Abutment Geometry Research Articles

INFLUENCE OF ABUTMENT GEOMETRY ON THE MICROGAP SIZE IN THE CONICAL CONNECTION

BACKGROUND: To provide prosthetics for patients on implants, dentists resort to using not only original, but also non-original suprastructures. Previously, the authors carried out an finite element analysis, which showed that the size of the microgap of the conical connection depends on the choice of abutments, which affects the condition of the marginal bone around the implant. AIMS: to find out the factor that distinguishes the original and non-original abutments and largely influences the size of the microgap in the conical connection. MATERIALS AND METHODS: The experiment involved implants and standard abutments of Straumann BL, BioHorizons Tapered Internal and Nobel Biocare CC implant systems, and non-original abutments of ADM Dental. At the first stage of the experiment, four main factors were identified: the material of the screw and abutment, the geometry of the screw and abutment. The calculations were based on data from the authors' previous research and were carried out through the ANSYS Workbench using the finite element analysis. The second stage of the study was carried out on the microtomography complex “Neoscan 80”, where, in order to clarify the geometric features of the samples, the size of the microgap and the length of the conical generatrices between the constituent elements were measured. RESULTS: We can talk about the predominant influence of the abutment geometry on the micro-gap of the conical connection of Straumann and BioHorizons. In Nobel, the width of the microgap depends largely on the geometry of the abutment screw. Measurements of the microtomographic complex determined the difference in the length of the conical “implant-abutment” components for Straumann (0.1 mm) and BioHorizons (0.07 mm), and did not determine it between the original and non-original abutment for Nobel. The conical generatrix of the screw with the original Nobel abutment is smaller than with the non-original one. CONCLUSIONS: As a result of the study, it was determined that the choice between the original and non-original suprastructure has a greater influence on the size of the microgap of the conical connection due to the different geometric configuration of the abutment, in particular, the geometry of its fixing screw.

Comparative study of axial displacement in digital and conventional implant prosthetic components

Axial displacement of prosthetic components is a major concern in implant dentistry, particularly during screw tightening. However, implant manufacturers provide different recommended torques for tightening implant prosthetic components, which can lead to errors in prosthesis fit before and after impression making. Implant–abutment connection angle or abutment geometries can affect axial displacement. This study aimed to compare the axial displacement between conventional and digital components based on the tightening torque and differences in the implant–abutment connection angles and geometries. The results showed that scan bodies with different implant-abutment connection geometries exhibited smaller axial displacement with increasing tightening torque than other prosthetic components. Except for the scan bodies, there was no difference in the axial displacement of prosthetic components when tightened with the same torque. However, regardless of the use of digital or conventional method of impression making, the axial displacement between the impression making component and the abutment when tightened to the recommended torques were significantly different. In addition, axial displacement was affected by the internal connection angle. The results of this study indicate that the tightening torque and geometry of prosthetic components should be considered to prevent possible misfits which can occur before and after impression making.

Examination of Various Abutment Designs Behavior Depending on Load Using Finite Element Analysis.

Studies on dental implant abutments' geometric design and material selection offer significant innovations and results. These studies aim to improve the abutments' functionality and aesthetic performance, minimize microcavities' formation, and ensure implant-supported prostheses' longevity. For example, CAD-CAM fabricated custom abutments have been found to produce a better marginal fit and fewer microgaps than standard abutments. In an in vitro study, transepithelial abutments offered lower microgap values than titanium-based abutments and provided a better fit at the implant-abutment interface. It is known that studies to improve mechanical and biological performance with Polyether Ether Ketone (PEEK) material have been addressed. New materials such as PEEK and zirconia have offered significant advantages in biocompatibility and aesthetics. Along with those studies, different abutment designs are also important. Abutment geometry is optimized to improve stress distribution and minimize peri-implant bone loss. In implant and abutment connections with different angles, mechanical life performances may vary depending on static and dynamic load. These studies emphasize the importance of material research on different types of connections to improve dental implants' durability, homogeneous load distribution, and reliability. The abutment parts used in implant treatment are insufficient to distribute the load homogeneously against chewing pressure due to their materials and geometry. Non-uniform load distribution damages the abutment and the prosthetic crown, accelerating the wear process. This study aimed to create different abutment designs to improve dental implants' biomechanical performance and longevity. This study aimed to increase the mechanical durability of the implant-abutment connection by reducing stress concentrations in response to masticatory compression on the abutment in different directions and forces and to guarantee the long-term success of the implant system by providing a more homogeneous stress distribution. It aimed to apply different forces in the axial direction to these models in a simulation environment and to calculate and compare the deformation and stress load distribution. As a method, three-dimensional models of the parts used in implant treatments and forming the implant system were designed. Different abutment designs were created with these models. Taking the current material values used in implant treatments as a reference, finite element analysis (FEA) was performed by applying different axial loads to each implant system model in the ANSYS software (version 24.1). Comparative analysis graphs were prepared and interpreted for the stress values obtained after the applied load. This study evaluated the mechanical performance of different abutment models (A, B, C, D, and E) under a 100 N load using the Kruskal-Wallis test. The Kruskal-Wallis test showed significant differences between the groups (p < 0.001). The greatest difference was observed between models E and A (q' = 6.215), with a significant difference also found between models C and A (q' = 3.219, p < 0.005). Regarding stress values, the highest stress on the abutment was observed in Model B (97.4 MPa), while the lowest stress was observed in Model E (9.6 MPa). The crown exhibited the highest stress in Model B (22.7 MPa) and the lowest in Model E (17.3 MPa). The implant stress was highest in Model C (14.8 MPa) and lowest in Model B (11.3 MPa). The stress values for the cortical bone and cancellous bone were quite similar across the models, showing no significant differences. These findings indicate that the abutment design and material selection significantly impact mechanical performance. Among the implant systems created with five different abutment models, in which the existing abutment geometry was also compared, homogeneous and axial distribution of the load on the abutment was achieved, especially with viscoelastic and surface area increased abutment designs. Clinically, the inadequacy and limited mounting surface or geometry of the abutments used in today's implant treatment applications have led to different design searches. It was concluded that the designs in this study, which are considered alternatives to existing abutment models, contribute positively to the mechanical life of the abutment material, considering the von Mises stresses and directions. This study brings a new perspective to today's practices and offers an alternative to treatment practices.

The influence of titanium-base abutment geometry and height on mechanical stability of implant-supported single crowns.

This study aimed to investigate the influence of titanium base (ti-base) abutment macro- and micro-geometry on the mechanical stability of polymer-infiltrated ceramic network (PICN) screw-retained implant-supported single crowns (iSCs). Twelve specimens per group were used, comprising six different implant/ti-base abutment combinations restored with PICN iSCs: Nb-T (gingival height [GH]: 1.5 mm, prosthetic height [PH]: 4.3 mm), CC (GH: 0.8 mm, PH: 4.3 mm), CC-P (GH: 0.8 mm, PH: 7 mm), Nb-V (GH: 1.5 mm, PH: 6 mm), St (GH: 1.5 mm, PH: 5.5 mm), and Th (GH: 0.5 mm, PH: 9 mm). The specimens underwent thermo-mechanical aging, and those that survived were subsequently subjected to static loading until failure. The data were analyzed using a one-way ANOVA test followed by Tukey post hoc test (α = .05). All specimens survived thermo-mechanical aging without complications, namely, visible cracks, debonding, or screw loosening. Th group demonstrated the highest strength values among all the groups, with significant differences compared to Nb-T (p < .05), CC (p < .001), and St (p < .001). Additionally, CC-P group exhibited significantly superior fracture strength results compared to CC (p < .05) and St (p < .05). The choice of ti-base, particularly prosthetic height, had a significant influence on fracture resistance of PICN iSCs. Nevertheless, the height or geometrical features of the ti-base did not exhibit a significant influence on the mechanical behavior of the iSC/ti-base assembly under thermomechanical loading, as all specimens withstood the aging without complication or failure.

Electron Microscopy (EM) Analysis of Collagen Fibers in the Peri-Implant Soft Tissues around Two Different Abutments.

The design of the implant prosthesis-abutment complex appears crucial for shaping healthy and stable peri-implant soft tissues. The aim of the present animal study was to compare two implants with different healing abutment geometries: a concave design (TEST) and a straight one (CTRL). Transmission electron microscopy (TEM) was used to quantify the three-dimensional topography and morphological properties of collagen at nanoscale resolution. 2 swine were included in the experiment and 6 implants per animal were randomly placed in the left or right hemimandible in either the physiologically mature bone present between the lower canine and first premolar or in the mandibular premolar area, within tooth extraction sites. Each CTRL implant was positioned across from its respective TEST implant on the other side of the jaw. After 12 weeks of healing, 8 specimens (4 CTRL and 4 TEST) were retrieved and prepared for histological and TEM analysis. The results showed a significantly higher percentage of area covered by collagen bundles and average bundle size in TEST implants, as well as a significant decrease in the number of longitudinally oriented bundles with respect to CTRL implants, which is potentially due to the larger size of TEST bundles. These data suggest that a concave transmucosal abutment design serves as a scaffold, favoring the deposition and growth of a well-organized peri-implant collagen structure over the implant platform in the early healing phase, also promoting the convergence of collagen fibers toward the abutment collar.

Impact of Different Implant Abutment Geometry on Retention of Implant-supported Cement Retained Prosthesis: A Comparative Study

Impact of Different Implant Abutment Geometry on Retention of Implant-supported Cement Retained Prosthesis: A Comparative Study

Field Monitoring and Analysis of Abutment Foundation Behavior for a Curved Integral Abutment Bridge under Thermal Loading

The construction of integral abutment bridges (IABs), including semi-IABs, has increased substantially in the past two decades, partly because of reduced construction and maintenance costs. However, temperature-driven lateral movements, associated with the elimination of expansion joints, lead to a complex interaction between the bridge structure and the soils behind and under the abutment, which could result in soil densification, void formation, and settlement in the approach slab. The bridge's structure, geometry, and location all play an essential role in how the IAB responds to those movements. In addition, if the IAB is curved, it brings more complexity to its behavior. Nonetheless, there has been very little research on the behavior of curved IABs to date. This study investigates the behavior of a newly constructed curved IAB via field monitoring and numerical simulation. Field measurements included the backfill pressure, horizontal translation, and rotation imposed on the abutments during seasonal thermal fluctuations. The abutments rotate and translate toward backfill in summer and away from it in winter because of thermal expansion and contraction of the superstructure. Such thermal movements contributed to the increase in the lateral pressure to 85 kPa in the first year and to 140 kPa in the second year of monitoring. This implies that irreversible deformation may occur during seasonal temperature changes, supported by the monitored displacements. The bridge curvature, different skew angles at both ends, and the abutment geometry resulted in different movements and backfill pressures at each corner. A numerical simulation is also performed to provide more insights into the behavior of the curved IAB with more seasonal temperature cycles.

Factors influencing retention of resin-based luting systems on implants: A systematic review

The large variety in materials makes it difficult for dentists to select the right material for appropriate retention of single crowns on implants. An assessment of the retentive force and influencing parameters is lacking. The aim of this systematic review is to provide an overview of the retention values of resin-based luting materials of single tooth crowns on implants. Influencing factors, such as the abutment geometry, different pretreatment options, or the application of resin-based systems, are taken into account. A Pubmed-Medline library search was conducted, supported by manual searching, to collect available studies between the years 2005 to 2020. The following MeSH terms were used: “dental AND implant AND crown AND cementation AND retention”, as well as other combinations to identify as many studies as possible. After setting the filters and deleting the duplicates, 269 studies were identified. Finally, 23 studies were considered eligible for this review. Resin-based adhesive luting materials in combination with a primer showed the highest retention values. The retention is significantly influenced by a small cement gap, high loading during cementation, and pretreatment of the abutment. A low bias risk was shown for all included studies. The large number of available resin-based luting materials offer dentists the possibility to influence the individual retention of single-tooth crowns on implants. According to the present study, retentive strength can be clinically influenced not only by the choice of luting material. A pretreatment using sandblasting and an appropriate primer influences retention positively. Exerting pressure on the restoration after cementation also leads to increased retention. However, clinical studies would be desirable for the future to further investigate the results of this review.

Impact of abutment geometry on early implant marginal bone loss. A double-blind, randomized, 6-month clinical trial.

The objective of this study was to analyze the impact of the abutment width on early marginal bone loss (MBL). A balanced, randomized, double-blind clinical trial with two parallel experimental arms was conducted without a control group. The arms were "cylindrical" abutment and "concave" abutment. Eighty hexagonal internal connection implants, each with a diameter of 4 × 10 mm, were placed in healed mature bone. The main variable was the peri-implant tissue stability, which was measured as MBL at 8 weeks and 6 months. The final sample consisted of 77 implants that were placed in 25 patients. 38 (49.4%) were placed using the cylindrical abutment, and the other 39 (50.6%) were placed using the concave abutment. The early global MBL of -0.6 ± 0.7 mm in the cylindrical abutment group was significantly higher than it was in the concave abutment group, in which the early global MBL was -0.4 ± 0.6 mm (p=.030). The estimated effect size (ES) was negative for the cylindrical abutment (ES=-1.3730, CI -2.5919 to -0.1327; t-value=-2.4893; p=.0139), therefore implying a loss of mean bone level, and it was positive for the concave abutment (ES=2.8231; CI: 1.4379 to 4.2083; t-value=4.0957; p=.0002), therefore implying an increase in the average bone level. The concave abutments presented significantly less early MBL at 6 months post-loading than classical cylindrical abutments did.

Effect of Abutment Geometry and Luting Agents on the Vertical Marginal Discrepancy of Cast Copings on Implant Abutments: An In Vitro Study.

Aim Vertical marginal discrepancy (VMD) influences the success of implant-supported restorations. However, there is little literature that has investigated the influence of geometry and cementing agent on changes in VMD of metal copings on implant abutments. The objective was to evaluate the effect of the geometry of the abutment and cementing agents on VMD. Methods Cast copings were cemented on implant abutments customized cylindrical (4, 5.5, and 7 mm) and on hexagonal implant abutments (4 mm) cemented or uncemented molded copings were placed (n = 4, totally 64 samples) with different luting agents. The VMD of the copings were measured in the coping-abutment interface at three reference points using a stereomicroscope. The independent Student's t test was used for comparison between the two different abutment walls. The post hoc statistical analysis was performed by the Tukey test. Results There was a significant VMD increase between noncemented and cemented cast copings using different luting agents. Abutment geometry and luting agents significantly influenced the VMD (p ≤ 0.05). Cylindrical abutment at 7 mm in height cemented with different luting agent tested showed significantly higher VMD values than cylindrical abutments of 4 mm (p=0.019). Hexagonal abutments with a 4 mm height showed significantly higher VMD values than cylindrical 4 mm abutments using zinc oxide noneugenol and glass ionomer cements (p=0.032). Conclusions Abutment geometry and luting agents influence the VMD of cast copings cemented on implant abutment. The higher the cylindrical abutment, the greater the VMD, and hexagonal wall abutments promote greater marginal gap.

Limit analysis of bearing capacity and failure geometry of GRS bridge abutments

The paper presents analytical investigation of bearing capacity of geosynthetic reinforced soil (GRS) bridge abutments with vertical or nearly vertical facing batter angle. A limit analysis (LA) method is proposed using a y-shaped failure mechanism to determine the bearing capacity and the corresponding failure surface geometry within GRS bridge abutments. The proposed method is validated against results from numerical simulations and limit-equilibrium methods. Parametric analyses are subsequently carried out to examine the effects of backfill strength, reinforcement properties, and abutment geometry on the bearing capacity and failure surface geometry of GRS bridge abutments.

In Vitro Simulation of Dental Implant Bridges Removal: Influence of Luting Agent and Abutments Geometry on Retrievability.

Implant fixed dental prostheses are widely used for the treatment of edentulism, often preferred over the screw-retained ones. However, one of the main features of an implant-supported prosthesis is retrievability, which could be necessary in the case of implant complications. In this study, the retrievability of implant-fixed dental prostheses was investigated considering two of the main factors dental practitioners have to deal with: the abutments geometry and the luting agent. Impulsive forces were applied to dental bridge models to simulate crowns’ retrievability in clinical conditions. The number of impulses and the impulsive force delivered during each test were recorded and used as retrievability indexes. One-hundred-and-five tests were conducted on 21 combinations of bridges and luting agents, and a Kruskal-Wallis test was performed on the results. The abutment geometry significantly influenced the number of impulses needed for retrieval (p < 0.05), and a cement-dependent trend was observed as well. On the other hand, the forces measured during tests showed no clear correlation with bridge retrievability. The best retrievability was obtained with long, slightly tapered abutments and a temporary luting agent.

Prediction equations for estimating maximum lateral displacement and settlement of geosynthetic reinforced soil abutments

Abstract The Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS), which consists of closely-spaced layers of geosynthetic reinforcement and compacted granular fill material, is a fast, sustainable and cost-effective method for bridge support. The in-service performance of this innovative bridge support system is largely evaluated through the vertical and horizontal deformations of the GRS abutments. This paper presents the development of nonlinear equations for estimating the maximum lateral displacement and settlement of GRS abutments. The parameters that are considered in the prediction equations include abutment geometry (height, facing batter and foundation width), backfill friction angle, reinforcement characteristics (stiffness, spacing, and length), and applied static loads from 50 to 400 kPa. In the development of the prediction equations, a parametric study was first conducted using a validated finite difference numerical model. The results of the parametric study were then used to conduct a regression analysis to develop the equations for estimating the maximum lateral displacement and settlement of GRS abutments under service loads. The equations were validated using three case studies. The developed prediction equations can contribute to a better understanding and enable simple calculations in designing these structures.

In Vitro Impact Testing to Simulate Implant-Supported Prosthesis Retrievability in Clinical Practice: Influence of Cement and Abutment Geometry.

Cement-retained implant-supported prosthetics are gaining popularity compared to the alternative screw-retained type, a rise that serves to highlight the importance of retrievability. The aim of the present investigation is to determine the influence of luting agent, abutment height and taper angle on the retrievability of abutment–coping cementations. Abutments with different heights and tapers were screwed onto an implant and their cobalt-chrome copings were cemented on the abutments using three different luting agents. The removals were performed by means of Coronaflex®. The number of impulses and the forces were recorded and analyzed with a Kruskal–Wallis test. Harvard cement needed the highest number of impulses for retrieval, followed by Telio CS and Temp Bond. However, abutment height and taper showed a greater influence on the cap’s retrievability (p < 0.05). Long and tapered abutments provided the highest percentage of good retrievability. The influence of the luting agent and the abutment geometry on the cap’s retrieval performed by Coronaflex® reflects data from literature about the influence of the same factor on the maximum force reached during uniaxial tensile tests. The impulse force was slightly affected by the same factors.

Anodized anisotropic titanium surfaces for enhanced guidance of gingival fibroblasts.

Ensuring the formation of a robust trans-mucosal soft-tissue seal at the dental abutment surface is crucial towards protecting the underlying dental implant associated tissues from the external microbial-rich oral environment. The ability to mechanically enhance fibroblast functions at the dental abutment-mucosa interface, without the use of bioactive agents, holds great promise towards reducing the ingress of oral pathogens into the dental implant microenvironment. We hereby propose fabrication of unique anisotropic titania nanopores (TNPs) on the surface of titanium (via electrochemical anodization, EA) towards enhancing the soft-tissue integration and wound healing abilities of the conventional abutments. Using optimized EA, mechanically robust TNPs of varied diameters were fabricated on Ti surfaces with preserved underlying substrate micro-features: dual micro-nanostructured surfaces. Next, we evaluated the mechanical stability of such structures and demonstrated the ease of fabrication on commercial abutment geometries. The functions of primary human gingival fibroblasts (GFs) cultured on these surfaces in vitro were evaluated from 1h to 7days, and were compared between TNPs and clinically relevant titanium controls: as-received irregular rough Ti (Rough Ti) and mechanically prepared micro-rough Ti (Micro Ti). Improved cell viability was observed on TNPs as compared to controls. Additionally, cellular spreading morphology indicated cell alignment along the direction of the nanopores with strong anchoring evident by enhanced filopodia and stress fibers. RT-PCR showed improved wound healing, cell migration/adhesion and angiogenesis related mRNA, especially for TNPs with large diameters. This study provides a proof-of-concept towards using anodization for improving soft-tissue sealing around dental abutment surfaces, with implications towards reducing implant failure/peri-implantitis and achieving long-term success, especially in compromised patient conditions.

Removal forces of adhesively and self-adhesively luted implant-supported zirconia copings depend on abutment geometry

This in vitro study evaluated the effects of different abutment axial heights on the retentiveness of adhesively and self-adhesively luted zirconia copings. Ankylos implants were embedded in resin blocks. Two groups of titanium abutments (“long”, height: 6.79 mm, taper: 4.8°; “short”, height: 4.31 mm, taper: 4.8°; Compartis-ISUS, DeguDent) were used for the luting of CAD/CAM-fabricated zirconia copings (Compartis, DeguDent) with an adhesive (Multilink Automix; Ivoclar Vivadent) and a self-adhesive (RelyX Unicem; 3M ESPE) composite. After water storage and 5000 thermocycles (5 °C/55 °C), retention forces were evaluated using a universal testing machine (Zwick). Significant differences were determined via two-way ANOVA and t-tests with Bonferroni-Holm correction. Significant interactions between abutment geometry and luting agents were observed. RelyX Unicem showed the highest levels of retentiveness, irrespective of the varying abutment geometries (mean values long/short: 487.7 N/447.9 N). When Multilink Automix was used, removal forces were significantly lower (311.7 N/101.1 N) and negatively affected by the use of the shorter abutments. Customized long abutments supported better retention forces than customized short abutments for both luting agents.

Numerical study on maximum reinforcement tensile forces in geosynthetic reinforced soil bridge abutments

This paper presents a numerical study of maximum reinforcement tensile forces for geosynthetic reinforced soil (GRS) bridge abutments. The backfill soil was characterized using a nonlinear elasto-plastic constitutive model that incorporates a hyperbolic stress-strain relationship with strain softening behavior and the Mohr-Coulomb failure criterion. The geogrid reinforcement was characterized using a hyperbolic load-strain-time constitutive model. The GRS bridge abutments were numerically constructed in stages, including soil compaction effects, and then loaded in stages to the service load condition (i.e., applied vertical stress = 200 kPa) and finally to the failure condition (i.e., vertical strain = 5%). A parametric study was conducted to investigate the effects of geogrid reinforcement, backfill soil, and abutment geometry on reinforcement tensile forces at the service load condition and failure condition. Results indicate that reinforcement vertical spacing and backfill soil friction angle have the most significant effects on magnitudes of maximum tensile forces at the service load condition. The locus of maximum tensile forces at the failure condition was found to be Y-shaped. Geogrid reinforcement parameters have little effect on the Y-shaped locus of the maximum tensile forces when no secondary reinforcement layers are included, backfill soil shear strength parameters have moderate effects, and abutment geometry parameters have significant effects.

Numerical Simulation of Deformation and Failure Behavior of Geosynthetic Reinforced Soil Bridge Abutments

This paper presents a numerical investigation of the deformation and failure behavior of geosynthetic reinforced soil (GRS) bridge abutments. The backfill soil was characterized using a nonlinear elastoplastic constitutive model that incorporates a hyperbolic stress–strain relationship with strain-softening behavior and the Mohr–Coulomb failure criterion. The geogrid reinforcement was characterized using a hyperbolic load–strain–time model. The abutments were numerically constructed in stages, including soil compaction effects, and then monotonically loaded in stages to failure. Simulation results indicate that a nonlinear reinforcement model is needed to characterize deformation behavior for high applied stress conditions. A parametric study was conducted to investigate the effects of reinforcement, backfill soil, and abutment geometry on abutment deformation and failure behavior. Results indicate that reinforcement vertical spacing, reinforcement stiffness, backfill soil friction angle, and lower GRS wall height are the most significant parameters. The shape of the failure surface is controlled primarily by abutment geometry and can be approximated as bilinear.

Fatigue life prediction and stress distribution of straight and angled abutments using numerical techniques

The durability of an implant-bone structure depends mainly on the capability of the implants and bone-implant interface to support masticatory forces. The mechanical behavior of both bone and implant varies from one configuration to another and thus, it is still an attractive topic for many researchers in dental biomechanics. This paper investigated stress distribution in four different applications/configurations of commercial implants by employing three dimensional finite element analyses. Fatigue analysis was also conducted to estimate the assembly’s life-cycles. The results indicated that the application of a straight abutment is more suitable for a situation where the implant is placed in an ideal position, perpendicular to the occlusal plane. Whereas an angled abutment may be implanted for conditions in which the implant is not placed in a perpendicular position to the occlusal plane. The results were found to be in agreement with the experimental data available in the literature. Although different clinical conditions, using angled abutments, may lead to different severities and regions of crack initiation, approximately infinite life was predicted for all analyzed cases. The abutment geometry whether straight or angled and the implant position, do not have a significant effect on the assembly’s life.

Development and validation of p‐y modeling approach for seismic response predictions of highway bridges

SummaryThis study aims to realistically simulate the seismic responses of typical highway bridges in California with considerations of soil–structure interaction effects. The p‐y modeling approaches are developed and validated for embankments and pile foundations of bridges. The p‐y approach models the lateral and vertical foundation flexibility with distributed p‐y springs and associated t‐z and q‐z springs. Building upon the existing p‐y models for pile foundations, the study develops the nonlinear p‐y springs for embankments based on nonlinear 2D and 3D continuum finite element analysis under passive loading condition along both longitudinal and transverse directions. Closed‐form expressions are developed for two key parameters, the ultimate resistant force pult and the displacement y50, where 0.5pult is reached, of embankment p‐y models as functions of abutment geometry (wall width and height, embankment fill height, etc.) and soil material properties (wall‐soil friction angle, soil friction angle, and cohesion). In order to account for the kinematic and site responses, depth‐varying ground motions are derived and applied at the free‐end of p‐y springs, which reflects the amplified embankment crest motion. The modeling approach is applied to simulate the seismic responses of the Painter Street Bridge and validated through comparisons with the recorded responses during the 1992 Petrolia earthquake. It is demonstrated that the flexibility and motion amplification at end abutments are the most crucial modeling aspects. The developed p‐y models and the modeling approach can effectively predict the seismic responses of highway bridges. Copyright © 2016 John Wiley &amp; Sons, Ltd.