Title of Invention

SYSTEM FOR ANALYZING THE RELIABILITY OF STRUCTURAL ELEMENTS

Abstract

The present invention relates to System and method for determining the durability and reliability of structural elements made up of concrete, steel and combined material subject to bending, torsion, combined bending and torsion, twist for the purpose of quality control, grading, designing purpose and non destructive testing. The system of the present invention provides fast feed back and in mill can be operating on line thereby for improving quality control. The system of the present invention provides non destructive testing of the structural element in position to know the performance at anytime during its design life.

Full Text

Field of the Invention:- The present invention relates to System and method for determining the durability and reliability of structural elements made up of concrete, steel and combined material subject to bending, torsion, combined bending and torsion, twist for the purpose of quality control, grading, designing purpose and non destructive testing. The system of the present invention provides fast feed back and in mill can be operating on line thereby for improving quality control. The system of the present invention provides non destructive testing of the structural element in position to know the performance at anytime during its design life. Description to prior Art:- A conventional prior art method for detecting surface cracks in a structural elements is to examine under ultra-violet light after coating the surface with a liquid which will fluoresce when illuminated. The liquid penetrates into the surface cracks and the cracks glow when illuminated with the ultra-violet light. Another conventional method for examining a part for the presence of internal flaws is to X-ray the part. Both these prior art methods have limitations in that very small cracks and flaws are not readily detected and considerable risk remains because imperfect parts with small or hidden flaws may not be discovered. In Canada and US, structural elements are manufactured to comply with the requirements of the element or performance standards such as those of the CSA and ASTM. This does not, however, preclude some variability in the product properties within a mill or between the mills are responsible for the quality of their own product and compliance with standards, but design implementations and after some time under working load what was its performance is required to be judged. The vibration theory concept has been used for establishing a measure of the modulus of elasticity of a wooden element as disclosed in US pat no 4,722,223 issued Feb. 1988 to Lars Bach et.al. Pure bending vibration on the element is produced by transversely impacting the panel along its central axis while it is supported flat-wise on a three point support system. A single sensor is used to detect the resonant frequency of bending vibration which is used, along with the panel weight and dimensions, to calculate the dynamic modulus of elasticity. The presence of loading which produces simultaneous bending and torsion in a member means that some degree of Interaction between the two effects will occur. In case of bending plus torsion, the angle of twist (0) caused by the torsion is amplified by the bending moment, inducing additional warping moment and torsional shear. EP1087278 disclose method of generating control data for bending and torsion apparatus. The proposal for software program such as Numerical control program was given for collecting data and transferring to the processor and computer for analysis. US Pat No.4722223 dealing with Vibration testing of panel products, the method of panel support restricts the measurement to a single panel property, namely the modulus of elasticity from the single impact that produces panel vibration. DE 37 16 215 Al reveals a rotating bending test equipment also Torsion loading mechanism for introducing a circulating bending moment and a torsion loading into a test From the JP 4232441 it is actually well-known to bring to the production of a torsion vibration a sample at their two ends by means of electric motors in rotation and to detect the angles of rotation of the engines over function givers. Devices of this kind, with which the two electric motors with different number of revolutions, coupled at in each case an end of the sample, are operated, are particularly suitable for examining wires. From the EP 0,410,370 a device is well-known, with which a sample at in each case an end is shiftable by means of an electric motor in turn, whereby the rotating motion of an electric motor, which is coupled with an end of the sample, can by means of a blocking device be blocked and suddenly again released. The prior Art concerning complex bending and torsional effects and the theory applicable to torsional vibration are known to be applicable to rod like material of circular or rectangular cross section, but it has not been known to be applicable to rolled steel sections and products of different shapes, also it should be pointed out that the combined bending and torsion technique in the prior art requires multiple impacts and sensors to generate, capture and separate the two types of signals. Summary of Invention:- The present invention relates to System and method for determining the durability and reliability of structural elements made up of concrete, steel and combined material subject to bending, torsion, combined bending and torsion, twist for the purpose of quality control, grading, designing purpose and non destructive testing comprising:- a) Apparatus for testing the specimen under bending, torsion, combined bending and torsion. b) Strain gages, LVDT for displacement, Load cell for reactions at supports with maximum 64 channels data acquisition system. c) Controller for maintaining operating stream line as per requirement. d) Throughput for permitting time domain data acquisition to throughput disk for analysis. e) Networking to connect data acquisition system to programme generated computer system to plot the results attached with data storage system in term of drive diskette, compact disk. f) Reliability analysis module comprising a computer programme code causing a computer to capture design and analysis data in accordance with an overall co ordinate system for analyzing the test results for elements and output in term of reliability index in term of probability of failure and factor of safety of different material property comprising :- • Computer programme code causing the computer to determine different load combinations of live load and dead load (1.3DL+1.5LLto 1.7DL+2.0LL). • Computer programme code causing the computer to determine probability of failure from the test specimen results and calibrate the reliability index. • Computer programme code causing the computer to generate general failure equation for said element. • Computer programme code causing the computer to analyze the structural element using two method AFOSM and LRFD and find out factor of safety for different property of element and compare with the actual test results give the reliability of that element as member of structure. g) Design and checking for durability module causing the computer to calculate the additional property checking for safety under combined bending and torsion, shear, warping and twist generated in section and compare these with actual test data's to verify reliability of that element comprising. :- • Computer programme code causing the computer to determine particular factor of safety as transferred from reliability analysis module and calculate the additional property required for designing • Computer programme code causing the computer to calculate the design strength and plastic moment for the particular section. • Computer programme code causing the computer to calculate the buckling resistance moment, critical elastic moment, co-efficient, equivalent slenderness ratio and check for combined bending and torsion as per codal provision. • Computer programme code causing the computer to calculate shear stress due to bending, warping, torsion, and check for safety of element in shear. • Computer programme code causing the computer to calculate working torque and corresponding twist and check the values with codal provision. • Computer programme code causing the computer to tabulate the results as factor of safety of material, sectional property, working torque working stress induced, twist and reliability index in term of probability of failure. In accordance with one aspect of the present invention there is provided an apparatus for non destructive testing of structural elements to know about the durability of elements anytime during design period of structure comprising:- a) Reaction frame with support system to provide a mounting point for actuators. b) Support mean with griping and clamping system for holding the structural element in position like horizontally for beam. c) Force excitation mean associated with supported structural elements with control system for electrodynamics actuators/ shakers having frequency of 5-3000 hz, rating sine frequency upto 750kgf and maximum allowable displacement upto 50mm. d) Transducer mean for converting the amplitude of vibration from vibrating structural element to an electrical signal. e) Displacement measuring means i.e. LVDT for generating data of displaced longitudinal axis w.r.to frequency of vibrations. f) Strain measuring mean for recording strain during force excitation produced in the element to trace out the change in sectional property. g) Controller for operating dynamic parameter on different interval and change of rate in dynamic parameters offering online measurement of structural element before, during and after the test. h) Vibration detection mean for detecting complex vibration induced in the structural elements, said vibration including both bending and torsional vibration. In accordance with one aspect of the present invention there is provided a method of testing the quality and durability of structural elements comprising:- a) Supporting the structural elements in such a manner as to hence the end conditioned requirements (simply supported, Fixed, cantilever). b) Attaching strain gages, LVDT and load cells on the position as specified for study on different points as per requirement. c) Connect the strain gages load cells and LVDT's with data acquisition system by network or wireless system of 32 to 64 channel as per requirements, to connect at least two no's of strain gage with 3 rosettes placed at opposite of loading and at center and at point of zero shear. d) Causing complex vibration in said element with required degree of freedom, so as to induce bending and torsional vibrations. e) Sensing complex vibration and generating output signal as a result thereof. f) Tabulate the data generated and plot the results. g) Analyze the output in bending, torsion, combined bending and torsion as durability of element. In accordance with one aspect of the present invention there is provided method for determining the reliability of structural elements further comprising steps of :- h) Generate different load combinations of live load and dead load (1.3DL+1.5LLto 1.7DL+2.0LL). i) Calculate probability of failure from the test specimen results and calibrate the reliability index using Monte Carlo technique, j) Generate general failure equation for said element depending upon the support conditioned. k) Analyze the structural element using two methods AFOSM and LRFD and find out factor of safety for different property of element and compare with the actual test results give the reliability of that element as member of structure. 1) Calculate the design strength and plastic moment for the particular section. m) Calculate the buckling resistance moment, critical elastic moment, coefficient, equivalent slenderness ratio and check for combined bending and torsion as per codal provision. n) Calculate shear stress due to bending, warping, torsion, and check for safety of element in shear. o) Calculate working torque and corresponding twist and check the values with codal provision. p) Tabulate the results as factor of safety of material, sectional property, working torque working stress induced, twist and reliability index in term of probability of failure. List of Drawings:- Fig1 is a block diagram schematically illustrating the structure of a system for analyzing reliability. Fig-2. is block diagram schematically illustrating the structure of computer program flow chart for reliability module. Fig-3. is block diagram schematically illustrating the structure of computer program flow chart for checking durability module. Fig-4. is a perspective view illustrating a machine co-ordinate system set on the structure element with torsional moment effect. Fig.5:- Diagrammatic elevation view of an apparatus provided in accordance with the Detailed Description of preferred Embodiment:- The invention is concerned with improved system for non-destructive testing of structural element with a mean for analyzing reliability and durability of said structural element. The system is also used for online quality control and to calculate the working strength of that structural element as a member of structure, the necessity for having a mean for periodically detecting the occurrence of any degradation of structural element is obvious. Fig. 1 shows the system referring member 1 illustrating a line diagram of apparatus for non destructive testing of structural element. Apparatus as elevation view is shown in fig. 4 is embodiment of the invention for testing the structural element horizontal specimen made up of rolled steel joists, concrete, composite material subjected to bending, torsion, combined bending and torsion as shown in fig., the apparatus is comprising a rigid frame 1 that includes vertical posts (a, b) horizontally spaced apart interconnected by horizontal member. Posts are rigidly fixed on the integrated strong floor with extended floor system, with nut and bolt arrangement at bottom and connected with plate Girder of sufficient strength at top. At least two electrodynamics actuators (5) with rolling and fixture system are running on the horizontal beam. A mild steel loading frame 2 (a, b) is used to support the structural specimen according to different end conditions. f The loading arm is rigidly attached to free end of the beam. It has a movable collar (3, 3') allowing both the bending and the combined bending and torsion to be examined. At least two digital displacement indicators (4,4') gages are fixed to the loading arm. As the beam deflects the gage attached on the surface of the beam transfer the data through LVDT and displacement from the reference frame is indicated in data acquisition system. These sensors are used to measure both deflection (h) and angle of twist (0) at the end of the beam as shown. At least two rosette strain gages are mounted in 45° orientation along the longitudinal axis of the beam. The strain indicator box (11) allows the rosette strains to be read digitally. The strain indicator box houses the register (R3), the variables register (R4) power supply and the galvanometer. The bridge can be balanced by adjusting R4. For rosette, the gage factor is 2.03 ± 1.00% The structural specimen RSJ or other structural specimen are position in the apparatus i.e. for simply supported end condition fixed at one grip and rolling on other side, similarly both end fixed and cantilever end condition are maintained. Electrodynamic actuators are positioned on the top surface of the structural element to produce bending and torsional vibrating effects. At least two rosettes are mounted on top, two on bottom just opposite to loading and two on the vertical side for studying the twist strain as per study conditions. All the rosette strain gages are attached with strain indicator box. The bridge can be balanced by adjusting R4. The vibration sensor can be used as alternate of gages to transfer strain data to data acquisition system. Impulse force generator that is suitable for setting the structural element under vibration utilizes a rigid hammer tip of hardened steel. One end of spring is attached with hammer tip and another end is clamped with rigid frame y means of clamping plate and screw. Electromagnet holds the spring member in raised position by virtue of DC current which passes through magnet windings. When push button switch is pressed the switch contacts are spread open for an instant. Due to generation of electromagnetic field in electrodynamic actuator hammer tip strikes on the structural element with a frequency of 5 to 3000HZ which generate a sine force maxi upto 750kgf and allowable displacement upto 5Ommas per requirement. The impulse strike cycle can be repeated by pressing switch. The striking process and generation of vibration and required sine force to be generated in member in different steps is controlled by a controller. After the impulse force is applied to the structural element, the part will be into vibration at its free resonance frequency mode. Thus vibration amplitude of vibrating structure is converted to an electrical signal by a suitable transducer, such as microphone which picks up the sound vibration generated by the vibrating structure or alternately an accelerometer may be attached to the surface of the structure under test. Microphone will be the preferable transmitter because it requires no mechanical attachment to the vibrating structure under test. The output of the amplifier as a signal represents the amplitude of the vibration of structure as a function of time is an exponentially signal from amplifier is applied to the input of signal processor which include detector and microprocessor for measuring change in property.. LVDT attached with the specimen transfer the displacement data with respect to frequency and plot a relationship in frequency Vs displacement. Similarly at different interval of time and amplitude of frequency, strain produced in the member is also transferred in data acquisition system through strain gage attached with the specimen. The vibration sensors may be used as alternative to detect torsional and bending vibration. Computation of modulus of elasticity from the bending frequency measured by the test was done using the equation from the vibration theory. All the data was collected in the data acquisition system through controller and transferred to a computer system connected with wireless network or through USB port. The progress to generate the relationship between different data in the computer system gives results as first output to trace out the durability. The same data should be saved in the storage system like compact disk, diskette etc. The data storage module is connected to reliability analysis module through network. When the shape data, the mechanical property, sectional property and condition data have been prepared depending upon the end conditions of structural element simply supported, fixed, cantilever. The numerical controlled program generating module may be provided with operator with manipulation through a graphic user interface. Program code causing the computer to determine different load combination of live load and dead load varies from 1.3DL+1.3LL to 1.7DL+2.0LL depending upon different bo/tf, do/tw, LL/DL ratio. Probability programme code to generate failure equation of said element and calculate the constants alpha for different material property and reliability index using two different methods separately i.e. AFOSM and LRFD. Transfer the results to failure equation and output in term of factor of safety of element property i.e. yields strength sectional modulus, loads. Data from reliability module is transferred to design and checking module to find out reliability and durability of structural element w.r.to design data. Computer program to calculate bending effects, torsional effects, plastic moment and design strength are prepared in code. Based upon the test data different co-efficient, equivalent slenderness ratio and buckling resistance was calculated through NC program available in module based upon the formulation of limit state design and structure element was checked under combined bending and torsion, shear due to warping, torsion and bending should follow limit state codal requirements. Numerical code also calculates working torque on element, corresponding twist and check as per codal requirement provided therein. If follow the codal provisions, output in the form of working load, working torque, reliability index in term of probability of failure and relationship between different parameters in term of graph comes out. Which indicate the reliability of that element. While a few specific embodiments of the present invention have been shown and described, it should be understood that various additional modification and alteration, constructional features may be made without departing from the scope of the invention. Therefore, the claims are intended to cover all such equivalent alternative features that fall within the scope. Claims:- 1. System for analyzing the reliability of structural elements comprising an apparatus for non destructive testing of structural elements under bending, torsion or combined bending-torsion effect having strain gages; LVDT for displacement measurement; load cell for reactions at supports with data acquisition system of capacity 64 channels; controller for maintaining operations; throughput for permitting time domain data acquisition to throughput disk for analysis; networking to connect data acquisition system and characterized in the reliability analysis module, for capturing data in accordance with an overall co-ordinate system for analyzing the test results of elements for taking output in terms of reliability index and factor of safety of different elements. 2. System for analyzing the reliability of structural elements as claimed in claim 1 wherein the said apparatus for checking the safety aspects of having a reaction frame with support system providing a mounting point for actuators; support means with gripping and clamping system for holding the structural element in position like horizontally for beam; force excitation mean associated with supported structural elements with control system for electrodynamics actuators/ shakers having frequency of 5-3000 Hz, maximum allowable displacement up to 50mm; transducer for converting the amplitude of vibration from vibrating structural element to an electrical signal; displacement measuring means for generating data of displaced longitudinal axis w.r.t. frequency of vibrations; strain measuring means for recording strain during force excitation produced in the element to trace out the change in sectional property; controller for operating dynamic parameters on different intervals and change of rate in dynamic parameters offering online measurement of structural element (before, during and after the test); vibration detection means for detecting complex vibration induced in the structural elements, said vibration including both bending and torsional vibration. 3. The method of testing the quality and durability of structural elements with the help of system as claimed in claim 1 comprising of following steps: a) Supporting the structural elements in such a manner to enhance the end conditioned requirements (simply supported, fixed, cantilever); attaching strain gages, LVDT and load cells on the element at different points. b) Connecting the strain gages, load cells and LVDT with data acquisition system by network or wireless system of 32 to 64 channels. c) Inducing bending and torsional vibration in said element with the help of electrodynamic actuators having required degree of freedom; sensing complex vibration and generating output signal as a result. d) Generating different load combinations of live load and dead load (1.3DL+1.5LL to 1.7DL+2.0LL) on the structural specimens tested; calculating probability of failure from the test specimen results and calibrating the reliability index. e) Analyzing the structural element for factor of safety for different properties of element and comparing with the actual test results giving the reliability of that element as member of the structure. t) Plotting the various analytical as well as experimental parameters observed during testing. 4. The apparatus as claimed in claim 2, wherein portal load frame and supporting structure are made up of steel plates. 5. The apparatus as claimed in claim 2, wherein the clamping means is grip and fixture arrangement with grip control device fixed perpendicular to the support structure. 6. The system for analyzing the reliability of structural elements subjected to bending and torsion as described with reference to the accompanying drawings. 7. The method for testing structural elements subjected to bending and torsion as described with reference to the accompanying specification and drawings.

Documents:

1124-del-2007-abstract.pdf

1124-DEL-2007-Claims-(24-06-2008).pdf

1124-del-2007-claims.pdf

1124-DEL-2007-Correspondence-Others-(24-06-2008).pdf

1124-del-2007-description (complete)-24-06-2008.pdf

1124-del-2007-description (complete).pdf

1124-DEL-2007-Drawings-(24-06-2008).pdf

1124-del-2007-drawings.pdf

1124-DEL-2007-Form-1-(24-06-2008).pdf

1124-del-2007-form-1.pdf

1124-del-2007-form-18.pdf

1124-DEL-2007-Form-2-(24-06-2008).pdf

1124-del-2007-form-2.pdf

1124-del-2007-form-3.tif.pdf