CANDE

Abstract: A unified computer methodology is presented for the structural design, analysis, and evaluation of buried culverts made of corrugated steel, aluminum, reinforced concrete, and a class of plastic pipe. Through proper representation of soil-structure interaction, the engineer can test and evaluate either old or new culvert design concepts. The engineer may select any of three solution levels in the computer program, depending on the complexity of the problem and vigor of solution derived. Level 1 is a closed-form elasticity solution (Burns), whereas levels 2 and 3 are based on finite element methods. Each solution characterizes the culvert-soil system by plain strain geometry and loading. Analytical modeling features incremental construction and non-linear constitutive models for characterizing culvert and soil behavior. Culvert material models account for ductile yielding and brittle cracking. CANDE designs are compared with traditional design solutions for both corrugated metal and reinforced concrete pipe. Field experimental data compared to CANDE predictions demonstrate good condition. /Author/

Abstract: Precast reinforced-concrete box culverts are relatively new products in culvert technology. Currently, the most widely used design procedure is ASTM C789 (Specifications on Precast Reinforced Concrete Box Sections for Culverts, Storm Drains and Sewers). These ASTM design tables give maximum allowable earth-cover heights for standard box sizes and steel reinforcement, determined by a linear-elastic frame analysis of the box section with an assumed soil pressure loading. No consideration is given to soil stiffness or soil-structure interaction. In this study, the final objective is to evaluate the structural adequacy of the ASTM box designs by using the finite-element program Culvert Analysis and Design (CANDE), which includes nonlinear elements for reinforced concrete, incremental soil construction, and fully automated mesh-generation schemes for culvert applications. To this end, the CANDE reinforced-concrete box model is validated with experimental data from out-of-ground box culverts loaded to ultimate. Next, the CANDE box-soil model is validated with experimental data from an in-ground box-culvert test with incremented soil loading. After the CANDE box-soil model has been validated, it is used to evaluate the ASTM box designs with regard to the 0.01-in crack-width limitation and the load factor for ultimate failure. In general it is concluded that the ASTM box designs are conservative but not uniformly conservative and the effect of soil stiffness is significant. (Author)

Abstract: This report documents research performed to develop, modernize, and upgrade CANDE (Culvert ANalysis and DEsign). The new version is called CANDE-2007. The report details the research performed to update the program. CANDE installation files are included on a CD-ROM (CRP-CD-69) with this report. The installed program includes integrated help files and 14 tutorial examples. The report and software will be of immediate interest to culvert designers.

Abstract: 1. GENERAL INTRODUCTION 1.1 Objectives and Scope 1.2 Literature Review PART I. EVALUATION OF HIGH DENSITY POLYETHYLENE PIPE INSTALLATIONS 2. INTRODUCTION AND METHODOLOGY 2.1 Objective 2.2 Methodology 2.3 MN. DOT specifications for HDPE Pipe instalations 3. DATA EVALUATION AND INTERPRETATIONS 3.1 Structural Problems 3.2 Sediments 4. CONCLUSIONS PART II. BURIED FLEXIBLE PIPE ANALYSIS USING FINITE ELEMENT ANALYSIS 5. INTRODUCTION 5.1 General Background 5.2 Objectives and Scope 5.3 Modeling 6. ANSYS AND CANDE ANALYSES 6.1 Elastic Soil, Comparison of ANSYS and CANDE 6.2 Soil Models 6.3 Comparison of ANSYS and CANDE 6.4 Pipe Material Effect 6.5 Construction Process Modeling