Walid Aboumoussa

Apparent Thermal Coefficient of Expansion of Concrete Building with Restraint

The expansion coefficient of a four-story open reinforced concrete parking structure subjected to wide temperature variation was measured in this paper. The structure consists of a waffle-slab floor system with regularly placed columns and measures 52.42 x 71.32 m (172 x 234 ft). An expansion joint was instrumented and monitored for 4.5 years and the joint was instrumented using four vibrating wire displacement transducers with integrated temperature sensors. Transducer measurements were recorded hourly. A description of the instrumentation and monitoring results is presented, which included annual, seasonal, and daily ranges of movement and the corresponding values of the apparent coefficient of thermal expansion (ACTE) of the constructed structure in service. In general, the paper found that values of the annual ACTE were primarily dependent on the degree of restraint and, to a lesser extent, temperature. The measured ACTE ranged from 0.000586 to 0.0793% per 100°C (0.00032 to 0.044% per 100°F), depending on the temperature and imposed structural restraint.

Parametric Study of Earth Pressure behind RFERS at Backfill Stage

This chapter presents the results of parametric finite element analyses performed to explore the relationship between earth pressure and the stiffness of Rigidly Framed Earth Retaining Structures (RFERS). A plane strain model was employed. The stages of construction were incorporated in the analysis to simulate an initial stage where a structural frame is first completed followed by the addition of backfill soil in several stages. The displacement of the structures, as well as the earth pressure and resultant load developed behind them were obtained to examine the relationship between the stiffness of the retaining structure and the development of lateral earth pressure in the retained soil mass.

Analysis of Single Story RFERS Subject to Temperature Variations

This chapter presents the results of numerical parametric analysis of single-story structures with varying geometries and properties. The primary purpose of this analysis is to investigate the effect of thermal movements of Rigidly Framed Earth Retaining Structures (RFERS) on (1) the displacement of the rigid frames, (2) the stresses developed in the structural elements, and (3) the lateral earth pressure developed in the soil mass. The results are reported for 1, 10, 20 bay frames in this Chapter and for 3, 6, 15 bay frames in Appendix A for φ = 30°. Results for φ = 40° are also presented in Appendix A.

Multi-story RFERS Subject to Temperature Variation

This chapter presents the results of numerical parametric analysis of multi-story structures with varying geometries and properties. The primary purpose of this analysis is to investigate the effects of thermal movements of Rigidly Framed Earth Retaining Structures (RFERS) on (1) the displacement of the rigid frames, (2) the stresses developed in the structural elements, and (3) the lateral earth pressure developed in the soil mass. The results are reported for three and five story structures in this Chapter and for two and four story structures in Appendix B.

Numerical Analysis of Instrumented RFERS

This chapter presents the finite element analysis of the building monitored in Chapters 4 and 5. A plane strain model was employed through dividing the column properties by the tributary width of the frame, and utilizing the equivalent area and moment of inertia per foot of length of the waffle slab. The analysis confirms many of the results gleaned from the discrete instrumentation measurements. In particular, the lateral earth pressure exerted on the rigid frame developed during the thermal expansion cycles is considerably larger than the lateral earth pressure at rest.

Relationship between temperature and earth pressure for RFERS

The relationship between temperature and earth pressure acting on a Rigidly Framed Earth Retaining Structure (RFERS) subject to wide temperature variation was explored in this chapter. The open concrete garage RFERS presented in Chapter 4 was instrumented and monitored for a period of four and a half years. The structure retains 11 m (36 ft) of soil on one side only. The measured displacements were used to calculate the earth pressure coefficient using closed form equations that were developed in Chapter 3. The data indicated that the coefficient of earth pressure behind the monitored RFERS had a strong linear correlation with temperature. The study also reveals that thermal cycles, rather than lateral earth pressure, caused some of the structural elements to fail.

Classical Earth Pressure Theory Related to Framed Structures

The development of earth pressure theory as it relates to rigidly framed earth retaining structures is chronicled in this chapter. Inadequacies of classical theories are explored along with studies related to earth pressure acting against integral bridges, which resemble, in some ways, a single story rigidly framed earth retaining structure.

Closed-form expressions for lateral deflection of rigid frames

Determining the magnitude of the lateral deflection of the building frame of low-rise rigidly framed structures, due to external loads, is needed in order to meet appropriate serviceability and design code requirements. In this chapter, a simplified rational closed form analytical expression is formulated for calculating the lateral deflection of low rise rigidly framed structures subjected to different lateral force distributions varying with the height of the frame.

Case Study of a Full Scale RFERS in Service

A distressed Rigidly Framed Earth Retaining Structure (RFERS) open concrete garage that retains 11 m (36 ft) of soil was instrumented. After some repairs, movement of the building was monitored and recorded hourly. The monitoring revealed complex temperature-dependent soil structure interactions, which are reported in this chapter.

Instrumentation and Monitoring of a Four-Story Earth-Retaining Concrete Building

A four-story reinforced concrete building retaining earth on one side and exhibiting large lateral displacement and structural distress was instrumented and monitored for over four years. The rectangular building measuring 52.42 m by 71.32 m is open to the elements and thus subjected to large temperature variation. The application of classical lateral earth pressure theories and analysis methods for back analysis were unsuccessful in predicting the observed behavior of the building. The instrumentation program involved the installation of eight vibrating-wire displacement transducers measuring the building movements in the longitudinal and transverse directions, and 12 electrolytic tiltmeters mounted on the building wall abutting the retained soil backfill to measure the wall rotation. The instruments were equipped with temperature sensors and were connected to an automatic data acquisition system accessible via a remote connection. The monitoring results revealed the presence of a complex soil-structure interaction involving the effects of temperature on the volumetric strains of the building and their effects on the building movements and the development of lateral pressures in the retained earth mass. The results of the monitoring program are presented in this paper.