Methods for measuring and modeling the process of prestressing concrete during tensioning/detensioning based on electronic distance measurements

• US 10,203,268 B2
• Filed: 05/26/2016
• Issued: 02/12/2019
• Est. Priority Date: 12/04/2008
• Status: Active Grant

• Current Assignee: Laura P. Solliday, Sophie Lin, Trustee Of The John Michael Payne Family Trust
• Original Assignee: Laura P. Solliday, Sophie Lin
• Inventors: Parker, David H., Payne, John M.
• Primary Examiner(s): Betsch, Regis
• Application Number:
  US15/165,563
• Publication Number:
  US 20160274001A1
• Time in Patent Office: 992 Days
• CPC Class Codes: E04C 5/08 Members specially adapted to be used in prestressed constructions production of reinforced objects in general B28B23/00; prestressed structures produced in situ E04G21/12
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/03 by measuring coordinates of points
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01M 99/007 by applying a load, e.g. for resistance or wear testing G01M99/001 takes precedence; testing the elasticity of structures G01M5/00
• CPC Class Codes: G01N 33/383 Concrete or cement
• CPC Class Codes: G06F 30/13 Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
• CPC Class Codes: G06F 30/23 using finite element methods [FEM] or finite difference methods [FDM]

Abstract

Methods are disclosed for nondestructive testing and measuring the structural health of prestressed concrete structures, such as slabs, columns, girders, bridges, towers, elevated storage tanks, silos, cooling towers, wind power generation towers, liquefied gas storage tanks, nuclear power containment buildings, and the like. Measurements are made as the structure undergoes tensioning and detensioning operations. By measuring actual movements of cardinal points on the structure, in an absolute three-dimensional coordinate system, and comparing the measurements to a model—as tension on a tendon is changed—a margin of safety is assured. High accuracy measurements are made by electronic distance measurement (EDM) instruments over hundreds of meters, which yield coordinates of cardinal points with an uncertainty of the order of one part per million. The methods are proposed as possible alternatives to prior failures of post-tensioned concrete, including the Las Lomas Bridge, the Kapiolani Interchange On-Ramp, Turkey Point Unit 3 Nuclear Power Plant, and Crystal River Unit 3 Nuclear Power Plant. An extensive review of the most closely related prior arts is included.

Claims

1. A method for post-tensioning a concrete structure with steps comprising:

(a) programming a finite element model of the concrete structure, which when executed by a processor predicts coordinates of a plurality of points on the concrete structure as a function of a plurality of tensions applied to a corresponding plurality of tendons within the concrete structure;

(b) developing a post-tensioning plan for applying the plurality of tensions, wherein the post-tensioning plan is a written document that specifies an order in which the plurality of tendons are tensioned and a tensioning force to be applied to each of the plurality of tendons;

(c) identifying a plurality of cardinal points from the plurality of points on the concrete structure, wherein the identifying is based at least in part on the finite element model, the post-tensioning plan, the predicted coordinates of the plurality of cardinal points, and engineering experience;

(d) attaching a plurality of retroreflectors to the concrete structure at locations corresponding to the plurality of cardinal points;

(e) measuring at least a first range from a first electronic distance measurement instrument to a first cardinal point, a second range from a second electronic distance measurement instrument to the first cardinal point, and a third range from a third electronic distance measurement instrument to the first cardinal point, wherein

the first electronic distance measurement instrument is at a first location, the second electronic distance measurement instrument is at a second location, the third electronic distance measurement instrument is at a third location, and

the first location, the second location, and the third location are three different locations;

(f) storing at least the first, second, and third ranges;

(g) computing a first three-dimensional coordinate of the first cardinal point, based at least in part on the first, second, and third ranges;

(h) applying a first tensioning force to a first of the plurality of tendons as specified by the post-tensioning plan;

(i) measuring at least a fourth range from the first electronic distance measurement instrument to the first cardinal point, a fifth range from the second electronic distance measurement instrument to the first cardinal point, and a sixth range from the third electronic distance measurement instrument to the first cardinal point;

(j) storing the fourth, fifth, and sixth ranges;

(k) computing a second three-dimensional coordinate of the first cardinal point, based at least in part on the fourth, fifth, and sixth ranges;

(l) modifying the post-tensioning plan based at least in part on the finite element model, the applied first tensioning force, the first three-dimensional coordinate, the second three-dimensional coordinate, and the engineering experience; and

(m) applying a second tensioning force to a second of the plurality of tendons as specified by the modified post-tensioning plan.

2. The method of claim 1 wherein the modifying is selected from the group consisting of halting execution of the post-tensioning plan, modifying the order in which the plurality of tendons are tensioned, and modifying the tensioning force to be applied to each of the plurality of tendons.

3. The method of claim 1 wherein the programming of the finite element model is modified based at least in part on the finite element model, the applied first tensioning force, the first three-dimensional coordinate, the second three-dimensional coordinate, and the engineering experience.

4. The method of claim 1 wherein the engineering experience includes general factors based on Hooke'"'"'s law, crack behavior, elastic limits, hysteresis, smooth functions, harmonic analysis, creep, damping coefficient, or symmetry.

5. The method of claim 1 wherein the engineering experience includes factors specific to the concrete structure based on history of accidents, history of floods, history of earthquakes, history of fire, seasonal weather conditions, industry and government standards, regulatory requirements, lessons learned from previous projects in the industry, contractor performance history, level of confidence in quality control, level of confidence in the finite element model, complexity and uniqueness of the design, confidence in assumptions made, test results, consequences of a failure, litigation potential, establishment of liability, safety concerns for the workers and final users, schedule, cost, weather conditions, preservation of personal and company reputation, demonstration of understanding to convince others, or prototype evaluation.