JP2006207260A - Design method of pile head reinforced concrete pile, and construction method of pile head reinforced concrete pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a design method of a pile head reinforced concrete pile and a construction method of the pile head reinforced concrete pile using reinforcing pipe without ribs on the inner peripheral surface. <P>SOLUTION: In the design method of a concrete pile 10 with a steel pipe wherein a head 10a of a concrete pile body 13 formed of reinforced concrete is surrounded by the steel pipe 11 without ribs on the inner peripheral surface, a pile model 100 with the steel pipe formed to transmit only horizontal force between the steel pipe 11 and the concrete pile body 13, is prepared, and seismic force Q is applied to the pile model 100 with the steel pipe to confirm generated stress. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for designing a pile head reinforced concrete pile in which the head of a concrete pile body such as a cast-in-place concrete pile is surrounded by a reinforcing pipe material such as a steel pipe, and a method for constructing a pile head reinforced concrete pile.

  Conventionally, a concrete pile 1 with a steel pipe in which a head 1a as shown in FIG. 4 is surrounded by a steel pipe 2 with a rib is known (see Patent Documents 1 and 2, etc.).

  This steel pipe-equipped concrete pile 1 has a ribbed steel pipe 2 disposed on the head 1a of a cast-in-place concrete pile 3 that is constructed by inserting a reinforcing bar 3a into a hole excavated in the ground 4 and pouring the concrete 3b. Built.

  A plurality of ribs 2a,... Are provided on the inner peripheral surface of the steel pipe 2 with ribs, and can be firmly integrated with the concrete 3b poured therein.

For this reason, the design of the conventional steel pipe-equipped concrete pile 1 has been performed on the assumption that the ribbed steel pipe 2 and the cast-in-place concrete pile 3 are integrated.
JP 60-47117 A JP-A-8-199565

  However, the above-described ribbed steel pipe 2 has a problem in that the manufacturing cost is high and the construction cost increases because the ribs 2a,... Must be provided on the inner peripheral surface.

  In addition, steel pipes without ribs 2a,... Cannot be integrated with cast-in-place concrete pile 3, and if each design is made as a completely separate member, the head of cast-in-place concrete pile 3 Since the effect of surrounding the part 1a with the steel pipe cannot be taken into account, the design method has not been established due to problems such as overdesign, and steel pipes without ribs 2a, ... are used. Was not.

  Furthermore, prestressed concrete pipes (PC pipes) and centrifugally reinforced concrete pipes (fume pipes, etc.) are difficult to provide ribs on the inner peripheral surface due to material properties and manufacturing processes, so reinforcement for reinforcing the head 1a. It could not be used as a pipe material.

  Therefore, an object of the present invention is to provide a method for designing a pile head reinforced concrete pile and a method for constructing a pile head reinforced concrete pile using a reinforcing pipe member having no rib on the inner peripheral surface.

  In order to achieve the above object, the invention of claim 1 is directed to a design method of a pile head reinforced concrete pile in which the head of a concrete pile body made of reinforced concrete is surrounded by a reinforcing pipe member having no rib on the inner peripheral surface. A design method for a pile head reinforced concrete pile that creates an analytical model in which only a horizontal force is transmitted between the reinforcing pipe material and the concrete pile body, and confirms the generated stress by applying an external force to the analytical model. It is characterized by.

  Further, the invention of claim 2 is a design method of a pile head reinforced concrete pile in which a head of a concrete pile body made of reinforced concrete is surrounded by a reinforcing pipe member having no ribs on an inner peripheral surface. It is a design method of a pile head reinforced concrete pile in which an analytical model is created so that only the horizontal displacement of the concrete pile body matches and an external force is applied to the analytical model to check the generated stress. .

  Furthermore, the method of Claim 3 is the design method of the pile head reinforcement | strengthening concrete pile of Claim 1 or 2 which is the force which the said external force acts on the said pile head reinforcement concrete pile at the time of an earthquake. .

  And the method of Claim 4 is the design method of the pile head reinforced concrete pile in any one of Claims 1 thru | or 3 in which the said generated stress is bending stress and shear stress.

  The invention of claim 5 is a method for constructing a pile head reinforced concrete pile for constructing a pile head reinforced concrete pile designed by the method for designing a pile head reinforced concrete pile according to any one of claims 1 to 4. It is characterized by that.

  The invention configured in this way models the reinforcing pipe material without ribs and the concrete pile separately, and transmits only the horizontal force or matches only the horizontal displacement, thereby applying the horizontal external force. Is modeled to behave integrally in the horizontal direction.

  For this reason, it is possible to appropriately design a pile head reinforced concrete pile using a reinforcing pipe member without ribs. Moreover, when constructing a pile head reinforced concrete pile designed by this design method, it is not necessary to provide ribs on the inner peripheral surface of the reinforcing pipe material, so that the cost can be reduced.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 2 shows a configuration of a concrete pile 10 with a steel pipe as a pile head reinforced concrete pile according to the present embodiment.

  This concrete pile 10 with a steel pipe is mainly comprised by the concrete pile body 13 formed of a reinforced concrete, and the steel pipe 11 as a reinforcement pipe material arrange | positioned so that the head 10a may be surrounded.

  This concrete pile 13 is constructed by inserting a reinforcing bar 13a into a cylindrical hole excavated in the ground 4 and pouring the concrete 13b.

  The reinforcing bar 13 a is manufactured by combining reinforcing bars in a cylindrical shape, and is disposed over almost the entire length of the concrete pile 13. The amount of reinforcing bars used in the reinforcing bar bar 13a is an amount capable of withstanding the generated stress generated in the concrete pile 13 when a design external force is applied, and the minimum reinforcing bar ratio is 0.4%.

  Moreover, the full length of the concrete pile 10 with a steel pipe is set to 5 times the diameter of the concrete pile body 13 as a standard.

  Furthermore, the fixing | fixed part 12 comprised from a reinforcing bar etc. is connected to the upper end of this reinforcement bar | burr 13a, and it is used for joining with the structure or foundation etc. which are constructed | assembled on the upper part of the concrete pile 10 with a steel pipe.

  Moreover, since the rib is not provided in the internal peripheral surface of the steel pipe 11, the concrete 13b poured into the inside of the steel pipe 11, and the adhesion strength can hardly be expected.

  Further, the maximum length of the steel pipe 11 is a length that can be accommodated to a depth of 20 m from the construction ground surface.

  In addition, the lower end of the concrete pile body 13 can raise a front-end | tip support force by widening as needed.

  The above is the structure of the concrete pile 10 with a steel pipe constructed actually, and the pile model 100 with a steel pipe as an analysis model for checking the stress at the time of design is demonstrated below, referring FIG.

  This pile model 100 with a steel pipe is a model of a concrete pile 10 with a steel pipe. The steel pipe 11 is replaced with a rod-like steel pipe model 110 with an equivalent bending rigidity, and the concrete pile body 13 has an equivalent bending rigidity. Replace with a rod-shaped concrete pile model 130.

  And the steel pipe model 110 and the concrete pile model 130 are connected by the horizontal axial force member 140, .... These horizontal axial force members 140,... Are fixed to the concrete pile model 130, but are connected to the steel pipe model 110 by a sliding bearing to which no vertical force is transmitted.

  Therefore, only the horizontal force is transmitted from the steel pipe model 110 to the concrete pile model 130 or from the concrete pile model 130 to the steel pipe model 110.

  Further, since the horizontal axial force members 140,... Themselves are not deformed, the horizontal displacements of the steel pipe model 110 and the concrete pile model 130 connected thereby are equal.

  Further, as a boundary condition between the upper ends of the steel pipe model 110 and the concrete pile model 130, a horizontal sliding bearing 160 is arranged, and the model is modeled so that only horizontal displacement occurs.

  And the ground spring 150 which modeled the ground 4 is arrange | positioned on the back surface of the concrete pile model 130. FIG. The spring constants of the ground springs 150,... Are determined for each formation with reference to a value such as an N value representing the hardness of the ground 4 for example.

  FIG. 3 is an enlarged view of a portion of the pile model 100 with steel pipe shown in FIG. Here, the stiffness matrix of the node i and the node j for analyzing the pile model 100 with a steel pipe is shown as follows.

  Here, l (el) is a distance between nodes i and j, N is an axial force, P is a shearing force, M is a bending moment, V is an axial displacement, U is a horizontal displacement, and θ is a rotation angle. Subscripts i and j represent nodes, s represents a steel pipe model 110, and c represents a concrete pile model 130.

  If the axial force (N) and axial deformation (V) of the pile are ignored, the following equation is obtained.

  As shown in FIG. 1, when the seismic force Q as an external force is applied to the upper end of the pile model with steel pipe 100 from the horizontal direction and analyzed by the above-described stiffness matrix, each node i of the steel pipe model 110 and the concrete pile model 130 is obtained. The shearing force (P) and bending moment (M) generated in j,.

  Based on the bending moment (M) calculated in this way, the bending stress generated in the steel pipe 11 and the concrete pile 13 is calculated, and it is checked whether or not it is below the allowable stress level of each member.

  Here, since the axial force is not borne on the steel pipe 11 at the time of member design, but only on the concrete pile 13, the steel pipe 11 can be used only for the bending moment (Ms) when calculating the generated stress. No. 13 performs stress verification on the combined force of bending moment (Mc) and axial force.

  In addition, regarding the shear force (P), the shear stress generated in the steel pipe 11 and the concrete pile 13 at each node i, j,... Is calculated, and it is checked whether it is below the allowable stress level of each member. To do.

  Although the best embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are possible. Are included in the present invention.

  For example, in the present embodiment, the steel pipe 11 is used as the reinforcing pipe material. However, the present invention is not limited to this, and a PC pipe, a fume pipe, or the like can be used as the reinforcing pipe material.

  Moreover, although the concrete pile body 13 was demonstrated as a cast-in-place concrete pile, it is not limited to this, The design method of this invention is applicable also to the ready-made concrete pile manufactured at a factory etc.

It is explanatory drawing explaining the analysis model of the concrete pile with a steel pipe of the best embodiment of this invention. It is sectional drawing explaining the structure of a concrete pile with a steel pipe. It is explanatory drawing for demonstrating the rigidity matrix of an analysis model. It is sectional drawing of the concrete pile with a steel pipe which uses the steel pipe with a rib of a prior art example.

Explanation of symbols

10 Concrete pile with steel pipe (Pile head reinforced concrete pile)
10a Head 11 Steel pipe (reinforcing pipe material)
13 Concrete pile body 100 Pile model with steel pipe (analysis model)
110 Steel pipe model 130 Concrete pile model 140 Horizontal axial force member Q Seismic force (external force)

Claims (5)

In the design method of a pile head reinforced concrete pile in which the head of a concrete pile body made of reinforced concrete is surrounded by a reinforcing pipe member without ribs on the inner peripheral surface,
A pile head reinforced concrete pile design characterized in that an analytical model in which only a horizontal force is transmitted between the reinforcing pipe material and the concrete pile body is created, and the generated stress is confirmed by applying an external force to the analytical model. Method. In the design method of a pile head reinforced concrete pile in which the head of a concrete pile body made of reinforced concrete is surrounded by a reinforcing pipe member without ribs on the inner peripheral surface,
A pile head reinforced concrete pile characterized in that an analytical model is created so that only a horizontal displacement of the reinforcing pipe material and the concrete pile body coincides, and an external force is applied to the analytical model to check the generated stress. Design method.   The method for designing a pile head reinforced concrete pile according to claim 1 or 2, wherein the external force is a force acting on the pile head reinforced concrete pile during an earthquake.   The method for designing a pile head reinforced concrete pile according to any one of claims 1 to 3, wherein the generated stress is bending stress and shear stress.   A method for constructing a pile head reinforced concrete pile, wherein a pile head reinforced concrete pile designed by the method for designing a pile head reinforced concrete pile according to any one of claims 1 to 4 is constructed.

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