(3)J2007-Experimental_behavior_of_circular_concrete-filled
Journal of Constructional Steel Research63(2007)
165–174
https://www.wendangku.net/doc/9c343340.html,/locate/jcsr
Experimental behavior of circular concrete-?lled steel tube stub columns
Zhi-wu Yu a,Fa-xing Ding a,C.S.Cai b,?
a College of Civil Architectural Engineering,Central South University,Changsha,Hunan Province410075,PR China
b Department of Civil and Environmental Engineering,Louisiana State University,Baton Rouge,LA70803,USA
Received28November2005;accepted17March2006
Abstract
This paper presented an experimental study on the behavior of circular,concrete-?lled,steel tube(CFT)stub columns with self-compacting concrete(SCC)and normal concrete(NC)concentrically loaded in compression to failure.Four measurement methods on the axial deformation of specimens were compared.Seventeen specimens were tested to investigate the effects of concrete strength,notched holes or slots,and different loading conditions on the ultimate capacity and the load–deformation behavior of the columns.The behavior of these stub columns in con?nement was discussed.
It is concluded that for the specimens with the entire section loaded,strain gauges with different dimensions could record the strains of the steel tubes,and electronic displacement transducers with certain gauge lengths could record the axial displacement.By using higher strength concrete, the specimens with the entire section loaded experienced a signi?cant increase in the ultimate capacity,but their residual capacity after failure is almost constant.However,once the steel tube was notched,the axial compressive stiffness of specimens was reduced;in some cases the ultimate capacity was also reduced,and the steel tube acted more as a transverse con?nement than an axial compression component.Eurocode4predicted a reasonable capacity for the unnotched CFT stub columns with both SCC and NC if the entire section of the specimen is loaded.
c 2006Elsevier Ltd.All rights reserved.
Keywords:Self-compacting concrete;Concrete-?lled steel tube;Axial load behavior;Ultimate capacity;Con?nement effect
1.Introduction
Concrete-?lled steel tube(CFT)columns can provide excellent structural properties for seismic resistance,such as high ductility and large energy absorption capacity.In addition to the enhancement in structural properties,a considerable amount of construction time can be reduced due to the elimination of permanent formwork.As a result,various studies on CFT columns with normal and high-strength concrete have been conducted in recent years[1–8].
The enhancement of CFT columns in structural properties is due to the composite action between the constituent elements.The steel tube acts as both longitudinal and transverse reinforcement and also provides a con?ning pressure to the concrete,which puts the concrete under a triaxial state of stress. On the other hand,the steel tube is stiffened by the concrete core.It is well-known that the ultimate strength of CFT columns is in?uenced by their constituent material properties,such as the ?Corresponding author.Tel.:+12255788898;fax:+12255788652.
E-mail address:CSCAI@https://www.wendangku.net/doc/9c343340.html,(C.S.Cai).compressive strength of concrete,the yield strength of steel,and the steel ratio.
Although there have been a large number of studies on CFT columns with normal and high-strength concrete,there has been relatively little research on CFT columns with self-compacting concrete(SCC)[5,6].SCC possesses high workability,whereby the concrete can?ow under its own weight and?ll the formwork completely.Due to the rheological properties of SCC,the expense of vibration is eliminated whilst still obtaining a good compaction.Furthermore,advantages of SCC include a reduction of noise level in manufacturing plants and a reduction in construction time and labor costs.Therefore, there is a good potential for using CFT columns with SCC in structures.Previous research[5]indicated that the load carrying capacity and failure modes of CFT columns?lled with SCC and with NC were very similar if the concrete strength is close.
The axial compressive stiffness and ultimate capacity are the basic properties of CFT stub columns.In the literature there are different opinions and conclusions about the axial compressive stiffness of the stub columns,and one of the main reasons may be that researchers used different deformation measurement
0143-974X/$-see front matter c 2006Elsevier Ltd.All rights reserved. doi:10.1016/j.jcsr.2006.03.009
166Z.-w.Yu et al./Journal of Constructional Steel Research63(2007)165–174
Nomenclature
D Diameter of circular steel tube
E s Steel modulus of elasticity
E sc Composite modulus of elasticity
f s Yield strength of steel
f cu Cubic compressive strength of concrete
f cyl Compressive cylinder strength of concrete
h Vertical dimension of full slot
L Length of the stub column
N Axial load
N u Axial compressive capacity
N uc Predicted ultimate capacity
N ue Experimental ultimate capacity
NC Normal concrete
SCC Self-compacting concrete
u L Axial compressive deformation
t Wall thickness of steel tube
εθ,s Perimeter expansion stain
εL Axial compressive strain
v sc Strain ratio of steel
methods for the stub columns under axial compressive loading. However,there have been very few reports that compare these measurement methods for CFT stub columns.For example, the following three measurement methods were adopted to represent the deformation behavior of the stub columns in the literature:(1)the overall axial deformation of the CFT stub columns was measured with electronic displacement transducers[2–4,7],(2)the axial strain of steel tubes was measured with strain gauges in the mid-height region of the stub columns[5,6],and(3)the axial deformation of steel tubes was measured with electronic displacement transducers with a certain gauge length near the mid-height region of the stub columns[9].
To examine different mechanical behaviors of the stub columns,various loading conditions were studied,namely, the load is applied to(a)the entire section,(b)the concrete section initially,but to the entire section after the concrete was compressed,(c)the steel section initially,but to the entire section after the steel tube was compressed,and(d)the concrete section only.These tests[4,8]were carried out,emphasizing more on the ultimate capacity and less on the axial stiffness of the stub columns.There were only a few discussions on the in?uence of axial to perimeter strain ratio in the steel tube behavior when loaded to failure.Frame structures which consist of CFT columns and reinforced concrete(RC)beams are used extensively in the construction of medium-to high-rise buildings in China.In these cases steel rebars in RC beams need to pass through the steel tubes at frame joints,which could be simulated by a loading condition(e),namely,the load is applied to the entire section,but the mid-height region of the steel tube was notched with holes or slot in different manners.
The aim of this investigation was thus?vefold:?rst,to discuss the in?uence of four measurement methods in the axial deformation of stub column specimens;second,to investigate the effect of concrete core strength on the load capacity of the stub columns;third,to study the effect of small notched holes and full perimeter notched slots(with different vertical dimensions)of the steel tube on the ultimate capacity,the load–deformation behavior,and the failure mode of the stub columns;fourth,to probe into the behavior of these stub columns in con?nement;and?fth,to compare the experimental results of the unnotched specimens with the predicted ultimate capacities using Eurocode4.
2.Experimental study
2.1.Specimens
A total of17test specimens were constructed and tested under concentric axial compression loads.All specimens were three times the diameter in length to reduce the end effects and to ensure that the specimens would be stub columns with minimum effect from slenderness.Each tube was welded to a square,steel base plate of5mm thick at the bottom.The SCC and NC for?lling in the steel tube stub columns were mixed ?rst,and then the CFT stub columns were cast.Meanwhile,the corresponding SCC and NC specimens of nine150mm cubes were cast for concrete strength tests.For the NC the specimens were compacted with vibration but without vibration for SCC specimens.A summary of the specimen information is given in Table1,and the mix designs of SCC and NC are given in Table2.In Table1,the specimens labeled as SZ are for stub columns;the third letter labeled as5or3is for the nominal wall thickness(mm)of the steel tubes;the fourth letter labeled as S is for SCC and C for NC;the?fth letter labeled as3,4,or6is for concrete strength of30,40,or60MPa;the sixth letter labeled as A,B,C,D or E is for different loading conditions;the seventh letter labeled as1or2after A is for the specimen unnotched or notched with small holes,and the eighth letter labeled as a or b is the serial number.However,1,2,3,or4after E is the serial number of the specimens notched with slots.There are sixteen CFT stub columns with SCC;among them3specimens were notched with small holes and4specimens notched with slots, and one CFT stub column with NC in this test.
All the specimens were cured for30days using water spaying,and then the top surface was leveled with cement. After about90days,the top surfaces of CFT stub columns are ready for testing.For the specimens where the load is applied to the entire section,another square steel cover plate of5mm in thickness was welded to the top surface of the steel tube(see Fig.1(a)–(c)).This was done to ensure that the load was applied evenly across the cross-section and simultaneously to the steel and concrete core.But for the specimens where the load is?rst applied to the steel or concrete section,the5mm base plate at the bottom of the steel tube was cut off,and corresponding circular steel plates of1.5mm(Fig.1(d)and(e))and20mm (Fig.1(f))thick were prepared for loading.For the specimens with small holes or full notched slots with different vertical dimensions in the mid-height region of the steel tubes,the holes or slots were notched using a grinding wheel with diamond cutters.
Z.-w.Yu et al./Journal of Constructional Steel Research63(2007)165–174167 Table1
Test program and results for CFT stub columns
No.Specimens Test
layout D×t×L(mm)f s
(MPa)
f cu
(MPa)
N ue
(kN)
Note
1SZ5S4A1a Fig.1(a)219×4.78×650
35050.5
3400
2SZ5S4A1b Fig.1(a)219×4.72×6503350
3SZ5S3A1Fig.1(a)219×4.75×65042.63150
4SZ5S4A2Fig.1(b)219×4.74×65050.53160Small holes notched at steel tube with20×10mm 5SZ5S3A2Fig.1(b)219×4.73×65042.63150
6SZ5S4E1Fig.1(c)219×4.72×650
50.53380Full slot notched at steel tube with vertical dimension h=10mm
7SZ5S4E2Fig.1(c)219×4.73×6503600Full slot notched at steel tube with vertical dimension h=50mm 8SZ5S4E3Fig.1(c)219×4.73×6502900Full slot notched at steel tube with vertical dimension h=100mm 9SZ5S4E4Fig.1(c)219×4.74×6501680Full slot notched at steel tube with vertical dimension h=200mm
10SZ3S6A1Fig.1(a)165×2.73×510
77.22080
11SZ3S6A2Fig.1(b)165×2.76×5102060Small holes notched at steel tube with20×10mm 12SZ3S6B Fig.1(d)165×2.81×5002160
13SZ3S6C Fig.1(e)165×2.81×5002095
14SZ3S6D Fig.1(f)165×2.76×5002250
15SZ3S4A1Fig.1(a)165×2.72×510
57.01750
16SZ3S4A2Fig.1(b)165×2.74×5101785Small holes notched at steel tube with20×10mm
17SZ3C4A1Fig.1(a)165×2.75×51046.31560Normal concrete
Table2
Mix design of concrete
Concrete strength(MPa)Cement(kg/m3)UPFA(kg/m3)Sand(kg/m3)Aggregate(kg/m3)Water(kg/m3)Super-plasticizer(kg/m3) SCC-60396.4201.4867858165 3.88
SCC-40360.8199.3852805.6201.6 3.64
SCC-30300.0208.5814.6882.5203.4 3.30
NC-40430–5101300170–
To determine the steel material properties,three tension coupons were cut from randomly-selected steel tubes of each type,with dimensions in accordance with the Chinese standard GB/T228-2002.From these tests,the average yield strength (f s)of all types of steel tubes is350MPa,and the modulus of elasticity(E s)is2.13×105MPa.
2.2.Test arrangements and measurements
Before the column specimens were tested,the150mm cubes were crushed,and the cubic compressive strength(f cu)of SCC and NC was recorded.Then the column specimens were placed directly into the testing machine for compression tests.
A typical column test layout and instrumentation location is shown in Fig.1.
Electronic displacement transducers were placed to monitor the axial deformation at symmetric locations.Strain gauges were placed on the exterior surfaces of the stub columns to measure the vertical deformations and the perimeter expansion of the steel tubes in the mid-height region at symmetric locations.These transducers and strain gauges were also monitored in the early stage of loading to ensure that a uniform compression was imposed on the compression specimens.Four measurement methods of displacement or strain were applied in this test,as can be seen in Fig.1.For convenience,“method 1”,“method2”,“method3”,and“method4”represent strain rosettes with dimensions of3×2mm,strain gauges with dimensions of100×3mm recording the axial shortening and perimeter expansion of specimens in the mid-height region,electronic displacement transducers recording the axial shortening of specimens in the mid-height region with a certain gauge length,and electronic displacement transducers recording the full length axial shortening of specimens, respectively.
All of the columns were tested with a universal testing machine with a5000kN capacity.The load,as measured by the test machine’s load cell and electronic load transducer, was applied in small increments at a very slow rate(about 50–100kN/min).Each load interval was maintained for 2–3min.At each load increment the strain readings and the displacement measurements were recorded by a computer-controlled data acquisition system.When near to their ultimate capacity,the loads were applied continuously,and the loads, displacements,and strains were recorded.The strain softening characteristics of the specimens were also recorded.Each test took approximately1h to reach the maximum load and1.5h to complete.The maximum loads(N ue)obtained from the tests are listed in Table1.
3.Experimental results and discussions
3.1.In?uence of different measurement methods
Fig.2shows the in?uence of four measurement methods in load–deformation curves for typical specimens SZ5S4A1a
168Z.-w.Yu et al./Journal of Constructional Steel Research 63(2007)
165–174
Fig.1.Test layout and instrumentation.
Table 3
In?uence of different test methods on E sc Specimens SZ5S4A1a
SZ5S4A1b
SZ5S3A1
SZ5S4A2
SZ5S3A2
E sc (MPa)Method 14.34×1044.69×1044.20×1043.63×1043.90×104Method 24.57×1044.51×1043.99×1043.61×1043.92×104Method 3
4.65×104
5.04×104
4.29×104
3.28×104
3.36×104
and SZ5S3A1.All of these deformation values were axially averaged,and the displacements were transformed into strains by dividing by the gauge length.For the composite modulus of elasticity (E sc )of unnotched specimens SZ5S4A1a,SZ5S4A1b,and SZ5S3A1,there was no signi?cant difference in the results of “method 1”,“method 2”,and “method 3”when the specimens were loaded at the elastic stage,as can be seen from Table 3.There is also little difference at the inelastic stage as shown in Fig.2.Therefore,for the unnotched specimens,the three measurement methods are equally valid.However,“method 3”could record the deformation behavior of the specimens loaded even at the strain softening stage (seen from Figs.2and 3),but “method 1”and “method 2”could not.The measured results of “method 4”are higher
Z.-w.Yu et al./Journal of Constructional Steel Research63(2007)165–174
169
https://www.wendangku.net/doc/9c343340.html,parison of four measurement methods on load–strain relations. than those of the other three methods because the deformation might have included the end constraining effects at the top and bottom of the specimens and could not re?ect the behavior of the axial compressive stiffness.Therefore,“method4”is not recommended for measuring the axial deformation of specimens.
3.2.In?uence of concrete strength
Previous research[5]indicated that the in?uence of SCC and NC with close concrete strength on the load carrying capacity and failure modes of CFT columns is very small.So it is assumed in this paper that SCC performed identically to NC. The experimental load(N)versus axial strain(εL)curves for the stub columns of SZ5S4A1a,SZ5S4A1b,and SZ5S3A1,
and for the stub columns of SZ3C4A1,SZ3S4A1,and SZ3S6A1are presented in Fig.3.As the cubic compressive strength of concrete(SCC or NC)increased,the limit load of elasticity and ultimate capacity of the stub columns reached a higher value,but the residual capacity almost maintained the same value.It was found that the concrete strength hardly in?uenced the failure mode of the stub columns,as seen from Fig.4.
3.3.In?uence of notched holes
When the beam is relatively small and some steel rebars pass through the steel tubes at frame joints,its effect could be simulated by a steel tube notched with small holes.The experimental curves of the load versus axial strain of the notched specimens with small holes(A1specimens)in the mid-height region of steel tubes are compared in Fig.5with that of unnotched specimens(A2specimens),and the
composite
Fig.3.Effect of concrete
strength.
https://www.wendangku.net/doc/9c343340.html,parison of typical failure mode of columns with respect to concrete strength.
modulus of elasticity(E sc)of these specimens is listed in https://www.wendangku.net/doc/9c343340.html,pared to unnotched specimens,the E sc of notched ones was reduced,and the deformation increased slightly,even at elastic stage.Meanwhile,as shown in Fig.5,the limit load of elasticity decreased,the deformation grew rapidly at inelastic stage,and the strain corresponding to the ultimate capacity increased slightly.However,there was hardly any in?uence on the ultimate capacity and residual capacity between the notched and the unnotched specimens.But,as seen from Fig.6, the failure mode of the notched specimens with small holes
170Z.-w.Yu et al./Journal of Constructional Steel Research63(2007)
165–174
Fig. https://www.wendangku.net/doc/9c343340.html,parison of load–axial strain relations between the specimens notched with small holes and unnotched ones.
was different from that of unnotched ones.For the notched specimens,local buckling of the steel tube happened earlier, the concrete core at the holes was crushed,and the small holes were staved;but they have almost the same apparent distortions compared to those unnotched specimens.
Fig.7shows the relationship of the strain ratio(v sc)of the steel tube versus the axial load(N)and compares the notched specimens with small holes and the unnotched ones.The strain ratio was de?ned as the absolute value of the perimeter strain divided by the axial strain,and the values were averaged for the axial and the lateral strain gauges on the specimen.
For the behavior shown in Fig.7,an increase in the strain ratio would indicate an increased con?nement effect of the concrete core offered by the steel tube.For the unnotched specimens,such as specimens SZ5S4A1a,SZ5S3A1,and SZ3S6A1,the strain ratio increased slowly,and it is even
less https://www.wendangku.net/doc/9c343340.html,parison of typical failure mode between the specimens notched with small holes and unnotched ones.
than the Poisson’s ratio of steel when the specimens were loaded at the elastic stage.Beyond the level of the limit load of elasticity,the strain ratio increased faster as the load grew gradually(v sc is even larger than0.5),then the con?nement effect between the steel tube and the concrete core took place. As the load increased,the perimeter stress increased,and the axial stress decreased after the yielding of the steel tube,which made the strain ratios grow continually(v sc is even closer to1).Con?nement effect of the concrete core is thus enhanced, and the axial compressive strength increased.Therefore,the composite action enhanced the ultimate capacity of the stub columns.
For the notched specimens with small holes in the mid-height region of steel tubes,such as specimens SZ5S4A2, SZ5S3A2,and SZ3S6A2,the experimental curves of load versus strain ratio had a notable change.Even at the early loading stage,the strain ratio of notched specimens increased faster than the unnotched ones.At a loading of about50%–70% of their ultimate capacity,the strain ratio increased up to 0.5–0.7.Then,the strain ratio was nearly constant with the load within a certain level.Beyond this load level,the strain ratio increased faster again,and would catch up with,or even exceed, the unnotched specimens at the same load level.
In summary,experimental research shows that the mechan-ical behavior of the stub columns is signi?cantly in?uenced by the notched holes.The stress?ows of the steel tube were changed due to the holes,and the behavior was also affected. The axial compressive stiffness of the notched specimens was reduced;therefore,the steel tube notched with small holes acted
Z.-w.Yu et al./Journal of Constructional Steel Research63(2007)165–174
171
https://www.wendangku.net/doc/9c343340.html,parison of axial load versus strain ratio of notched specimens with
small holes and unnotched ones.
more as transverse con?nement and less as an axial compres-
sion component than the unnotched ones.
3.4.In?uence of notched slots
When the beam is relatively large and many steel rebars
pass through steel tubes at frame joints,their effects could be
simulated by a steel tube notched with full slots(with different
vertical dimensions).The experimental load(N)versus axial
displacement(u L)curves for the specimens notched with full perimeter slots with different vertical dimension(h)at the mid-
height region of steel tubes are presented in Fig.8.When
the full slot has a small vertical dimension,such as h/D=
0.046(h=10mm,SZ5S4E1)and0.228(h=50mm,
SZ5S4E2),the load capacity is hardly affected,but when h
increased subsequently(SZ5S4E3and SZ5S4E4),the
load Fig.8.Load(N)versus axial displacement(u L)curves for full slot notched
specimens.
Fig.9.In?uence of h/D on ultimate capacity.
Table4
In?uence of different test methods on axial deformations of slot notched specimens
Specimen SZ5S4E1SZ5S4E2SZ5S4E3SZ5S4E4 h/D0.0460.2280.4570.913
E sc(MPa)
Method13.40×1043.64×1043.72×1043.42×104 Method32.33×1041.81×1041.63×1041.50×104 capacity decreased gradually.The in?uence of h/D on the ultimate capacity(N ue)of full notched specimens is given in Fig.9.It can be found that the ultimate capacity of the specimens notched with a full slot is about86%and50%of the unnotched ones when h/D=0.457(h=100mm)and h/D=0.913(h=200mm),respectively.
Seen in Table4,the composite modulus of elasticity(E sc) decreased gradually as h/D increased when the strains were measured by“method3”,but remained nearly constant when the strains were measured by“method1”.Obviously,for specimens notched with a full slot,slip occurred between the concrete core and steel tube.With the increase in h/D,the bonding force between the concrete core and the steel tube decreased,thus slip increased.
172Z.-w.Yu et al./Journal of Constructional Steel Research 63(2007)
165–174
Fig.10.Typical failure mode of the full slot notched specimens with different vertical slot
dimension.
Fig.11.Load (N )versus axial displacement (u L )curves for notched specimens.
The failure mode of the slot-notched specimens was different from the unnotched ones,which can be seen from Fig.10.For specimen SZ5S4E1,the concrete core was crushed near the notched slot,and the steel tube buckled due to a radial expansion;but for specimens SZ5S4E2,SZ5S4E3,and SZ5S4E4,the concrete core was split,and no buckling occurred in the steel tube.
The experimental load (N )versus axial displacement (u L )curves for the slot-notched specimens with a vertical dimension of 10mm (SZ5S4E1),the hole-notched specimen (SZ5S4A2),and the unnotched specimen (SZ5S4A1b)are presented in Fig.11.The deformation behavior of specimen SZ5S4E1was similar to that of specimen SZ5S4A2,but the axial stiffness was reduced compared to specimen SZ5S4A1b.
Therefore,once the steel tube was notched with a full slot in the perimeter direction,the stress ?ows of the steel tube cannot pass through the slot.The concrete behavior with three-dimensional compression was changed,and the capacity and axial compressive stiffness were also reduced as a whole.The con?nement effect was enhanced when the vertical dimension of the full slot was reduced.When the dimension was large,the con?nement effect decreased and the concrete core is hardly strengthened;then the ultimate capacity of these specimens decreased.
3.5.In?uence of different loading conditions
The in?uence of different loading conditions on the mechanical behaviors of specimens was also studied.The loading conditions included load applied to:(a)the entire section,(b)the concrete section initially,but to the entire section after the concrete was compressed,(c)the steel section initially,but to the entire section after the steel was compressed,and (d)only the concrete section.
The typical load–axial strain curves of the tested specimens under the four loading conditions are presented in Fig.12(a),where the axial strain was measured from the steel tube using “method 3”as discussed earlier.It can be observed that for the specimens of loading conditions (b)(SZ3S6B)and (d)(SZ3S6D),the ultimate capacity and load–axial strain curves were similar,and compared with that of loading condition (a)(SZ3S6A1),the ultimate capacity for both reached slightly higher values and the strain in the steel tube reached a lower value.Therefore,the steel tubes in cases (b)and (d)carried less axial compressive stress than case (a)under the same load.For the specimen of loading condition (c)(SZ3S6C),compared with that of loading condition (a),the ultimate capacity
was
(a)Load versus axial strain curves.(b)Load versus strain ratio curves.
Fig.12.In?uence of different loading conditions on mechanical behavior of columns.
Z.-w.Yu et al./Journal of Constructional Steel Research63(2007)165–174
173
Fig.13.Typical failure mode of the specimens under different loading conditions.
in the same range for both,and the strain in the steel tube
has a higher value;thus,the steel tube carried more axial
compressive stress under the same load.The residual capacity
of the stub columns under the four loading conditions was
hardly in?uenced.
The typical load–strain ratio curves of the tested specimens
under the four loading conditions are plotted in Fig.12(b).For
the specimens of loading conditions(b)and(d),the load–strain
ratio curves were similar,and compared with that of loading
condition(a),the strain ratio for both had slightly higher values
under the same load.The value of v sc<1indicated(since the absolute value of the perimeter strain is less than the axial
stain)that the steel tube carried axial compressive stress mainly
because of the bonding stress between the steel tube and the
concrete core.When the load reached about90%of its ultimate
capacity,the strain ratio increased faster and the specimen
had a higher critical load,as seen from Fig.12(b),which
indicated that the steel tube carried less axial compressive stress
and yielded later.For the specimen of loading condition(c),
compared with that of loading condition(a),initially the strain
ratio was in the same range for both and had a lower critical
load,which indicated that the steel tube in case(a)carried more
axial compressive stress and yielded earlier.
Typical failure mode of the specimens under different
loading conditions is shown in Fig.13.There was no signi?cant
difference in the failure mode for the specimens under these
four loading conditions;however,in general,the specimens had
more local bulking with higher apparent distortions for loading
conditions(d),(b),(a),and(c)in order.
4.Analysis of test results and discussion
The existing international standards,such as ACI-1999[10],
AIJ-1997[11],AISC-LRFD-1999[12],and Eurocode4-
1994[13],were applied to predict the ultimate capacity and
were compared with the tested ones by many researchers[5–7].
The general conclusion[5–7]has been made that ACI-1999,
AIJ-1997,and AISC-LRFD-1999are excessively conservative
for predicting the ultimate capacities of specimens,while Eu-
rocode4-1994gives reasonable predictions.For demonstra-
tions,the Eurocode4and ACI codes were applied to predict Table5
Conversion relations between f cyl and f cu
f cu(MPa)20–4050607080 f cyl/f cu0.800.830.860.8750.89 Table6
Comparison of test results with Eurocode4
Specimens N ue(kN)N uc(kN)N ue/N uc SZ5S4A1a34003140.2 1.083 SZ5S4A1b33503121.9 1.073 SZ5S3A131502960.3 1.064 SZ3S6A120802207.40.942 SZ3S4A117501886.70.928 SZ3C4A115601632.90.955 Table7
Comparison of test results with ACI
Specimens N ue(kN)N uc(kN)N ue/N uc SZ5S4A1a34002375.8 1.431 SZ5S4A1b33502363.4 1.417 SZ5S3A131502215.2 1.422 SZ3S6A120801776.8 1.171 SZ3S4A117501493.1 1.172 SZ3C4A115601268.5 1.230 the ultimate capacity of the unnotched specimens under load-ing condition(a),namely,the entire section is loaded simulta-neously,and was compared with these test results.In the design calculations,the material partial safety factors were set to be unity.
The conversion relations between cylinder compressive strength of concrete(f cyl)and cubic compressive strength f cu that were proposed by CEB-FIP-1990[14]are seen in Table5. The ultimate capacities of the tested specimens were compared with the predicted capacities from Eurocode4and ACI,as shown in Tables6and7.For Eurocode4,the predicted values are in good agreement with the test results.The mean value is1.008,and the standard deviation is0.073.But for ACI, the predicted values are very conservative,due to the fact that concrete con?nement is ignored in their estimation of ultimate capacities.The mean value is1.307,and the standard deviation is0.129.
5.Conclusions
This paper presents an experimental study on CFT stub columns with SCC and NC under concentrically loaded conditions.Based on experimental observations of the behavior of specimens,the in?uence of several parameters including measurement methods of deformation,concrete strength,and small holes or full slots notched in the perimeter direction of the steel tube on the con?nement of the concrete core and compression shared by the steel tube was investigated.The following conclusions may be drawn:
(1)An increase in compressive strength of concrete(SCC or NC)resulted in a signi?cant increase in load capacity,but
174Z.-w.Yu et al./Journal of Constructional Steel Research63(2007)165–174
nearly maintained a constant value in residual capacity after failure.
(2)The measured load versus strain ratio curves of the steel tubes suggested that a signi?cant con?nement effect was present for most specimens after the axial load reached a certain percentage of the ultimate capacity of stub columns. Once a steel tube was notched with small holes in the mid-height region,the con?nement effect was presented earlier and enhanced,but the axial compressive stiffness was reduced. However,the ultimate capacity and residual capacity were hardly in?uenced.
(3)When a steel tube was notched with a full perimeter slot in the mid-height region,the stress?ows of steel tube could not pass through the slot;the concrete behavior with three-dimensional compressive stress was changed;and the capacity and axial compressive stiffness were also reduced as a whole. The con?nement effect was enhanced when the dimension of the full slot was reduced.But when the dimension was large,the con?nement effect decreased,and the concrete core was hardly strengthened;thus,the ultimate capacity of these specimens decreased.
(4)For the frame joints,that steel rebars pass through the steel tubes is not recommended in the construction of buildings.
(5)Under different loading conditions the sequence of con?nement effect for the specimens https://www.wendangku.net/doc/9c343340.html,pared to the specimen with the load applied to the entire section, when the load was applied to the steel section initially,the con?nement effect appeared earlier but decreased,and the ultimate capacity was almost the same.When the load was applied to the concrete section initially or only to the concrete section,the con?nement effect appeared later but enhanced,and the ultimate capacity increased slightly.However,the residual capacity of the stub columns under the four loading conditions was hardly in?uenced.
(6)Eurocode4provides a good prediction of the ultimate capacities of the unnotched CFT stub columns with SCC and NC when the entire section was loaded. Acknowledgments
This research work was?nancially supported by the National Natural Science Foundation of China,Grant No.50278097,50578162,and50438020and the Natural Science Foundation of Human Province,China,Grant No.03JJY3089. The authors wish to thank Miss You-Lan Chen for her assistance in the experiments.
References
[1]O’Shea MD,Bridge RQ.Design of circular thin-walled concrete?lled
steel tubes.Journal of Structural Engineering,ASCE2000;126(11): 1295–303.
[2]Schneider SP.Axially loaded concrete-?lled steel tubes.Journal of
Structural Engineering,ASCE1998;124(10):1125–38.
[3]Sakina K,Nakahara H,Morino S,et al.Behavior of centrally
loaded concrete-?lled steel-tube short columns.Journal of Structural Engineering,ASCE2004;130(2):180–8.
[4]Johansson M,Gylltoft K.Mechanical behavior of circular steel–concrete
composite stub columns.Journal of Structural Engineering,ASCE2002;
128(8):1073–81.
[5]Han L-H,Yao G-H.Experimental behaviour of thin-walled hollow
structural steel(HSS)columns?lled with self-consolidating concrete (SCC).Thin-Walled Structures2004;42(9):1357–77.
[6]Han L-H,Yao G-H,Zhao X-L.Tests and calculations for hollow structural
steel(HSS)stub columns?lled with self-consolidating concrete(SCC).
Journal of Constructional Steel Research2005;61(9):1241–69.
[7]Giakoumelis G,Lam D.Axial capacity of circular concrete-?lled tube
columns.Journal of Constructional Steel Research2004;60(7):1049–68.
[8]Sakina K,Tomii M,Watanabe K.Sustaining loading resistance of
plain concrete stub columns by circular steel tube.In:Proceedings of the international conference on concrete-?lled steel tubular structures.
The Science and Technology Exchange of Heilongjian Province;1985.
p.112–8.
[9]Wu H,Xiao https://www.wendangku.net/doc/9c343340.html,pressive stress–strain behavior of concrete con?ned
by carbon?ber jackets.In:Proceeding of6th ASCCS conference.2000.
p.919–26.
[10]ACI318-99.Building code requirements for structural concrete and
commentary.Farmington Hills(MI),Detroit(USA):American Concrete Institute;1999.
[11]AIJ.Recommendations for design and construction of concrete?lled steel
tubular structures.Tokyo(Japan):Architectural Institute of Japan;1997.
[12]AISC-LRFD.Load and resistance factor design speci?cation for structural
steel buildings.2nd ed.Chicago(USA):American Institute of Steel Construction(AISC);1999.
[13]Eurocode4.Design of composite steel and concrete structures,Part1.1:
General rules and rules for buildings(together with United Kingdom National Application Document).DD ENV1994-1-1:1994.London: British Standards Institution;1994.
[14]Comite Euro-International du Beton.Bulletin D’information No.213/214.
CEB-FIP Model Code1990(Concrete Structures).Lausanne,Switzerland, 1993.
森林防火心得体会
森林防火心得体会1 班级：134班姓名： 进入冬季森林防火期，做好森林防火工作迫在眉睫。为了保护森林资源，响应建设美丽中国、生态中国的号召，更为了营造一个全社会关注防火、参与防火、支持防火的良好氛围。通过小手牵大手、大手管小手的方式，提高广大群众的防火意识，就可保证今冬明春的森林防火工作顺利进行。 通过学校老师广泛宣传和家长的教育，我们和家长都很好的受到了如何做好森林防火工作的教育，我也有了自己的一些心得体会。 首先，森林防火，人人有责是做好森林防火工作的群众基础。家长做为我们的监护人，有责任配合学校，加强对我们的森林防火安全教育。从维护国家、集体、个人的利益高度出发，把森林防火教育作为家庭教育的重要内容，即可以强化我们的防火安全意识和法律意识，也可以带动更多的家庭成员领会森林防火的重要性，提高森林防火的责任意识和法律意识。进而做到全社会都来关心、参与、支持森林防火工作的良好氛围，为森林防火工作建立一个广泛的群众基础。其次，管好火源是做好森林防火工作的重要保障。家长配合学校强化火源管理，加强对我们的教育，加大监护力度，监督好我们节假日、休息日的活动。不要让我们进入山林搞任何形式的野炊，不要让我们随意携带火种、火具、火药品、易燃易爆物进山，更不得在林区随意用火。尤其是外出带我们从事上坟、野外游玩等活动时，要特别加强对火源的管理。在春节期间，我们燃放烟花爆竹时，一定要有成年人陪同并在指定的安全区域进行。
再次，加强宣传教育，提高防火意识也是做好森林防火工作的重要一环。学校每年都通过一定的形式开展了森林防火宣传教育活动，我们经过近四年的学习，已经初步树立了森林防火，人人有责的意识，懂得了造成森林火灾事故要承担的法律责任，明白了谁烧山，谁犯法，谁坐牢的道理。只要我们每个同学都把加强森林防火，提高防火意识，避免森林火灾的理念传输给家里的所有亲人，就能在全社会营造出一种重视森林防火工作的氛围，也可以极大的保护好我们的亲人，避免因发生森林火灾而受到处罚。 最后，我们做为未成年人，一定要提高自我防护意识，在发生森林火灾时，不要参与扑火工作。原因是，做为未成年人的我们参加扑火工作不但极其危险，而且还可能会给参加扑火工作的成年人添加更多的麻烦，严重影响到扑火工作的开展。总之，在森林防火工作中，我们要提高责任意识，管好自己，做好家长的宣传教育工作，不参与森林扑火，就是我们对森林防火工作的最大支持！
承揽合同范本3篇
编号：_______________本资料为word版本，可以直接编辑和打印，感谢您的下载 承揽合同范本3篇 甲方：___________________ 乙方：___________________ 日期：___________________
承揽合同范本3篇2020新版 甲方：______________________________________ 乙方: _______________________________________ 20 年月日
在承揽合同中，完成工作并交付工作成果的一方为承揽人；接受工作成果并支付报酬的一方称为定作人。以下是华律网小编为大家精心准备的：3篇承揽合同范本。欢迎参考阅读！ 承揽合同范本一 经甲乙双方协商一致，签订本合同，共同信守。 一、甲方提供原料情况： 品(材料)名： 规格型号： 单位： 数量： 单价： 金额： 交货日期： 超欠幅度％ 供应办法： 二、乙方加工产品的义务 1. 质量标准： 2. 质量检验及验收办法： 3. 包装要求及费用负担： 4. 交货(运输)办法及地点： 5. 货款共计人民币(大写): 6. 结算办法及期限： 7. 其他： 三、违约责任： 第一点：甲方的违约责任 (1) 变更产品品种、质量或包装的规格给乙方造成损失时，应负责赔偿乙方损失。 (2) 中途退货的，偿付乙方以退货部分货款总值％勺违约金。
(3) 自提产品未按规定日期提货的，每延期一天，应偿付乙方以延期提货部分货款总值千分之 的违约金。 (4) 未按合同规定时间和要求提供原材料、技术资料、包装物的，除交货日期予以顺延外，每 日应偿付乙方顺延交货产品总值千分之一的违约金。 (5) 未按合同规定日期付款的，每延期一天，应偿付乙方以延期付款总值千分之一的违约金。 (6) 实行送货或代运的产品无故拒绝接货的，应承担因而造成的损失并付给运输部门违约金。 (7) 错填到货地点或接货人的，应承担因此造成的损失。 (8) 其他。 第二点：乙方承担的违约责任 (1) 产品、花色、品种、规格、质量、包装不符合合同规定，甲方同意收货的，按质论价；甲方不同意收货的，乙方应包修、包退、包换，并承担因此造成的损失。 (2) 未按合同规定的数量交货，少交而甲方仍然需要的，应照数补交；不需要的，可以退货，并承担损失；不能交货的，应偿付甲方以不能交货的货款总值％勺违约金。 (3) 包装不符合合同规定的，必须返修或重新包装，并承担因此而支付的费用；甲方不要求返修或重新包装，而要求赔偿损失的应予赔偿。 (4) 未按合同规定时间交货的，每延期一天，应偿付甲方以延期交货部分货款总值千分之一的 违约金。 (5) 不符合合同规定产品，在甲方代保管期内应偿付甲方实际支付的保管、保养费。 (6) 产品错发到货地点或接货人的，除按合同规定负责运到指定的到货地点或接货人外，并承 担因此多付的运杂费和造成的延期交货责任。 (7) 未按甲方对技术资料及图纸的保密要求履行保密义务而给甲方造成损失的，应负责赔偿。 (8) 其他： 本合同一式份。有效期自请填写有效起始时间到请填写有效终止时间止。 甲方：请填写定作方乙方：请填写承揽方 法定代表人：法定代表人： 电话：填写定作方办公电话电话：填写承揽方办公电话 地址：填写定作方住所地址：填写承揽方住所 开户银行：填写定作方开户银行开户银行：填写承揽方开户银行 账号：填写定作方账号账号：填写承揽方账号
森林防火心得体会优秀范例三篇
森林防火心得体会优秀范例三篇 为认真做好森林防火工作，有效的预防和控制森林火灾，的限度的减少森林火灾损失，有效的保护人民群众生命财产安全。我乡领导高度重视，举办森林防火探讨会，签订森林防火责任书，成立森林防火领导小组。切实把森林防火各项工作规划好、部署好、落实好，杜绝各种森林火灾隐患，做到"宁可千日无火，不可一日不防".我曾经在防震减灾局实习过，对于做好防灾减灾工作有一些经验。要切实做好森林防火工作要做到以下几点： 宣传为先，加强思想认识。每年各地发生森林火灾给人民群众造成的损失不可计数，而大多数火灾是由于人们对森林火灾的思想认识不够，存在麻痹、侥幸心理，随意烧荒、炼山、祭祖、鸣放鞭炮，成为森林火灾的重要隐患。为扎实做好森林防火工作，加强人民群众的思想认识。必须加大宣传力度，营造防火氛围。充分利用森林防火宣传周、森林防火宣传月等重要活动，在各村、学习、医院等人口密集的地方张贴宣传标语，悬挂宣传横幅，营造防火氛围；开设防火辅导课程，经常召开防火探讨会，交流意见，强化防火思想；利用好网络媒体，采用通俗易懂的方式，在电视定期播放森林防火宣传片，提高防火意识。 加强督查，落实防火措施。要把森林防火工作列入重要议事日程，积极研究解决各种突出问题，及时掌握各村、各小组森林防火职责的落实情况，做到有部署、有检查、有督促、有落实。加强救援队伍力量，保障工作条件，切实保证森林防火基层管理责任得到全面落实；建立完善森林火灾监督检查和责任追究制度，依法加大对森林防
火工作落实情况的督查力度；各部门要严格执行24小时值班制度，确保信息畅通；各村要加强对各分管区域的巡查、监管力度，切实做到有火报火，无火报平安。 完善机制，提高救援能力。森林火灾具有潜在性和突发性，防不胜防，这就要求我们在火灾突然降临时，备有完善的应急机制。首先，健全完善各项森林火灾应急预案体系，进一步增强森林火灾预案的科学性、针对性和可操作性，经常性地开展预案演练，切实提高救援能力；其次，建立火灾应急救援队伍，开展森林火灾相关的培训，完善救援扑火装备，落实好各项准备工作，确保应急救灾的各项工作能在第一时间启动并得到落实。 森林防火，人人有责。宜未雨而绸缪，毋临渴而掘井，我们应时刻保持警惕之心，防患于未然，让家园青山永绿。 森林防火心得体会（二） 进入春季，万物复苏，一片生机盎然，我们物电系和机电系三月二十五这天一起组织了森林防火活动。 我们在这次活动中捡白色垃圾，向去森林公园玩的游人们宣传一些森林防火知识。 其中包括： 1、人人树立"森林防火"意识。无论是进入林区从事垦荒、采集、采矿等生产性活动，还是进入林区祭祀、旅游度假、狩猎野炊等生活性活动，都要时刻不忘森林防火。特别是在森林防火期内，在林区禁止野外用火；因特殊情况需要用火的，必须按照《森林防火条例》的有关规定，经过审批后方可进行。
森林防火心得体会
森林防火心得体会 森林防火心得体会（一） 为认真做好森林防火工作，有效的预防和控制森林火灾，最大的限度的减少森林火灾损失，有效的保护人民群众生命财产安全。我乡领导高度重视，举办森林防火探讨会，签订森林防火责任书，成立森林防火领导小组。切实把森林防火各项工作规划好、部署好、落实好，杜绝各种森林火灾隐患，做到”宁可千日无火，不可一日不防”.我曾经在防震减灾局实习过，对于做好防灾减灾工作有一些经验。要切实做好森林防火工作要做到以下几点： 宣传为先，加强思想认识。每年各地发生森林火灾给人民群众造成的损失不可计数，而大多数火灾是由于人们对森林火灾的思想认识不够，存在麻痹、侥幸心理，随意烧荒、炼山、祭祖、鸣放鞭炮，成为森林火灾的重要隐患。为扎实做好森林防火工作，加强人民群众的思想认识。必须加大宣传力度，营造防火氛围。充分利用森林防火宣传周、森林防火宣传月等重要活动，在各村、学习、医院等人口密集的地方张贴宣传标语，悬挂宣传横幅，营造防火氛围；开设防火辅导课程，经常召开防火探讨会，交流意见，强化防火思想；利用好网络媒体，采用通俗易懂的方式，在电视定期播放森林防火宣传片，提高防火意识。 加强督查，落实防火措施。要把森林防火工作列入重要议事日程，积极研究解决各种突出问题，及时掌握各村、各小组森林防火职责的
落实情况，做到有部署、有检查、有督促、有落实。加强救援队伍力量，保障工作条件，切实保证森林防火基层管理责任得到全面落实；建立完善森林火灾监督检查和责任追究制度，依法加大对森林防火工作落实情况的督查力度；各部门要严格执行24小时值班制度，确保信息畅通；各村要加强对各分管区域的巡查、监管力度，切实做到有火报火，无火报平安。 完善机制，提高救援能力。森林火灾具有潜在性和突发性，防不胜防，这就要求我们在火灾突然降临时，备有完善的应急机制。首先，健全完善各项森林火灾应急预案体系，进一步增强森林火灾预案的科学性、针对性和可操作性，经常性地开展预案演练，切实提高救援能力；其次，建立火灾应急救援队伍，开展森林火灾相关的培训，完善救援扑火装备，落实好各项准备工作，确保应急救灾的各项工作能在第一时间启动并得到落实。 森林防火，人人有责。宜未雨而绸缪，毋临渴而掘井，我们应时刻保持警惕之心，防患于未然，让家园青山永绿。 森林防火心得体会（二） 进入春季，万物复苏，一片生机盎然，我们物电系和机电系三月二十五这天一起组织了森林防火活动。 我们在这次活动中捡白色垃圾，向去森林公园玩的游人们宣传一些森林防火知识。 其中包括： 1、人人树立”森林防火”意识。无论是进入林区从事垦荒、采集、
承揽合同范本3篇新整理版
承揽合同范本3 篇新整理版 在承揽合同中，完成工作并交付工作成果的一方为承揽人; 接受工作成果并支付报酬的 一方称为定作人。以下是华律网小编为大家精心准备的：3 篇承揽合同范本。欢迎参考阅读承揽合同范本一 经甲乙双方协商一致，签订本合同，共同信守。 一、甲方提供原料情况：品(材料)名：规格型号：单位：数量：单价：金额：交货日期：超 欠幅度%：供应办法： 二、乙方加工产品的义务 1.质量标准： 2.质量检验及验收办法： 3.包装要求及费用负担： 4.交货(运输)办法及地点： 5.货款共计人民币(大写)： 6.结算办法及期限： 7.其他： 三、违约责任：第一点：甲方的违约责任 (1)变更产品品种、质量或包装的规格给乙方造成损失时，应负责赔偿乙方损失。 (2)中途退货的，偿付乙方以退货部分货款总值%的违约金。 (3)自提产品未按规定日期提货的，每延期一天，应偿付乙方以延期提货部分货款总值千分之的违约金。 (4)未按合同规定时间和要求提供原材料、技术资料、包装物的，除交货日期予以顺延外，每日应偿付乙方顺延交货产品总值千分之一的违约金。 (5)未按合同规定日期付款的，每延期一天，应偿付乙方以延期付款总值千分之一的违约金。 (6)实行送货或代运的产品无故拒绝接货的，应承担因而造成的损失并付给运输部门违约金。 (7)错填到货地点或接货人的，应承担因此造成的损失。 (8)其他。第二点：乙方承担的违约责任 (1)产品、花色、品种、规格、质量、包装不符合合同规定，甲方同意收货的，按质论价;甲方不同意收货的，乙方应包修、包退、包换，并承担因此造成的损失。 (2)未按合同规定的数量交货，少交而甲方仍然需要的，应照数补交;不需要的，可以退货，并承担损失;不能交货的，应偿付甲方以不能交货的货款总值%的违约金。 (3)包装不符合合同规定的，必须返修或重新包装，并承担因此而支付的费用;甲方不要求返修或重新包装，而要求赔偿损失的应予赔偿。 (4)未按合同规定时间交货的，每延期一天，应偿付甲方以延期交货部分货款总值千分之一的违约金。 (5)不符合合同规定产品，在甲方代保管期内应偿付甲方实际支付的保管、保养费。 (6)产品错发到货地点或接货人的，除按合同规定负责运到指定的到货地点或接货人外，并承担因此多付的运杂费和造成的延期交货责任。 (7)未按甲方对技术资料及图纸的保密要求履行保密义务而给甲方造成损失的，应负责赔偿。 (8)其他：本合同一式份。有效期自请填写有效起始时间到请填写有效终止时间止。甲方：请填写定 作方乙方：请填写承揽方 法定代表人：法定代表人：电话：填写定作方办公电话电话：填写承揽方办公电话地址：填写定作
森林防火心得体会.doc
森林防火心得体会 森林防火心得体会怎么写?今天为您整理了森林防火工作心得体会范例大全，仅供参考。 森林防火心得体会 12月15日下午，辰山植物园在辰山区域举行了森林防火消防救灾演练。演练邀请了佘山度假区派出所以及佘山消防中队的领导做专业指导。此次演练主要是检验灭火人员应急响应速度以及各自工作内容和工作职责的落实情况，考查志愿消-防-队人员是否正确掌握使用各类消防设施、设备器材的方法以及操作的熟练成度，同时也检验各部门在突发事件中的协调配合能力。 下午14时许，随着总指挥的一声令下，各组人员迅速到位，进入演习程序。此前，由于园方安全部门已制定了详细的演练方案并予以落实，因此整个演习过程井然有序，完成了既定的任务，达到了演练的目的。 此次消防救灾演练使职工增强了森林防火的意识、了解正确掌握森林火灾的扑救方法，从中吸取经验，进一步完善、改进林区火灾扑救的能力。 乡地处偏僻山区，是**、**、**的交界处，总面积有*****亩，其中林地面
积有******亩。若遇上高火险天气时，马上就面临着极大的火灾隐患。根据《森林防火条例》的有关规定，现将**乡的森林防火工作提出以下几点措施：一、建立健全森林防火组织机构 **乡实行**乡人民政府行政领导负责制，其中***乡长担任 **乡森林防火领导小组组长，***担任副组长，成员有***、***等。我乡以《森林防火条例》和《**省森林防火实施办法》为依据，以“抓基层、抓基幢为重点，以抓具体措施为突破口，深入贯彻“预防为主，积极消灭”的森林防火方针，不断改革、不断创新，建立“立足基层，立足基础，乡自为战，村自为战，群防群治，自治自救”的森林防火新机制。 二、加强宣传教育 根据**乡目前的实际情况，利用护林员每天早晚敲锣二次、宣传车巡逻、通告张贴、利用学生带给家长的一封信进行广大面积的宣传。 三、强化野外火源管理 在乡政府的带领下，每村成立防火领导小组，在高火险天气，对各个紧要路口进行严防死守，不准放田坎、烧灰、烧纸钱、不准带火上山。在森林防火戒严期间，乡政府成立森林防火值班室，24小时轮流值班，指挥好各村的森林防火工
森林防火主题班会总结
六年级“森林防火主题班会”活动总结 森林是人类的一种宝贵的物质财富，是再生的自然资源。预防森林火灾是当前学校教育工作的一项重任。为了落实好学校安排的“森林防火”知识宣传教育活动，2011年3月28日，我六年级班在班主任的组织、班委会的积极配合下，成功开展了“六年级班‘森林防火’主题班会活动”。这次主题班会，内容主要是学习“森林防火”知识问答，围绕“针对森林火灾，小学生能做什么”、“如何预防‘森林火灾’”等问题进行讨论。现把本次主题班会活动开展情况总结如下： 一、大力宣传“森林防火”知识，使学生深受教育 本次主题班会，带领学生学习了“森林防火知识问答”，全班学生认真听讲，深受教育。懂得了什么叫做“森林火灾”，当发现火情后应该立即向当地人民政府或森林防火指挥部报告或拨打119、110报警电话。并迅速向安全地带转移。知道了老人、妇女、中小学生、儿童及身残体弱者不能上山扑救森林火灾，以及进入林区“五不准”：不准在林区内乱扔烟蒂、火柴梗；不准在林区内燃放爆竹；不准在林区内烧火驱兽、烧蜂；不准在林区内烧火取暖、烧烤食物；不准在林区内玩火……等“森林防火”知识。 二、深入讨论，引导言行 在班长的主持下，全班学生围绕“小学生能够为‘森林防火’做什么”这一话题展开了激烈的讨论。讨论中，有的学生认为，我们小学生虽然不能上山参加扑救森林火灾，但我们可以为预防森林火灾贡
献出自己的力量。比如：自己以身示范不在山上及林区玩火；对于在林区玩火及用火的行为要加以制止，不能制止的要尽快告诉大人制止或向政府报告；告诉父母亲不要随便在野外烧荒，以防引起火灾；清明节来临，劝戒家人上山扫墓不要烧香烧纸、烧放鞭炮，用其它方式代替。通过大家的讨论交流，全班学生都表示愿意用自己的言行，为“森林防火”这项工作做出自己的贡献。 三、活动延伸，巩固成果 为了使本次主题班会讨论结果得以实施，首先，要求每位学生放学回家后，把所了解到的“森林防火”知识向身边的亲人作宣传，使家人也懂得“森林防火”的重要性；其次，要求每位学生写一篇“森林防火主题班会活动”心得体会；再次，以“森林防火”主题为专刊，办一期有关森林防火知识内容的黑板报，加大宣传力度。 总之，通过这次主题班会，全班学生对“森林防火”的重要性有了深刻的认识。但是，“森林防火”是一项长期性工作，宣传教育必须常抓不懈，并纳入学校常规教育。相信，通过大家的共同努力，家乡的天会更蓝，山会更青。
Win7系统绕过开机密码的具体操作办法
Win7系统绕过开机密码的具体操作方法 怎么才能绕过系统开机密码？如何不破解密码直接进入加密电脑？下面就给大家介绍Win7系统绕过开机密码的具体操作方法。 第一步： 首先进入windows错误恢复界面，选择启动启动修复（推荐），至于这个怎么进去很关键，这里小编教大家一个方法，就是在Windows启动时，就是启动电脑后显示Windows旗帜登录界面时按下主机的开关机键断电（把握好断电时机是成功与否的关键），人工造成异常关机之后，然后再开机就会出现这样的界面了。 第二步： 在进入“启动修复”界面之后，会自动“正在尝试修复”，这里需要几分钟大家稍等下。 第三步： 在扫描完之后，后弹出【启动修复】小窗口界面，窗口中选择“查看问题详细信息”，接着将滚动条拉下来，找到“如果无法获取联机隐私声明，请脱机阅读我们的隐私声明”点击下方的连接。
第四步： 在弹出【erofflps-记事本】中，点击“文件”选择打开，你也可使用组合键Ctrl+O进行打开。 第五步： 在弹出的【打开】窗口中，打开“计算机”选择C盘—Windows—System32。在窗口下面的“文件类型”选择“所有文件”。
第六步： 选择完“所有文件”类型之后，在列表中找到“Utilman”，右键点“重命名”更改为“Utilman1”，接着继续在列表中找到“cmd”右键点击“重命名”更改为“Utilman”。
第七步： 都改好名字之后，关闭“打开窗口”—“erofflps-记事本”—“启动修复”窗口。接着最后一个窗口注意要点击“取消”不要点击“完成”，电脑将会自动重启。 第八步： 在重启之后，点击登录界面的左下角“小按钮”，将会弹出“cmd”运行与命令。 第九步： 在cmd的窗口中，输入以下操作命令：
承揽合同格式范本
承揽合同格式 签订合同单位：＿＿＿＿＿＿（以下简称甲乙方）签订条款如下： １．产品名称、型号及规格、数量、价格及交货日期等如下表规定： ┌───┬───┬─┬─┬──┬────────┬──────────┐ │产品名│型号规│单│数│单价│总价金额│交货日期及数量│ │称│模│位│量│（元├────────┼─┬─┬─┬──┬─┤ │││││）│十万千百十元角分││││││ ├───┼───┼─┼─┼──┼────────┼─┼─┼─┼──┼─┤ ││││││││││││ ├───┼───┼─┼─┼──┼────────┼─┼─┼─┼──┼─┤ ││││││││││││ ├───┼───┼─┼─┼──┼────────┼─┼─┼─┼──┼─┤ ││││││││││││ ├───┼───┴─┴─┴──┴────────┴─┴─┴─┴──┴─┤ │合计│ 人民币（大写）│ └───┴──────────────────────────────┘ ２．交货办法： （１）交货地点：＿＿＿＿＿＿＿＿＿ （２）运输：由甲代办，但一切运杂费用等由乙负责，甲交运日期即为交货日期。 ３．付款办法：货物交货后，供方随同提单向乙托收或将单据寄交乙方，乙方根据供方单据电汇供方。 ４．验收办法：乙应派员到甲仓库验收，如不能派员验收，甲方即按合同规定产品规格数量代为检验。 ５．附则： （１）合同如有修改须经双方同意，双方另行签订合同。 （２）在执行合同期间，如遇市场情况变化或其他原因乙方须在＿＿＿＿天前通知撤销加工合同，否则按违约处以＿＿＿＿＿＿罚金赔偿对方损失。 （３）本合同须经双方签章并鉴证后生效。
森林防火心得体会
---------------------------------------------------------------范文最新推荐------------------------------------------------------ 森林防火心得体会 森林防火心得体会（一） 为认真做好森林防火工作，有效的预防和控制森林火灾，最大的限度的减少森林火灾损失，有效的保护人民群众生命财产安全。我乡领导高度重视，举办森林防火探讨会，签订森林防火责任书，成立森林防火领导小组。切实把森林防火各项工作规划好、部署好、落实好，杜绝各种森林火灾隐患，做到”宁可千日无火，不可一日不防”.我曾经在防震减灾局实习过，对于做好防灾减灾工作有一些经验。要切实做好森林防火工作要做到以下几点： 宣传为先，加强思想认识。每年各地发生森林火灾给人民群众造成的损失不可计数，而大多数火灾是由于人们对森林火灾的思想认识不够，存在麻痹、侥幸心理，随意烧荒、炼山、祭祖、鸣放鞭炮，成为森林火灾的重要隐患。为扎实做好森林防火工作，加强人民群众的思想认识。必须加大宣传力度，营造防火氛围。充分利用森林防火宣传周、森林防火宣传月等重要活动，在各村、学习、医院等人口密集的地方张贴宣传标语，悬挂宣传横幅，营造防火氛围；开设防火辅导课程，经常召开防火探讨会，交流意见，强化防火思想；利用好网络媒体，采用通俗易懂的方式，在电视定期播放森林防火宣传片，提高防火意识。 加强督查，落实防火措施。要把森林防火工作列入重要议事日程， 1 / 23
积极研究解决各种突出问题，及时掌握各村、各小组森林防火职责的落实情况，做到有部署、有检查、有督促、有落实。加强救援队伍力量，保障工作条件，切实保证森林防火基层管理责任得到全面落实；建立完善森林火灾监督检查和责任追究制度，依法加大对森林防火工作落实情况的督查力度；各部门要严格执行24小时值班制度，确保信息畅通；各村要加强对各分管区域的巡查、监管力度，切实做到有火报火，无火报平安。 完善机制，提高救援能力。森林火灾具有潜在性和突发性，防不胜防，这就要求我们在火灾突然降临时，备有完善的应急机制。首先，健全完善各项森林火灾应急预案体系，进一步增强森林火灾预案的科学性、针对性和可操作性，经常性地开展预案演练，切实提高救援能力；其次，建立火灾应急救援队伍，开展森林火灾相关的培训，完善救援扑火装备，落实好各项准备工作，确保应急救灾的各项工作能在第一时间启动并得到落实。 森林防火，人人有责。宜未雨而绸缪，毋临渴而掘井，我们应时刻保持警惕之心，防患于未然，让家园青山永绿。 森林防火心得体会（二） 进入春季，万物复苏，一片生机盎然，我们物电系和机电系三月二十五这天一起组织了森林防火活动。 我们在这次活动中捡白色垃圾，向去森林公园玩的游人们宣传一些森林防火知识。 其中包括：
森林防火心得体会
森林防火心得体会 我们作为当代大学生更要好好保护的我们的森林自然环境，为我们能够拥有一个美好的明天而努力奋斗。森林防火心得体会范文，小编为你推荐。 范文一：我校森林防火教育工作在上级主管部门的正确指导下，在学校的高度重视下，出色地完成了森林防火教育任务。 森林是人类生存环境不可缺少的组成部分。 保护森林，也就是保护人类自己; 保护森林，造福子孙、有益当代的千秋大业。 然而，森林火灾又是森林最凶恶的敌人。 森林防火具有长期性、艰巨性、复杂性、突发性强、危害大的特点。 作为一名当代大学生我们要做好一是积极宣传、预防; 二是加强对联系村森林防火工作的领导和督导; 三是一旦发生火情，及时组织扑救，做到“打早、打小、打了”，确保我镇森林资源和人民生命财产的安全。 森林防火既是一项重要的“安林”工程，又是一项重要的“安民”工程，我校根据实际我校接到教育局要近期在学校开展森林防火宣传教育活动的通知后，迅速开展了森林防火宣传教育活动。 提出了“预防为主、积极消灭”的方针，及“森林防火，
人人有责”的口号，宣传森林防火，提高森林防火意识是每个公民的光荣义务。 学校建立责任制，由班主任做好对学生的森林防火工作，做到常抓不懈有备无患，同时落实责任追究制。通过检查发现的问题如专室电源线路不规范、有些电器缺乏维修、有些电源安装不规范、用线不合格、有的没有安装线盒容易造成用电不安全甚至引发火灾。 检查过程中对有关部门有些容易发生火灾隐患部位工作组都通知有关人员引起重视，不能有侥幸和半点疏忽，否则会造成不可弥补的损失和终身遗憾。 同时将检查结果向校长做了汇报。 校长对全部隐患当即责成有关人员加以整改彻底消除火灾隐患。 通过活动，使学生充分认识到“森林防火，人人有责”的深刻含义，大家纷纷表示，本次活动很有意义，不仅学到了森林防火知识，还学到了做为社会的一分子，有责任从自身做起，从身边做起，做一名优秀的好青年。 范文二：进入春季，万物复苏，一片生机盎然，我们物电系和机电系三月二十五这天一起组织了森林防火活动。 我们在这次活动中捡白色垃圾，向去森林公园玩的游人们宣传一些森林防火识。 其中包括：1、人人树立“森林防火”意识。无论是进
森林防火心得体会精选5篇600字
森林防火心得体会精选5篇600字 森林防火心得体会1 森林，是人类最亲密的朋友。它有很多的用处，可以阻挡风沙，净化空气，吸收二氧化碳，避免水土流失。据记载，一亩阔叶林在夏天能蒸发十六千克水分，可以湿润空气，所以，森林对人类好处多多。 但是，造林育林却是非常的不容易。一棵种子从长成小树，再长成参天大树，其中不知要经历多少风风风雨雨，再播种，再长大……多少年，才能构成一片延绵的森林。可是，森林火灾却成了威胁自然森林的罪魁祸首。 火是可怕的，只要一点燃草木，就会随意四处漫延。开始是火星，烧开后，就串成火苗，直至熊熊大火。所到之处，树木、村庄、房屋都被烧个精光，即使火扑灭了，但原来绿色的海洋，却已化成灰烬! 所以，森林火灾是森林最危险的敌人，也是林业最可怕的灾害，它会给森林带来毁灭性的后果。它不只是烧毁成片的森林，伤害林内的动物，而且还降低森林的更新能力，引起土壤的贫瘠和破坏森林涵养水源的作用，甚而导致生态环境失去平衡。因此，我们要慎重用火，避免森林发生火灾。
大自然是和谐的，只要处处小心，它就都能给我们带来益处。春天，我们向往百花争艳;夏天，我们向往绿树成荫;秋天，我们向往瓜果飘香;冬天，我们向往千山一绿。绿色是我们最向往的。让我们一起挽起手来，为森林防火工作添砖加瓦，一起保护好森林吧! 森林防火心得体会2 森林是我们的乐园，是动物们的家园，是制造空气的唯一机械。森林非常重要，正因为有了森林，我们的地球才有生机。 森林在我们的生活中扮演着至关重要的角色。首先，森林有“地球之肺”的美称，它能大口地吸收二氧化碳，不断制造人类和其他动物所需的氧气，净化空气;其次，森林能阻止强台风、山洪、泥石流等自然灾害，减少自然灾害给人类带来的损失;再次，森林是动物们赖以生存的家园，失去森林，动物们将无家可归，这必然导致动物数量的急剧下降，甚至灭绝，所有生活在森林中的生物都将面临灭顶之灾! 森林“消失”的最大元凶是火灾!森林火灾发生的原因有许多种，总的来说可以分为两种：一种是人为造成的;一种是自然发生的。而其中最主要的原因是前者。 每年各个地方都会发生大大小小多起火灾。导致火灾的原因各种各样，比如每年的清明节，人们在祭拜祖先时点香烛、燃放
小度写范文承揽合同范本3篇模板
承揽合同范本3篇 在承揽合同中，完成工作并交付工作成果的一方为承揽人;接受工作成果并支付报酬的一方称为定作人。以下是第一范文网小编为大家精心准备的：3篇承揽合同范本。欢迎参考阅读! 承揽合同范本一 经甲乙双方协商一致，签订本合同，共同信守。 一、甲方提供原料情况： 品(材料)名： 规格型号： 单位： 数量： 单价： 金额： 交货日期： 超欠幅度%： 供应办法： 二、乙方加工产品的义务 1. 质量标准： 2. 质量检验及验收办法： 3. 包装要求及费用负担： 4. 交货(运输)办法及地点： 5. 货款共计人民币(大写)：
6. 结算办法及期限： 7. 其他： 三、违约责任： 第一点：甲方的违约责任 (1)变更产品品种、质量或包装的规格给乙方造成损失时，应负责赔偿乙方损失。 (2)中途退货的，偿付乙方以退货部分货款总值%的违约金。 (3)自提产品未按规定日期提货的，每延期一天，应偿付乙方以延期提货部分货款总值千分之的违约金。 (4)未按合同规定时间和要求提供原材料、技术资料、包装物的，除交货日期予以顺延外，每日应偿付乙方顺延交货产品总值千分之一的违约金。 (5)未按合同规定日期付款的，每延期一天，应偿付乙方以延期付款总值千分之一的违约金。 (6)实行送货或代运的产品无故拒绝接货的，应承担因而造成的损失并付给运输部门违约金。 (7)错填到货地点或接货人的，应承担因此造成的损失。 (8)其他。 第二点：乙方承担的违约责任 (1)产品、花色、品种、规格、质量、包装不符合合同规定，甲方同意收货的，按质论价;甲方不同意收货的，乙方应包修、包退、包换，并承担因此造成的损失。 (2)未按合同规定的数量交货，少交而甲方仍然需要的，应照数补交;不需要的，可以退货，并承担损失;不能交货的，应偿付甲方以不能交货的货款总值%的违
森林防火作文心得体会
森林防火作文心得体会 篇一 为有效预防和扑救森林火灾，保护本镇森林资源和人 民生命财产安全，根据上级防火要求，结合实际我校组织了 一次关于《森林防火安全意识》的宣传活动，并由各班主任 负责上一堂以“森林防火，人人有责”为主题的森林防火知 识班会课，对本班学生进行一次主题教育，加强学生的意识，并努力通过活动，化成内在品质。 我校森林防火教育工作在上级主管部门的正确指导下， 在学校的高度重视下，出色地完成了森林防火教育任务。森 林是人类生存环境不可缺少的组成部分。保护森林，也就是 保护人类自己;保护森林，造福子孙、有益当代的千秋大业。然而，森林火灾又是森林最凶恶的敌人。森林防火具有长期 性、艰巨性、复杂性、突发性强、危害大的特点。 作为一名当代大学生我们要做好一是积极宣传、预防;二是加强对联系村森林防火工作的领导和督导;三是一旦发生火情，及时组织扑救，做到“打早、打小、打了”，确保我镇森林资源和人民生命财产的安全。 森林防火既是一项重要的“安林”工程，又是一项重 要的“安民”工程，我校根据实际我校接到教育局要近期在 学校开展森林防火宣传教育活动的通知后，迅速开展了森林 防火宣传教育活动。提出了“预防为主、积极消灭”的方针，
及“森林防火，人人有责”的口号，宣传森林防火，提高森 林防火意识是每个公民的光荣义务。 学校建立责任制，由班主任做好对学生的森林防火工 作，做到常抓不懈有备无患，同时落实责任追究制。通过检 查发现的问题如专室电源线路不规范、有些电器缺乏维修、 有些电源安装不规范、用线不合格、有的没有安装线盒容易 造成用电不安全甚至引发火灾。检查过程中对有关部门有些 容易发生火灾隐患部位工作组都通知有关人员引起重视，不 能有侥幸和半点疏忽，否则会造成不可弥补的损失和终身遗 憾。同时将检查结果向校长做了汇报。校长对全部隐患当即 责成有关人员加以整改彻底消除火灾隐患。 通过活动，使学生充分认识到“森林防火，人人有责”的深刻含义，大家纷纷表示，本次活动很有意义，不仅学到 了森林防火知识，还学到了做为社会的一分子，有责任从自 身做起，从身边做起，做一名优秀的好青年。 篇二 进入春季，万物复苏，一片生机盎然，我们物电系和 机电系三月二十五这天一起组织了森林防火活动。 我们在这次活动中捡白色垃圾，向去森林公园玩的游 人们宣传一些森林防火识。 其中包括：1、人人树立“森林防火”意识。无论是进 入林区从事垦荒、采集、采矿等生产性活动，还是进入林区
承揽合同格式范本
承揽合同 签订日期：__________ 年_____ 月 _____ 日 承揽方（全称）：_____________________________ 定作方（全称）：_____________________________ 经双方协商，签订本合同，以资共同信守。 1?品名、规格、数量、价格、交提货日期： 2.质量标准、验收方法及地点：______________________________________ 3.原材料来源及互禾寸方法：___________________________________ 4?交（收）货方法、地点及运杂费负担：________________________________________ 5.货款结算时间及方法：______________________________________ 6.包装要求及包装物回收办法、费用负担：_________________________________ 7.违约责任：____________________________________ 8.其他：___________________________________
9 .不可抗力 ___________________________________ 10?本合同自签订之日起，双方盖章签字后生效。 11?本合同在有效期内任何一方违约，双方都有权向仲裁机关提出书面申诉，要求调解、仲裁处理。 12?本合同正本两份，双方各执一份； 13.本合同有效期自年月日至年月日止 营业执照号码______________________ 供方：（盖章） 负责人：____________________ 代表：______________________ （签字）开户银行：__________________________ 帐号：：__________________________ 电话号码：__________________ 住址：______________________________ 营业执照号码______________________ 需方：（盖章） 负责人：____________________ 代表：（签字）_____________________ 开户银行：：_______________________ 帐号：：__________________________ 电话号码：__________________ 住址：_____________________________
森林防火的心得体会
森林防火的心得体会 篇一：森林防火主题班会总结 六年级“森林防火主题班会”活动总结 森林是人类的一种宝贵的物质财富，是再生的自然资源。预防森林火灾是当前学校教育工作的一项重任。为了落实好学校安排的“森林防火”知识宣传教育活动，XX年3月28日，我六年级班在班主任的组织、班委会的积极配合下，成功开展了“六年级班‘森林防火’主题班会活动”。这次主题班会，内容主要是学习“森林防火”知识问答，围绕“针对森林火灾，小学生能做什么”、“如何预防‘森林火灾’”等问题进行讨论。现把本次主题班会活动开展情况总结如下： 一、大力宣传“森林防火”知识，使学生深受教育 本次主题班会，带领学生学习了“森林防火知识问答”，全班学生认真听讲，深受教育。懂得了什么叫做“森林火灾”，当发现火情后应该立即向当地人民政府或森林防火指挥部报告或拨打119、110报警电话。并迅速向安全地带转移。知道了老人、妇女、中小学生、儿童及身残体弱者不能上山扑救森林火灾，以及进入林区“五不准”：不准在林区内乱扔烟蒂、火柴梗；不准在林区内燃放爆竹；不准在林区内烧火驱兽、烧蜂；不准在林区内烧火取暖、烧烤食物；不准在林区内玩火??等“森林防火”知识。 二、深入讨论，引导言行
在班长的主持下，全班学生围绕“小学生能够为‘森林防火’做什么”这一话题展开了激烈的讨论。讨论中，有的学生认为，我们小学生虽然不能上山参加扑救森林火灾，但我们可以为预防森林火灾贡 献出自己的力量。比如：自己以身示范不在山上及林区玩火；对于在林区玩火及用火的行为要加以制止，不能制止的要尽快告诉大人制止或向政府报告；告诉父母亲不要随便在野外烧荒，以防引起火灾；清明节来临，劝戒家人上山扫墓不要烧香烧纸、烧放鞭炮，用其它方式代替。通过大家的讨论交流，全班学生都表示愿意用自己的言行，为“森林防火”这项工作做出自己的贡献。 三、活动延伸，巩固成果 为了使本次主题班会讨论结果得以实施，首先，要求每位学生放学回家后，把所了解到的“森林防火”知识向身边的亲人作宣传，使家人也懂得“森林防火”的重要性；其次，要求每位学生写一篇“森林防火主题班会活动”心得体会；再次，以“森林防火”主题为专刊，办一期有关森林防火知识内容的黑板报，加大宣传力度。 总之，通过这次主题班会，全班学生对“森林防火”的重要性有了深刻的认识。但是，“森林防火”是一项长期性工作，宣传教育必须常抓不懈，并纳入学校常规教育。相信，通过大家的共同努力，家乡的天会更蓝，山会更青。
承揽合同模板(合同范本)
承揽合同模板(合同范本) Effectively restrain the parties’ actions and ensure that the legitimate rights and interests of the state, collectives and individuals are not harmed ( 合同范本 ) 甲方：______________________ 乙方：______________________ 日期：_______年_____月_____日 编号：MZ-HT-071978
承揽合同模板(合同范本) 签订日期：________经甲乙双方协商，签订本合同，共同信守。货款共计人民币（大写）： 1.质量标准：___________ 2.交货（运输）办法及地点：________ 3.质量检验及验收办法：_________ 4.包装要求及费用负担：__________ 5.结算办法及期限：_____________ 6.原材料供应办法：____________ 7.其他：_______________ 违约责任： 第一点：甲方承担 （1）变更产品品种、质量或包装的规格给乙方造成损失时，应
偿付乙方实际损失____ （2）中途退货的，偿储乙方以退货部分货款总值____的违约金。 （3）自提产品未按规定日期提货的，每延期一天，应偿付乙方以延期提货部分货款总值千分之___的违约金。 （4）未按合同规定时间和要求提供原材料、技术资料、包装物的，除交货日期予以顺延外，每日应偿付乙方顺延交货产品总值千分之一的违约金。 （5）未按合同规定日期付款的，每延期一天，应偿付乙方以延期付款总值千分之一的违约金。 （6）实行送货或代运的产品无故拒绝接货的，应承担因而造成的损失并付给运输部门违约金。 （7）错填到货地点或接货人的，应承担因此造成的损失。 （8）其他___________ 第二点：乙方承担 （1）产品、花色、品种、规格、质量、包装不符合合同规定，甲方同意收货的，按质论价；甲方不同意收货的，乙方应包修、包
2020小学生森林防火心得体会范文5篇
2020小学生森林防火心得体会范文5篇 ----WORD文档，下载后可编辑修改---- 最新小学生森林防火心得体会范文篇一 森林防火，人人有责。“管好星星火，护林靠大家”这几个显然易见的大字经常出现在我们眼前。时刻提醒着我们保护森林，管好火种。有了森林，我们呼吸到了新鲜空气。有了森林，为小动物们创造了一个可爱又温暖的家。还可以调节气温、防风固沙、蓄水防洪......作用还大着呢!可想而知，森林在我们的生活中是多么的重要。“2011年上半年我国全国共接报火灾83983起，死亡749人，受伤359人，直接财产损失11。6亿元，与去年同期相比，起数和损失分别上升15。4%和12。3%，死亡和受伤人数分别增加50人和78人......” 森林火灾不仅能烧死许多树木，降低林分密度，破坏森林结构，同时还引起树种演替，降低森林利用价值，是森林失去森林涵养水源和保持水土的作用，引起水涝、干旱、山洪、泥石流、滑坡、风沙等其他自然灾害发生。如今，为了保护森林，人们又有了新的规定：一、在山上扫墓时禁止烧香烧纸。二、禁止在山上生火、吸烟、燃放鞭炮。 三、教育老人、小孩不随意用火等许多新的规定......一旦森林没了，就会造成山体滑坡，水土流失等一系列的自然灾害。大家都动员起来，积极参与到保护森林的行列中吧! 最新小学生森林防火心得体会范文篇二 森林火灾是森林最危险的敌人，所以我们要把危险到最小。
那作为我们小学生能做些什么?我想应该先从我们自己做起，严格遵守小学生守则，不在野外玩火。并要做好森林防火宣传员的工作，走进各自的村庄，和保护森林的叔叔阿姨门一道，宣传防火的重要性，告诉人们森林防火重在预防。我要向各位叔叔阿姨们呼吁：林防火人人有责。森林防火贵在预防! 森林火灾会给森林带来危害，具有毁灭性的后果。森林火灾不只是烧毁成片的森林，伤害林内的动物，而且还降低了森林的更新能力，引起土壤胡贫瘠肯破坏森林涵养水源作用，甚而导致生态环境失去平衡。尽管当今世界的科学在日新月异地向前发展，但是，人类在制服森林火灾上，却依然未取得长久胡进展。 大家要知道一棵大树可造千万根火柴，可是一根火柴可以烧掉整个森林。 我们可以把一些标语放在森林里，比如“小小的烟头不算大，森林景观它吞下。”“一棵树木十年才成树，一根火柴瞬间可毁树。”“片片绿叶汇成万顷绿洲，星星之火可毁涛涛林海。” 最新小学生森林防火心得体会范文篇三 想必大家对“火”这个名词并不陌生吧!我们的生活时刻需要着它----烧饭做菜时，天黑停电时都少不了它‘但它也是破坏大自然，烧毁森林的杀手。 自我国成立以来最严重的一起火灾便是1987年大兴安岭的那一件。那件事中烧毁了100万亩林地，624万吨粮食，受灾群众共有5万人，受伤人数为126人，直接造成了经济损失为5亿人民币。