CN104047428A - Method for enhancing ductility of high-strength concrete pier stud - Google Patents

Abstract

The invention discloses a method for enhancing the ductility of a high-strength concrete pier stud. The method comprises the following steps of 1, determining the ductility requirements, i.e. the displacement ductility factor required to reach, of the high-strength concrete pier stud according to needs; 2, determining the content of high-strength steel bars according to the reinforcement relation between the required displacement ductility factor and the high-strength steel bars of the high-strength concrete pier stud, wherein the strength ratio of high-strength stirrups is 0.90, and the strength ratio of high-strength longitudinal reinforcements is 0.71; 3, determining the grade and the spacing of the high-strength stirrups and the grade and the quantity of the longitudinal reinforcements according to the content of the high-strength steel bars. The method has the characteristics of simpleness, feasibility and low cost, and is suitable for popularization and application.

Description

A kind of method that strengthens high-strength concrete pier stud ductility

Technical field

The invention belongs to technical field of buildings, relate to a kind of method that strengthens high-strength concrete pier stud ductility.

Background technology

In prior art, the basic principle of utilizing high tensile reinforcement to improve high-strength concrete pier stud anti-seismic performance is by the relatively intensive horizontal high-strength stirrup of configuration, effectively retrain core core concrete, make it in three dimension stress state, improve to greatest extent intensity and the deformability of core core concrete; In addition, along post longitudinally except the suitable plain bars of configuration, also configure appropriate high tensile reinforcement.Test shows, the method for this configuration reinforcement will make the integral body of post in favourable power consumption state, and its ductility can meet macroseism requirement.

The ductility technical scheme of existing raising high-strength concrete pier stud mainly contains two kinds:

(1) adopt concrete filled steel tube technology

Method is to water high-strength concrete in reinforcing bar the inside, is mainly used in the middle of Loads of Long-span Bridges and highrise building, and its binding effect is obvious, but cost is high, and construction is complicated, and is subject to the restriction of execution conditions.

(2) adopt FRP (FiberReinforcedPlastics) reinforcing technique

Utilize FRP to reinforce, can effectively improve the ductility of high-strength concrete pier stud, its practice is the method for FRP material that wraps in the outside of high-strength concrete pier stud, and its essence is also to utilize the principle of confined concrete to improve ductility, but FRP modulus of elasticity is low, its key technology need further research.

At present, strengthen high-strength concrete deformability, the major measure that improves high-strength concrete ductility has:

(1) improve the stirrup ratio of reinforced components, or user's graticule mesh confined concrete, by providing lateral deformation to retrain to high-strength concrete member, realize the object that strengthens longitudinal strain ability.

(2) in high-strength concrete, admixture steel fibre forms high strength steel fibre concrete, utilizes the feature of modified concrete to improve concrete deformability, improves concrete ductility.

(3) adopt encased structures.

(4) adopt steel-concrete combined structure.

These method constructions are complicated, and cost is high, and some key technology is also immature.China < < Code for design of concrete structures > > and < < building structure aseismatic standard > > mention, in the method for frame column root place employing encryption stirrup, improve the ductility of ordinary concrete post, but this method is only adapted to ordinary concrete at present, to high-strength concrete, not explanation.These several years due to high-strength concrete plurality of advantages, has obtained application more and more widely, how effectively to improve the ductility of high-strength concrete pier stud, in the urgent need to a kind of more reasonable science, simple, intuitive, economical and practical method, to meet the needs of antidetonation area to high-strength concrete.

Summary of the invention

In order to overcome the defect existing in prior art, the present invention proposes a kind of method of simple possible, cheap enhancing high-strength concrete pier stud ductility.High-strength concrete is because intensity is high, fragility is large, use in antidetonation area is restricted, if utilize high tensile reinforcement confined concrete, can widen high tensile reinforcement in the range of application in antidetonation field on the one hand, can effectively improve on the other hand the anti-seismic performance of high-strength concrete pier stud.Its method of operating is simple, Seismic mechanism is clear and definite, can not only save total steel using amount, and anti seismic efficiency is obvious, can meet the demand of high-strength concrete pier stud antidetonation completely, solving structural engineer does not for a long time have the difficult problem solving, for the revision of building aseismicity standard provides very valuable data, for house and bridge security provide good guarantee.

Significance of the present invention is embodied in following several respects:

(1) can meet the demand of industry development.In field of civil engineering, the progress of reinforced concrete post and the progress of its material are closely related.Along with the improvement of reinforcing bar and concrete material performance, the shape of post and mechanical property occur obviously to improve.At present, the materials such as concrete and reinforcing bar have obtained significant progress, and the use in the industry of high-strength concrete and high tensile reinforcement is very general, carry out being furnished with the application of high-strength concrete pier stud of high tensile reinforcement extremely urgent.

(2) effectively solve the bottleneck problem of restriction high-strength concrete pier stud.High-strength concrete pier stud deformation performance relatively a little less than, cause its anti-earthquake ductility poor-performing, although the intensity of high-strength concrete pier stud material is higher, deformation performance relatively a little less than, anti-seismic performance relatively a little less than.Yet the poor deformation performance that might not its member (or structure) of the deformation performance of material is also poor.Reasonable disposition high strength cast iron is effective measures that promote high-strength concrete pier stud deformation performance and solve this bottleneck problem.

(3) utilize high tensile reinforcement to improve the technology of anti-seismic performance of high-strength concrete pier stud ripe gradually, its crucial Key technique problem is effectively solved.Domestic and international many correlative study achievements are verified, and it is feasible utilizing high tensile reinforcement to improve the deformation performance of high-strength concrete pier stud and improve its shock resistance, are also that effectively the prospect of its application is very wide.

(4) research of this technology and application, will bring huge economic and social benefit.China's concrete and reinforcing bar rich material resources, reinforced concrete structure application is very wide.In addition, the development and utilization of high-strength material can effectively economize on resources, and is beneficial to environmental protection, meets the state basic policy of energy-saving and emission-reduction.

Its technical scheme is as follows:

A method that strengthens high-strength concrete pier stud ductility, comprises the following steps:

(1) determine as required the ductility demand of high-strength concrete pier stud, need the displacement ductility reaching;

(2) the arrangement of reinforcement relation of the high tensile reinforcement of displacement ductility as required and high-strength concrete pier stud, determines the content of high tensile reinforcement: the strength ratio of high-strength stirrup is 0.90, and the strength ratio of high-strength vertical muscle is 0.71;

(3) according to the content of high tensile reinforcement, determine rank and the spacing of high-strength stirrup, and the rank of longitudinal reinforcement and quantity.

Preferably, the reinforcing bar that the yield strength of the high tensile reinforcement described in step (2) is 1460MPa.

Preferably, the quantity of high tensile reinforcement adopts the strength ratio λ of high tensile reinforcement to represent, its formula is:

$\mathrm{\&lambda;}=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_{\mathrm{py}}\&CenterDot;A_p)}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_{\mathrm{py}}\&CenterDot;A_p)+\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}(f_y\&CenterDot;A_s)}$

In formula, f _pyfor the yield strength of high tensile reinforcement, A _parea for high tensile reinforcement; f _yfor the yield strength of plain bars, A _yarea for plain bars.

Beneficial effect of the present invention is: the present invention is not only adapted to ordinary concrete, and is adapted to high-strength concrete.This method does not need special material or special technology, and constructing operation is convenient, simple.The present invention reduces the content of plain bars, widens the application of high tensile reinforcement in the middle of non-prestressed concrete, so more economical.Be mainly reflected in the following aspects:

(1) supporting capacity is high.Owing to having used strong concrete (intensity can reach C90) and high strength cast iron (ultimate strength can reach 1000MPa), its bending resistance, shearing resistance and anti-pressure ability are all significantly improved;

(2) anti-seismic performance is good.Owing to having adopted the intensive stirrup of high strength, improved the effect of contraction to core core concrete, the deformability of concrete material is significantly improved, and under rarely occurred earthquake effect, the plastic deformation ability of pier stud is enhanced, and anti-seismic performance significantly improves;

(3) profile is more attractive in appearance.Owing to adopting Materials with High Strength, effectively reduced high-strength concrete pier stud sectional dimension, make its body become more very thin, more attractive in appearance;

(4) applied widely.This novel high-strength performance of concrete column confined can be used for the Highrise Frame trestle that bearing capacity demand is very high, the bridge pier of large bridge structure and the cushion cap of visual plant etc., and height, the span of the structure of building and the weight of bearing equipment all have significantly and promote;

(5) economy, society and environmental benefit are good.Because sectional dimension is relatively little, its materials'use amount is significantly reduced, although unit price is slightly improved, but the cost of total is totally on a declining curve, reduce occupation of land simultaneously and produce the environment pollution that constructional materials may cause, good anti-seismic performance has promoted reliability of structure, and while running into disaster, life and property loss are less, and social harmonious development is played to positive role.

Accompanying drawing explanation

Fig. 1 is reinforcing bar plan, and Fig. 1 (a)-Fig. 1 (f) is followed successively by the reinforcing bar plan of test specimen numbering HHH91, HHL92, HLL91, HHL91, UHL61, LHL91.

The specific embodiment

Below in conjunction with the drawings and specific embodiments, technical scheme of the present invention is described in more detail.

The present invention, in conjunction with the feature of high tensile reinforcement and high-strength concrete, has adopted a kind of more reasonably method of new raising Ductility of Reinforced High Strength Concrete Columns, and its hysteresis loop is full, and energy dissipation capacity is strong, and the ductility factor being calculated by hysteresis loop is as shown in table 1.According to the stirrup ratio of displacement ductility and high tensile reinforcement, a fitting formula has been proposed simultaneously: the specific design parameter of the member in Fig. 1 is listed in table 1

Table 1 member designs parameter

In table 1, member stirrup is except adopting high tensile reinforcement, and all the other adopt I grade reinforcing steel, the employing high tensile reinforcement that longitudinal reinforcement diameter is 10.7, and all the other adopt II grade reinforcing steel, and protective layer thickness is 15mm.In Fig. 1, DT represents stirrup diameter, and S represents stirrup spacing, and both are the design parameters value according to different test specimens by table all.

The above; it is only the preferably specific embodiment of the present invention; protection scope of the present invention is not limited to this; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses, the simple change of the technical scheme that can obtain apparently or equivalence are replaced and are all fallen within the scope of protection of the present invention.

Claims (3)

1. a method that strengthens high-strength concrete pier stud ductility, is characterized in that, comprises the following steps:

(1) determine as required the ductility demand of high-strength concrete pier stud, need the displacement ductility reaching;

(2) the arrangement of reinforcement relation of the high tensile reinforcement of displacement ductility as required and high-strength concrete pier stud, determines the content of high tensile reinforcement: the strength ratio of high-strength stirrup is 0.90, and the strength ratio of high-strength vertical muscle is 0.71;

(3) according to the content of high tensile reinforcement, determine rank and the spacing of high-strength stirrup, and the rank of longitudinal reinforcement and quantity.

2. the method for enhancing high-strength concrete pier stud ductility according to claim 1, is characterized in that, the reinforcing bar that the yield strength of the high tensile reinforcement described in step (2) is 1460MPa.

3. the method for enhancing high-strength concrete pier stud ductility according to claim 1, is characterized in that, the quantity of high tensile reinforcement adopts the strength ratio λ of high tensile reinforcement to represent, its formula is:

$\mathrm{\&lambda;}=\frac{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_{\mathrm{py}}\&CenterDot;A_p)}{\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}(f_{\mathrm{py}}\&CenterDot;A_p)+\underset{i=1}{\overset{m}{\mathrm{\&Sigma;}}}(f_y\&CenterDot;A_s)}$

In formula, f _pyfor the yield strength of high tensile reinforcement, A _parea for high tensile reinforcement; f _yfor the yield strength of plain bars, A _yarea for plain bars.