1、An ACI Technical Publication SYMPOSIUM VOLUMESP-321Recent Developments in Two-Way Slabs: Design, Analysis, Construction, and EvaluationEditors:Mustafa Mahamid and Myoungsu (James) ShinRecent Developments in Two-Way Slabs: Design, Analysis, Construction, and EvaluationSP-321Editors:Mustafa Mahamid an
2、d Myoungsu (James) ShinDiscussion 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 publication. Discussion of material received after specified dates will be considered indivi
3、dually 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 or opinions expressed in its publications. Institute publications are not able to, nor intend
4、ed 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 by individuals expert in the subject areas of the papers.Copyright 2017AMERICAN CONCRETE INS
5、TITUTE38800 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 by any electronic or mechanical device, printed or written or oral, or recording for sound or
6、 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 production: Ryan JayISBN-13: 978-1-945487-76-7First printing, September 2017PrefaceDuring the last
7、couple of decades, there have been new developments on the design and analysis of two-way slab systems, particularly associated with safety issues against earthquakes. In regard of the recent developments, Joint ACI-ASCE Committee 421 published a comprehensive state-of-the-art report, “Guide to Desi
8、gn of Reinforced Two-Way Slab Systems (ACI 421.3R-15)”, with indebted contributions from many dedicated members. To appreciate this achievement, Committee 421 organized two technical sessions titled, “Two-Way Slab Systems: Recent Developments and Showcases on Design, Analysis, Construction, and Eval
9、uation Methods”, which were held at previous ACI Conventions on November 2015 in Denver, CO, and April 2016 in Milwaukee, WI. The presentation topics included new design and construction methods in two-way slab systems; innovative reinforcement methods for punching shear prevention; practical design
10、 and analysis experiences in recent projects of complex geometries; showcases on serviceability and maintenance issues encountered in RC or PT slabs; experimental tests and/or numerical modeling against extreme hazards, such as earthquake, fire, blast, and progressive collapse; and nondestructive ev
11、aluation techniques for in-place two-way slabs.This Special Publication is a grateful outcome of the two technical sessions. The co-editors, Dr. Mustafa Mahamid and Dr. Myoungsu (James) Shin, sincerely thank and congratulate all the authors for their valuable contributions to the literature.Mustafa
12、Mahamid and Myoungsu (James) ShinCo-EditorsTABLE OF CONTENTSSP-3211Plastic Model for Asymmetrically Loaded Reinforced Concrete SlabsAuthors: Eva O. L. Lantsoght, Cor van der Veen, and Ane de BoerSP-3212Probabilistic Analysis of Interior Reinforced Concrete Flat SlabsAuthors: Georgios P. Balomenos, A
13、ikaterini S. Genikomsou, Mahesh D. Pandey, and Maria A. PolakSP-3213Shear and Punching Strength of Reinforced Concrete Voided SlabsAuthors: Dario Coronelli, Francesco Foti, Luca Martinelli, and Elisa BarbarelliSP-3214Punching Shear Systems for Flat Slabs Evaluation of Tests and Comparison with Codes
14、Authors: Dominik Kueres, Carsten Siburg, Alaa G. Sherif, and Josef HeggerSP-3215Boundary Condition Effects on Static Response of Ultra-High-PerformanceConcrete (UHPC) SlabsAuthors: Bradley Foust and Theodor KrauthammerSP-3216Finite Element Analysis of RC Flat Slabs with Different Amount and Placemen
15、t of Shear Bolts Authors: Aikaterini S. Genikomsou and Maria A. PolakSP-3217Application of an Inclined Shear Reinforcing Assembly for Slab-Column ConnectionsAuthors: Mario Glikman, Gabriel Polo, Oguzhan Bayrak, and Trevor D. HrynykSP-3218Modeling of Reinforced and Fiber-Reinforced Concrete Slabs und
16、er Impact LoadsAuthors: Trevor D. Hrynyk and Frank J. VecchioSP-3219Highly Effective Lattice Punching Shear Reinforcement Authors: Johannes Furche, Carsten Siburg, and Ulrich BauermeisterSP-32110Inclined Stirrups and Inclined Stud Shear Reinforcement in Zones of High Shear Author: Walter H. DilgerSP
17、-32111Inclined Headed Stud Shear Reinforcement: Design and Detailing Authors: Amin Ghali and Ramez B. GayedSP-32112Design of Flat Plate Voided Concrete Slab Systems Authors: David A. Fanella, Mustafa Mahamid, and Michael Mota, SP-321 1 1.1 PLASTIC MODEL FOR ASYMMETRICALLY LOADED REINFORCED CONCRETE
18、SLABS Eva O. L. Lantsoght, Cor van der Veen and Ane de Boer Synopsis: Most methods for the design and analysis of reinforced concrete slabs for punching are based on experiments on slab-column connections, reflecting the situation in building slabs. Slab-column connections with unbalanced moments ha
19、ve also been studied in the past. Experiments indicate that the accuracy of models for asymmetrically loaded slabs is lower than for symmetrically loaded slabs. In this paper, the difference in accuracy between test predictions for symmetrically and asymmetrically loaded slabs is tackled. A plastic
20、model, the Extended Strip Model, is proposed. The results of maximum loads according to this model are compared to experimental results of symmetrically and asymmetrically loaded slabs. The comparison between the proposed Extended Strip Model and the experimental results shows that the model has a c
21、onsistent performance for both symmetrically and asymmetrically loaded slabs. Moreover, the model has as an advantage that it combines the failure modes of flexure, shear and punching. The proposed model can be used for the analysis of slabs. In particular, it can be used for the assessment of exist
22、ing slab bridges subjected to concentrated live loads. Keywords: asymmetrically loaded slabs; extended strip model; flexure; one-way slabs; plasticity; punching; reinforced concrete slabs; shear; symmetrically loaded slabs. Lantsoght et al. 1.2 ACI member Eva O. L. Lantsoght is an assistant professo
23、r at Universidad San Francisco de Quito, Ecuador and a researcher at Delft University of Technology, The Netherlands. She is a member of ACI Sub-Committee 445-0D Shear k the size effect factor, with dlin mm; lthe flexural reinforcement ratio; fckthe characteristic cylinder compressive strength of th
24、e concrete in MPa; k10.15; cpthe axial stress on the cross-section in MPa; bwthe web width of the section in m; dlthe effective depth to the main flexural reinforcement in mm. According to the Eurocode procedures, the values of CRd,cand vminmay be chosen nationally. The default values are CRd,c= 0.1
25、8/c with c=1.5 in general and vmin(fckin MPa): 3/2 1/20.035min ckvkf inMPa (3) NEN-EN 1992-1-1:2005 6.2.2 (6) accounts for the influence of the shear span to depth ratio on direct load transfer. The contribution of a load applied within a distance 0.5dl av 2dlfrom the edge of a support to the shear
26、force VEdmay be multiplied by the reduction factor = av/2dl. In that clause of the code, the distance avis considered as the distance between the face of the load and the face of the support, or the center of the support for flexible supports. The punching shear (two-way shear) provisions from NEN-E
27、N 1992-1-1:2005 (CEN, 2005) follow a similar format as the beam shear provisions. The design punching shear capacity is calculated as follows: 1/3, 1 1100Rdc Rdc l ck cp min cpvCk f k vk (4) with 0.02llxlythe geometric reinforcement ratio; lx, ly relate to the bonded tension steel x- and y-direction
28、s respectively. The values lx and ly should be calculated as mean values taking into account a slab width equal to the column width plus 3d each side. Plastic Model for Asymmetrically Loaded Reinforced Concrete Slabs 1.5 All other parameters are determined in the same way as for the one-way shear pr
29、ovisions. The shear stress vEd(in MPa) on the perimeter should not exceed vRd,c. The stress vEdcan be calculated in a simplified manner as: EdEd puiVvud (5)with VEdthe shear force in kN; uithe perimeter of the critical section in m; d the effective depth, determined as the average of the effective d
30、epth to the longitudinal reinforcement and the effective depth to the transverse reinforcement, in mm; pua correction factor, approximate values are: internal column: pu= 1.15; edge column: pu= 1.4; corner column: pu= 1.5. A more detailed method for asymmetric loading conditions determines vEdas fol
31、lows: 1EdiEd pu puiVuvkeud W(6) with kpua parameter, equal to 0.6 when the column has a square cross-section; eputhe eccentricity ratio, determined by the eccentricity between the center of the load and the center of gravity of the area within the perimeter; W corresponds to a distribution of shear
32、on the punching parameter, which can be determined for a rectangular column as: 22112 2 141622cWcccdddc (7)with c1the column dimension parallel to the eccentricity of the load; c2the column dimension perpendicular to the eccentricity of the load. It should be noted that the determination of epuis an
33、 approximation, and that, to determine the true eccentricity, a nonlinear finite element analysis should be carried out. The eccentricity should then be determined as the ratio of the design moment MEdand the design shear force VEd. The critical perimeter is taken at 2d from the loaded area. Around
34、rectangular loaded areas, rounded corners are used for the perimeter. For loads close to the support (within a distance 0.5d av 2d), the design shear capacity can be increased with 2d/av, and the perimeter uiis based on the distance avinstead of a distance 2d. Eq. (7) for loads close to the support
35、(within a distance 0.5d av 2d), becomes: 22112 2 1242vv vcWcccaaac (8) ACI 318-14 The beam shear (on e-way shear) provisions from ACI 318-14 (ACI Committee 318, 2014) are also semi-empirical formulas. The shear capacity Vcin kN is determined for normal weight concrete ( = 1) as follows (in SI-units,
36、 fc in MPa, 1 MPa = 145 psi): 0.16 17 0.16 17 0.29ulcclwlclwlcwluVdV f bd f bd fbdM (9) with fc the specified concrete compressive strength in MPa, and the limit of cf is 100 psi (8.3 MPa); lthe longitudinal reinforcement ratio; Vuthe sectional shear force in kN; Muthe sectional moment; where Muoccu
37、rs simultaneously with Vuat the section considered in kNmm; dlthe effective depth to the longitudinal reinforcement in mm; bwthe web width in m. Lantsoght et al. 1.6 ACI 318-14 recommends the use of nonlinear analysis or strut-and-tie models for members with concentrated loads within a distance twic
38、e the member depth from the support. Likewise, the punching shear (two-way shear) provisions from ACI 318-14 are semi-empirical formulas. The nominal punching shear capacity Vcin kN for normal weight concrete ( = 1) is determined as follows (in SI-units, fc in MPa, 1 MPa = 145 psi): 0.3330.166min 0.
39、1660.333copunsccoocof bddVfbdbfbd(10) with punthe ratio of the long side to the short side of the column, concentrated load or reaction area; bothe perimeter of the critical section for shear, taken at a distance d/2 away from the periphery of the loaded area, in m; s40 for interior columns, 30 for
40、edge columns, 20 for corner columns; d the average of the effective depth to the longitudinal reinforcement and the effective depth to the transverse reinforcement, in mm; fc the specified concrete compressive strength, in MPa, and the limit of cf is 100 psi (8.3 MPa). The punching shear capacity is
41、 compared to the shear stress on the critical perimeter. This critical perimeter is taken at d/2 from the periphery of the loaded area, as was determined in seminal punching shear experiments (Moe, 1961). The idea behind the ACI equations for punching shear is that the shear stress on the punching p
42、erimeter will be limited, so that a ductile flexural failure will always occur before a brittle shear failure. For eccentric loading conditions, the shear stress on the critical perimeter is composed of the direct shear vugand a contribution to the shear stress from the unbalanced moments, vMsc, see
43、 Figure 1. The total maximum factored shear stress on the perimeter is then calculated as the largest absolute value of: ,vscABuAB ugcM cvvJ (11) ,vscCDuCD ugcM cvvJ (12) with vugthe factored shear stress determined at the centroidal axis of the critical section: uugoVvbd (13) Vuthe factored shear f
44、orce determined at the centroidal axis of the critical section; va parameter that determines the fraction of moment transferred by eccentricity of shear: 1vf (14) 121213fbb (15) b1dimension of the critical section bomeasured in the direction of the span for which moments are determined; b2dimension
45、of the critical section bomeasured in the direction perpendicular to b1; Mscthe factored slab moment that is resisted by the column at a joint; Plastic Model for Asymmetrically Loaded Reinforced Concrete Slabs 1.7 Jca property of the assumed critical section analogous to the polar moment of inertia.
46、 ACI 318-14 R8.4.4.2.3 gives an expression for an internal column, and mentions that similar equations can be developed for edge and corner columns. The distances cABand cCDare as shown in Figure 1. Figure 1 also shows the combination of the shear contributions of direct shear and unbalanced moment
47、from Eqs. (14) and (15). This proposed simplified method is based on experimental observations (Hanson and Hanson, 1968). However, revisiting these test results (Alexander and Simmonds, 2003) showed that the contribution of unbalanced moments is lower than calculated with this method. Figure 1 Deter
48、mination of governing factored shear stress from the combination of direct shear and unbalanced moments: (a) for an interior column; (b) for an edge column. AVAILABLE EXPERIMENTS Short description of slab shear experiments The analysis is carried out based on the slab shear experiments from Delft Un
49、iversity of Technology (Lantsoght et al., 2013; Lantsoght et al., 2015). The slabs that are modeled are half-scale models of reinforced concrete solid slab bridges tested in the Stevin II Laboratory. The slabs are 5 m 2.5 m 0.3 m (16.4 ft 8.2 ft 1.0 ft) and are placed in a test setup as shown in Figure 2. The load is applied through a steel plate of 200 mm 200 mm (
