CE 200L Report 5_Timber

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California State University, Long Beach *

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200L

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Civil Engineering

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Feb 20, 2024

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California State University Long Beach Civil Engineering Department Materials for Civil Engineering Laboratory CE 200 L Short-Form Lab Report Report N o : 5 Report Title: Timber in Static Bending, Compression, and Shear Submitted By: Section: Team N o : Date Due: Date Submitted: Grading Distribution of the 8 Points Total Score for the Report Item Criterion Max Points Earned Points 1 Use of Laboratory Equipment 2 2 Data Collection, Compilation, Reduction, and Interpretation 2 3 Technical Presentation — tables, graphs, sketches, etc. 2 4 Written Communication — results and discussion of results and test procedures 2 Total Please Upload the Completed Report to The Designated Dropbox Folder on Canvas. One Team Member Can Submit the Report on Behalf of the Team.

CE 200 L Report N o 5 Timber in Static Bending, Compression, and Shear 1. Objectives a) Static Bending — To determine a timber beam’s Load-Deflection properties, and to clas- sify the type of its failure b) Compression — To determine the ultimate unconfined compressive strength of timber parallel to the grain, and to calculate a factor of safety therefor 2. Reference ASTM D 143 — Standard Test Method of Testing Small Clear Specimens of Timber 3. Procedure The above-listed reference is read, and the instructions given in the laboratory during the briefing period are followed. a) Compression Parallel to the Grain Test ( i ) The dimensions of the timber specimen are measured and recorded. ( ii ) The timber specimen is placed in the testing machine for loading in compression, and a cage is placed around the specimen. ( iii ) The timber specimen is loaded to failure, and upon failure of the test specimen, the failure data is saved on USB Drive and used to extract: • The failure load • The time to failure ( iv ) The failure of the timber is sketched and classified per ASTM D143 c) Static Bending Test ( i ) The dimensions of timber beam specimen are taken, and the loading and simply supported points are marked for a mid-point loading test setup. ( ii ) The timber beam specimen is placed in the testing machine for loading in bending, with the beam oriented in such a way that the load bearing points are closest to the pith, per ASTM D 143 — “Standard Test Method of Testing Small Clear Specimens of Timber.” The deflection bracket is mounted at the center and the LVDT gage is in- stalled. – 1/8 –

( iii ) The test setup is sketched with all pertinent dimensions of loading, support, and de- flection measurement points, as well as the physical dimension of the beam dimen- sioned and marked on the sketch. ( iv ) An increasing point-load is applied at the mid-span of the beam up to 1,200 lb . Un- der this relatively small load, the beam’s behavior remains Elastic (i.e., linear). This task is repeated for each team in the lab. The load vs. deflection data (raw data) is downloaded and saved in Excel format. ( iv ) The raw data from the elastic bending deformation is further processed in Excel. For this purpose, a seating load of 100 lb is considered to induce zero deflection in the beam (said seating load herein). The data column is reduced to reflect this adjust- ment. The process will be demonstrated by the instructor in the lab. ( v ) The beam’s Load-Deflection curve is plotted with vertical axis presenting the load in pounds. A Linear Trendline is passed through the curve. The slope of this straight line is the Load-Deflection Constant of the beam. ( vii ) The last team to conduct the test: • Removed the load • Removed the deflection measuring devices • Loaded the specimen at the rate 20 lb/second to failure ( viii ) Upon failure of the beam: • The failure load is recorded (by all teams) • The time to failure is recorded (by all teams) • The failure is sketched (or photographed and classified (by all teams) • The test set up is sketched in appropriate box (by all teams) 4. Data Recorded by Team a) Team Information — Day 1 — Tests: Compression parallel to Grains Section: Team: Leader: Recorder: Other members: Member(s) absent: Day 1 Date Time of day: Room temp.: °F Relative humidity: % – 2/8 –

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b) Compression Parallel to the Grain Test Data ( i ) Ultimate Force: _____________ lb ( ii ) Time to Failure: _____________ s ( ii ) Specimen Dimensions (nearest 0.1″) ( iii ) Sketch of Failed Specimen Instructor’s initials: ___ – 3/8 –

c) Team Information — Day 2 — Test: Bending Test Section: Team: Leader: Recorder: Other members: Member(s) absent: Day 2 Date Time of day: Room temp.: °F Relative humidity: % Type of timber tested: Clear grade Douglas fir d) Static Bending Test Failure Data: Please include a screenshot of test results summary and test plot for loading to failure. In addition, fill out the following table accordingly. Time duration to failure: ______ s Beam failure load (ultimate load): _________ lb e) Static Bending Test Setup and Specimen Failure Sketches Sketch of the Test Set-up Including Dimensions Sketch of the Failed Beam Instructor’s initials: ___ – 4/8 –

5. Plotted Data: Elastic Load-Deflection Curve Use Microsoft Excel to plot the adjusted test data for the Elastic (linear) portion of the bending test (up to 1200 lb). Add a linear trendline to find the slope of the curve. Timber Beam Bending Load vs. Deflection Data (A schematic figure) Note: The straight line in the chart above is schematic for your reference. You should draw the actual line based on data collected from the timber test in flexure. – 5/8 –

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6. Results and Discussion Please write/type your response and discussion in Black ink and with 12-Pts font Times New Roman (if typed). 6.1 Results For results, using Standard American English and complete sentences, please state: a) What is the strength for the timber tested in compression parallel to the grain by your team? b) What is the type of failure for the specimen tested in compression parallel to the grain for your team? d) What is the Load–Deflection constant determined by your team in the tim- ber in static bending test? e) What are the failure load and time to failure for the timber specimen tested by the class in the timber in static bending test? f) What is the type of failure for the specimen tested in static bending by the class? – 6/8 –

6.2 Discussion For discussion, using Standard American English and complete sentences, please state: a) For the test conducted in the CE 200 L Laboratory ( i ) Whether or not there are deviations from the procedures pre- scribed in ASTM D 143 — “Standard Test Method for Testing Small Clear Specimens of Timber” ( ii ) If so, list such deviation(s) b) Address the acceptability of the test results by responding to: ( i ) Whether or not such deviations affect the test results? ( ii ) If yes, how did such deviations affect test results? ( iii ) why could the test results be considered acceptable, or why should they be rejected? c) Using the following equation for calculating the bending strength or modulus of rupture ( MOR ) determined in center-point loading test: – 7/8 –

MOR = 3 PL 2 bd 2 where: P = the failure load (in pounds), L = the span length of the beam (between two supports, in inches) d = the depth of the beam (in inches), and b = the width of the beam (in inches) determine the bending strength of the beam tested by the class in the laboratory in static bending. d) Using 8,000 psi as the allowable stress for the type of timber loaded in flex- ure, determine the factor of safety for flexure of the timber tested in the labo- ratory. e) Using 3,150 psi as the allowable stress for the type of timber loaded in com- pression parallel to the grain, determine the factor of safety for compression parallel to the grain for the timber tested in the laboratory. – 8/8 –

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CE 200L Report 5_Timber

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