The end regions of prestressed concrete members are a small portion of the element, yet they are crucial for securing the serviceability and safety of the whole structural system. High prestressing forces and the eccentricity of strand locations during prestress transfer induce bursting and spalling stresses. These stresses result in cracking at the end region of concrete beams (i.e., entrant corners of dapped-end beams, girder web-flange zones, and girder web). This study investigates mitigating these cracks by using shape memory alloy bars as transverse reinforcement in the end regions of prestressed concrete beams, replacing conventional steel stirrups. An experimental study is performed to evaluate stress transfer by shape memory alloy’s shape memory effect to the concrete surface during shape memory alloy activation, and its numerical modeling technique is devised using finite element method. The effectiveness of stirrup is validated by finite element analysis in a large-scale girder designed based on the American Association of State Highway and Transportation Officials Load and Resistance Factor Design. Shape memory alloy bar detailing is also investigated experimentally and numerically to evaluate the feasibility of shape memory alloy transverse reinforcement. Experimental and numerical results demonstrate the effectiveness of shape memory alloy reinforcement in the end region of concrete beams.
AbuzaidWWuYSidharthR, et al. (2019) FeMnNiAl iron-based shape memory alloy: Promises and challenges. Shape Memory and Superelasticity5: 263–277.
3.
ACI Committee 318 (2019) Building Code Requirements for Structural Concrete and Commentary. American Concrete Institute.
4.
American Association of State Highway and Transportation Officials (AASHTO) (2012) AASHTO LRFD Bridge Design Specifications, 6th edn. Customary U.S. units. Washington, DC: AASHTO
AswinMAl-FakihASyedZ, et al. (2023) Influence of different dapped-end reinforcement configurations on structural behavior of RC dapped-end beam. Buildings13(1): 116.
7.
AttaATamanM (2016) Innovative method for strengthening dapped-end beams using an external prestressing technique. Materials and Structures49: 3005–3019.
8.
ChenQAndrawesB (2017) Cyclic stress-strain behavior of concrete confined with NiTiNb-shape memory alloy spirals. Journal of Structural Engineering143(5): 04017008.
9.
ChoiEChungYSKimYW, et al. (2011) Monotonic and cyclic bond behavior of confined concrete using NiTiNb SMA wires. Smart Materials and Structures20(7): 075016.
10.
ChoiEKimDJHwangJH, et al. (2016) Prestressing effect of cold-drawn short NiTi SMA fibres in steel reinforced mortar beams. Smart Materials and Structures25(8): 085041.
11.
DagdelenFAydogduY (2019) Transformation behavior in NiTi–20Ta and NiTi–20Nb SMAs. Journal of Thermal Analysis and Calorimetry136: 637–642.
12.
DagdelenFBalciEQaderIN, et al. (2020) Influence of the Nb content on the microstructure and phase transformation properties of NiTiNb shape memory alloys. The Minerals, Metals & Materials Society72(4): 1664–1672.
13.
DerkowskiWDybaM (2017) Behaviour of end zone of pre-tensioned concrete elements. Procedia Engineering193: 19–26.
14.
DommerKAndrawesB (2012) Thermomechanical characterization of NiTiNb shape memory alloy for concrete active confinement applications. Journal of Materials in Civil Engineering24(10): 1274–1282. https://doi.org/10.1016/j.proeng.2017.06.181
15.
GergelyPSozenMA (1967) Design of Anchorage-zone reinforcement in prestressed concrete beams. PCI Journal12: 63–75.
16.
GhafooriENeuenschwanderMShahverdiM, et al. (2019) Elevated temperature behavior of an iron-based shape memory alloy used for prestressed strengthening of civil structures. Construction and Building Materials211: 437–452.
17.
HillerborgAModéerMPeterssonPE (1976) Analysis of crack formation and crack growth in concrete by means of fracture mechanics and finite elements. Cement and Concrete Research6(6): 773–781.
18.
HognestadE (1951) A study of combined bending and axial load in reinforced concrete members. Engineering Experiment Station, University of Illinois.
19.
HongKLeeSHanS, et al. (2018) Evaluation of Fe-based shape memory alloy (Fe-SMA) as strengthening material for reinforced concrete structures. Applied Sciences8(5): 730.
20.
IbellTJBurgoyneCJ (1993) Experimental investigation of behaviour of anchorage zones. Magazine of Concrete Research45(165): 281–291.
21.
IzadiMRGhafooriEShahverdiM, et al. (2018) Development of an iron-based shape memory alloy (Fe-SMA) strengthening system for steel plates. Engineering Structures174: 433–446.
22.
MarshallWTMattockAH (1962) Control of horizontal cracking in the ends of pretensioned prestressed concrete girders. PCI Journal7: 56–74.
23.
Mata-FalcónJYuKLPallarés RubioL, et al. (2025) Experimental and analytical investigation of the crack behaviour of dapped-end beams. Engineering Structures322: 119040.
24.
MattockAHChanTC (1979) Design and behavior of dapped-end beams. PCI Journal24(6): 28–45.
25.
MazzerEMKiminamiCSBolfariniC, et al. (2016) Phase transformation and shape memory effect of a Cu-Al-Ni-Mn-Nb high temperature shape memory alloy. Materials Science and Engineering A663: 64–68.
26.
McCormickNLordJ (2010) Digital image correlation. Materials Today13(12): 52–54.
27.
MorenoJYMeliR (2013) Experimental study and numerical simulation of the behaviour of concrete dapped-end beams. International Journal for Engineering Modelling26(1–4): 15–25.
28.
OkumusP (2012) Nonlinear analysis of pretensioned bridge girder ends to understand and control cracking at prestress release. PhD Dissertation, University of Wisconsin Madison, Madison.
29.
PatelSKBeheraA (2022) Evolution of phases and their influence on shape memory effect by varying sintering parameters of NiTi Alloys. Metals and Materials International28: 2691–2705.
30.
Precast/Prestressed Concrete Institute (PCI) (2010) PCI Design Handbook, 7th edn.Chicago, IL: Prestressed Concrete Institute (PCI).
31.
Precast/Prestressed Concrete Institute (PCI) (2014) PCI Bridge Design Manual, 3rd edn. Second Release. Chicago, IL: Prestressed Concrete Institute (PCI).
32.
ProkoshkinSDKhmelevskayaIYDobatkinSV, et al. (2005) Alloy composition, deformation temperature, pressure and post-deformation annealing effects in severely deformed Ti–Ni based shape memory alloys. Acta Materialia53: 2703–2714.
33.
QiangXLiuQChenL, et al. (2024) Experimental study on flexural performance of prestressed concrete beams strengthened by Fe-SMA plates. Construction and Building Materials422: 135797.
34.
RogowskiJKotyniaR (2022) Comparison of prestressing methods with CFRP and SMA materials in flexurally strengthened RC members. Materials15(3): 1231.
35.
RossBEWillisMDHamiltonHR, et al. (2014) Comparison of details for controlling end-region cracks in precast, pretensioned concrete I-girders. PCI Journal59(2): 96–108.
36.
SantarsieroGPiccianoV (2024) Post-tension retrofitting of RC dapped-end beams: A numerical investigation. Structural Concrete25: 3246–3264.
37.
SchleitingMWetzelABauerA, et al. (2023) Potential of Fe-Mn-Al-Ni shape memory alloys for internal prestressing of ultra-high performance concrete. Materials16(10): 3816.
38.
SherifMOzbulutOLandaA, et al. (2014) Self-post-tensioning for concrete beams using shape memory alloys. In: Smart materials, adaptive structures and intelligent systems, p.V002T04A014. American Society of Mechanical Engineers. https://doi.org/10.1115/SMASIS2014-7564
39.
ShinMAndrawesB (2010) Experimental study of concrete columns confined with shape memory alloys. In: 9th US National and 10th Canadian conference on earthquake engineering, Toronto, Canada, 25–29 July.
40.
SiegertWNeukingKMertmannM, et al. (2003) First cycle shape memory effect in the ternary NiTiNb system. Journal de Physique IV (Proceedings)112: 739–742.
41.
SinhaATatarNTatarJ (2020) Rapid heat-activated post-tensioning of damaged reinforced concrete girders with unbonded near-surface mounted (NSM) NiTiNb shape-memory alloy wires. Materials and Structures53(4): 88.
42.
SteenselsRVandorenBVandewalleL, et al. (2019) Evaluation of end-zone detailing of pre-tensioned concrete girders. Engineering Structures187: 372–383.
43.
SuhailRAmatoGMcCrumDP (2020) Active and passive confinement of shape modified low strength concrete columns using SMA and FRP systems. Composite Structures251: 112649.
44.
SungMAndrawesB (2021a) Adaptive prestressing system using shape memory alloys and conventional steel for concrete crossties. Smart Materials and Structures30(6): 065016.
45.
SungMAndrawesB (2021b) Innovative local prestressing system for concrete crossties using shape memory alloys. Engineering Structures247: 113048.
46.
TabrizikahouAKuczmaMTriantafyllidisZ, et al. (2025) Prestressing of concrete using iron-based shape memory alloy (Fe-SMA) short fibers: Experimental and numerical analysis. Construction and Building Materials467: 140309.
47.
WillisMD (2014) Post-tensioning to prevent end-region cracks in pretensioned concrete girders. Master’s Thesis, Clemson University.
48.
ZhaoHAndrawesB (2020) Local strengthening and repair of concrete bridge girders using shape memory alloy precast prestressing plate. Journal of Intelligent Material Systems and Structures31(11): 1343–1357.
