1、An ACI Technical Publication SYMPOSIUM VOLUMESP-306Analytical and Finite Element Concrete Material Models - Comparison of Blast Response Analysis of One Way Slabs with Experimental DataEditors: Ganesh Thiagarajan and Eric WilliamsonAnalytical and Finite Element Concrete Material Models - Comparison
2、of Blast Response Analysis of One Way Slabs with Experimental DataSP-306Editors:Ganesh Thiagarajan Eric Williamson Discussion is welcomed for all materials published in this issue and will appear ten months from this journals date if the discussion is received within four months of the papers print
3、publication. Discussion of material received after specified dates will be considered individually for publication or private response. ACI Standards published in ACI Journals for public comment have discussion due dates printed with the Standard.The Institute is not responsible for the statements o
4、r opinions expressed in its publications. Institute publications are not able to, nor intended to, supplant individual training, responsibility, or judgment of the user, or the supplier, of the information presented.The papers in this volume have been reviewed under Institute publication procedures
5、by individuals expert in the subject areas of the papers.Copyright 2016AMERICAN CONCRETE INSTITUTE38800 Country Club Dr.Farmington Hills, Michigan 48331All rights reserved, including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or b
6、y any electronic or mechanical device, printed or written or oral, or recording for sound or visual reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors.Printed in the United States of AmericaEditorial product
7、ion: Ryan JayISBN-13: 978-1-942727-77-4First printing, March 2016PrefaceThe mission of ACI-ASCE Committee 447 is to develop and report information on the application of finite element analysis methods to concrete structures. The mission of ACI 370 is to develop and report information on the design o
8、f concrete structures subjected to blast, impact, and other short-duration dynamic loads. In this Special Publication (SP) and the accompanying presentations made at the ACI Fall 2013 Convention in Phoenix, Arizona, these committees have joined efforts to report on the state of practice in determini
9、ng the Behavior of Concrete Structures Subjected to Blast and Impact Loadings. Recently, the (2008-2014) National Science Foundation (NSF) funded a study by University of Missouri Kansas City (UMKC) (CMMI Award No: 0748085, PI: Ganesh Thiagarajan) to perform a series of blast resistance tests on rei
10、nforced concrete slabs. Based on these results, a Blast Blind Simulation Contest was sponsored in collaboration with American Concrete Institute (ACI) Committees 447 (Finite Element of Reinforced Concrete Structures) and 370 (Blast and Impact Load Effects) and UMKC School of Computing and Engineerin
11、g. The goal of the contest was to predict the response of reinforced concrete slabs subjected to a specified blast load using a variety of simulation methods. The blast experiments were performed using a Shock Tube (Blast Loading Simulator) located at the Engineering Research and Design Center, U.S.
12、 Army Corps of Engineers at Vicksburg, Mississippi.Over 40 entries were received from researchers and practitioners worldwide; the competition was open to methods used in both research and practice. There were four categories in the contest: 1) Advanced Modeling of slabs with Normal Strength Concret
13、e and Normal Strength Steel, 2) Analytical or Single-Degree-of-Freedom (SDOF) Modeling of slabs with Normal Strength Concrete and Normal Strength Steel, 3) Advanced Modeling of slabs with High Strength Concrete and High Strength Steel, and 4) Analytical or SDOF Modeling of slabs with High Strength C
14、oncrete and High Strength Steel. The first- and second-place winners were invited to present their work at the Fall 2013 convention. Furthermore, all teams were invited to submit papers for this SP, and original experimental data were provided to allow the teams to compare their results with those m
15、easured. This SP is a result of all the papers that were submitted and reviewed in accordance with ACI peer review requirements. In this SP, there are three papers from academic researchers and six from industry personnel, providing a healthy cross section of the community that works in this area.Th
16、e editors gratefully acknowledge all the hard work by the authors, the reviewers, and ACI staff, especially Ms. Barbara Coleman, who have helped very enthusiastically during every stage of the process. The editors also thank members of ACI Committees 447 and 370 for their continuous support in revie
17、wing the papers.TABLE OF CONTENTSSP-3061Parameters Influencing Finite Element Results for Concrete Structures . 1.1Authors: Joseph M. Magallanes, Youcai Wu, Shengrui Lan, and John E. CrawfordSP-3062Numerical Computation of Reinforced Concrete Slabs Subjected to BlastLoading . 2.1Authors: Ran Ganel,
18、Eytan Kochavi, and Gabi Ben-DorSP-3063Numerical Modelling For Reinforced Concrete Response to Blast Load: Understanding The Demands On Material Models .3.1Authors: Jiaming Xu and Yong LuSP-3064Blast Response Simulation of Reinforced Concrete Panels Bridges over State Ave in Kansas City, KS 4.1Author
19、s: Ravi Mullapudi and Yavuz MentesSP-3065Modeling The Response of Concrete Slabs Under Blast Loading 5.1Authors: Pierluigi Olmati, Patrick Trasborg, Clay Naito, Luca Sgambi, and Franco BontempiSP-3066Simulation of Concrete Slabs Subjected To Blast Using The Cohesive Crack Model 6.1Authors: G. Morale
20、s-Alonso, D.A. Cendn, and V. Snchez-GlvezSP-3067SDOF and HYDROCODE Simulation of Blast-Loaded Reinforced Concrete Slabs . 7.1Author: Tarek H Kewaisy,SP-3068Blind Simulation of Blast Loaded Slabs Using Rcblast Software . 8.1Authors: Eric Jacques and Murat SaatciogluSP-3069Finite Element Analysis and
21、Experimental Validation of Reinforced Concrete Single-Mat Slabs Subjected to Blast Loads . 9.1Authors: Gunjan Shetye, Kavya Thadisina, and Ganesh ThiagarajanSP-3061 1.1 PARAMETERS INFLUENCING FINITE ELEMENT RESULTS FOR CONCRETE STRUCTURES Joseph M. Magallanes, Youcai Wu, Shengrui Lan, and John E. Cr
22、awford Karagozian however, it is difficult to match the larger set of data without carefully considering each of these parameters. Guidance is provided to produce meaningful computational results using the constitutive model developed by the authors. Keywords: Concrete; Reinforced Concrete; Finite E
23、lement Method; Constitutive Model; Parameters; Transient Loads; Blast; Shock. Magallanes et al. 1.2 Joseph M. Magallanes, P.E., S.E. Joe Magallanes is President of Karagozian developing engineering tools and first principle finite element codes; and testing components and systems with blast and impa
24、ct loads. Parameters Influencing Finite Element Results for Concrete Structures 1.3 1. INTRODUCTION Three-dimensional finite element method (FEM) calculations for concrete structures are now commonplace in many applications. Common applications range from academic studies of structural behaviors und
25、er transient loads to informing designs for new structures or retrofits. The objective of this paper is to identify factors that influence response predictions obtained with FEM models for concrete structures under transient loadings. This is accomplished by computing the response of several simple
26、concrete structures and comparing the results with data and observations taken from experiments. The FEM calculations focus on codes solving nonlinear continuum mechanics equations 1 capable of treating concrete behaviors under transient loads and large deformations. All of the computational results
27、 presented here are executed using the LS-DYNA code 2, which is a widely used commercial FEM software. It is widely recognized that a competent constitutive model for concrete, and a set of calibrated constitutive parameters for it, are important to producing accurate response predictions using FEM.
28、 Several studies already exist comparing many of the widely used models 3 4 5 6. In this paper, four concrete models available in LS-DYNA are considered. The goal is not to redo some of the comparisons presented in those publications or advocate for use of any one model; instead, our purpose is to d
29、emonstrate that although each of these models differ in their assumptions and formulations, the accuracy of structural response predictions computed with them depend on nuanced material model parameters, and often, parameters of the FEM calculations that have little to do with the material model. Fo
30、r this reason, the discussion herein is primarily focused on results obtained using the constitutive model developed and enhanced over the last twenty years by the authors and the late Dr. L. Javier Malvar 7 8 9, which is known as the Karagozian the Continuous Surface Cap Model (CSCM, MAT159); and t
31、he Reidel-Hiermaier-Thoma model (RHTM, MAT272). Each of the concrete models can be exercised by entering all of the model variables directly, if mechanical data is available to calibrate those variables, or values can be automatically generated using a “simple input” feature available in each model
32、(e.g., see 8 and 9 for the KCCM). Because data needed to calibrate these models for a specific concrete is costly, and therefore not commonly acquired in practice, the latter is more widely used and the paper focuses on results obtained using this option. Five concrete structures tests are selected
33、for the FEM calculations. Each serves to illustrate an important behavior, feature, or response regime for concrete structures that are highly desirable for the FEM calculation to replicate. The first are standardized concrete cylinder and cube specimens placed under compression to measure the uncon
34、fined compressive strength (cf). When comparing standard cylinders and cubes, experimental evidence suggests that cube strength is typically greater than cylinder strength, by a factor that varies up to 1.54 for normal strength concretes 10 11 12. In practice, specimen size is standardized to 152-mm
35、 diameter, 304-mm tall (6-in diameter, 12-inch tall) cylinders, or 150-mm (6-in) cubes. Typically, cylinder specimens are capped (following ASTM C 617) and placed between grooved platens having various amounts of friction that result in lateral restraint at the top and bottom. An unrestrained form o
36、f testing cylinders for compressive strength is relatively recent (ASTM C 1231 was first established in 1993). The DIN 1048 standard for the cube specimens, however, does not prevent restraint at the top and bottom of the cube specimen. The FEM calculations address the factors that affect these spec
37、imens, i.e., specimen shape and end restraint. The second is the splitting tension (or Brazilian) test (DIN 1048 and ASTM C 496), where compression is used to generate failure by indirect tensile stresses. Rupture strengths (rf ) measured with the splitting tension tests are known to result in value
38、s exceeding the direct tensile strength (tf ). CEB-FIP reports the ratio of rtf f as 1.11 11. Rocco et al. report this ratio between about 1.05 and 1.25 depending on specimen shape, aggregate size, concrete strength, and plywood strip width 13. For 25-mm (1-inch) aggregates, cylindrical specimens, a
39、nd increasing strengths from 30 to 80 MPa (4,350 to 11,600 psi), the ratio decreases from 1.16 to 1.08. The third consists of a split-Hopkinson Pressure Bar (SHPB) test 14, in both compression and tension. SHPB tests generate a dynamic uniaxial stress pulse into a concrete sample, thereby deforming
40、the material rapidly. SHPB tests for concrete are not commonly performed nor are they standardized. SHPB and sample diameters are commonly several times the maximum aggregate size (MAS) of the concrete. In compression, the sample is placed between the two bars and lubricated; in tension, the sample
41、is adhered to the bars. Loading rate effects have been observed from SHPB measurements for decades 15-18. The data exhibits a two branch behavior when plotted with normalized peak strength versus strain rate in both compression and tension and are often termed Dynamic Increase Factor (DIF) curves 11
42、 15 16 17. Rate effects in concrete are believed to be due initially to moisture (for example, below 1 s-1), and, at higher strain rates, to inertia effects 18. Magallanes et al. 1.4 The fourth structure is a thin reinforced concrete (RC) panel blast tested by the U.S. Army Corp of Engineers Enginee
43、ring Research and Development Center (ERDC) using a blast load simulator. Details of the test, the panel, and the support frame are described in 19. The RC panel, PH-Set 1a, is loaded by a dynamic pressure loading applied over the front surface of the panel, which deforms the panel in flexure. The p
44、anel is reinforced with longitudinal and horizontal mild steel rebars placed on the tensile-side of the panel; no transverse reinforcement is provided that can provide confinement to the concrete. The panel is placed in a support frame with its two long sides supported with structural steel tubes on
45、 both sides of it (i.e., on the front and back face of the panel). The last structure consists of a series of confined RC column tests described in 20. The column is loaded with a monotonically-increasing uniform lateral loading by way of servo-hydraulic actuators operated under displacement-control
46、. An initial axial load is held constant during the lateral loading. Confinement to the column is provided by Carbon Fiber Reinforced Plastic (CFRP) wraps placed around the columns cross-section. As the RC column is loaded laterally, the concrete cracks, due to the flexure and shear deformations, di
47、lates, and the CFRP acts to resist the lateral expansion of the concrete, thereby increasing confinement. Contrary to the thin RC panel, the confinement affords the column large levels of strength and ductility until deformations are large enough to break the CFRP wraps. Four tests are of interest,
48、corresponding to the number of CFRP wraps placed around the column (0 wraps, 2 wraps, 4 wraps, and 6 wraps). This paper is organized into five sections. Section 2 provides a brief description of the numerical methods employed in the FEM calculations, the constitutive models, and the FEM models devel
49、oped for each test. Comparisons produced using each constitutive model are shown for simple triaxial compression and unconfined tension load paths. Triaxial compression behaviors are important in highly confined RC structures while unconfined tension behaviors can dominate in lightly confined RC structures. In Section 3, the results of the FEM calculations are presented. Section 4 provide a brief discussion of the results and Section 5 states our conclusions. 2. METHODS FEM Solver A structural dynamics code solving
