrating string extensometer 5 with the result measured with gauge length amesdial Comparison；Result of the test can be compared with the result of hand computation simultaneously.